F I N A L R E P O R T

HARBOR GENERATING STATION

CLEAN WATER ACT

SECTION 316(b) IMPINGEMENT

MORTALITY AND ENTRAINMENT

CHARACTERIZATION STUDY

Prepared by

MBC Applied Environmental Sciences

Tenera Environmental, Inc.

URS Corporation

for

City of Los Angeles Department of Water and Power

111 N. Hope Street

Los Angeles, California 90012-2607

December 26, 2007
Harbor Generating Station

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TABLE OF CONTENTS

SECTION PAGE

1.0 EXECUTIVE SUMMARY ............................................................................. 1-1

1.1 Entrainment.................................................................................................................1-1

1.2 Source Water...............................................................................................................1-2

1.3 Impingement ...............................................................................................................1-2

1.4 Impact Assessment ......................................................................................................1-3

2.0 INTRODUCTION......................................................................................... 2-1

2.1 Background and Overview...........................................................................................2-1

2.1.1 Section 316(b) of the Clean Water Act ............................................................2-2

2.1.2 Development of the Study Plan .......................................................................2-3

2.1.3 Study Plan Objectives .....................................................................................2-5

2.1.4 Study Plan Approach.......................................................................................2-6

2.2 Report Organization ....................................................................................................2-7

2.3 Contractors and Responsibilities..................................................................................2-7

3.0 DESCRIPTION OF THE GENERATING STATION AND CHARACTERISTICS

OF THE SOURCE WATER BODY.................................................................. 3-1

3.1 Description of the Generating Station...........................................................................3-1

3.2 Description of the Cooling Water Intake System..........................................................3-2

3.2.1 Circulating Water Pump Flows........................................................................3-5

3.3 Environmental Setting .................................................................................................3-6

3.3.1 Physical Description........................................................................................3-6

3.3.1.1 Physical Features................................................................................3-7

3.3.1.2 Temperature and Salinity....................................................................3-8

3.3.1.3 Tides and Currents .............................................................................3-8

3.3.2 Source Water Definition..................................................................................3-9

3.3.2.1 Study Requirements and Rationale .....................................................3-9

3.3.2.2 Methods for Calculating HGS Source Water.....................................3-12

3.3.3 Biological Resources.....................................................................................3-13

3.3.3.1 Habitat Variation..............................................................................3-13

3.3.3.2 Nursery Grounds..............................................................................3-15

3.3.3.3 Fish Diversity...................................................................................3-16

3.3.3.4 Shellfish Diversity............................................................................3-17

3.3.3.5 Protected Species .............................................................................3-17

4.0 COOLINGWATER INTAKE STRUCTURE ENTRAINMENT AND SOURCE

WATER STUDY .......................................................................................... 4-1

4.1 Introduction.................................................................................................................4-1

4.1.1 Discussion of Species to be Analyzed..............................................................4-1

4.1.1.1 Fishes.................................................................................................4-2

4.1.1.2 Shellfishes..........................................................................................4-2

4.1.1.3 Protected Species ...............................................................................4-2

4.2 Historical Data.............................................................................................................4-3
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4.2.1 Summary of Historical Data ............................................................................4-3

4.2.2 Relevance to Current Conditions.....................................................................4-6

4.2.3 QA/QC Procedures and Data Validation..........................................................4-7

4.3 Methods ......................................................................................................................4-7

4.3.1 Field Sampling................................................................................................4-7

4.3.1.1 Cooling-Water Intake System Entrainment Sampling .........................4-7

4.3.1.2 Source Water Sampling......................................................................4-7

4.3.2 Laboratory Analysis........................................................................................4-8

4.3.3 QA/QC Procedures & Data Validation ............................................................4-9

4.3.4 Data Analysis................................................................................................4-10

4.3.4.1 Entrainment Estimates......................................................................4-10

4.3.4.2 Demographic Approaches ................................................................4-11

4.3.4.3 Empirical Transport Model (ETM)....................................................4-14

4.4 Sampling Summary ...................................................................................................4-16

4.5 Results.......................................................................................................................4-17

4.5.1 Cooling Water Intake Structure Entrainment Summary..................................4-17

4.5.1.1 Fishes...............................................................................................4-17

4.5.1.2 Shellfishes........................................................................................4-24

4.5.2 Source Water Summary.................................................................................4-25

4.5.2.1 Fishes...............................................................................................4-25

4.5.2.2 Shellfishes........................................................................................4-29

4.5.3 Results by Species for Cooling Water Intake Structure Entrainment ..............4-30

4.5.3.1 Anchovies (Engraulidae)..................................................................4-30

4.5.3.2 White croaker (Genyonemus lineatus) ..............................................4-40

4.5.3.3 Combtooth blennies (Hypsoblennius spp.)........................................4-50

4.5.3.4 CIQ Goby complex (Clevelandia, Ilypnus, Quietula)........................4-60

4.5.3.5 Yellowfin Goby (Acanthogobius flavimanus) ...................................4-68

4.5.3.6 Bay Goby (Lepidigobius lepidus) .....................................................4-75

5.0 IMPINGEMENT STUDY............................................................................... 5-1

5.1 Introduction.................................................................................................................5-1

5.1.1 Species to be Analyzed....................................................................................5-1

5.2 Historical Data.............................................................................................................5-1

5.2.1 Summary of Historical Data ............................................................................5-1

5.2.2 Relevance to Current Conditions.....................................................................5-2

5.2.3 QA/QC Procedures & Data Validation ............................................................5-2

5.3 Methods ......................................................................................................................5-2

5.3.1 Field Sampling................................................................................................5-3

5.3.2 QA/QC Procedures & Data Validation ............................................................5-4

5.3.3 Data Analysis..................................................................................................5-5

5.4 Sampling Summary .....................................................................................................5-6

5.5 Results.........................................................................................................................5-6

5.5.1 Impingement Results.......................................................................................5-6

5.5.2 Fish Impingement Results by Species............................................................5-17

5.5.2.1 Round stingray (Urobatis halleri).....................................................5-17

5.5.2.2 Black perch (Embiotoca jacksoni) ....................................................5-21

5.5.2.3 Specklefin midshipman (Porichthys myriaster).................................5-26

5.5.2.4 Shiner perch (Cymatogaster aggregata) ...........................................5-30

5.5.2.5 Barred sand bass (Paralabrax nebulifer)...........................................5-34

5.5.2.6 Giant kelpfish (Heterostichus rostratus) ...........................................5-39

5.5.2.7 Northern anchovy (Engraulis mordax)..............................................5-43
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5.5.3 Shellfish Impingement Results by Species.....................................................5-43

5.5.3.1 California spiny lobster (Panulirus interruptus)................................5-44

5.5.3.2 California two-spot octopus (Octopus spp.) ......................................5-49

6.0 IMPACT ASSESSMENT................................................................................ 6-1

6.1 Impact Assessment Overview: Data and Approach ......................................................6-1

6.1.1 CWIS impacts.................................................................................................6-2

6.1.2 Review of IM&E Sampling Approach.............................................................6-2

6.1.3 Approaches for assessment of CWIS impacts..................................................6-4

6.1.3.1 Adverse Environmental Impact (AEI) Standard ..................................6-5

6.1.4 Relating measured impacts to source populations ............................................6-6

6.2 Summary of Entrainment and Impingement Results.....................................................6-9

6.2.1 Taxa Composition...........................................................................................6-9

6.2.1.1 Temporal Occurrence .......................................................................6-14

6.2.2 Combined Analysis and Modeling Results for Selected Species.....................6-14

6.3 Assessment of Taxa by Habitat Type .........................................................................6-17

6.3.1 Background on Oceanographic Setting and Population Trends ......................6-17

6.3.1.1 Habitat Associations and Fisheries ...................................................6-19

6.3.2 Bay and Harbor Habitats...............................................................................6-20

6.3.3 Rocky Reef and Kelp Bed Habitats ...............................................................6-24

6.3.4 Coastal Pelagic Habitats................................................................................6-26

6.3.5 Shelf Habitats................................................................................................6-29

6.3.6 Deep Pelagic Habitats ...................................................................................6-29

6.4 Conclusions and Discussion.......................................................................................6-30

6.4.1 IM&E Losses Relative to 1977 EPA AEI Criteria..........................................6-32

6.4.2 IM&E Losses Relative to Other AEI Criteria.................................................6-33

7.0 LITERATURE CITED.................................................................................. 7-1

APPENDICES

Appendix A. Study Procedures

Appendix B. Model Parameterization

Appendix C. Entrainment Data

Appendix D. Impingement Data

Appendix E. Master Species Lists
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LIST OF TABLES

Table 1.4-1. Summary of HGS entrainment and impingement sampling results and model output

for common fish and shellfish species based on actual CWIS flows in 2006*..................................1-6

Table 1.4-2. Summary of HGS entrainment and impingement sampling results and model output

for common fish and shellfish species based on design CWIS flows in 2006*.................................1-7

Table 1.4-3. Habitat associations for taxa included in assessment of CWIS effects at the HGS. .............1-8

Table 4.2-1. Summary of larval fish and fish egg densities, and annual entrainment mortality

estimates for critical taxa for HGS in 19781979 (from IRC 1981).................................................4-5

Table 4.2-2. Summary of planktonic invertebrate densities and annual entrainment mortality

estimates for critical taxa for HGS in 1978 1979 (from IRC 1981). ...............................................4-6

Table 4.4-1. Entrainment and source water surveys and number of samples collected from January

through December 2006. ..............................................................................................................4-16

Table 4.5-1. Average concentration of larval fishes and fish eggs in entrainment samples collected

at HGS (Station E1) in 2006. ........................................................................................................4-18

Table 4.5-2. Calculated total annual entrainment of larval fishes and fish eggs at HGS in 2006

based on actual and design (maximum) cooling water intake pump flows. ....................................4-20

Table 4.5-3. Average concentration of target shellfish larvae in entrainment samples collected at

HGS (Station E1) in 2006.............................................................................................................4-24

Table 4.5-4. Calculated total annual entrainment of target shellfish larvae at HGS in 2006 based on

actual and design (maximum) cooling water intake pump flows....................................................4-25

Table 4.5-5. Average concentration of larval fishes collected at HGS source water stations in the

Los AngelesLong Beach Harbor Complex (Stations H1H6) in 2006. ........................................4-26

Table 4.5-6. Average concentration of larval target shellfishes in samples collected at HGS source

water stations in Los Angeles-Long Beach Harbor Complex in 2006. ...........................................4-29

Table 4.5-7. Annual landings and revenue for northern anchovy in the Los Angeles region based on

PacFIN data..................................................................................................................................4-33

Table 4.5-8. Stage-specific life history parameters for northern anchovy (Engraulis mordax)

modified from Butler et al. (1993). ...............................................................................................4-36

Table 4.5-9. Survivorship table for adult northern anchovy (Engraulis mordax) from Butler et al.

(1993) showing spawners (Lx) surviving at the start of age interval and numbers of eggs

spawned annually (Mx).................................................................................................................4-37

Table 4.5-10. Results of FH modeling for anchovy larvae based on entrainment estimates

calculated using actual and design (maximum) CWIS flows. ........................................................4-38

Table 4.5-11. Results of AEL modeling for northern anchovy larvae based on entrainment estimates

calculated using actual and design (maximum) CWIS flows. ........................................................4-39

Table 4.5-12. ETM data and results for northern anchovy larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3. ...........4-40

Table 4.5-13. Annual landings and revenue for white croaker in the Los Angeles region based on

PacFIN data..................................................................................................................................4-43
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Table 4.5-14. Results of FH modeling for white croaker eggs based on entrainment estimates

calculated using actual and design (maximum) CWIS flows. ........................................................4-48

Table 4.5-15. ETM data and results for white croaker larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3. ...........4-49

Table 4.5-16. ETM data and results for unidentified croaker larvae based upon actual and design

(maximum) CWIS flow volumes and fixed source water volume of 431,694,503 m3.....................4-50

Table 4.5-17. Survivorship table for adult combtooth blenny from data in Stephens (1969) showing

spawners (Lx) surviving to the age interval and numbers of eggs spawned annually (Mx). .............4-56

Table 4.5-18. Results of FH modeling for combtooth blenny larvae based on entrainment estimates

calculated using actual and design (maximum) CWIS flows. ........................................................4-57

Table 4.5-19. Results of AEL modeling for combtooth blenny larvae based on entrainment

estimates calculated using actual and design CWIS flows. ............................................................4-58

Table 4.5-20. ETM data and results for combtooth blenny larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3. ...........4-59

Table 4.5-21. Total lifetime fecundity estimates for three goby species based on a life table in

Brothers (1975). ...........................................................................................................................4-66

Table 4.5-22. Results of FH modeling for CIQ goby complex larvae based on entrainment

estimates calculated using actual and design (maximum) CWIS flows. .........................................4-66

Table 4.5-23. Results of AEL modeling for CIQ goby complex larvae based on entrainment

estimates calculated using actual and design (maximum) CWIS flows. .........................................4-67

Table 4.5-24. ETM data and results for CIQ goby larvae based upon actual and design (maximum)

CWIS flow volumes using the fixed source water volume of 431,694,503 m3. ..............................4-68

Table 4.5-25. Results of FH modeling for yellowfin goby larvae based on entrainment estimates

calculated using actual and design (maximum) CWIS flows. ........................................................4-74

Table 4.5-26. ETM data and results for yellowfin goby larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3. ...........4-75

Table 4.5-27. ETM data and results for bay goby larvae based upon actual and design (maximum)

CWIS flow volumes using the fixed source water volume of 431,694,503 m3. ..............................4-81

Table 5.5-1. Summary of HGS fish impingement from January through December 2006, and

estimated annual impingement based on actual cooling water flows................................................5-7

Table 5.5-2. Estimated annual fish impingement at the HGS from January through December 2006

based on both actual and design (maximum) cooling water flows....................................................5-8

Table 5.5-3. Summary of HGS invertebrate impingement from January through December 2006,

and estimated annual impingement based on actual cooling water flows. ........................................5-9

Table 5.5-4. Estimated annual invertebrate impingement at the HGS from January through

December 2006 based on both actual and design (maximum) cooling water flows. .......................5-11

Table 5.5-5. Annual landings and revenue for surfperches in the Los Angeles region based on

PacFIN data..................................................................................................................................5-23

Table 5.5-6. Annual recreational landings (numbers) of barred sand bass in southern California

based on RecFIN data...................................................................................................................5-36

Table 5.5-7. Annual landings and revenue for California spiny lobster in the Los Angeles region

based on PacFIN data. ..................................................................................................................5-45
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Table 6.1-1. Habitat associations for taxa included in assessment of CWIS effects at the HGS.

Primary habitat in bold, upper case and secondary habitat in lower case..........................................6-9

Table 6.2-1. Rank and estimated annual entrainment of common fish larvae, fish eggs and target

shellfish larvae at HGS in 2006.....................................................................................................6-11

Table 6.2-2. Rank and estimated annual impingement of top ten most common fish taxa at HGS in

2006 by estimated abundance and weight for actual and design flows. ..........................................6-12

Table 6.2-3. Rank and estimated annual impingement of top ten most common invertebrate taxa at

HGS in 2006 by estimated abundance and weight for actual and design flows...............................6-13

Table 6.2-4. Summary of HGS entrainment and impingement sampling results and model output

for common fish and shellfish species based on actual CWIS flows in 2006. Model estimates

indicate whether the number was based on eggs (E), larvae (L), or both combined (C)..................6-15

Table 6.2-5. Summary of HGS entrainment and impingement sampling results and model output

for common fish and shellfish species based on design CWIS flows in 2006. Model estimates

indicate whether the number was based on eggs (E), larvae (L), or both combined (C)..................6-16

Table 6.3-1. Percent of larvae entrained (abundance) or adults/juveniles impinged (biomass)

associated with general habitat types and fisheries. .......................................................................6-19

Table 6.4-1. Comparison of larval fish densities and total annual entrainment at HGS from studies

in 19781979 and studies in 2006.................................................................................................6-31

Table 6.4-2. Fish and shellfish species under NMFS federal management or with CDFG special

status entrained and/or impinged at HGS in 2006 based on actual flow volumes. ..........................6-33
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LIST OF FIGURES

Figure 3.1-1. Location of the LADWP Harbor Generating Station (HGS)..............................................3-1

Figure 3.2-1. General configuration of LADWP HGS. ..........................................................................3-3

Figure 3.2-2. Diagram of HGS intake structure at Slip 5 in ILAH..........................................................3-3

Figure 3.2-3. Plan view and cross section of HGS intake screenhouse. ..................................................3-4

Figure 3.2-4. Daily cooling water flow volumes at the HGS from January 2006 through January

2007...............................................................................................................................................3-5

Figure 3.3-1. Aerial view (looking south) of Harbor Generating Station and the vicinity of Los

Angeles and Long Beach Harbors...................................................................................................3-7

Figure 3.3-2. Current patterns in Los Angeles and Long Beach Harbors predicted by a depthaveraged two-dimensional hydrodynamic model developed by the USACE. .................................3-11

Figure 3.3-3. HGS source water boundaries and bathymetry. ..............................................................3-14

Figure 3.3-4. HGS intake structure near East Basin Channel in Inner Los Angeles Harbor...................3-15

Figure 4.2-1. Locations of entrainment and near-field (top) and far-field (bottom) plankton

sampling stations in IRC (1981) study of HGS................................................................................4-4

Figure 4.3-1. Locations of the HGS entrainment and source water sampling stations.............................4-8

Figure 4.5-1. Mean concentration (#/1,000 m3[264,172 gal] wide bars) and standard deviation

(narrow bars) of all larval fishes collected at HGS entrainment Station E1 during 2006.................4-22

Figure 4.5-2. Mean concentration (#/1,000 m3[264,172 gal] wide bars) and standard deviation

(narrow bars) of all fish eggs collected at HGS entrainment Station E1 during 2006......................4-22

Figure 4.5-3. Mean concentration (#/1.0 m3[264 gal]) of all fish larvae at entrainment Station E1

during night (Cycle 3) and day (Cycle 1) sampling. ......................................................................4-23

Figure 4.5-4. Mean concentration (#/1.0 m3[264 gal]) of all fish eggs at entrainment Station E1

during night (Cycle 3) and day (Cycle 1) sampling. ......................................................................4-23

Figure 4.5-5. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of all larval fishes collected at HGS source water stations during 2006....................4-28

Figure 4.5-6. Mean concentration (#/1.0 m3[264 gal]) of all fish larvae at HGS source water

stations during night (Cycle 3) and day (Cycle 1) sampling...........................................................4-28

Figure 4.5-7. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of anchovy larvae collected at HGS entrainment Station E1 during 2006.................4-34

Figure 4.5-8. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of anchovy larvae collected at HGS source water stations during 2006. ...................4-34

Figure 4.5-9. Mean concentration (#/1.0 m3[264 gal]) of anchovy larvae at entrainment Station E1

during night (Cycle 3) and day (Cycle 1) sampling. ......................................................................4-35

Figure 4.5-10. Length (mm) frequency distribution for larval anchovy collected at entrainment

Station E1.....................................................................................................................................4-35

Figure 4.5-11. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of white croaker larvae collected at HGS entrainment Station E1 during 2006.........4-44
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Figure 4.5-12. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of white croaker larvae collected at HGS source water stations during 2006. ...........4-44

Figure 4.5-13. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of unidentified croaker larvae collected at HGS entrainment Station E1 during

2006.............................................................................................................................................4-45

Figure 4.5-14. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of unidentified croaker larvae collected at HGS source water stations during

2006.............................................................................................................................................4-45

Figure 4.5-15. Mean concentration (#/1.0 m3[264 gal]) of white croaker larvae at entrainment

Station E1 during night (Cycle 3) and day (Cycle 1) sampling. .....................................................4-46

Figure 4.5-16. Mean concentration (#/1.0 m3[264 gal]) of unidentified croaker at entrainment

Station E1 during night (Cycle 3) and day (Cycle 1) sampling. .....................................................4-46

Figure 4.5-17. Length (mm) frequency distribution for larval white croaker collected at entrainment

Station E1.....................................................................................................................................4-47

Figure 4.5-18. Length (mm) frequency distribution for larval unidentified croakers collected at

entrainment Station E1. ................................................................................................................4-47

Figure 4.5-19. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of combtooth blenny larvae collected at HGS entrainment Station E1 during

2006.............................................................................................................................................4-54

Figure 4.5-20. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of combtooth blenny larvae collected at HGS source water stations during 2006. ....4-54

Figure 4.5-21. Mean concentration (#/1.0 m3[264 gal]) of combtooth blenny larvae at entrainment

Station E1 during night (Cycle 3) and day (Cycle 1) sampling. .....................................................4-55

Figure 4.5-22. Length (mm) frequency distribution for combtooth blenny larvae collected at

entrainment Station E1. ................................................................................................................4-55

Figure 4.5-23. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of unidentified goby larvae (CIQ gobies) collected at HGS entrainment Station

E1 during 2006.............................................................................................................................4-63

Figure 4.5-24. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of unidentified goby larvae (CIQ gobies) collected at HGS source water stations

during 2006..................................................................................................................................4-63

Figure 4.5-25. Mean concentration (#/1.0 m3[264 gal]) of unidentified goby larvae at entrainment

Station E1 during night (Cycle 3) and day (Cycle 1) sampling. .....................................................4-64

Figure 4.5-26. Length (mm) frequency distribution for unidentified goby larvae collected at

entrainment Station E1. ................................................................................................................4-64

Figure 4.5-27. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of yellowfin goby larvae collected at HGS entrainment Station E1 during 2006.......4-71

Figure 4.5-28. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of yellowfin goby larvae collected at HGS source water stations during 2006..........4-71

Figure 4.5-29. Mean concentration (#/1.0 m3[264 gal]) of yellowfin goby larvae at entrainment

Station E1 during night (Cycle 3) and day (Cycle 1) sampling. .....................................................4-72
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Figure 4.5-30. Length (mm) frequency distribution for yellowfin goby larvae collected at

entrainment Station E1. ................................................................................................................4-72

Figure 4.5-31. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of bay goby larvae collected at HGS entrainment Station E1 during 2006................4-78

Figure 4.5-32. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of bay goby larvae collected at HGS source water stations during 2006...................4-78

Figure 4.5-33. Mean concentration (#/1.0 m3[264 gal]) of bay goby larvae at entrainment Station

E1 during night (Cycle 3) and day (Cycle 1) sampling. .................................................................4-79

Figure 4.5-34. Length (mm) frequency distribution for bay goby larvae collected at entrainment

Station E1.....................................................................................................................................4-79

Figure 5.5-1. Mean concentration (#/1,000,000 m3[264.2 million gallons] –wide bars) and

standard error (narrow bars) of fishes collected in HGS impingement samples during 2006. .........5-13

Figure 5.5-2. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of fishes collected in HGS impingement samples during 2006.................................5-13

Figure 5.5-3. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of invertebrates collected in HGS impingement samples during 2006..............5-14

Figure 5.5-4. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of invertebrates collected in HGS impingement samples during 2006......................5-14

Figure 5.5-5. Mean concentration (#/1,000,000 m3[264.2 million gal]) of fishes in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling. .........................................................5-15

Figure 5.5-6. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of fishes in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling. .........................................................5-15

Figure 5.5-7. Mean concentration (#/1,000,000 m3[264.2 million gal]) of invertebrates in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ....................................5-16

Figure 5.5-8. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of invertebrates in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling. .........................................................5-16

Figure 5.5-9. Mean concentration (#/1,000,000 m3[264.2 million gal]) and standard error of round

stingray collected in HGS impingement samples during 2006. ......................................................5-19

Figure 5.5-10. Mean biomass (kg/1,000,000 m3[264.2 million gal]) and standard error of round

stingray collected in HGS impingement samples during 2006. ......................................................5-19

Figure 5.5-11. Mean concentration (#/1,000,000 m3[264.2 million gal]) of round stingray in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ....................................5-20

Figure 5.5-12. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of round stingray in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ....................................5-20

Figure 5.5-13. Disc width (mm) frequency distribution for round stingray collected in impingement

samples. .......................................................................................................................................5-21

Figure 5.5-14. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of black perch collected in HGS impingement samples during 2006................5-24

Figure 5.5-15. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of black perch collected in HGS impingement samples during 2006. .......................5-24

Figure 5.5-16. Mean concentration (#/1,000,000 m3[264.2 million gal]) of black perch in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ....................................5-25
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Figure 5.5-17. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of black perch in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling. .........................................................5-25

Figure 5.5-18. Length (mm) frequency distribution for black perch collected in impingement

samples. .......................................................................................................................................5-26

Figure 5.5-19. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of specklefin midshipman collected in HGS impingement samples during

2006.............................................................................................................................................5-28

Figure 5.5-20. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of specklefin midshipman collected in HGS impingement samples during 2006. .....5-28

Figure 5.5-21. Mean concentration (#/1,000,000 m3[264.2 million gal]) of specklefin midshipman

in impingement samples during night (Cycle 4) and day (Cycle 2) sampling. ................................5-29

Figure 5.5-22. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of specklefin midshipman in

impingement samples during night (Cycle 4) and day (Cycle 2) sampling.....................................5-29

Figure 5.5-23. Length (mm) frequency distribution for specklefin midshipman collected in

impingement samples. ..................................................................................................................5-30

Figure 5.5-24. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of shiner perch collected in HGS impingement samples during 2006. .............5-32

Figure 5.5-25. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of shiner perch collected in HGS impingement samples during 2006.......................5-32

Figure 5.5-26. Mean concentration (#/1,000,000 m3[264.2 million gal]) of shiner perch in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ....................................5-33

Figure 5.5-27. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of shiner perch in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling. .........................................................5-33

Figure 5.5-28. Length (mm) frequency distribution for shiner perch collected in impingement

samples. .......................................................................................................................................5-34

Figure 5.5-29. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of barred sand bass collected in HGS impingement samples during 2006. .......5-37

Figure 5.5-30. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of barred sand bass collected in HGS impingement samples during 2006. ...............5-37

Figure 5.5-31. Mean concentration (#/1,000,000 m3[264.2 million gal]) of barred sand bass in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ....................................5-38

Figure 5.5-32. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of barred sand bass in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ....................................5-38

Figure 5.5-33. Length (mm) frequency distribution for barred sand bass collected in impingement

samples. .......................................................................................................................................5-39

Figure 5.5-34. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of giant kelpfish collected in HGS impingement samples during 2006. ...........5-41

Figure 5.5-35. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of giant kelpfish collected in HGS impingement samples during 2006.....................5-41

Figure 5.5-36. Mean concentration (#/1,000,000 m3[264.2 million gal]) of giant kelpfish in

impingement samples during night (Cycle 4) and day (Cycle 2) sampling. ....................................5-42
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Figure 5.5-37. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of giant kelpfish in

impingement samples during night (Cycle 4) and day (Cycle 2) sampling. ....................................5-42

Figure 5.5-38. Length (mm) frequency distribution for giant kelpfish collected in impingement

samples. .......................................................................................................................................5-43

Figure 5.5-39. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of California spiny lobster collected in HGS impingement samples during

2006.............................................................................................................................................5-47

Figure 5.5-40. Mean biomass (kg / 1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of California spiny lobster collected in HGS impingement samples during 2006......5-47

Figure 5.5-41. Mean concentration (#/1,000,000 m3[264.2 million gal]) of California spiny lobster

in impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ................................5-48

Figure 5.5-42. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of California spiny lobster in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ....................................5-48

Figure 5.5-43. Length (mm) frequency distribution for California spiny lobster collected in

impingement samples. ..................................................................................................................5-49

Figure 5.5-44. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of California two-spot octopus collected in HGS impingement samples

during 2006..................................................................................................................................5-51

Figure 5.5-45. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of California two-spot octopus collected in HGS impingement samples during

2006.............................................................................................................................................5-51

Figure 5.5-46. Mean concentration (#/1,000,000 m3[264.2 million gal]) of California two-spot

octopus in impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ...................5-52

Figure 5.5-47. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of California two-spot octopus

in impingement samples during night (Cycle 3) and day (Cycle 1) sampling. ................................5-52

Figure 5.5-48. Arm spread (mm AS) length frequency distribution for California two-spot octopus

collected in impingement samples. ...............................................................................................5-53

Figure 6.1-1. Marine habitat types in California (from Allen and Pondella [2006b]). .............................6-8

Figure 6.3-1. Sea surface temperature anomalies for Newport Pier, California. Values are ± the

long-term average (19252006)....................................................................................................6-18

Figure 6.3-2. Abundance per minute fished for fish collected in HGS and LBGS NPDES

monitoring otter trawl surveys, 1980-2006. Northern anchovy was excluded from this analysis. ...6-23

Figure 6.3-3. White croaker fishery and population trends...................................................................6-28
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LIST OFACRONYMS AND ABBREVIATIONS

ADCP acoustic Doppler current profiler

AEL adult equivalent loss

BMPs best management practices

BTA best technology available

CDFG California Department of Fish and Game

CDS Comprehensive Demonstration Study

CEQA California Environmental Quality Act

cfs cubic feet per second

CIQ Clevelandia, Ilypnus, Quietula

cm centimeters

cm/s centimeters per second

CPFV commercial passenger fishing vessels

CWA Clean Water Act

CWIS cooling water intake system

DML dorsal mantle length

EAM equivalent adult model

EFH Essential Fish Habitat

El. Elevation (relative to mean sea level)

EPA United States Environmental Protection Agency

ETM Empirical Transport Model

FH fecundity hindcasting

FMP Fishery Management Plan

ft feet

ft/s feet per second

g grams

gal gallons

GIS Geographic Information System

gpm gallons per minute

HGS Harbor Generating Station

ILAH Inner Los Angeles Harbor

IM&E Impingement Mortality and Entrainment

in inches

kg kilograms

km kilometers

LADWP Los Angeles Department of Water and Power

LARWQCB Los Angeles Regional Water Quality Control Board

lbs pounds

m meter

m

3

cubic meters

mgd million gallons per day

ml milliliter

ML mantle length

MLLW mean lower low water

mm millimeters

m/s meters per second

MSL mean sea level

MW megawatts

NL notochord length

NMFS National Marine Fisheries Service
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LIST OF ACRONYMS AND ABBREVIATIONS (CONTINUED)

NOAA National Oceanic and Atmospheric Administration

NPDES National Pollutant Discharge Elimination System

PacFIN Pacific Fisheries Information Network

PDO Pacific Decadal Oscillation

PE proportional entrainment

PFMC Pacific Fisheries Management Council

PIC Proposal for Information Collection

PM probability of mortality

POLA Port of Los Angeles

PSU practical salinity units

QA/QC Quality Assurance/Quality Control

QC quality control

RecFIN Recreational Fisheries Information Network

rpm revolutions per minute

RWQCB California Regional Water Quality Control Board

SCB Southern California Bight

SL standard length

SWRCB State Water Resources Control Board

TLF total lifetime fecundity

USFWS U.S. Fish and Wildlife Service

YOY young-of-the-year
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1.0 EX E CU TI V E SUM M A RY

This report presents data from in-plant and offshore field surveys performed for the Los Angeles

Department of Water andPower’sHarborGeneratingStation(HGS)ImpingementMortalityand

Entrainment (IM&E) Characterization Study. This study was designed and performed to comply with the

United States Environmental Protection Agency (EPA) 2004 316(b) Phase II regulations. Originally,

results from the study were to be used in determining impingement mortality and entrainment from oncethrough cooling, evaluating potential fish protection technologies and operational measures at the facility,

scaling potential restoration projects, and/or evaluating the cost-benefits in reducing IM&E at the facility.

However, in March 2007, the EPA suspended the Phase II regulations and directed administrators to

determine compliance with 316(b) on a best professional judgment (BPJ) basis.

PriortothePhaseIIRule,316(b)decisionswerebasedonprecedentsfromcaselawandonEPA’s(1977)

draft“GuidanceforEvaluatingtheAdverseImpactofCoolingWaterIntakeStructuresontheAquatic

Environment: Section 316(b) P.L. 92-500.”AsSection316(b) requires that an intake technology employs

the‘besttechnologyavailable’(BTA)forminimizing‘adverseenvironmentalimpacts’(AEI),thereare

two steps in determining compliance:

1. Whether or not an AEI is caused by the intake and, if so,

2. What intake structure represents BTA to minimize that impact?

The usual approach for a 316(b) demonstration would be to only consider the question of BTA if a

determination has been made that a facility is causing an AEI. The purpose of this report is to assess the

potential for AEI from the operation of the HGS cooling water intake system (CWIS). The two primary

impacts of a once-through power plant CWIS are impingement of juvenile and adult life stages of fishes,

shellfishes, and other organisms on screens at the openings to the CWIS, and entrainment of smaller

organisms, usually larval forms of fishes and shellfishes, and other forms of plankton, into the CWIS. The

information in this report will also be used to assist in the renewal of the National Pollutant Discharge

Elimination System (NPDES) permit for the HGS. This report provides a characterization of the fish and

invertebrate species subject to entrainment and impingement at the HGS, information on the current

levels of IM&E at the HGS, and a discussion on the level of significance of the IM&E losses.

1.1 ENTRAINMENT

The composition and abundance of ichthyoplankton and shellfish larvae entrained at HGS were

determined by sampling in the immediate proximity of the cooling water intake every two weeks from

January 2006 to January 2007. A total of 8,692 entrainable fish larvae from 45 separate taxonomic

categories was collected during the 26 entrainment surveys. The most abundant larval fish taxon in the

samples was unidentified gobies, which comprised 49.3% of the total larvae collected, followed by

yellowfin goby (25.2%) and white croaker (12.0%). Densities of fish larvae peaked in early March at an

average concentration of approximately 6,000 per 1,000 m3[264,172 gal]. Unidentified goby larvae

occurred year-round in the samples whereas yellowfin goby larvae were mainly found only in samples

collected during February and March. White croaker primarily occurred in spring while another common

taxon, combtooth blennies, were predominantly summer spawners.
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In addition to the fish larvae, 14,845 fish eggs from 10 taxa were enumerated from the surveys. The most

abundant taxonomic group of fish eggs in the samples was unidentified eggs, which made up 46.6% of

the total eggs collected, followed by croaker eggs (15.7%). Fish eggs had peak abundances in late

February and early May with concentrations of approximately 8,000 per 1,000 m3. Larvae were

substantially more abundant in samples collected at night than those collected during the day in nearly

every survey, while egg abundances were more evenly distributed between day and night surveys. Total

annual entrainment was estimated to be 65.3 million fish larvae and 99.9 million fish eggs during 2006

using the HGS CWIS actual flows as the basis for calculations. Using the design (maximum capacity)

CWIS flows, total annual entrainment was estimated to increase to 153.3 million fish larvae and 269.4

million fish eggs.

A total of 2,262 larval target shellfishes (late-stage larvae of crabs, spiny lobsters, and market squid)

representing 16 taxa (combined species designations) was collected from the HGS entrainment station

(E1) during 26 bi-weekly surveys in 2006. The most abundant target shellfish larvae in the samples were

kelp crab megalops (Pugettia spp.) followed by spider crab megalops (Majidae unid.), which made up

63.4% and 16.8%, respectively of the total target shellfish larvae collected. Total annual entrainment was

estimated to be 18.9 million target shellfish larvae based on actual cooling water flows. Using the design

CWIS flows, total annual entrainment was estimated to increase to 41.3 million target shellfish larvae.

1.2 SOURCE WATER

To determine composition and abundance of the early life stages of fish and shellfish in the source waters

of the HGS, sampling at six stations in the waters of the Los AngelesLong Beach Harbor Complex was

conducted once monthly on the same day that the entrainment station (E1) was sampled.

A total of 13,986 larval fishes representing 72 taxa was collected from HGS source water stations during

12 monthly surveys in 2006. White croaker, combtooth blennies, unidentified gobies (CIQ goby

complex), anchovies, bay goby, unidentified croakers and yellowfin goby were the most abundant taxa

and comprised nearly 90% of all specimens collected. The greatest concentrations of larval fishes

occurred during May 2006 (ca. 2,400/1,000 m3) and the fewest in November 2006 (ca. 400/1,000 m

3

).

Seasonality in the taxa with the most abundant larvae was similar to the entrainment samples.

A total of 6,942 larval target shellfishes representing 20 taxa was collected from the HGS source water

stations. Megalops of kelp crabs, pea crabs, spider crabs, unidentified megalops, California spiny lobster,

and cancer crabs were the most abundant taxa and comprised over 90% of all specimens collected.

1.3 IMPINGEMENT

During 2006, normal operation impingement surveys were performed during 50 of 52 weeks at the HGS

between January 5 and December 29, 2006, from the single screening facility. The two weeks with no

samples collected (in late-April and early-May) represent periods when no circulating water pumps were

operating due to a facility outage. A total of 1,290 fishes representing 25 species and weighing 188.85 kg

(416.41 lbs) was collected during impingement sampling in 2006. The estimated annual total

impingement, based on cooling water flow volumes in 2006, was 8,851 individuals weighing 1,316 kg

(2,903 lbs) (Table 5.5-1). Round stingray was the most abundant species, with 877 individuals collected

(68% of the abundance total) and an estimated annual impingement of 6,150 individuals weighing
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1,231 kg (2,715 lbs). The annual impingement of round stingray represented 70% of the total

impingement abundance and 94% of the biomass. The next most abundant species in impingement

samples were black perch, specklefin midshipman, shiner perch, barred sand bass, and giant kelpfish.

Combined these taxa accounted for 91.2% of the sampled impinged fish abundance.

The estimated annual total impingement of fish based on actual cooling water flow volumes in 2006 was

8,851 individuals weighing 1,316 kg (2,903 lbs). The estimated annual impingement based on design

flows was 19,861 fishes weighing 2,938 kg (6,477 lbs). Impingement abundance and biomass in 2006

were highest in fall months (SeptemberNovember). In general, fish impingement abundance and

biomass were greater during nighttime surveys than daytime surveys.

A total of 1,014 macroinvertebrates representing at least 41 distinct taxa and weighing 37.3 kg (82.3 lbs)

was collected during impingement sampling in 2006. The nudibranch Hermissenda crassicornis was the

most abundant species, with 271 individuals collected (27% of the abundance total) and an estimated

annual impingement of 1,840 individuals weighing 0.6 kg (1.4 lbs). The next most abundant species in

impingement samples were unidentified sea spiders (Pycnogonida), tuberculate pear crab, California

spiny lobster (Panulirus interruptus), intertidal coastal shrimp, and California two-spot octopus.

Combined these species accounted for 82.6% of the sampled impinged macroinvertebrate abundance.

The estimated annual total impingement of macroinvertebrates based on actual cooling water flow

volumes in 2006 was 6,753 individuals weighing 260 kg (574 lbs) (Table 5.5-2). The estimated annual

impingement based on design flow was 13,538 macroinvertebrates weighing 575 kg (1,268 lbs).

Invertebrate impingement abundance was greatest in summer (June through August), while biomass had

peaks in early-March and early-September.

1.4 IMPACT ASSESSMENT

The data collected from the entrainment, source water, and impingement sampling was used to assess the

potential for AEI to fish and shellfish populations. The assessment was limited to the taxa that were

sufficiently abundant to provide a reasonable assessment of impacts. The list of taxa was reviewed and

approved by the Los Angeles Regional Water Quality Control Board (LARWQCB) and other

stakeholders. The most abundant taxa typically had the greatest frequency of occurrence among surveys

and among stations. Since the most abundant organisms may not necessarily be those that experience the

greatest IM&E effects on the population level, the data were also examined to determine if additional taxa

should be included in the assessment. For example, this might include taxa with commercial or

recreational fisheries, taxa with limited habitats, and any threatened or endangered fish or shellfish

species. The National Marine Fisheries Service (NMFS) requested that all species managed under the

Magnuson-Stevens Fishery Conservation and Management Act be included in the impingement results.

None of these species was included in the entrainment assessment since they were scarce in entrainment

and source water samples. No species listed as threatened or endangered by the state or federal

governments were entrained or impinged at the HnGS during the study.

The assessment was done primarily by calculating impingement and entrainment estimates for individual

taxa based on CWIS actual and design flow volumes, and then using these results to model the losses to

adult and larval source populations using two general modeling approaches and three different models.
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One approach used species life history information in two different demographic models to estimate the

equivalent number of adults (adult equivalent loss [AEL]) or adult females (fecundity hindcasting [FH])

lost due to entrainment or impingement. The other modeling approach was only used with the entrainment

data. This model (empirical transport model [ETM]) estimates the conditional mortality on a population

resulting from entrainment. The demographic model estimates from entrainment and impingement were

added together to evaluate the combined effects of the CWIS.

The assessment included twelve taxonomic groups or species of fishes and two taxonomic groups or

species of shellfishes (Tables 1.4-1 and 1.4-2). These taxa were categorized into four habitat types that

were simplified from a more detailed categorization of habitats developed by Allen and Pondella (2006b)

(Table 1.4-3). Taxa that occurred in more than one habitat were included in the habitat group that best

reflected the primary distribution for those taxa. This approach was used because it focused the

assessment on the taxa and habitats that were most at risk to CWIS effects.

Impacts to Southern California Bight (SCB) fish and invertebrate populations caused by the entrainment

of planktonic larvae through the HGS CWIS can only be assessed indirectly through modeling. These

impacts are additive with the direct impingement losses. Three taxa (CIQ goby complex, yellowfin goby

and white croaker) comprised 86% of all entrained fish larvae. Of the ten most abundant fish taxa

entrained at HGS, only two (croakers [including white croaker] and anchovies) have any direct

commercial or recreational fishery value. All of the abundantly entrained species can be considered

forage species for larger predatory fishes, sea birds, or marine mammals. Approximately 40% of the 45

different fish taxa entrained belonged to species with some direct fishery value (e.g., northern anchovies,

croakers, sand basses, and California halibut) even though most of those (except northern anchovies and

white croaker) were in very low abundance in the samples and, as a result, were not assessed for potential

impacts.

The ETM procedure estimated the annual probability of mortality due to entrainment (PM). It puts the

entrainment estimate into context by comparing it with a known source population at risk of entrainment.

The greatest PM estimate for a target taxon was for the CIQ goby complex with a predicted fractional

larval loss of 2.6% based on actual cooling water flows. The next greatest probabilities of mortality were

for northern anchovy (0.7%) and yellowfin goby (0.7%). The distance of shoreline potentially affected by

entrainment was directly proportional to the estimate of time that the larvae are exposed to entrainment.

Both goby taxa had local populations associated with the soft-bottom habitats of the Los Angeles-Long

Beach Harbor Complex, and most larvae were entrained at sizes that indicated they were recently

hatched. The modeled species with primarily nearshore (non-bay) distributions included white croaker

and northern anchovy, and these had PM estimates well below 1%. These levels of additional mortality are

considered low, especially when the populations of these species are known to extend over a much larger

geographic range than the extrapolated source water bodies. No shellfish taxa were modeled for

entrainment impacts due to the low abundance of the target taxa (e.g., spiny lobsters, Cancer crabs).

Fish impingement has been routinely measured for decades at several coastal power plants in southern

California, and these data are reported annually as part of their NPDES receiving water monitoring

studies. The same core group of fish species continues to be impinged at these power plants, and there is

no measurable effect on fish populations from the operation of the cooling water systems. For species that
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are harvested commercially, such as northern anchovy, and others that are the target of sport fisheries,

such as barred sand bass, the biomass of fish impinged is orders of magnitude less than annual landings.

Compared to the IM&E study conducted at HGS in 19781979 (IRC 1981), concentrations of northern

anchovy, unidentified gobies, and queenfish larvae were an order of magnitude less abundant in 2006

while combtooth blennies and white croaker were approximately the same (Table 6.4-1). Anchovy larvae

in particular were significantly more abundant in the earlier study, due in part to the cooler water climatic

regime in the SCB that favored anchovy populations at that time. The most abundantly impinged species

in 19781979 were Pacific pompano (Peprilus simillimus), white croaker, and queenfish, which

combined accounted for 76% of the total impingement abundance. In the 2006 samples, the most

abundant species were round stingray, black perch and specklefin midshipman with round stingray

accounting for 75% of all impinged fishes. The estimated annual fish impingement (normal operations

and heat treatments) was 2,827 kg (6,232 lbs) in 19781979 compared to 1,317 kg (2,903 lbs) in 2006. In

the 1978-1979 study HGS was operating Units 15 with a combined flow of 86,652 MG, whereas in 2006

only Unit 5 was operational with an annual flow of 17,885 MG, an 80% reduction in flows between

studies. Therefore, changes in total impingement and entrainment through time were affected not only by

natural changes in biological and oceanographic factors but also by changes in plant operation.

No federal/state threatened or endangered fish/shellfish species were identified in entrainment and

impingement samples collected from HGS. This is consistent with past entrainment and impingement

sampling conducted at HGS. Off southern California, species managed under the Magnuson-Stevens

Fishery Conservation and Management Act are listed in the Coastal Pelagic Fishery Management Plan

(FMP) and the Pacific Groundfish FMP. Essential fish habitat (EFH) includes all waters off southern

California offshore to the Exclusive Economic Zone. Five species covered under the two FMPs that

occurred in entrainment and/or impingement samples at HGS included Pacific sanddab, northern

anchovy, Pacific hake, Pacific sardine, and market squid. None of these species was significantly

impacted by HGS operations.

Although it seems clear that there is very low risk of any AEI to taxa that are not primarily distributed in

the Harbor Complex, the potential risk to the fishes included in the assessment that are primarily

associated with bay and harbor habitats (e.g. gobies and blennies) was also low, particularly compared to

other power plants situated in embayments in southern California. This is a reflection of both the lower

abundances of these fishes in the Inner Los Angeles Harbor (ILAH) and the low cooling water volumes of

HGS relative to other facilities. Larvae potentially lost due to entrainment at small sizes near the plant

may be replaced by larvae transported into the ILAH that were spawned in similar habitats which are

abundant in the Harbor Complex area.
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Table 1.4-1. Summary of HGS entrainment and impingement sampling results and model output for common fish

and shellfish species based on actual CWIS flows in 2006*.

Species Common Name

Est. Annual

Larval Ent.

(millions)

Est. Annual

Egg Ent.

(millions)

ETM

PM 2*FH AEL

Annual

Imping.

Estimate

Imping.

Weight

(kg)

Fishes

Gobiidae unid. CIQ gobies 33.29 0 2.65 86,720L36,231L0

Acanthogobius flavimanus yellowfin goby 15.41 0 0.65 1,936L163 3.15

Genyonemus lineatus1 white croaker 7.16 17.87 0.19 20E25 0.20

Lepidogobius lepidus bay goby 2.38 0 0.24 0

Hypsoblennius spp. combtooth blennies 2.26 0 0.06 2,826L6,024L0

Engraulis mordax. northern anchovy 0.94 0.8 0.71 11,506C25,863L24 0.02

Urobatis halleri round stingray   6,150 1,231.68

Embiotoca jacksoni black perch   646 18.49

Porichthys myriaster specklefin midshipman   484 11.96

Cymatogaster aggregata shiner perch   390 3.36

Paralabrax spp.2sand bass 0.12  209 7.51

Heterostichus rostratus giant kelpfish 0  192 15.73

Shellfishes

Panulirus interruptus spiny lobster 0.22  717 169.37

Octopus spp. two-spot octopus   184 36.25

1

larval entrainment estimate includes white croaker and unidentified croakers combined

2

only barred sand bass collected in abundance in impingement sampling

* Model estimates indicate whether the number was based on eggs (E), larvae (L), or both combined (C).
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Table 1.4-2. Summary of HGS entrainment and impingement sampling results and model output for common fish

and shellfish species based on design CWIS flows in 2006*.

Species Common Name

Est. Annual

Larval Ent.

(millions)

Est. Annual

Egg Ent.

(millions)

ETM

PM 2*FH AEL

Annual

Imping.

Estimate

Imping.

Weight

(kg)

Fishes

Gobiidae unid. gobies 75.94 0 5.70 197,812L82,665L0

Acanthogobius flavimanus yellowfin goby 37.60 0 1.54 4,724L399 7.48

Genyonemus lineatus1 white croaker 18.78 43.11 0.42 48E48 0.43

Lepidogobius lepidus bay goby 5.07 0 0.50 0

Hypsoblennius spp. combtooth blennies 4.36 0 0.12 5,466L11,650L0

Engraulis mordax. northern anchovy 2.07 1.93 1.53 25,306C56,879L36 0.03

Urobatis halleri round stingray   13,771 2,756.09

Embiotoca jacksoni black perch   1,371 41.03

Porichthys myriaster specklefin midshipman   1,379 26.84

Cymatogaster aggregata shiner perch   719 6.77

Paralabrax spp.2sand bass 0.27  442 16.20

Heterostichus rostratus giant kelpfish 0  424 32.60

Shellfishes

Panulirus interruptus spiny lobster 0.36  1,544 369.56

Octopus spp. two-spot octopus   428 85.96

1

larval entrainment estimate includes white croaker and unidentified croakers combined

2

only barred sand bass collected in abundance in impingement sampling

* Model estimates indicate whether the number was based on eggs (E), larvae (L), or both combined (C).
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Table 1.4-3. Habitat associations for taxa included in assessment of CWIS effects at the HGS.

Fishery Habitats

Scientific name Common name

S-Sport,

C-Comm.

bays,

harbors

reefs,

kelp

beds

coastal

pelagic shelf

Fishes

Acanthogobius flavimanus yellowfin goby X

Cymatogaster aggregata shiner perch S X x

Embiotoca jacksoni black perch S, C x X

Engraulidae unid. anchovies C X

Genyonemus lineatus white croaker S, C x X x

Gobiidae unid. CIQ goby complex X

Heterostichus rostratus giant kelpfish X

Hypsoblennius spp. combtooth blennies X x

Lepidogobius lepidus bay goby X

Paralabrax nebulifer Barred sand bass S x X

Porichthys myriaster specklefin midshipman X x x

Sciaenidae unid. croakers S, C X x

Urobatis halleri round stingray X

Shellfishes

Octopus spp. two-spot octopus C x X

Panulirus interruptus California spiny lobster S X

Primary habitat in bold, upper case and secondary habitat in lower case.
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2.0 IN T R OD UC TI O N

The Harbor Generating Station (HGS) is a fossil-fueled steam electric power generating station that began

operation in 1954. HGS is owned and operated by the Los Angeles Department of Water and Power

(LADWP) and is located in the Inner Los Angeles Harbor (ILAH), in Wilmington, CA, near Long Beach.

HGS has seven natural gas-fired units, which do not require circulating water and one steam turbine, Unit

5, which requires cooling water that is drawn from the ILAH through an intake structure along the shore

of Slip 5. After passing through the plant, the water is discharged into the West Basin of the ILAH.

Cooling water intake systems (CWIS) are regulated under §316(b) of the federal Clean Water Act

(CWA). In July 2004, the U.S. Environmental Protection Agency (EPA) published new regulations for

§316(b) applicable to large existing power plants with daily cooling water volumes in excess of 50 mgd.

Due to the design, location, and operating characteristics of the cooling water system for HGS, which

withdraws a maximum of 0.41 million m3per day (108 mgd) for Unit 5, it was subject to these new

regulations that required submittal of a comprehensive plan for compliance by January 2008. The new

regulations were challenged by a coalition of environmental groups that was heard by the Second U.S.

Circuit Court of Appeals. The court rendered a decision in January 2007 that remanded several key

components of the regulations back to the EPA. In March 2007, the EPA issued a memorandum

suspending the new regulations and directing that all permits for Phase II facilities implement 316(b) on a

case-by-casebasisusing“bestprofessionaljudgment”(BPJ).Thelanguageofthememorandum was

expanded and published in the Federal Register in July 2007 (Volume 72, 130:37107-37109).

The studies presented in this report were conducted in partial fulfillment of the requirements of the new

regulations. With the suspension of the Phase II regulations, the results of the studies will be used to

determine if impingement and entrainment losses pose any significant risk of adverse environmental

impact (AEI) to the species and life stages of fish and shellfish impinged or entrained. The absence of any

significant impacts would be a technically sound basis under BPJ for determining that the cooling water

intake structure represents the best technology available. This would allow any additional requirements to

further reduce impingement and/or entrainment to be deferred until issues with the Phase II Rule are

resolved.

2.1 BACKGROUND AND OVERVIEW

On July 9, 2004, the EPA published the second phase of new regulations under §316(b) of the CWA. The

final Phase II regulations went into effect in September 2004, and apply to existing generating stations

(Phase II facilities) with CWISs that withdraw at least 50 mgd from rivers, streams, lakes, reservoirs,

oceans, estuaries, or other waters of the United States. Pursuant to the Phase II regulations, the LADWP

submitted a Proposal for Information Collection (PIC) for HGS to the Los Angeles Regional Water

Quality Control Board (LARWQCB) in October 2005 (LADWP 2005). The PIC included the study plan

for the HGS Impingement Mortality and Entrainment (IM&E) Characterization Study.
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2.1.1 Section 316(b) of the Clean Water Act

The suspended Section 316(b) of the CWA required that the location, design, construction, and capacity

of CWISs reflect the best technology available (BTA) to minimize adverse environmental impacts (AEI)

due to the impingement mortality of aquatic organisms (i.e., fish, shellfish, and other forms of aquatic

life) on intake structures and the entrainment of eggs and larvae through cooling water systems. The

suspended 316(b) Phase II regulations established performance standards for CWISs of existing power

plants that withdraw more than 50 mgd of surface waters and use more than 25% of the withdrawn water

for cooling purposes. The regulations required all large existing power plants to reduce impingement

mortality by 8095% and to reduce entrainment of smaller aquatic organisms drawn through the cooling

system by 60–90% whencomparedagainsta“calculationbaseline.”Thewaterbodytypeonwhichthe

facility is located, the capacity utilization rate, and the magnitude of the design intake flow relative to the

waterbody flow were to be used to determine whether a facility was required to meet the performance

standards for only impingement or both impingement and entrainment.

The suspended Phase II regulations provided power plants with five options for meeting the performance

standards, but unless a facility could show that it could meet the standards using the existing intake design

or was installing one of the approved EPA technologies for IM&E reduction, it must submit information

documenting its existing levels of IM&E. These data can come from existing data that may have

previously been collected at the facility or a similar facility nearby. The data were then required to be

submitted in an IM&E Characterization Study that was one component of the §316(b) Comprehensive

Demonstration Study (CDS) required under the suspended Phase II regulations. The impingement

mortality component of the studies was not required if the through-screen intake velocity was less than or

equal to 15 centimeters (cm) (0.5 ft) per second. The entrainment characterization component is not

required if a facility:

1. Has a capacity utilization rate of less than 15%;

2. Withdraws cooling water from a lake or reservoir, excluding the Great Lakes; or

3. Withdraws less than 5% of the mean annual flow of a freshwater river or stream.

Based on previously collected intake velocity measurements and plant operating characteristics, both the

IM&E components of the study were required at the HGS. Previous §316(b) CDSs were conducted at

HGS from October 1978 through November 1979 (IRC 1981). The entrainment sampling was conducted

biweekly at the intake while impingement samples were collected on approximately a weekly basis. A

detailed summary of the historical IM&E studies is provided in Sections 4.2 and 5.2. Due to the time

period since the original data were collected, a Study Plan for new IM&E studies was submitted with the

PIC to the LARWQCB in October 2005. The PIC was submitted prior to the publication of the Second

U.S. Circuit Court of Appeals Decision on the §316(b) Phase II regulations issued on January 25, 2007.

The EPA issued a memorandum to its Regional Offices dated March 20, 2007. This memorandum

announced that EPA was withdrawing the §316(b) Phase II Rule for existing steam electric generating

stations in its entirety based on the Court decision. The memorandum further directed EPA Regional

Offices to implement §316(b) in NPDES permits on a BPJ basis until the issues raised by the Court

decision are resolved. EPA is currently considering several alternatives for responding to the Court
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decision and it may be several years before it is resolved either through further litigation and/or

rulemaking. The guidance in this memorandum was published in the Federal Register on July 9, 2007

(Volume 72, 130:37107-37109).

The information in this report is being submitted to assist in the evaluation of fish protection technologies

and operational measures described in the PIC so that when the issues with the suspended Phase II Rule

are resolved, LADWP will be in a position to move forward in a timely manner to comply with the Rule.

The information is also important in evaluating the potential for AEI potentially caused by impingement

and entrainment. In support of this approach for compliance, the assessment of the IM&E study focuses

on determining if impingement and entrainment losses pose any significant risk of AEI to the species and

life stages of fish and shellfish impinged or entrained. The AEI assessment in this report is based on

previous EPA guidance on 316(b) (EPA 1977) and focuses on evaluating the following:

 potential impacts that could pose a risk to populations of any impinged or entrained species;

 impacts to the local commercial or recreational fishery; or

 any impacts to a protected species.

For entrained and juvenile species the analysis will provide estimates of adult losses for a representative

set of commercial and recreational species. For forage species, estimates of the reductions to commercial

and recreational species will be made due to the reduction in biomass as a result of impingement and

entrainment. Demonstrating no significant risk of AEI would be a technically sound basis to defer

requirements for reducing impingement and/or entrainment until issues with the Phase II Rule are

resolved. The rationale and approach for the AEI assessment in this report and the results and conclusions

from our analysis are provided in Section 6.0.

2.1.2 Development of the Study Plan

The suspended Phase II §316(b) regulations required that the plan for the IM&E Characterization Study

include sufficient data to develop a scientifically valid estimate of IM&E, including all methods and

Quality Assurance/Quality Control (QA/QC) procedures for sampling and data analysis. The sampling

and data analysis methods must be appropriate for a quantitative survey and include consideration of the

methods used in other studies performed in the source waterbody. The sampling plan must also include a

description of the study area (including the area of influence of the CWIS), and provide taxonomic

identifications of the sampled or evaluated biological assemblages (including all life stages of fish and

shellfish) that are known to be relevant to the development of the plan.

The regulations also require that the PIC include summaries of any historical studies characterizing

IM&E, and/or the physical and biological conditions in the vicinity of the CWISs and their relevance to

the proposed studies. These are required to assist the LARWQCB in reviewing and commenting on the

IM&E Study Plan. If the data from previous studies was used in characterizing the existing levels of

IM&E, then the PIC must demonstrate that the data were representative of current conditions and were

collected using appropriate QA/QC procedures.
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The HGS IM&E Characterization Study Plan was developed in 2005 by MBC Applied Environmental

Sciences (MBC) and Tenera Environmental (Tenera). The Study Plan was designed to provide the

biological information necessary to fulfill all pertinent 316(b) Phase II requirements, and was based on

entrainment and impingement studies performed in California in recent years for California Energy

Commission relicensing studies (such as those at the AES Huntington Beach, Duke Morro Bay, Duke

Moss Landing, and Duke South Bay Power Plants), and 316(b) Demonstrations (such as at the PG&E

Diablo Canyon and NRG Encina Power Plants). All of these studies were performed with input from

technical working groups, comprised of representatives from the project applicants, the California

Regional Water Quality Control Board (RWQCB), California Department of Fish and Game (CDFG),

National Marine Fisheries Service (NMFS), U.S. Fish and Wildlife Service (USFWS), and consultants.

The Study Plan was submitted to the LARWQCB in October 2005. LADWP and its consultants

subsequently met with the LARWQCB to review the Study Plan and address comments. Pursuant to

comments during the meeting that were included in a letter from the LARWQCB in April 2006, the

following changes were made to the Study Plan:

 An agreement to identify and enumerate all fish eggs (to the extent practicable) from entrainment

samples; and

 An agreement to identify and enumerate all crab megalopae (to the extent practicable) from

entrainment samples.

The revisions to the Study Plan only affected sample processing and did not affect the sampling that

started in January 2006. On January 30, 2007, representatives from the LADWP, URS, MBC, and Tenera

met with representatives from the LARWQCB, EPA Region IX, State Water Resources Control Board

(SWRCB), CDFG, and NMFS to review preliminary data from the HGS IM&E Characterization Study,

and determine the fish and shellfish species that would be assessed in the IM&E Report. The USFWS was

invited to the meeting but did not attend. The meeting was also attended by a representative from Tetra

Tech, a consultant to the EPA and Regional Board, and representatives from the following environmental

groups: Heal the Bay and Santa Monica Baykeeper.

An initial draft of the IM&E results with the species identified at the January meeting was sent to the

attendees in early May for review. Another meeting with the group was held on May 7, 2007 to finalize

the list of species that would be included in the assessment presented in this report.

As a result of these meetings, there was agreement that the impingement sampling would identify, count,

weigh, and measure all collected fishes, crabs, lobsters, shrimp, squid and octopus. This approach was

taken to include all of theimpingeable‘shellfish’thatarerecreationallyorcommerciallyimportantanda

large number of other species that are not targeted by a fishery. It was also agreed that the entrainment

sampling would identify and count all fish eggs and larvae, megalops stage larvae for all species of crabs,

California spiny lobster phyllosoma larvae, and market squid hatchlings.

At the January 30 meeting, NMFS requested that all species managed under the Magnuson-Stevens

Fishery Conservation and Management Act (Magnuson-Stevens Act) be assessed in the HGS IM&E

report. Off southern California, these species are listed in the Coastal Pelagics Fishery Management Plan

(FMP) and the Pacific Groundfish FMP. It was agreed that for entrainment, additional demographic or
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ETM calculations would only be performed on these species if they were collected in sufficient

abundance in entrainment and source water samples, and if sufficient life history information was

available to permit those calculations. For impingement, it was agreed that only market squid would need

additional assessment since impingement estimates were calculated for all species, and no additional

modeling was proposed.

2.1.3 Study Plan Objectives

Under the suspended §316(b) regulations, the IM&E Characterization Study must include the following

elements (for all applicable components):

1. Taxonomic identifications of all life stages of fish, shellfish, and any species protected under

federal, state, or tribal law (including threatened or endangered species) that are in the vicinity of

the CWIS and are susceptible to impingement and entrainment;

2. A characterization of all life stages of fish, shellfish, and any species protected under federal, state,

or tribal law (including threatened or endangered species) identified in the taxonomic

identification noted previously, including a description of the abundance and temporal and spatial

characteristics in the vicinity of the CWIS, based on sufficient data to characterize the annual,

seasonal, and diel variations in the IM&E; and

3. Documentation of current IM&E of all life stages of fish, shellfish, and any protected species

identified previously and an estimate of IM&E to be used as the calculation baseline.

The suspended Phase II §316(b) regulations provided the LARWQCB with considerable latitude in

determiningthelevelofdetailnecessaryinmeetingtheseobjectivesandstatedthat“whilethetaxonomic

identification in item 1 will need to be fairly comprehensive, the quantitative data required in elements 2

and 3 may be more focusedonspeciesofconcern,and/orspeciesforwhichdataareavailable.”Ifthe

CDS was based on a given technology, restoration or site-specific standards, the level of detail in terms of

the quantification of the baseline could be tailored to the compliance alternative selected and did not have

to address all species and life stages. Logically it could be based on dominant species and/or

commercially or recreationally important species.

The data collected from the study will be used in developing a characterization of baseline levels of

IM&E for HnGS required under the suspended Phase II regulations. The calculation baseline is defined in

the suspended Phase II §316(b) regulations as follows:

“Calculationbaselinemeansanestimateofimpingementmortality and entrainment that would

occur at your site assuming that: the cooling water system has been designed as a once-through

system; the opening of the cooling water intake structure is located at, and the face of the

standard 3/8-inch mesh traveling screen is oriented parallel to, the shoreline near the surface of

the source waterbody; and the baseline practices, procedures, and structural configuration are

those that your facility would maintain in the absence of any structural or operational controls,

including flow or velocity reductions, implemented in whole or in part for the purposes of

reducing impingement mortality and entrainment. You may also choose to use the current level of

impingement mortality and entrainment as the calculation baseline. The calculation baseline may

be estimated using: historical impingement mortality and entrainment data from your facility or
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another facility with comparable design, operational, and environmental conditions; current

biological data collected in the waterbody in the vicinity of your cooling water intake structure;

or current impingement mortality and entrainment data collected at your facility. You may

request that the calculation baseline be modified to be based on a location of the opening of the

cooling water intake structure at a depth other than at or near the surface if you can demonstrate

to the Director that the other depth would correspond to a higher baseline level of impingement

mortality and/or entrainment.”

As presented in the PIC, the HGS CWIS does not conform to the calculation baseline. Significant

deviations from the calculation baseline are:

 The intake is submerged, rather than at or near the surface;

 The traveling screens are located more than 305 meters (m) (1,000 feet [ft]) from the shoreline

rather than at the shoreline; and

The suspended Phase II regulations allow facilities to request that the calculation baseline be modified

due to deviations from the calculation baseline if it can be demonstrated that these deviations provide

reduced levels of IM&E. After the calculation baseline has been determined, then potential credits from

the calculation baseline could be requested. A potential credit is the use of closed-cycle cooling for Units

10-14. With the suspension of the Phase II regulations the same arguments regarding deviations from the

calculation baseline would apply to determining if the current design represents the BTA for minimizing

AEI.

Another objective of the study is to provide data that can be used in meeting different alternatives for

compliance that might be used by LADWP. One approach that was the subject of the Court Decision was

the use of restoration to meet the performance standards for IM&E reduction. To this end, source water

data were collected to estimate the sizes of the populations potentially subject to entrainment. The Court

decision rejected the use of restoration, but the source water data will still be important in assessing the

impacts of entrainment at a population level that would otherwise be limited to a few species with

adequate life history information. The study provides data that could be used to evaluate and estimate the

economic value of the environmental benefit of meeting the performance standards. While the Court

decision has limited the use of the data in cost-benefit analysis this aspect is still important in evaluating

the potential AEI of IM&E and is one of the approaches used in the assessment presented in Section 6.0.

2.1.4 Study Plan Approach

The IM&E studies at HGS were designed to examine losses resulting from both impingement of juvenile

and adult fish and shellfishes on traveling screens at the intake during normal operations and from

entrainment of larval fishes and shellfishes into the CWIS. The sampling methodologies and analysis

techniques were designed to collect the data necessary for compliance with the suspended §316(b) Phase

II Final Rule and were similar to recent impingement and entrainment studies conducted for the AES

Huntington Beach Generating Station (MBC and Tenera 2005), the Duke Energy South Bay Power Plant

(Tenera 2004), and the Cabrillo Power I LLC, Encina Power Station (Tenera 2007). The studies at

Huntington Beach were performed as part of the California Energy Commission California

Environmental Quality Act (CEQA) process for permitting power plant modernization projects, while the
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South Bay and Encina projects were for §316(b) compliance. The study plans for these projects were

subject to review by state and federal resource agency staff and independent scientists from various

environmental organizations.

The impingement sampling methods used in the study are similar to the National Pollutant Discharge

Elimination System (NPDES) monitoring program, conducted at the HGS since 2003. The existing

NPDES permit for the plant requires impingement sampling semiannually during heat treatments.

However, since heat treatments are not conducted at the HGS, NPDES samples were collected during

periods of normal operations. The sampling frequency for the IM&E characterization study was increased

to weekly to capture seasonal variation and to collect additional data on diel variation.

The entrainment sampling was designed to reflect the uncertainties surrounding the use of restoration for

compliance with the suspended §316(b) regulations. If the use of restoration had not been disallowed as a

result of the court decision, the entrainment data would have been used in baseline calculations of losses

that would be required to estimate the commercial and recreational values of adult fish losses in a cost

benefit analysis of various technology and operational alternatives being considered to comply with

required reductions in entrainment mortality. Larval fish and shellfish abundances can vary greatly

through the year and therefore biweekly sampling was used for characterizing entrainment. If the

restoration option had been upheld in the Second Circuit Court decision, models of the conditional

mortality due to entrainment could have been used in designing appropriate restoration projects for

offsetting entrainment losses. These models are based on proportional comparisons of entrainment and

source water abundances and are theoretically insensitive to seasonal or annual changes in the abundance

of entrained species. Therefore, source water sampling occurred monthly, which is consistent with the

sampling frequency for recently completed studies in southern California.

2.2 REPORT ORGANIZATION

The remainder of this report is organized as follows. Section 3.0 includes a detailed description of the

HGS and CWIS. Data on circulating water pump flows from the study period are presented and discussed,

as these are the data used in calculating estimates of IM&E presented in other sections of the report.

Section 3.0 also provides a description of the environmental setting for the plant, including the physical

oceanographicdatausedtosupporttheboundariesofthesourcewaterpotentiallyaffectedbytheplant’s

CWIS. The methods and results for the entrainment and source water sampling are presented in Section

4.0 and the methods and results for the impingement sampling are presented in Section 5.0. The results

from the entrainment and impingement sampling are integrated into an overall impact assessment for the

HGS CWIS in Section 6.0. The references used in the report are presented in Section 7.0. Appendices

include detailed summaries of the physical studies, and the entrainment, source water, and impingement

data.

2.3 CONTRACTORS AND RESPONSIBILITIES

The IM&E Study was designed and performed by EPRI Solutions (Palo Alto, California), MBC Applied

Environmental Sciences (Costa Mesa, California), and Tenera Environmental (San Luis Obispo,
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California), and URS Corporation (Santa Ana, California). The roles of each of the respective firms were

as follows:

 EPRI Solutions

 Input on sampling design

 MBC Applied Environmental Sciences

 Study design

 Field sampling

 Impingement Mortality data entry and analysis

 Reporting

 Tenera Environmental

 Study design

 Physical oceanographic data collection and analysis

 Field sampling Quality Assurance/Quality Control (QA/QC)

 Laboratory processing of entrainment and source water plankton samples

 Entrainment data entry and analysis

 Reporting

 URS Corporation

 Project management

Each of the two biological contractors (i.e., MBC and Tenera) was responsible for ensuring that all data

were verified prior to being entered, and that appropriate QA/QC measures were employed during data

entry and analysis.
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3.0 DE S C RI P T I ON O F T H E GE N E RATI N G STAT I O N AN D

CH A R AC T E RI ST I CS OF T HE SO UR C E WAT E R BO D Y

3.1 DESCRIPTION OF THE GENERATING STATION

The Harbor Generating Station (HGS) is located in the city of Wilmington, CA (Figure 3.1-1). The total

plant output is 450 megawatts (MW) with Units 1 and 2 rated at 80 MW each, Unit 5 at 75 MW, and

Units 1014 each at 43 MW. Units 1 and 2 are natural gas-fired combustion turbines with a heat recovery

steam generator (combined-cycle with one steam turbine, Unit 5). Units 10-14 are natural gas-fired

combustion turbines equipped with cooling towers. Only Unit 5 requires circulating water from the harbor

as the other units utilize alternative cooling methods. Two circulating water pumps provide a total of

408,824 m3per day (108 mgd; 75,000 gpm) of cooling water for Unit 5 at full load. In addition, a 38,157

m

3

per day (10.1 mgd; 7,000 gpm) auxiliary pump is operated intermittently that also utilizes seawater

from the same CWIS. Ocean water for cooling purposes for Unit 5 is conveyed to the generating station

from the northwest corner of Slip 5 in the ILAH. Water flows from a curtain wall intake structure (17 m

wide by 3 m high, [56 ft by 10 ft]) in the bulkhead of the harbor through two 2.4 m (8 ft) diameter closed

conduits approximately 335 m (1,100 ft) to the screen and pump chamber at HGS. After passing through

the condensers, the cooling water is discharged into a two-sided chamber running the length of the

generating station. From this chamber, the water is conveyed through two 2.4 m (8 ft) diameter

underground conduits approximately 490 m (1,600 ft) to a submerged, multi-port discharge structure

located in the pier-head in the northeast corner of West Basin of ILAH.

Figure 3.1-1. Location of the LADWP Harbor Generating Station (HGS).
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3.2 DESCRIPTION OF THE COOLING WATER INTAKE SYSTEM

Cooling water for Unit 5 is withdrawn from the ILAH through an intake structure located in the northwest

corner of Slip 5 (Figures 3.2-1 and 3.2-2). The mean water depth in front of the intake is 11 m (35 ft)

mean lower low water (MLLW) level. The Unit 5 CWIS is equipped with six vertical bar racks to deflect

large debris (Figure 3.2-3). The bar racks are 0.95 cm by 7.6 cm (3/8 in by 3 in) bars spaced 11.4 cm

(4.5 in) on center. Cleaning of the bar racks is done on a weekly basis or as needed. The screenhouse is

located onshore, and connected to the intake structure by two 2.4 m (8 ft) internal diameter pipes, each

333.8 m (1,095 ft) long (Figure 3.2-4). The screenhouse has six screenbays; however, there is no flow in

four of the screenbays as they are blocked with stop logs. The other two screenbays are equipped with

functioning traveling water screens. Two of the blocked screenbays are equipped with spare traveling

water screens.

The screenbays are approximately 2.4 m (7.9 ft) wide, with the bottom at elevation1(El.) –4.9 m

(-16.0 ft). The top of the intake pipes are at El. –2.4 m (–8.0 ft) when they enter the screenhouse. The

traveling water screen is located about 10.2 m (33.5 ft) downstream from where the intake pipes enter the

screenhouse. The screens are 1.9 m (6.2 ft) wide and extend from the bottom of the screenhouse to the top

deck. The mesh size on the screen baskets ranges from 9.5 mm to 15.9 mm (3/8 in to 5/8 in). The two

operating screens are rotated once for 30 minutes during every 8-hour shift. A backwash system providing

up to 3.0 m3per minute (800 gpm) of cleaning water at 70 pounds per square inch gauge is used to

remove debris from the screens. Fish and debris removed from the screens are collected in a rectangular

sump for disposal.

Circulating water to Unit 5 is provided by two single-stage vertical mixed-flow pumps. The inlet of these

pumps is at El. –4.4 m (–14.5 ft). Each of the pumps is rated at 142 m3per minute (37,500 gpm). Chlorine

is added to the pump suctions to prevent biofouling in the condenser system. After passing through the

condensers, warmed cooling water flows through a 424.6 m (1,393 ft) long pipe to the discharge structure

inILAH’sWestBasin.Thelocationandsetupofthedischargecanalpreventsdischargedwaterfromrecirculating into the intake.

1 All elevations refer to mean sea level which is 0.86 m (2.82 ft) above the Mean Lower Low Water (MLLW) zero

tide level.
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Figure 3.2-1. General configuration of LADWP HGS.

Note that all measurements in drawing are in feet and do not include metric

conversions.

Figure 3.2-2. Diagram of HGS intake structure at Slip 5 in ILAH.
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Note that all measurements in drawing are in feet and do not include metric conversions.

Figure 3.2-3. Plan view and cross section of HGS intake screenhouse.
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3.2.1 Circulating Water Pump Flows

The HGS CWIS withdraws a maximum of 363,356 m3per day (96.0 mgd) of cooling water from the

ILAH. Velocities inside the circulating water system were calculated using the previous design flow of

the facility (408,780 m3per day, or 108.0 mgd), flow through two screenbays, and the water level at

MLLW. The water velocity at the trash racks was calculated to be 0.09 meters per second (m/s), or

0.3 ft/s, velocity in the intake pipes was calculated to be 0.5 m/s (1.7 ft/s), and at a location just prior to

traveling screens was calculated to be 0.1 m/s (0.4 ft/s). A conservative estimate of the through-screen

velocity would be 0.2 m/s (0.8 ft/s), or twice the screen approach velocity. Intake structure characteristics,

formulas, and velocity calculations for HGS are provided in Appendix B of the HGS PIC.

Daily cooling water flow volumes at the HGS from January 2006 to January 2007 are shown in

Figure 3.2-4. Highest flows generally occurred in late spring and summer, although there was substantial

variation throughout the year. One of the two circulating water pumps was always in operation, except for

the outage at the end of April and again after completion of the study in January 2007. Lowest flows

generally occurred during the first three months of 2006. Daily cooling flow in 2006 averaged 185,296 m3

per day (49.0 mgd), or about 51% of maximum design flow of 363,356 m3per day (96.0 mgd).

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07

H

G

S

C

o

olin

g

W

ater Flo

w

(P

erc

e

nt of M

a

xim

u

m)

0

20

40

60

80

100

Figure 3.2-4. Daily cooling water flow volumes at the HGS from January 2006 through January 2007.
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3.3 ENVIRONMENTAL SETTING

The following section describes the physical and biological environments in the vicinity of the HGS. The

HGS withdraws cooling water from the ILAH, which is hydraulically connected to Long Beach Harbor

and San Pedro Bay. Cooling water is discharged into the West Basin of the ILAH.

3.3.1 Physical Description

The harbor complex was historically an estuary formed at the mouth of the San Gabriel and Los Angeles

Rivers with extensive mudflats and marsh areas (Figure 3.3-1). The natural mudflats and marshlands

provided habitat for birds, fish, and invertebrates, and the barrier beach of Rattlesnake Island (now

Terminal Island) served as nesting habitat for terns and shorebirds. Urbanization and development led to

the construction and modifications associated with the Los Angeles-Long Beach Harbor complex.

Dredging, filling, channelization, and construction over the past 100 years has completely altered the

local estuarine physiography. The Los Angeles River course and the harbor area are no longer true

estuaries because they do not maintain significant year-round fresh water input, and the biota are not

distributed along salinity gradients as in most estuarine systems.

The habitats available for plants and animals have also changed as a result of harbor modifications. Very

little sandy beach and shallow subtidal habitats remain, and salt marsh habitat is essentially absent within

the harbor. Dredge and fill activities have resulted in changes to the benthic (bottom) habitat. The

placement of shoreline structures, such as bulkheads, riprap, and pier pilings, has greatly increased the

hard substrate available for fouling organisms, including mussels and barnacles. The construction of the

breakwaters greatly affected water movement patterns within the harbors, which in turn affected overall

circulation and water quality.
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Figure 3.3-1. Aerial view (looking south) of Harbor Generating Station and the vicinity of Los Angeles

and Long Beach Harbors.

3.3.1.1 Physical Features

The Los Angeles-Long Beach Harbor Complex consists of inner, middle, and outer harbors. Just north of

the breakwaters, the outer harbors consist of deeper, open water habitat, and channels that lead to basins

and slips in the middle and inner harbors. The channels, basins, and slips vary in size and distance from

the harbor entrances. In Los Angeles Harbor, the channels were recently dredged to -16.2 m (-53 ft).

During the mid-1900s, three breakwaters (i.e., San Pedro, Middle, and Long Beach) were constructed to

protect the harbors from damaging wave action. From that point on, the development of the harbor has

continued with a series of dredge and fill operations to deepen channels and accommodate deep draft

vessels, and provide fill for additional shoreline areas necessary for terminal development.

3.3.1.1.1 Climate and Weather

Southern California lies in a climatic regime defined as Mediterranean, characterized by mild winters and

warm, dry summers. In Long Beach, coolest temperatures generally occur from December through

February, with warmest temperatures in August and September (Weather Underground 2007). Average

temperatures range from 828°C (4683°F) (City of Long Beach 2007). Average annual precipitation in

Dominguez Channel

LosAngeles River

Long Beach Harbor

Queen’s Gate

Fed er al Br eak wall

Angel’sGate

Inner Los Angeles Harbor

Los Angeles

Harbor

San Pedro Bay

West

Basin
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the coastal regions ranges between 2538 centimeters (cm) (1015 in), with most precipitation occurring

from October through April.

A subtropical high-pressure system offshore the Southern California Bight (defined as the nearshore

coastal region from Point Conception south into Baja California) produces a net weak southerly/onshore

flow in the area (Dailey et al. 1993). Wind speeds are usually moderate, and are on the order of 10

kilometers (km) per hour (6.2 miles per hour). Wind speeds diminish with proximity to the coast,

averaging about one-half the speeds offshore. Coastal winds in southern California are about one-half

those found off central and northern California. However, strong winds occasionally accompany the

passage of a storm. A diurnal land breeze is typical, particularly during summer, when a thermal low

forms over the deserts to the east of the Los Angeles area. On occasion, a high-pressure area develops

over the Great Basin, reversing the surface pressure gradient and resulting in strong, dry, gusty offshore

winds in the coastal areas. These Santa Ana winds are most common in late summer and fall, but can

occur any time of year.

3.3.1.2 Temperature and Salinity

Waters within the Harbor Complex are primarily marine, though there are fresh water inputs from

regulated discharges, urban runoff, and Dominguez Channel, which enters Los Angeles Harbor

approximately three kilometers northeast of the HGS intake. Results of recent water quality studies within

the ILAH (near the HGS intake structure) indicated water temperatures averaged 16° to 18°C (61° to

64°F), dissolved oxygen averaged 6 to 7 mg/l, pH averaged 7.9, salinity averaged 32.7 to 33.4 parts per

thousand (ppt), and light transmission averaged 64 to 68% (MEC 2002). In winter 2006, temperatures in

West Basin (Los Angeles Harbor) ranged from 13.4 to 15.2°C (56 to 59°F) throughout the water column.

In summer 2006, temperatures were between 17.9 and 24.7°C (64 and 76°F) in West Basin. Salinity

ranged between 27.3 and 33.1 practical salinity units (psu) in winter and 33.3 and 33.9 psu in summer,

and generally increased with depth (MBC 2007a).

3.3.1.3 Tides and Currents

Tides in southern California are classified as mixed, semi-diurnal, with two unequal high tides (high

water and higher high water) and two unequal low tides (low water and lower low water) each lunar day

(approximately 24.5 hr). Between 1997 and 2002, water level extremes in Outer Los Angeles Harbor

ranged from -0.6 m to +2.35 m (-1.97 ft to + 7.71 ft) above MLLW.

Circulation patterns in the Ports of Los Angeles and Long Beach, which comprise the greater source

water area for HGS, were described in a study of suspended sediment transport in the Harbor region

(LACTSF 2005). The ports are protected from incoming waves by the Federal Breakwall, which consists

of three individual rock jetty structures. In addition to protecting the ports from waves, the Federal

Breakwall reduces the exchange of the water between the harbor and the rest of San Pedro Bay, hence

creating unique tidal circulation patterns.

Maximum flood and ebb current patterns in the Ports of Los Angeles and Long Beach under typical tidal

conditions are shown on Figure 3.3-2. The tidal currents shown on the figures were predicted by a depthaveraged two-dimensional hydrodynamic model, RMA2, developed by the U.S. Army Corps of
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Engineers (USACE). The model was calibrated against field data collected by the National Oceanic and

Atmospheric Administration (NOAA) at the Port of Long Beach, as well as against a more sophisticated

three-dimensional model. On the Long Beach side nearest Alamitos Bay, flood currents enter the harbor

throughtheQueen’sGate,aswellastheopeningneartheeasterntipoftheFederalBreakwall.Flood

currents passingthroughQueen’sGateflowtoeithersideofPierJ.

During ebb tide, the flow in the harbor is drawn from all directions toward the exits through the

breakwater.EbbcurrentsleavingtheLosAngelesHarborflowmainlythroughtheAngel’sGate.Onthe

LongBeachside,ebbcurrentsexiteitherthroughtheQueen’sGateortheeasternopeningpassingthetip

of the Federal Breakwall. Tidal currents within the Ports of Los Angeles and Long Beach are generally

very small. Typical maximum tidal currents within the harbor are less than 0.15 m/second (0.5 ft/second).

TidalcurrentsenteringandexitingAngel’sGateandQueen’sGatearehigher,butarestillingeneralless

than 0.24 m/second (0.8 ft/second). Significant offshore flows from flood control channels can also occur

during winter storms.

3.3.2 Source Water Definition

The source water study area is designed to 1) characterize the larvae of ichthyoplankton and shellfish

larvae potentially entrained by the HGS cooling water intake, and 2) be representative of the nearshore

habitats in the vicinity of the HGS intake.

3.3.2.1 Study Requirements and Rationale

The primary approach for assessing the effects of entrainment by the HGS requires an estimate of the

source water population for each species entrained. The spatial extent of the source water population

subject to entrainment is a function of larval duration and circulation. Information on larval duration is

estimated from data on the length of the larvae collected from the entrainment samples. Information on

circulationwithintheLosAngelesHarborComplex(“HarborComplex”)wascollectedfrom several

sources (McGehee et al. 1989a; McGehee et al. 1989b; Vemulakonda and Butler 1990; Vemulakonda et

al. 1991; Seabergh et al. 1994; Moffatt & Nichol and Reed Int. 2001; USACE 1992; LACSTF 2005)

during the initial phases of the study to determine the need for additional current meter data to determine

the extent of the source water. The following points summarize the information on currents in the ILAH

from the sources reviewed:

 Currents in the Harbor Complex are primarily driven by tides and to a lesser extent by winds.

 Tidal circulation in the Harbor Complex is far more important than any weak vertical circulation

associated with salinity stratification and inflow effects. Currents are stronger in the outer harbor

than in the Harbor Complex.

 Tidal dispersion is likely a major avenue for transport of planktonic larvae when the net current

flow is slight.

This information was used to determine that a reasonable estimate of the source water was possible using

existing bathymetry, current meter and model data to characterize the general current and circulation

patterns in the vicinity of HGS and Harbor Complex. Due to the low current velocities and highly variable

currents within the Harbor Complex, a more accurate estimate of the source populations would require
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current measurements at multiple locations combined with the use of a numerical model or analysis of

tidal dispersion.
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Figure 3.3-2. Current patterns in Los Angeles and Long Beach Harbors predicted by a depth-averaged

two-dimensional hydrodynamic model developed by the USACE.

Los Angeles/Long Beach Harbors

Flood Tide Current Simulation

Los Angeles/Long Beach Harbors

Ebb Tide Current Simulation

HGS

HGS

Angel’sGate

Queen’sGate

Federal Breakwall

Federal Breakwall

Pier J
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Because the limits of larval transport may primarily result from mechanisms other than currents (e.g.,

tidal dispersion), a first-order analysis appears sufficient for defining source water inside the breakwaters.

There is slight net circulation through the U-channel comprised of the Los Angeles Main Channel, East

Basin Channel, Cerritos Channel, and Long Beach Channel. Net plankton transport into the Slip 5 region

of the HGS intake thus occurs mainly by dispersive processes combined locally with HGS CWIS water

withdrawals. The distance from the outer harbor breakwaters to HGS is 6.48.0 km (45 mi) depending

on the direction, east or west. About half of that distance is restricted to smaller width inner harbor

channels.

The first order analysis justifies the use of the outer breakwater as the source water boundary. If only

advection were considered, a typical larval duration of 30 days would require an advection-only net

circulation of 3.0 mm per second (0.01 ft/s) to reach HGS from the outer breakwaters. Vemulakonda et al.

(1991) concluded that the magnitude of net circulation is rather slight to static and most likely clockwise.

Modeling done for the Harbor Complex by Moffatt & Nichol and Reed International (2001) also showed

clockwise circulation. The data from Vemulakonda et al. (1991) showed that net velocity was very low,

0.5 mm per second (0.00174 ft/s), and at that rate it would take 175 days to reach HGS from the San

Pedro breakwater. However, if other processes are included, the transport duration is lessened

considerably. In additional to shear flow dispersion, Fischer et al. (1979) suggested that tidal pumping

and tidal trapping can be important transport mechanisms. Jay and Largier (2004) also describe tidal

pumping as important determinants in a study to determine the source volume at South Bay Power Plant

in San Diego Bay. For example, based on data from Fischer et al. (1979) shear flow effects may increase

the estimated speed of larval dispersion, lessening time to travel the distance along the Main Channel and

Slip 5 considerably. Dispersion coefficients in estuaries such as San Diego Bay are typically much higher.

Other constituents of tidal dispersion such as those due to curvature were considered there. Therefore,

tidal transport of larvae would occur quickly in the stronger outer harbor currents and other processes

would add to net advection in the inner channels

In summary, there is sufficient information available to define the boundaries of the source water for the

HGS as the waters of the Harbor Complex that are enclosed by the San Pedro Breakwater and Middle

Breakwater, including an imaginary line extending from the easternmost edge of the Middle Breakwater

to the southeast corner of Pier J (Figure 3.3-3).. The past 316(b) study (IRC 1981) concluded that the

ILAH is the primary source of cooling water for the plant and that the waters of the outer harbor, and

even the waters of San Pedro Bay, exchange water with the inner harbor over a time scale of weeks. This

time period is consistent with the upper limits of larval durations for the species that were collected

during both this and the previous 316(b) studies.

3.3.2.2 Methods for Calculating HGS Source Water

All of the depths and elevations used for determining source water volumes and planimetric surface areas

for the Harbor Complex were relative to mean sea level (MSL) as measured at the tide gauge at Station

9410660 Los Angeles, CA. A coastline Geographic Information System (GIS) layer of the source water

was created from a U.S. Geological Survey (USGS) topographic chart at 1:24,000 scale and manually

edited in ArcGIS to approximate the available NOAA GIS coastline themes and latest aerial images from

Google Earth (March 2004) due to the new construction and landfill areas that were not present on the
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USGS coastline. This coastline GIS layer was used for representing the elevations relative to MSL for

creating a surface grid that was subsequently used to calculate areas and volumes.

Depth and elevations were derived from NOAA navigation data that included coverage for all of the

harbor and surrounding ENC Charts. Electronic Navigation Chart (ENC) Coastline information and ENC

Sounding depths were used for Harbor Complex bathymetry. The NOAA data were derived from a

combinationofchartedinformation,aswellasoriginal‘source’information.NOAAusedanumberof

sources in compiling this dataset including USACE surveys, drawings, and permits, U.S. Coast Guard

Local Notices to Mariner, National Imagery and Mapping Agency Notices to Mariners, NOAA

hydrographic surveys, and the largest scale paper chart of an area.

Depth data points were identified and selected from all the source datasets that fell within the water

portions of the source water regions for Harbor Complex. MLLW depths were adjusted to MSL

(shallower by 0.86 m [2.82 ft] per the tide gauge at Station 9410660 Los Angeles, CA). The corrected

depth data was then merged and exported to a new depth point GIS layer relative to MSL. A 20 m

(65.6 ft) surface grid representing the bathymetry relative to MSL was constructed from this new set of

combined points and contours constructed at 1.0 m (3.3 ft) intervals. This new grid was converted into a

polygon shapefile for area and volume calculations. An assumption made was that the depths in the

channels adjacent at the shoreline were deeper than MSL as a result of channelization for vessel traffic.

The resulting bathymetry surface grids were then clipped by the coastline of the source water boundary

and used for the area and volume calculations. The final calculations identified a source water volume of

431,694,503 m3.

3.3.3 Biological Resources

The following sections describe the aquatic biological habitats and communities in the vicinity of the

HGS, including both fish and invertebrate communities.

3.3.3.1 Habitat Variation

The habitats available for plants and animals within Los Angeles and Long Beach Harbors have changed

through time as a result of harbor modifications. Very little sandy beach and shallow subtidal habitats

remain, and salt marsh habitat is essentially absent within the harbor. Dredge and fill activities have

resulted in changes to the benthic (bottom) habitat. Giant kelp (Macrocystis pyrifera) grows along the

breakwaters, and eelgrass (Zostera marina) occurs in a few places in Los Angeles Harbor (Cabrillo and

Pier 300). The placement of shoreline structures, such as bulkheads, riprap, and pier pilings, has greatly

increased the hard substrate available for fouling organisms, including mussels and barnacles. A

photograph of the HGS intake structure is presented in Figure 3.3-4. The construction of the breakwaters

greatly affected water movement patterns within the harbors, which in turn affected overall circulation

and water quality.
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Figure 3.3-3. HGS source water boundaries and bathymetry.
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Figure 3.3-4. HGS intake structure near East Basin Channel in Inner Los Angeles Harbor.

3.3.3.2 Nursery Grounds

The role as a nursery grounds for juveniles of coastal fish species is probably the most widely recognized

and accepted function of bays and estuaries in their status as important fish habitats (Allen et al. 2006). In

southern California, harbors provide nearshore habitats that supplement, but do not adequately replace,

the habitats of natural bays and estuaries (Cross and Allen 1993). The subtidal areas of Los Angeles and

Long Beach Harbors provide several habitat types that support a diverse and abundant fish community.

Due to its physiography and biological assemblages, the harbor complex is also considered a nursery for

several fish species. MEC (2002) found that juvenile white croaker (Genyonemus lineatus) prefer

deepwater basins and slips within the harbor complex, although a greater variety of fish use the shallow

waters of the harbors as nursery grounds, such as bat rays (Myliobatis californica), California halibut

(Paralichthys californicus), diamond turbot (Pleuronichthys guttulatus), queenfish (Seriphus politus), and

topsmelt (Atherinops affinis).

Several features of bays and estuaries may be important to settling species, such as California halibut,

including warmer water temperatures, decreased turbulence, finer sediments, and different biological

communities compared with those on the open coast. MBC (1991) determined densities of recently settled

California halibut in southern California increased with decreasing depth. The semi-protected waters of

Queensway Bay and Outer Long Beach Harbor are also important habitats for juvenile fishes and

invertebrates. Recently transformed cheekspot goby (Ilypnus gilberti), California tonguefish (Symphurus

atricaudus), white croaker, and queenfish were the most abundant juvenile fishes collected in seasonal

surveys of Queensway Bay in 19901991 and 1994 (MBC 1994).
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3.3.3.3 Fish Diversity

The 2000 Biological Baseline Study (MEC 2002), as well as long-term monitoring data from the West

Basin (MBC 2007a) where the discharge for the plant is located, documented a fish community that

appears to have changed little in decades. The 2000 surveys of MEC (2002) used several gear types to

adequately characterize different habitat types within the harbor complex. The long-term trawl surveys in

West Basin used otter trawls, which target demersal (epibenthic) fish (MBC 2007a). In various biological

studies, more than 130 fish species have been collected within the harbor complex, with 60 to 70 of those

species commonly occurring (MEC 1988).

MEC (2002) found little variability in the abundance of pelagic, schooling fishes, between the inner and

outer harbor areas. In contrast, deepwater habitats of the outer and middle harbors generally had greater

number, biomass, and diversity of demersal fishes than inner harbor areas. However, species diversity

was generally consistent throughout the year. In 2000, a total of 76 taxa, representing 74 unique species,

was collected from the harbor complex using a combination of gear types designed to capture demersal,

pelagic, and schooling fishes. Non-indigenous species comprised about 15% of the invertebrate species

that inhabit the harbor complex.

Long-term surveys of demersal fishes and invertebrates have been conducted in the West Basin area near

the HGS discharge (MBC 2007a). At least 38 species of fishes have been collected since 1978, although

only about 14 species are collected annually. Abundance has been dominated by white croaker, northern

anchovy (Engraulis mordax), queenfish, and bay goby (Lepidogobius lepidus), which combined account

for 95% of the long-term abundance from the trawls. In 2006, abundance in summer was similar to that in

winter, and species richness was the same between surveys. The most abundant fish species collected in

2006 included white croaker, specklefin midshipman (Porichthys myriaster), California tonguefish, and

yellowchin sculpin (Icelinus quadriseriatus). White croaker was the most abundant species during both

seasons.

A similar trawl program has been conducted in Long Beach Harbor, near the Long Beach Generating

Station discharge (MBC 2007b). At least 54 species of fish have been collected since 1980, although

about 18 species are collected during each seasonal survey. Abundance has been dominated by white

croaker, northern anchovy, bay goby, and queenfish, which combined account for 94% of the long-term

abundance. In 2006, abundance in summer was substantially greater than that in winter, and species

richness was similar between surveys (19 species in winter and 21 in summer). The most abundant fish

species collected in 2006 included white croaker, yellowchin sculpin, specklefin midshipman, and

California tonguefish. In general, fish abundance is usually higher near the outer harbor in winter, and in

the inner harbor in summer, while species richness is generally highest in the inner harbor.

In 2000, 49 taxa representing 44 unique species of fish larvae and 13 categories of fish eggs were

collected from the harbor complex (MEC 2002). The most abundant fish larvae was Goby type A (arrow,

cheekspot, and shadow gobies [Clevelandia ios, Ilypnus gilberti, and Quietula y-cauda]), which

represented 33% of the total number of larvae collected. Other abundant taxa included bay goby (16%),

northern anchovy (14%), California clingfish (Gobiesox rhessodon) (13%), queenfish (10%), combtooth

blennies (Hypsoblennius spp.) (5%), and white croaker (5%). The most dominant taxa from fish eggs
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were unidentifiable eggs (57%), which likely included large numbers of California halibut eggs and

sciaenid (croaker) eggs (35%). Larval abundance was generally higher in Long Beach Harbor than Los

Angeles Harbor, which followed a similar pattern for adult fish caught in lampara nets. Sciaenid eggs

were generally more abundant in deepwater areas. Unidentified goby larvae were more abundant in

shallow areas, while bay gobies were collected in higher abundance at deepwater stations, as were most

flatfishes. Larval abundance was significantly higher in spring and summer, while peak egg abundance

occurred in winter.

3.3.3.4 Shellfish Diversity

Since 1978, a total of 5,811 macroinvertebrates representing 57 taxa have been collected in demersal fish

and invertebrate surveys in the West Basin area of the ILAH near the HGS discharge (MBC 2007a). The

most abundant macroinvertebrates were blackspotted bay shrimp (Crangon nigromaculata; 48% of total

abundance), tuberculate pear crab (Pyromaia tuberculata; 5%), New Zealand snail (Philine auriformis;

2%), and yellow crab (Cancer anthonyi; less than 1 percent). In 2006, blackspotted bay shrimp and

tuberculate pear crab comprised 92% of the annual trawl catch; both were more abundant in summer than

in winter. In the Back Channel of Long Beach Harbor, blackspotted bay shrimp comprised 78% of the

trawl-caught abundance in 32 surveys between 1980 and 2006 (MBC 2007b). Blackspotted bay shrimp

and New Zealand snail comprised 11% and 3% of the total abundance, respectively.

During the biological baseline surveys of 2000, a total of 63 epibenthic macroinvertebrate taxa

representing 61 unique species were collected throughout the harbor complex (MEC 2002). Five species

comprised 95% of total abundance: blackspotted bay shrimp (51%), tuberculate pear crab (28%), Xantus

swimming crab (Portunus xantusii; 10%), New Zealand snail (5%), and spotwrist hermit crab (Pagurus

spilocarpus; 1 percent). On average, mean abundance was higher at deep-water stations than at shallow

stations, and abundance and species richness were significantly greater in winter (February) than any

other season.

3.3.3.5 Protected Species

Some fish and invertebrate species (e.g., abalone) in southern California are protected under CDFG

regulations although few marine species are listed as either threatened or endangered. Special status fish

species that could occur in the vicinity of HGS and that have planktonic larvae potentially at risk of

entrainment include garibaldi (Hypsypops rubicundus), tidewater goby (Eucyclogobius newberryi), and

California grunion (Leuresthes tenuis).

Garibaldi, designated as the California state marine fish, is a bright orange shallow-water species that is

relatively common around natural and artificial rock reefs in southern California. Because of its territorial

behavior it is an easy target for fishers and could be significantly depleted if not protected. Garibaldi

spawn from March through October, and the female deposits demersal adhesive eggs in a nest that may

contain up to 190,000 eggs deposited by several females (Fitch and Lavenberg 1975). Larval duration

ranges from 1822 days (mean of 20 days) based on daily incremental marks on otoliths in recently

settled individuals (Wellington and Victor 1989). The larvae are susceptible to entrainment, particularly

in summer months when spawning is at its peak.
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The tidewater goby is a fish species endemic to California and is listed as federally endangered. The

tidewater goby is threatened by modification and loss of habitat resulting primarily from coastal

development. It appears to spend all life stages in lagoons, estuaries, and river mouths (Swift et al. 1989),

but may enter marine environments when flushed out of these preferred habitats during storm events.

Adults or larvae may not survive for long periods in the marine environment, but larval transport over

short distances may be a natural mechanism for local dispersal.

California grunion is a species with special status not because the population is threatened or endangered,

but because their spring-summer spawning activities on southern California beaches puts them at risk of

overharvesting, and CDFG actively manages the fishery to ensure sustainability. Spawning occurs only

three or four nights following each full or new moon, and then only for 1 to 3 hours immediately after the

high tide, from late February to early September (Love 1996). The female swims onto the beach, digs tailfirst into the wet sand, and deposits her eggs, which are then fertilized by the male. After the eggs hatch,

the larvae are carried offshore and can be susceptible to entrainment for approximately 30 days as they

develop in the plankton.

Off southern California, species managed under the Magnuson-Stevens Fishery Conservation and

Management Act are listed in the Coastal Pelagics Fishery Management Plan (FMP) and the Pacific

Groundfish FMP. The goals of the management plans include, but are not limited to: the promotion of an

efficient and profitable fishery, achievement of optimal yield, provision of adequate forage for dependent

species, prevention of overfishing, and development of long-term research plans (PFMC 1998, 2006).

There are four fish and one invertebrate species covered under the Coastal Pelagics FMP: northern

anchovy, Pacific sardine (Sardinops sagax), jack mackerel (Trachurus symmetricus), Pacific (chub)

mackerel (Scomber japonicus), and market squid (Loligo opalescens). There are 89 fish species covered

under the Pacific Groundfish FMP, including ratfish (Hydrolagus colliei), finescale codling (Antimora

microlepis), Pacific rattail (Coryphaenoides acrolepis); three species of sharks, three skates; six species of

roundfish; 62 species of scorpionfishes and thornyheads; and 12 species of flatfishes. For both the Coastal

Pelagics and Pacific Groundfish, EFH includes all waters off southern California offshore to the

Exclusive Economic Zone.
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4.0 CO O L I N G WATE R IN TA K E ST RUC T UR E ENT RAI N M EN T A N D

SO UR C E WAT E R ST U D Y

4.1 INTRODUCTION

The entrainment study incorporated two design elements: 1) CWIS sampling, and 2) source water

sampling. Sampling at the intake provided estimates of the total numbers of each larval species entrained

through the CWIS on a biweekly basis depending on pumping capacity. The source water populations of

fish and shellfish larvae were sampled to estimate proportional entrainment losses for selected species.

Abundances of larval fishes and shellfishes vary throughout the year due to changes in composition and

the oceanographic environment. Because it is desirable from an impact modeling standpoint to have a

higher resolution of temporal changes in the composition of entrained taxa than source water taxa,

entrainment sampling was conducted bi-weekly while source water sampling was conducted monthly.

The monthly source water sampling frequency was consistent with other recently completed entrainment

studies conducted for the AES Huntington Beach Generating Station (MBC and Tenera 2005), the Duke

Energy South Bay Power Plant (Tenera 2004), and the Cabrillo Power I LLC, Encina Power Station

(Tenera 2007).

The entrainment study was designed to specifically address the following questions:

 What are the species composition and abundance of the larval fishes, fish eggs, crab megalops,

and spiny lobster larvae entrained by HGS?

 What are the local species composition and abundance of the entrainable larval fishes, fish eggs,

crab megalops, and spiny lobster larvae in the ILAH and other areas of the Harbor Complex

(source water)?

 What are the potential impacts of entrainment losses on these populations due to operation of the

CWIS?

The following sections explain the entrainment study methods, quality assurance procedures, and study

results analyzed on a temporal and spatial basis in relation to power plant operation in 2006.

4.1.1 Discussion of Species to be Analyzed

Planktonic organisms in the source water body that are smaller than the CWIS traveling screen system

mesh are susceptible to entrainment. These include species that complete their entire life cycle as

planktonic forms (holoplankton) and those with only a portion of their life cycle in the plankton as eggs

or larvae (meroplankton). This study estimated entrainment effects on meroplanktonic species including

all fish eggs and larvae, and the advancedlarvalstagesofseveralinvertebrate(‘shellfish’)species

including all crabs, market squid (Loligo opalescens), and California spiny lobster (Panulirus

interruptus). None of the holoplanktonic forms (such as copepods) were enumerated because these

populations are typically widespread, the species have short generation times, and the small populationlevel impacts are difficult to accurately estimate. All target taxa in the samples were identified to the

lowest practical taxonomic level, but some specimens were combined into broader taxonomic groups

because the morphological characteristics of some species are not distinct at smaller stages, descriptions

are lacking for some of the larvae (particularly for many of the crab megalops), or specimens were
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damaged and could not be positively identified. Although all target taxa specimens were enumerated in

the samples, including uncommon species and those with no direct fishery value, detailed impact analysis

was only done for a few of the more abundant species or species-groups, in addition to the specific

shellfish taxa (e.g., spiny lobsters, market squid) regardless of abundance.

4.1.1.1 Fishes

Many of the marine fishes in the vicinity of the CWIS have free-floating larvae, with the notable

exception being surfperches, which bear well-developed live young. Planktonic larval development

promotes dispersal of the population but also puts larvae at risk of entrainment. Some groups (e.g.,

croakers, flatfishes, anchovies) broadcast eggs directly into the water column where they develop in a

free-floating state until hatching into the larval form. In this case, both eggs and larvae are potentially

susceptible to entrainment. For groups that deposit adhesive eggs onto the substrate (e.g., gobies, cottids)

or brood eggs internally until larvae are extruded (e.g., rockfishes, pipefishes), only the larvae are

potentially at risk of entrainment.

4.1.1.2 Shellfishes

“Shellfish”isageneraltermtodescribecrabs,shrimps,lobsters,clams,squids,andotherinvertebrates

that are consumedbyhumans,anditisusedtodifferentiatethisgroupoffisheryspeciesfrom“finfish”

which includes bony fishes, sharks and rays. In the present study, crabs, spiny lobsters, and market squid

were selected as representative of the shellfish species at potential risk of entrainment, some of which

have direct fishery value and others that are primarily important only as forage species for higher trophic

levels. The inclusion of certain shellfish larvae as target species, and the enumeration of only the later

stages such as megalops and phyllosomes, was a compromise between attempting to characterize the

abundance of all planktonic organisms entrained into the CWIS (a nearly impossible task) and only a few

species with commercial fishery value. In addition, only a few species have complete descriptions of their

complete larval development, which makes accurate identifications problematical and increases the

uncertainty associated with the impact analyses since they are based on broad taxonomic groupings.

Nevertheless, by including the megalops stage of all crabs in the sample identifications (e.g., hermit crabs,

porcelain crabs, shore crabs), there is some measure of the relative effects of entrainment on source

populations of some of the more abundant but lesser-known species that have planktonic larvae.

4.1.1.3 Protected Species

Larvae and eggs of some species managed under Federal, State, or Tribal Law (discussed in Section

3.3.3.5) were enumerated in entrainment samples. Most of these were represented by only a few

specimens out of the over 12,000 larvae collected during the entrainment surveys. At the January 30

meeting, NMFS agreed that demographic or ETM calculations would only be done for these species if

they were collected in sufficient abundance in entrainment and source water samples, and if sufficient life

history information was available to permit those calculations. Of five taxa on the list, only anchovies

were in sufficient abundance at HGS to justify a more detailed analysis of potential IM&E impacts.
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4.2 HISTORICAL DATA

4.2.1 Summary of Historical Data

The entrainment sampling program at HGS in 1978–1979(IRC1981)focusedonsampling‘criticaltaxa’

which provided representative information regarding the effects of the generating station on the marine

community, based upon criteria described in Federal and State 316(b) Guidelines at the time (EPA 1977).

These taxa were defined as those that supported fisheries, provided significant habitat to aquatic

communities, or constituted significant trophic links. Within this framework, critical taxa were selected

using information obtained from literature reviews, prior field experience in the region, and data collected

during sampling efforts conducted for a preliminary report. The critical taxa list for larval fishes was

reviewed by the CDFG and submitted to the LARWQCB for approval.

Zooplankton densities, including fish eggs and larvae, were measured bi-weekly at an entrainment station,

and two source water stations: a near-field and a far-field station (Figure 4.2-1). Plankton nets were used

to sample the source water stations and a high volume pump was used to sample in front of the intake

structure. The far-field station was located in outer Los Angeles Harbor and the near-field station was in

the north end of Slip 5 near the HGS intake structure. The entrainment station was located at the west end

of Slip 5 in front of the HGS intake structure.

Table 4.2-1 summarizes the entrainment densities of critical taxa recorded at the entrainment station over

the 12-month study. The mean cooling water flow rate at the generating station during sampling varied

from 200,605 to 1,502,645 m3per day (53 to 397 mgd), with a total annual flow of approximately

327,977,820 m3(86.652 billion gallons [gal]). Gobies had the greatest concentrations in the entrainment

samples with densities averaging 4,700 larvae per 1,000 m3(264,000 gallons). This translated to an

annual entrainment mortality of 520 million larvae. Entrainment estimates for all of the critical taxa

combined was approximately 700 million larvae annually, including relatively small numbers of

queenfish and diamond turbot.

Fish eggs were enumerated for three taxa: Engraulis mordax (northern anchovy), Anchoa spp. (bay

anchovies), and the Sciaenid (croaker) species complex (Table 4.2-1). Both Engraulis mordax and

Anchoa spp. eggs were relatively scarce in samples compared to densities of Sciaenid species complex

eggs. Croaker complex egg entrainment was estimated at 390 million eggs annually, while anchovy eggs

were too infrequent in the samples to calculate a reasonable estimate of annual entrainment.
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Figure 4.2-1. Locations of entrainment and near-field (top) and far-field (bottom) plankton sampling

stations in IRC (1981) study of HGS.
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Non-critical fish larvae were identified and enumerated to provide additional information about the

ichthyoplankton community, but these data were not statistically analyzed. The non-critical taxa included

Atherinopsidae species complex, Pleuronichthys spp. Sciaenidae unid. complex, and total unidentified

teleost larvae. Unidentified teleost larvae occurred in samples from 56% of the day surveys and 64% of

the night surveys. Maximum larval concentrations were observed for the period between mid-December

and mid-June and lowest values were observed from summer through mid-winter. Mean concentrations

varied from 0130 larvae per 1,000 m

3

(264,000 gal) for the day surveys and from 01,000 larvae per

1,000 m3(264,000 gal) for the night surveys. Unidentified teleost larvae occurred with greater frequency

and at greater concentrations at night.

Estimatesoflarvalconcentrationswerealsocalculatedforseveral‘critical’planktonicinvertebratetaxa,

including three species of mysid shrimps, larval rock crab, larval ghost shrimp, and the adults and larvae

of one taxon of copepod. Acartia spp. copepodites (larval stage) were the most abundant of the critical

taxa and were present year-round. These seven taxa accounted for estimated annual losses of 426.5 billion

organisms from the HGS CWIS, assuming 100% through-plant mortality.

Table 4.2-1. Summary of larval fish and fish egg densities, and annual entrainment mortality

estimates for critical taxa for HGS in 19781979 (from IRC 1981).

Taxon Common Name

Mean Day

Density

(#/1,000 m3)

Mean Night

Density

(#/1,000 m3)

Percent

Freq.

(Day)

Percent

Freq.

(Night)

Entrainment

Estimate

(# /year)

Larval Fishes

Engraulidae anchovies 60 470 76 84 1.0 x 108

Gobiidae gobies 2,190 7,220 100 100 5.2 x 108

Hypsoblennius spp. combtooth blennies 50 50 60 64 1.9 x 107

Genyonemus lineatus white croaker 120 150 40 52 5.2 x 107

Seriphus politus queenfish <10 20 12 24 

a

Pleuronichthys guttulatus diamond turbot <1  8  

a

Fish Eggs

Engraulis mordax northern anchovy <1 <1 8 12 

a

Anchoa spp. bay anchovies <10 <10 12 12 

a

Sciaenid complex croakers 1,180 970 68 60 3.9 x 108

a

annual estimate not calculated due to low densities of larvae or eggs.

A volume of 1,000 m

3

is equal to 264,000 gallons.
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Table 4.2-2. Summary of planktonic invertebrate densities and annual entrainment mortality

estimates for critical taxa for HGS in 1978 1979 (from IRC 1981).

Taxon Common Name

Mean Day

Density

(#/1,000 m3)

Mean Night

Density

(#/1,000 m3)

Percent

Freq.

(Day)

Percent

Freq.

(Night)

Entrainment

Estimate

(# /year)

Acartia spp. (adult) acopepods 1,445,600 1,892,070 100 100 2.7 x 1011

Acartia spp. (larvae) acopepods 916,610 1,166,880 100 100 1.5 x 1011

Cancer spp. (zoeae) rock crabs 13,630 48,820 100 96 3.6 x 109

Neotrypaea spp. (zoeae) ghost shrimp 920 2,510 84 84 3.0 x 108

Acanthomysis necropsis mysid shrimp 2,360 11,400 88 100 1.9 x 109

Neomysis kadiakensis mysid shrimp 110 1,280 48 96 2.3 x 108

Metamysidopsis elongata mysid shrimp 1,360 3,450 72 96 4.3 x 108

a

densities based on 202 μ net collections from JanuarySeptember 1979.

A volume of 1,000 m

3

is equal to 264,000 gallons.

The following conclusions were noted for the plankton entrainment portion of the study:

 The seasonal period of highest overall abundance occurred from January through August. An

exception to this was Acartia spp., which was abundant throughout the study and showed no real

seasonal trend. A decline in the abundance of almost all plankton taxa occurred from September

through December.

 Diel differences in abundance were significant for several plankton taxa. Mysids, Cancer spp.

zoeae, the engraulid larvae, G. lineatus larvae, and gobiid larvae were significantly more

abundant at night than during the day. The upward movement of mysids and fish larvae through

the water column at night may result in an increased susceptibility to entrainment.

 Greater numbers of larger sized engraulid and G. lineatus larvae were collected during night

sampling. For gobiid and Hypsoblennius spp., the smaller 0-5 mm size class was dominant

throughout the yearly sampling. Spawning peaks were evidenced by large influxes of small

larvae. Surveys following these peaks generally showed increasingly greater proportions of later

stage (larger) larvae.

Sciaenid species complex were the most numerous entrained fish eggs. Two species of sciaenids, G.

lineatus and S. politus dominated the species complex. Spawning of G. lineatus begins in October or

November and peaks between January and March and continues into April. Seriphus politus spawning

begins in April and continues through the summer. Egg entrainment peaked from January to April

suggesting that G. lineatus dominated the entrained eggs of the sciaenid population.

4.2.2 Relevance to Current Conditions

The historical impingement data presented in Section 4.2 is relevant for historical comparisons. During

the 1978–1979 study, the maximum cooling water flow of the HGS CWIS was 1,504,310 m3per day (397

mgd), and the average flow during the study year was 62% of maximum. Flow during the 2006 study

averaged about 185,296 m3per day (49 mgd), or 51% of current design flow, which was less than design

flow in the previous study due to the modifications to the CWIS.
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Some differences in study methods may affect the comparability of the entrainment data between the

earlier and present study. One is the use of a pump to collect samples in the earlier study in contrast to the

towed plankton nets used in the present study. Even though there may be some systematic bias in each

type of sampling method (differences in avoidance behavior, for example), the overall relative

abundances and seasonality patterns of the planktonic larvae were adequately sampled by both methods.

The earlier study used a 335μ mesh for the first seven surveys (as in the present study), but switched to a

finer 202μ mesh in later surveys, mainly to provide better estimates of Acartia spp. copepodites densities.

4.2.3 QA/QC Procedures and Data Validation

The sampling program during the 1978–1979 study was conducted with the approval of the LARWQCB,

and detailed procedures and methodologies, as well as QA/QC methods, can be found in Appendices G

(Biological Field Procedures), H (Laboratory Procedures), and I (Statistical and Analytical Procedures) of

IRC (1981).

4.3 METHODS

4.3.1 Field Sampling

4.3.1.1 Cooling-Water Intake System Entrainment Sampling

Composition and abundance of ichthyoplankton and shellfish larvae entrained by HGS were determined

by sampling in the immediate proximity of the cooling water intake every two weeks. Entrainment

samples were collected using an oblique tow through the water column at a station located just offshore

from the intake structure. The samples were collected using an oblique tow that sampled the water

column from the surface down to approximately 13 cm (6 in) off the bottom, and back to the surface. Two

replicate tows were taken at the intake with a target sample volume of 1520 m3(4,0005,300 gal) for

each net on the bongo frame. The net was redeployed if the target volume was not collected during the

initial tow. Sampling was conducted four times per 24-hour periodonce every six hours.

The wheeled bongo frame used for sampling consisted of 60 cm (2 ft) diameter net rings with plankton

nets constructed of 333 μm (0.013 in) Nitex® nylon mesh, similar to the nets used by the California

Cooperative Oceanic Fisheries Investigations (CalCOFI). Each net was fitted with a Dacron sleeve and a

plastic cod-end container to retain the organisms. Each net was equipped with a calibrated General

Oceanics 2030R flowmeter, allowing the calculation of the amount of water filtered. Coordinates of each

sampling station were determined using a differential global positioning system. At the end of each tow,

nets were retrieved and the contents of the net gently rinsed into the cod-end with seawater. Contents

were washed down from the outside of the net to avoid the introduction of plankton from the wash-down

water. Samples were then carefully transferred to pre-labeled jars with preprinted internal labels and

preserved in 410% buffered formalin-seawater.

4.3.1.2 Source Water Sampling

The configuration of the source water study area was designed to 1) characterize the larvae of

ichthyoplankton and shellfish potentially entrained by the HGS cooling water intake, and 2) represent

larval forms present in the nearshore habitats in the harbor complex in the vicinity of the HGS intake.
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To determine composition and abundance of ichthyoplankton in the source water, sampling was

conducted monthly on the same day that the entrainment station was sampled. Source water was sampled

at six stations located in the channels and inner and outer harbors of the Los Angeles and Long Beach

Harbor Complex (Figure 4.3-1).

Figure 4.3-1. Locations of the HGS entrainment and source water sampling stations.

All stations were sampled using a wheeled bongo plankton net using the same oblique tows described for

the entrainment sampling. Samples were also processed using the same procedures described for

entrainment sampling. During each source water survey, the six source water stations were sampled four

times per 24-hour period at 6-hour intervals. This interval allowed adequate time for one vessel and crew

to conduct all source water and entrainment sampling, while also partitioning samples into day-night

blocks for analysis of diel trends. During each sampling cycle, the order in which the stations were

sampled was varied to avoid introducing a systematic bias into the data. Detailed stepwise procedures are

presented in Appendix A.

4.3.2 Laboratory Analysis

Samples were returned to the laboratory and transferred from formalin to 70% ethanol after

approximately 72 hours. Samples were examined under a dissecting microscope and all fish eggs
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(entrainment samples only) and larvae were removed and placed in labeled vials, in addition, the

following shellfish larvae were also removed:

 crab megalopa;

 California spiny lobster phyllosoma; and

 market squid paralarvae (hatchlings).

The samples from the two nets were preserved in separate 400 milliliter (ml) (13.5 oz) jars and processed

separately, but the data from the two nets were combined for analysis. If the quantity of material exceeded

200 ml (6.8 oz), then the sample was split into multiple jars to ensure that the material was properly

preserved. In some cases the collection of ctenophores, salps, and other larger planktonic organisms

resulted in samples with large volumes of material, but these could be separated from other plankton with

little difficulty and were generally not split, depending upon the final volume of the material.

If the quantity of material in the two samples was very large, then only one of the two paired samples was

processed and analyzed. Specimens were enumerated and identified to the lowest practical taxon. A

representative sample of up to 50 larvae from each species for each survey (100 during the first two

surveys) was measured from the entrainment samples using a dissecting microscope and image analysis

system. If fewer than 50 individuals from a species were collected during the survey then all of the larvae

from the survey were measured. Total length was measured to an accuracy of at least 0.1 millimeter (mm)

(0.004 in).

4.3.3 QA/QC Procedures & Data Validation

A quality control (QC) program was implemented for the field and laboratory components of the study.

QC surveys were completed on a quarterly basis to ensure that the field sampling was conducted properly.

The dates of the QA/QC reviews of the entrainment field sampling were February 7, April 10, August 14,

and October 9, 2006. Prior to the start of the study, the field survey procedures were reviewed with all

personnel and all personnel were given printed copies of the procedures.

A more detailed QC program was applied to laboratory processing of all the entrainment and source water

samples. The first 10 samples sorted by an individual were resorted by a designated QC sorter. A sorter

was allowed to miss one target organism if the total number of target organisms in the sample was less

than 20. For samples with 20 or more target organisms the sorter was required to maintain a sorting

accuracy of 90 percent. After a sorter completed 10 consecutive samples with greater than 90% accuracy,

the sorter had one of their next 10 samples randomly selected for a QC check. If the sorter failed to

achieve an accuracy level of 90%, then their next 10 samples were resorted by the QC sorter until they

met the required level of accuracy. If the sorter maintained the required level of accuracy, random QC

checks resumed at the level of one sample checked per ten sorted.

A similar QC program was conducted for the taxonomists identifying the samples. The first 10 samples of

fish or shellfish identified by an individual taxonomist were completely re-identified by a designated QC

taxonomist. A total of at least 50 individual fish or shellfish larvae from at least five taxa must have been

present in these first ten samples. If not, additional samples were re-identified until this criterion was met.

Taxonomists were required to maintain a 95% identification accuracy level in these first 10 samples.
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After the taxonomist identified ten consecutive samples with greater than 95% accuracy, they had one of

their next 10 samples checked by a QC taxonomist. If the taxonomist maintained an accuracy level of

95%, then they continued to have one of each 10 samples checked by a QC taxonomist. If one of the

checked samples fell below the minimum accuracy level, then 10 more consecutive samples were

identified by the QC taxonomist until 10 consecutive samples met the 95% criterion. Identifications were

cross-checked against taxonomic voucher collections maintained by MBC and Tenera Environmental, and

specialists were consulted for problem specimens.

Occasionally, outside experts were consulted to assist in the identification of the fish eggs. Due to the

large overlap in diagnostic characteristics of several species of fishes in the egg and early embryo stages,

egg identification can be highly subjective and therefore no QC program was conducted to verify the egg

identification.

4.3.4 Data Analysis

4.3.4.1 Entrainment Estimates

Estimates of daily larval entrainment for the sampling period from January through December 2006 at

HGS were calculated from data collected at the entrainment station and data on daily cooling water flow

from the power plant. Estimates of average larval concentration for the day when entrainment samples

were collected were extrapolated across the days between surveys to calculate total entrainment during

the days when no samples were collected. The total estimated daily entrainment for the survey periods

and across the entire year were then summed to obtain estimates of total survey and annual entrainment,

respectively. The annual entrainment estimates, in conjunction with demographic data collected from the

fisheries literature, were used in modeling CWIS effects using adult equivalent loss (AEL) and fecundity

hindcasting (FH) models. Data for the same target taxa from sampling of the entrained larvae and

potential source populations of larvae was used to calculate estimates of proportional entrainment (PE)

that were used to estimate the probability of mortality (PM) due to entrainment using the ETM. Each

approach (e.g., AEL, FH, and ETM), as appropriate for each target taxon, was used to assess effects of

power plant losses. Parameters of the models used in the analyses are detailed in Appendix B.

All of the modeling approaches require an estimate of the age of the larvae being entrained. The

demographic approaches extrapolate estimates from the average age at entrainment, while the ETM

requires an estimate of the period of time that the larvae are exposed to entrainment. These estimates were

obtained by measuring a representative number of larvae of each of the target taxa from the entrainment

samples and using published larval growth rates. Although a large number of larvae may have been

collected and measured from entrainment samples, a random sample of 200 from the total measurements

was used to calculate the average age at entrainment and total larval duration. The average age at

entrainment was calculated by dividing the difference between the size at hatching and the average size of

the larvae from entrainment by a larval growth rate obtained from the literature. The period of time that

the larvae were exposed to entrainment was calculated by dividing the difference between the size at

hatching and the size at the 95th percentile by a larval growth rate obtained from the literature. The

duration of the egg stage was added to this value for species with planktonic eggs. The 95th percentile

value was used to eliminate outliers from the calculations. The size at hatching was estimated as follows:

Hatch Length = Median Length –((Median Length –1

st Percentile Length)/2).
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This calculated value was used because of the large variation in size among larvae smaller than the

average length that approximates the value of the 25th percentile used in other studies as the hatch length.

This calculation assumes that the length frequency distribution is skewed towards smaller sized larvae and

usually resulted in a value close to the hatch size reported in the literature. The length frequency

distributions for anchovies and yellowfin gobies did not follow this pattern and a hatch size calculated as

above resulted in a large value that far exceeded reported hatch sizes. Therefore the length of the 10th

percentile of the distribution was used as the hatch length for these two taxa to eliminate outlier values.

4.3.4.2 Demographic Approaches

AEL models evolved from impact assessments that compared power plant losses to commercial fisheries

harvests and/or estimates of the abundance of adults. In the case of adult fishes impinged by intake

screens, the comparison was relatively straightforward. To compare the numbers of impinged sub-adults

and juveniles and entrained larval fishes to adults, it was necessary to convert all these losses to adult

equivalents. Horst (1975) and Goodyear (1978) provided early examples of the equivalent adult model

(EAM) to convert numbers of entrained early life stages of fishes to their hypothetical adult equivalency.

Demographic approaches, exemplified by the EAM, produce an absolute measure of loss beginning with

simple numerical inventories of entrained or impinged individuals and increasing in complexity when the

inventory results are extrapolated to estimate numbers of adult fishes or biomass. Two different, but

related, demographic approaches were used in assessing entrainment effects at HGS: AEL, which

expresses effects as absolute losses of numbers of adults, and FH, which estimates the number of adult

females at the age of maturity (age at which 50% of the females are mature) whose reproductive output

has been eliminated by entrainment of larvae.

Age-specific survival and fecundity rates are required for AEL and FH. AEL estimates require

survivorship estimates from the age at entrainment to adult recruitment; FH requires egg and larval

survivorship up to the age of entrainment plus estimates of fecundity. Furthermore, to make estimation

practical, the affected population is assumed to be stable and stationary, and age-specific survival and

fecundity rates are assumed to be constant over time. Each of these approaches provides estimates of

adult fish losses, which ideally need to be compared to standing stock estimates of adult fishes.

Species-specific survivorship information (e.g., age-specific mortality) from egg or larvae to adulthood is

not available for many of the taxa collected during the study. These rates, when available, were inferred

from the literature. Uncertainty surrounding published demographic parameters is seldom known and

rarely reported, but the likelihood that it is very large needs to be considered when interpreting results

from the demographic approaches for estimating entrainment effects. For some well-studied species (e.g.,

northern anchovy), portions of early mortality schedules and fecundity have been reported. Because the

accuracy of the estimated entrainment effects from AEL and FH will depend on the accuracy of agespecific mortality and fecundity estimates, lack of demographic information may limit the utility of these

approaches.

The precursor to the AEL and FH calculations is an estimate of total annual larval entrainment. Estimates

of larval entrainment at HGS were based on bi-weekly sampling where ET is the estimate of total

entrainment for the study period and Ei is the entrainment estimate for the individual survey periods.
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Estimates of entrainment for the study period were based on two-stage sampling designs, with days

within surveys, and cycles (four six-hour collection periods per day) within days. The within-day

sampling was based on a stratified random sampling scheme with four temporal cycles and two replicates

per cycle. Estimates of variation for each survey were computed from the four temporal cycles.

There were usually no estimates of variation available for the life history information used in the models.

The ratio of the mean to standard deviation (coefficient of variation) was assumed to be 50% for all life

history parameters used in the models.

Fecundity Hindcasting (FH)

The FH approach compares larval entrainment losses with adult fecundity to estimate the amount of adult

female reproductive output eliminated by entrainment, hindcasting the numbers of adult females at the

age of maturity effectively removed from the reproductively active population. The accuracy of these

estimates of effects is dependent upon accurate estimates of age-specific mortality from the egg and early

larval stages to entrainment and accurate estimates of the total lifetime female fecundity. If it can be

assumed that the adult population has been stable at some current level of exploitation and that the male

to female ratio is constant and 50:50, then fecundity and mortality are integrated into an estimate of the

loss of adults at the age of maturity by converting entrained larvae back into females (e.g., hindcasting)

and multiplying by two allowing a comparison of the estimate with the AEL model.

A potential advantage of FH is that survivorship need only be estimated for a relatively short period of the

larval stage (e.g., egg to larval entrainment). The model requires age-specific mortality rates and

fecundities to estimate entrainment effects and some knowledge of the abundance of adults to assess the

fractional losses these effects represent. This method assumes that the loss of the reproductive potential of

a single female at the age of maturity is equivalent to the loss of two adult fish at the age of maturity,

assuming a 50:50 male to female ratio.

In the FH approach, the total larval entrainment for a species, ET, was projected backward from the

average age at entrainment to estimate the number of females at the age of maturity (age at which 50% of

the females are mature) that would produce over their lifetime the numbers of larvae seen in the

entrainment samples. The estimated number of breeding females at the age of maturity, FH, whose

fecundity is equal to the total loss of entrained larvae was calculated as follows:

1

T

n

j

j

E

FH

TLF S





 (1)

where:

ET = total entrainment estimate;

Sj = survival rate from eggs to entrained larvae of the j

th stage ; and

TLF = average total lifetime fecundity for females, equivalent to the average number of eggs

spawned per female over their reproductive years.
Harbor Generating Station CWIS Entrainment and

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The two key input parameters in Equation 1 are total lifetime fecundity TLF and survival rates Sj from

spawning to the average age at entrainment. The average age at entrainment was estimated from lengths

of a representative sample of larvae measured from the entrainment samples. Descriptions of these

parameters may be limited for many species and are a possible limitation of the method. TLF was

estimated in these studies using survivorship and fecundity tables that account for changes in fecundity

with age. The fecundity data used in calculating TLF is described below for each taxon.

Adult Equivalent Loss (AEL)

The AEL model uses estimates of the abundance of the entrained or impinged organisms to project the

loss of equivalent numbers of adults based on mortality schedules and age-at-recruitment. The primary

advantage of this approach is that it translates power plant-induced early life-stage mortality into numbers

of adult fishes, which is the life-stage most relevant to resource managers. AEL does not require source

water estimates of larval abundance in assessing effects. This latter advantage may be offset by the need

to gather age-specific mortality rates to predict adult losses and the need for information on the adult

population of interest for estimating population-level effects (i.e., fractional losses).

Starting with the number of age class j larvae entrained Ej, it is conceptually easy to convert these

numbers to an equivalent number of adults lost AEL at some specified age class from the formula:

1

n

j j

j

AEL E S



 (2)

where:

n = number of age classes from the average age at entrainment to adult recruitment;

Ej = estimated number of larvae lost in age class j; and

Sj = survival probability for the j th class to adulthood (Goodyear 1978).

Age-specific survival rates from the average age at entrainment to the age at first maturity must be

included in this assessment method. The age at first maturity, when 50% of the females are mature, was

used in the AEL extrapolations so the FH and AEL models are extrapolated to the same age and can be

compared using the equivalency that 2FH≈AEL. We used a modified form of Equation 2 where the total

entrainment was used having an average age a:

n

T j

j a

AEL E S



  (3)

where:

ET = annual estimate of larvae lost in all age classes.
Harbor Generating Station CWIS Entrainment and

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The average age at entrainment was estimated from lengths of a representative sample of larvae as

described above. For some commercial species, natural survival rates are known after the fish recruit into

the commercial fishery. For the earlier years of development, this information is not well known for

commercial species and may not exist for some non-commercial species.

4.3.4.3 Empirical Transport Model (ETM)

As an alternative to the demographic models described above, the ETM was proposed by the USFWS to

estimate mortality rates resulting from circulating water withdrawals by power plants (Boreman et al.

1978, and subsequently in Boreman et al. 1981). The ETM model provides an estimate of the incremental

(a conditional estimate in absence of other mortality, Ricker 1975) mortality imposed by HGS on local

Los Angeles Harbor Complex larval populations by using empirical data (plankton samples), rather than

relying solely on hydrodynamic and demographic calculations. Consequently, ETM requires an additional

level of field sampling to characterize the abundance and composition of source water larval populations.

The fractional loss to the source water population represented by entrainment is provided by estimates of

PE for each survey that can then be expanded to predict regional effects on appropriate adult populations

using ETM, as described below. ETM calculations were based on actual and design (maximum) cooling

water flows and a sampling volume of 431,694,503 m3.

Variations of this model have been discussed in MacCall et al. (1983) and have been used to assess

impacts at a southern California power plant (Parker and DeMartini 1989). The ETM has also been used

to assess impacts at the Salem Nuclear Generating Station in Delaware Bay, New Jersey (PSE&G 1993)

as well as other power stations along the East Coast. Empirical transport modeling permits the estimation

of conditional mortality due to entrainment, while accounting for the spatial and temporal variability in

distribution and vulnerability of each life stage to power plant withdrawals. The modeling approach

described below uses a PE approach that is similar to the method described by MacCall et al. (1983) and

used by Parker and DeMartini (1989) in their final report to the California Coastal Commission (Murdoch

et al. 1989a) for the San Onofre Nuclear Generating Station.

The general equation to estimate PE for a day on which entrainment was sampled is:

Ei

i

Si

N

PE

N



where:

estimated average number of larvae entrained during the day in survey i, calculated as

(estimated density of larvae in the water entrained that day) (average daily cooling flow

vo

NEi 



lume during the survey period),

estimated number of larvae in the source water that day in survey i (estimated density

of larvae in the souce water that day) (source water volume).

NSi 


Harbor Generating Station CWIS Entrainment and

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The PEi value represents the effects of a number of processes operating over a day and is estimated for

each survey. Since actual cooling water flow was used in calculating entrainment estimates, the PEi

estimate was calculated using the average daily cooling water flow over each entrainment survey period,

an approximate period of two weeks.

If larval entrainment mortality is constant throughout the period and a larva is susceptible to entrainment

over d days, then the proportion of larvae that escape entrainment in survey i is:

(1 )d PE

Larval duration from hatching to entrainment was calculated as described above.

The surveys in each study period were used to estimate larval mortality (PM) due to entrainment using the

following equation:

12

1

1 (1 )d

M i i

i

P f PE



   (4)

where:

estimate of proportional entrainment for the th survey,

proportion of the total annual source water population present during the th survey, and

the estimated number of days the larvae are

i

i

PE i

f i

d





 exposed to entrainment.

To establish independent survey estimates, it is assumed that during each survey a new and distinct cohort

of larvae is subject to entrainment. Each of the surveys was weighted by fi and estimated as the proportion

of the total annual source water population present during each ith survey period. For each study period,

the sum of the proportions equals one:

1

1

and 1.

n

S

i i n

i

S i

i

N

f f

N





  



The estimate of the population-wide probability of entrainment (PE) is the central feature of the ETM

approach (Boreman et al. 1981; MacCall et al. 1983). If a population is stable and stationary, then PM also

estimates the effects on the fully-recruited adult age classes when uncompensated natural mortality from

larva to adult is assumed.

Assumptions associated with the estimation of PM include the following:

 The samples at each survey period represent a new and independent cohort of larvae;

 The estimates of larval abundance for each survey represent a proportion of total annual larval

production during that survey;

 The conditional probability of entrainment PEiis constant within survey periods; and

 Lengths and applied growth rates of larvae accurately estimate larval duration.
Harbor Generating Station CWIS Entrainment and

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The variance calculations associated with PM only include the error directly associated with the sampling

in the PEi and was calculated using the average coefficient of variation (CV) (the ratio of the standard

deviation to the mean) from the estimates of PEi as follows:

Var P CV P ( ) ( /100) M M  PE .

This estimate does not include the error associated with the estimates of PS, the larval duration, and

source water, entrainment, and outflow volumes. It also does not account for the variance across the days

within a survey period. The sources of variation included in the estimate represent the sampling error and

natural variation of the entrainment and source water populations.

4.4 SAMPLING SUMMARY

A total of 26 surveys were conducted at the entrainment station between January 10 and December 18,

2006 (Table 4.4-1). Sampling efforts alternated between surveys where only entrainment samples were

collected and surveys where both entrainment and source water samples were collected. A total of 408

entrainment samples and 576 source water samples were processed for data analysis.

Table 4.4-1. Entrainment and source water surveys and number of samples

collected from January through December 2006.

Entrainment Samples Source Water Samples

Survey

Number Date

Number

Collected

Number

Processed

Number

Collected

Number

Processed

HGSEA01 1/10/06 16 16  

HGSEA02 1/23/06 16 16 48 48

HGSEA03 2/7/06 16 16  

HGSEA04 2/21/06 16 16 48 48

HGSEA05 3/8/06 16 15 a  

HGSEA06 3/20/06 16 16 48 48

HGSEA07 4/3/06 16 16  

HGSEA08 4/17/06 16 16 48 48

HGSEA09 5/1/06 16 16  

HGSEA10 5/15/06 16 16 48 48

HGSEA11 5/30/06 16 16  

HGSEA12 6/12/06 16 16 48 48

HGSEA13 6/26/06 16 16  

HGSEA14 07/12/06 16 16 48 48

HGSEA15 07/24/06 16 15 a  

HGSEA16 08/07/06 16 16 48 48

HGSEA17 08/21/06 16 16  

HGSEA18 09/05/06 16 14 b48 48

HGSEA19 09/18/06 16 16  

HGSEA20 10/02/06 16 16  

HGSEA21 10/16/06 16 16 48 48

HGSEA22 10/30/06 16 16  

HGSEA23 11/13/06 16 16 48 48

(table continued)
Harbor Generating Station CWIS Entrainment and

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Table 4.4-1 (continued). Entrainment and source water surveys and number of samples

collected from January through December 2006.

Entrainment Samples Source Water Samples

Survey

Number Date

Number

Collected

Number

Processed

Number

Collected

Number

Processed

HGSEA24 11/29/06 16 16  

HGSEA25 12/11/06 16 16 48 48

HGSEA26 12/26/06 12 c12  

412 408 576 576

a

One sample from Station E1 not preserved properly and could not be processed.

b

Two samples were lost (spilled) in transit (Stations H4 & H5).

c

One complete cycle (4 samples) was not collected due to adverse sea conditions.

4.5 RESULTS

4.5.1 Cooling Water Intake Structure Entrainment Summary

4.5.1.1 Fishes

A total of 8,692 larval fishes representing 48 taxa was collected from the HGS entrainment station (E1)

during 26 bi-weekly surveys in 2006 (Table 4.5-1 and Appendix C). In addition, 14,845 fish eggs from 10

taxa were enumerated in the 408 entrainment samples. Unidentified gobies (Clevelandia, Ilypnus,

Quietula [CIQ] goby complex), yellowfin goby, white croaker, and bay goby were the four most abundant

taxa and comprised nearly 90% of all specimens collected. The greatest concentrations of larval fishes

occurred during March 2006 and the fewest occurred in September (Figure 4.5-1). Fish eggs had a peak in

abundance in late February prior to the peak abundance of fish larvae (Figure 4.5-2). Fish eggs also had

increased abundances in early June that did not appear to be reflected in the larval concentrations. Larvae

tended to be more abundant in samples collected at night than those collected during the day, although

daytime collections occasionally yielded higher concentrations (Figure 4.5-3). As expected, there was less

difference between day and night concentrations of fish eggs (Figure 4.5-4), which act as passive particles

and would be unable to vertically migrate through the water column or exhibit net avoidance, as can occur

with developmentally advanced larvae. Damaged larval fishes that could not be positively identified

comprised 1.0% of the total catch. Total annual entrainment was estimated to be 65.30 million fish larvae

and 99.88 million fish eggs during 2006 using the HGS CWIS actual flows (Table 4.5-2). Using the

design (or maximum capacity) CWIS flows, the total annual entrainment was estimated to be 153.33

million larvae and 269.42 million eggs (Table 4.5-2). Commercially and recreationally important taxa

comprised 16.7% of the total larvae collected.
Harbor Generating Station CWIS Entrainment and

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Table 4.5-1. Average concentration of larval fishes and fish eggs in entrainment samples

collected at HGS (Station E1) in 2006.

Taxon Common Name

Avg. Conc.

(per 1,000 m3) Total Count

Percentage of

Total

Cumulative

Percentage

Larval Fish

Gobiidae unid. CIQ gobies 516.10 4,340 49.32 49.32

Acanthogobius flavimanus yellowfin goby 263.17 2,068 25.15 74.47

Genyonemus lineatus white croaker 125.26 1,090 11.97 86.44

Lepidogobius lepidus bay goby 34.02 294 3.25 89.70

Hypsoblennius spp. combtooth blennies 29.63 239 2.83 92.53

Sciaenidae unid. croakers 19.36 161 1.85 94.38

Engraulidae unid. anchovies 13.97 114 1.33 95.71

unidentified larvae, damaged unidentified damaged larvae 10.51 90 1.00 96.72

unidentified larvae, yolksac unidentified yolksac larvae 4.58 37 0.44 97.15

Gillichthys mirabilis longjaw mudsucker 3.70 38 0.35 97.51

Gobiesocidae unid. clingfishes 3.49 28 0.33 97.84

Icelinus spp. sculpins 2.93 25 0.28 98.12

Paralichthys californicus California halibut 2.83 25 0.27 98.39

Paralabrax spp. sea basses 1.96 16 0.19 98.58

Cheilotrema saturnum black croaker 1.45 13 0.14 98.72

Seriphus politus queenfish 1.23 10 0.12 98.84

Gibbonsia spp. clinid kelpfishes 1.17 9 0.11 98.95

Leptocottus armatus Pacific staghorn sculpin 1.13 8 0.11 99.06

Semicossyphus pulcher California sheephead 1.01 8 0.10 99.15

Rhinogobiops nicholsii blackeye goby 0.96 8 0.09 99.24

larval/post-larval fish unid. larval fishes 0.79 7 0.08 99.32

Citharichthys spp. sanddabs 0.76 6 0.07 99.39

Clinocottus spp. sculpins 0.67 10 0.06 99.46

Pleuronichthys guttulatus diamond turbot 0.61 6 0.06 99.52

Pleuronichthys spp. turbots 0.50 4 0.05 99.56

Labrisomidae unid. labrisomid blennies 0.47 4 0.05 99.61

Oxyjulis californica senorita 0.37 3 0.04 99.64

Pleuronectidae unid. righteye flounders 0.36 3 0.03 99.68

Ruscarius creaseri roughcheek sculpin 0.32 3 0.03 99.71

Pleuronectiformes unid. flatfishes 0.25 2 0.02 99.73

Clupeidae unid. herrings 0.25 2 0.02 99.76

Orthonopias triacis snubnose sculpin 0.23 2 0.02 99.78

Lythrypnus zebra zebra goby 0.23 2 0.02 99.80

Cottidae unid. sculpins 0.21 2 0.02 99.82

Sardinops sagax Pacific sardine 0.20 2 0.02 99.84

Typhlogobius californiensis blind goby 0.19 1 0.02 99.86

Roncador stearnsii spotfin croaker 0.14 1 0.01 99.87

Merluccius productus Pacific hake 0.14 1 0.01 99.89

Syngnathus spp. pipefishes 0.14 1 0.01 99.90

Paralichthyidae unid. sand flounders 0.14 1 0.01 99.91

Girella nigricans opaleye 0.13 1 0.01 99.93

(table continued)
Harbor Generating Station CWIS Entrainment and

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Table 4.5-1 (continued). Average concentration of larval fishes and fish eggs in

entrainment samples collected at HGS (Station E1) in 2006.

Taxon Common Name

Avg. Conc.

(per 1,000 m3) Total Count

Percentage of

Total

Cumulative

Percentage

Larval Fish

Pleuronichthys verticalis hornyhead turbot 0.13 1 0.01 99.94

Chitonotus / Icelinus sculpins 0.13 1 0.01 99.95

Artedius spp. sculpins 0.12 1 0.01 99.96

Bathymasteridae unid. ronquils 0.11 1 0.01 99.97

Atherinopsidae unid. silversides 0.10 1 0.01 99.98

Bathylagidae unid. blacksmelt 0.10 1 0.01 99.99

Lythrypnus spp. gobies 0.08 1 0.01 100.00

1,046.36 8,692

Fish Eggs

fish eggs unid. unidentified fish eggs 878.99 6,922 48.52 48.52

Sciaenidae unid. croaker eggs 283.99 2,334 15.68 64.20

Genyonemus lineatus white croaker eggs 281.18 2,560 15.52 79.72

Paralichthyidae unid. sand flounder eggs 207.24 1,683 11.44 91.16

Sciaenidae/Paralich./Labridae SPL fish eggs 78.00 616 4.31 95.46

Citharichthys spp. sanddab eggs 35.52 317 1.96 97.42

Pleuronichthys spp. turbot eggs 20.11 167 1.11 98.53

Paralichthys californicus California halibut eggs 13.20 139 0.73 99.26

Engraulidae unid. anchovy eggs 13.08 106 0.72 99.98

Atherinopsidae unid. silverside eggs 0.27 1 0.01 100.00

1,811.60 14,845
Harbor Generating Station CWIS Entrainment and

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Table 4.5-2. Calculated total annual entrainment of larval fishes and fish eggs at HGS in 2006

based on actual and design (maximum) cooling water intake pump flows.

Taxon Common Name

Annual

Entrainment

(Actual Flows)

Annual

Entrainment

(Design Flows)

Larval Fish

Gobiidae unid. gobies 33,290,815 75,938,007

Acanthogobius flavimanus yellowfin goby 15,407,999 37,604,336

Genyonemus lineatus white croaker 7,164,843 18,777,752

Lepidogobius lepidus bay goby 2,376,260 5,070,071

Hypsoblennius spp. combtooth blennies 2,255,907 4,362,576

Sciaenidae unid. croakers 995,438 2,856,932

Engraulidae unid. anchovies 940,784 2,068,979

unidentified fish, damaged unidentified damaged fish 646,175 1,571,226

larvae, unidentified yolksac unidentified yolksac larvae 288,308 679,015

Gillichthys mirabilis longjaw mudsucker 254,865 558,887

Gobiesocidae unid. clingfishes 236,654 515,917

Icelinus spp. sculpins 190,484 446,021

Paralichthys californicus California halibut 165,782 424,529

Paralabrax spp. sand bass 122,010 271,192

Cheilotrema saturnum black croaker 94,525 200,992

Seriphus politus queenfish 83,731 176,487

Gibbonsia spp. clinid kelpfishes 77,308 173,122

Rhinogobiops nicholsii blackeye goby 71,631 145,314

Leptocottus armatus Pacific staghorn sculpin 68,768 160,195

Semicossyphus pulcher California sheephead 64,438 141,346

larval/post-larval fish unid. larval fishes 58,152 119,578

Clinocottus spp. sculpins 55,826 112,731

Citharichthys spp. sanddabs 41,222 115,405

Pleuronichthys spp. turbots 36,951 73,078

Pleuronichthys guttulatus diamond turbot 36,799 93,021

Labrisomidae unid. labrisomid blennies 29,483 71,609

Oxyjulis californica senorita 24,673 52,620

Pleuronectidae unid. righteye flounders 23,120 52,521

Ruscarius creaseri roughcheek sculpin 20,616 50,242

Pleuronectiformes unid. flatfishes 16,347 40,493

Cottidae unid. sculpins 15,756 31,607

Lythrypnus zebra zebra goby 14,795 34,416

Syngnathus spp. pipefishes 14,250 20,766

Orthonopias triacis snubnose sculpin 13,806 32,367

Sardinops sagax Pacific sardine 11,836 29,933

Artedius spp. sculpins 10,653 17,916

Typhlogobius californiensis blind goby 10,523 26,455

Clupeidae unid. herrings 8,864 36,966

Roncador stearnsii spotfin croaker 8,735 21,531

(table continued)
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Table 4.5-2 (continued). Calculated total annual entrainment of larval fishes and fish eggs at HGS

in 2006 based on actual and design cooling water intake pump flows.

Taxon Common Name

Annual

Entrainment

(Actual Flows)

Annual

Entrainment

(Design Flows)

Larval Fish

Pleuronichthys verticalis hornyhead turbot 8,693 19,596

Merluccius productus Pacific hake 8,421 19,741

Girella nigricans opaleye 7,894 19,963

Bathylagidae unid. blacksmelt 6,622 14,928

Lythrypnus spp. gobies 6,249 11,481

Bathymasteridae unid. ronquils 5,843 14,511

Paralichthyidae unid. sand flounders 1,926 20,449

Chitonotus / Icelinus sculpins 1,798 19,097

Atherinopsidae unid. silversides 1,422 15,096

Total Larval Fish 65,298,000 153,331,013

Fish Eggs

fish eggs unid. unidentified fish eggs 49,261,253 130,894,994

Genyonemus lineatus white croaker eggs 17,867,461 43,114,182

Sciaenidae unid. croaker eggs 14,562,519 41,351,239

Paralichthyidae unid. sand flounder eggs 8,780,223 30,684,631

Sciaenidae/Paralichthyidae/Labridae SPL fish eggs 5,208,682 11,085,521

Citharichthys spp. sanddab eggs 1,499,868 5,319,639

Pleuronichthys spp. turbot eggs 1,018,933 2,987,271

Paralichthys californicus California halibut eggs 860,518 2,013,440

Engraulidae unid. anchovy eggs 803,290 1,932,617

Atherinopsidae unid. silverside eggs 22,147 40,690

Total Fish Eggs 99,884,894 269,424,224
Harbor Generating Station CWIS Entrainment and

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Concentration (#/1000 cubic meters)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-1. Mean concentration (#/1,000 m3[264,172 gal] wide bars) and standard deviation

(narrow bars) of all larval fishes collected at HGS entrainment Station E1 during 2006.

Concentration (#/1000 cubic meters)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-2. Mean concentration (#/1,000 m3[264,172 gal] wide bars) and standard deviation

(narrow bars) of all fish eggs collected at HGS entrainment Station E1 during 2006.
Harbor Generating Station CWIS Entrainment and

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Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

Note: Negative nighttime values are a plotting artifact

Figure 4.5-3. Mean concentration (#/1.0 m3[264 gal]) of all fish larvae at entrainment

Station E1 during night (Cycle 3) and day (Cycle 1) sampling.

Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-24.0 -20.0 -16.0 -12.0 -8.0 -4.0 0.0 4.0 8.0 12.0 16.0 20.0 24.0

Note: Negative nighttime values are a plotting artifact

Figure 4.5-4. Mean concentration (#/1.0 m3[264 gal]) of all fish eggs at entrainment

Station E1 during night (Cycle 3) and day (Cycle 1) sampling.
Harbor Generating Station CWIS Entrainment and

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4.5.1.2 Shellfishes

A total of 2,262 larval target shellfishes (late-stage larvae of crabs, spiny lobsters, and market squid)

representing 16 taxa was collected from the HGS entrainment station (E1) during 26 bi-weekly surveys in

2006 (Table 4.5-3 and Appendix C). The highest concentrations were collected during Survey 10 in May

(Appendix C). The megalops stage of kelp crabs, spider crabs, and pea crabs comprised over 90% of all

specimens collected. Advanced larvae of species with commercial fishery value (i.e., Cancer crabs,

California spiny lobster, market squid) each comprised less than 1% of the target shellfish. Total annual

entrainment was estimated to be 18.9 million target shellfish larvae using the actual cooling water flows,

including 217,477 California spiny lobster phyllosomes and 26,676 market squid paralarvae (Table 4.5-

4). Using the design (or maximum) capacity CWIS flows, entrainment increased to 41.3 million shellfish

larvae.

Table 4.5-3. Average concentration of target shellfish larvae in entrainment samples collected

at HGS (Station E1) in 2006.

Taxon Common Name

Avg. Conc.

(per 1,000 m3)

Total

Count

Percent

of Total

Cumul.

Percent.

Pugettia spp. (megalops) kelp crabs megalops 175.14 1,434 63.73 63.73

Majidae unid. (megalops) spider crab megalops 47.96 380 17.45 81.19

Pinnixa spp. (megalops) pea crabs megalops 30.05 265 10.94 92.12

unidentified crab (megalops) unidentified crab megalops 9.95 86 3.62 95.74

Grapsidae unid. (megalops) shore crab megalops 3.48 29 1.27 97.01

Paguridae unid. (megalops) hermit crab megalops 2.83 23 1.03 98.04

Panulirus interruptus (phyllosome) California spiny lobster (larval) 2.42 20 0.88 98.92

Brachyura unid. (megalops) unidentified crab megalops 0.88 7 0.32 99.24

Pinnotheres spp. (megalops) pea crab megalops 0.57 5 0.21 99.45

Loligo opalescens market squid 0.43 4 0.16 99.60

Lophopanopeus spp. (megalops) black-clawed crab megalops 0.36 3 0.13 99.73

Cancer spp. (megalops) cancer crabs megalops 0.24 2 0.09 99.82

Grapsidae / Cancridae (megalops) unidentified crab megalops 0.14 1 0.05 99.87

Diogenidae (megalops) left-handed hermit crabs megalops 0.13 1 0.05 99.92

Pinnotheridae (megalops) pea crab megalops 0.11 1 0.04 99.96

Pachygrapsus crassipes (megalops) striped shore crab megalops 0.11 1 0.04 100.00

274.80 2,262
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Table 4.5-4. Calculated total annual entrainment of target shellfish larvae at HGS in 2006 based

on actual and design (maximum) cooling water intake pump flows.

Taxon Common Name

Annual

Entrainment

(Actual Flows)

Annual

Entrainment

(Design Flows)

Pugettia spp. (megalops) kelp crabs megalops 12,009,598 26,357,647

Majidae unid. (megalops) spider crab megalops 3,520,320 7,285,587

Pinnixa spp. (megalops) pea crabs megalops 1,810,300 4,467,908

unidentified crab (megalops) unidentified crab megalops 727,346 1,480,727

Grapsidae unid. (megalops) shore crab megalops 241,523 526,881

Panulirus interruptus (phyllosome) California spiny lobster (larval) 217,477 360,853

Paguridae unid. (megalops) hermit crab megalops 165,787 422,270

Brachyura unid. (megalops) unidentified crab megalops 64,917 134,388

Pinnotheres spp. (megalops) pea crab megalops 38,804 84,172

Lophopanopeus spp. (megalops) black-clawed crab megalops 27,081 51,987

Loligo opalescens market squid 26,676 62,179

Cancer spp. (megalops) cancer crabs megalops 15,625 35,225

Grapsidae / Cancridae (megalops) unidentified crab megalops 12,015 21,990

Pinnotheridae (megalops) pea crab megalops 9,749 17,843

Diogenidae (megalops) left-handed hermit crabs megalops 7,894 19,963

Pachygrapsus crassipes (megalops) striped shore crab megalops 6,224 15,456

18,901,336 41,345,075

4.5.2 Source Water Summary

4.5.2.1 Fishes

A total of 14,025 larval fishes representing 72 taxa was collected from HGS source water stations in the

Los AngelesLong Beach Harbor Complex (Stations H1H6) during 12 monthly surveys in 2006 (Table

4.5-5 and Appendix C). White croaker, combtooth blennies, unidentified gobies (CIQ goby complex),

anchovies, bay goby, unidentified croakers and yellowfin goby were the most abundant taxa and

comprised nearly 90% of all specimens collected. The greatest concentrations of larval fishes occurred

during May 2006 (ca. 2,400/1,000 m3[264,172 gal]) and the fewest in November 2006 (ca. 400/1,000 m

3

[264,172 gal]) (Figure 4.5.5). Damaged fishes that could not be positively identified comprised 2.0% of

the total catch.
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Table 4.5-5. Average concentration of larval fishes collected at HGS source water stations in

the Los AngelesLong Beach Harbor Complex (Stations H1H6) in 2006.

Taxon Common Name

Avg. Conc.

(per 1,000 m3) Total Count

Percentage

of Total

Cumulative

Percentage

Larval Fish

Genyonemus lineatus white croaker 367.16 5,022 34.22 34.22

Hypsoblennius spp. combtooth blennies 208.17 2,614 19.40 53.62

Gobiidae unid. gobies 202.31 2,493 18.86 72.48

Engraulidae unid. anchovies 54.12 765 5.04 77.52

Lepidogobius lepidus bay goby 40.43 531 3.77 81.29

Sciaenidae unid. croakers 29.70 377 2.77 84.06

Acanthogobius flavimanus yellowfin goby 23.26 353 2.17 86.23

unidentified larvae, damaged unidentified damaged larvae 22.38 291 2.09 88.32

unidentified larvae, yolksac unidentified yolksac larvae 18.56 232 1.73 90.05

Seriphus politus queenfish 17.79 221 1.66 91.70

Gobiesocidae unid. clingfishes 7.44 94 0.69 92.40

Paralichthys californicus California halibut 7.29 94 0.68 93.08

Atherinopsidae unid. silversides 4.84 56 0.45 93.53

Rhinogobiops nicholsii blackeye goby 4.56 54 0.43 93.95

Icelinus spp. sculpins 4.32 54 0.40 94.35

Ruscarius creaseri roughcheek sculpin 4.27 58 0.40 94.75

Pleuronichthys guttulatus diamond turbot 3.46 45 0.32 95.07

Pleuronichthys ritteri spotted turbot 3.08 38 0.29 95.36

Orthonopias triacis snubnose sculpin 2.89 36 0.27 95.63

Bathymasteridae unid. ronquils 2.45 33 0.23 95.86

Stenobrachius leucopsarus northern lampfish 2.40 31 0.22 96.08

Cheilotrema saturnum black croaker 2.32 29 0.22 96.30

Gillichthys mirabilis longjaw mudsucker 2.27 31 0.21 96.51

Parophrys vetulus English sole 2.17 27 0.20 96.71

Clinocottus spp. sculpins 2.09 27 0.19 96.91

Labrisomidae unid. labrisomid blennies 2.03 26 0.19 97.10

Semicossyphus pulcher California sheephead 2.01 23 0.19 97.28

Cottidae unid. sculpins 1.96 26 0.18 97.47

Artedius spp. sculpins 1.90 22 0.18 97.64

Citharichthys spp. sanddabs 1.72 18 0.16 97.80

Oxyjulis californica senorita 1.58 20 0.15 97.95

Sebastes spp. rockfishes 1.49 18 0.14 98.09

Paralabrax spp. sand bass 1.41 18 0.13 98.22

Sphyraena argentea Pacific barracuda 1.30 17 0.12 98.34

Zaniolepis spp. combfishes 1.26 16 0.12 98.46

Pleuronichthys spp. turbots 1.03 14 0.10 98.55

Pleuronectidae unid. righteye flounders 1.02 13 0.10 98.65

Hypsypops rubicundus garibaldi 1.02 13 0.10 98.74

Pleuronichthys verticalis hornyhead turbot 1.02 14 0.10 98.84

Typhlogobius californiensis blind goby 1.01 15 0.09 98.93

Chitonotus / Icelinus sculpins 0.98 12 0.09 99.03

(table continued)
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Table 4.5-5 (continued). Average concentration of larval fishes and fish eggs collected at HGS source

water stations in the Los AngelesLong Beach Harbor Complex (Stations H1H6) in 2006.

Taxon Common Name

Avg. Conc.

(per 1,000 m3) Total Count

Percentage of

Total

Cumulative

Percentage

Larval Fish

Gibbonsia spp. clinid kelpfishes 0.92 12 0.09 99.11

Syngnathus spp. pipefishes 0.92 11 0.09 99.20

Paralichthyidae unid. sand flounders 0.85 10 0.08 99.28

larval/post-larval fish unid. larval fishes 0.73 10 0.07 99.34

Merluccius productus Pacific hake 0.67 10 0.06 99.41

Leuroglossus stilbius California smoothtongue 0.63 8 0.06 99.47

Roncador stearnsii spotfin croaker 0.62 8 0.06 99.52

Pleuronectiformes unid. flatfishes 0.54 7 0.05 99.57

Oxylebius pictus painted greenling 0.49 6 0.05 99.62

Lythrypnus spp. gobies 0.46 6 0.04 99.66

Bathylagidae unid. blacksmelt 0.35 4 0.03 99.69

Umbrina roncador yellowfin croaker 0.33 4 0.03 99.73

Oligocottus / Clinocottus sculpins 0.32 4 0.03 99.76

Lyopsetta exilis slender sole 0.29 4 0.03 99.78

Myctophidae unid. lanternfishes 0.26 3 0.02 99.81

Chitonotus pugetensis roughback sculpin 0.25 3 0.02 99.83

Scorpaenichthys marmoratus cabezon 0.20 2 0.02 99.85

Chaenopsidae unid. tube blennies 0.19 3 0.02 99.87

Menticirrhus undulatus California corbina 0.19 2 0.02 99.88

Pomacentridae unid. damselfishes 0.16 2 0.01 99.90

Stichaeidae unid. pricklebacks 0.15 2 0.01 99.91

Peprilus simillimus Pacific butterfish 0.15 2 0.01 99.93

Isopsetta isolepis butter sole 0.14 2 0.01 99.94

Sardinops sagax Pacific sardine 0.14 2 0.01 99.95

Xystreurys liolepis fantail sole 0.09 1 0.01 99.96

Diaphus theta California headlight fish 0.08 1 0.01 99.97

Oligocottus spp. sculpins 0.08 1 0.01 99.97

Triphoturus mexicanus Mexican lampfish 0.07 1 0.01 99.98

Hexagrammidae unid. greenlings 0.07 1 0.01 99.99

Labridae unid. wrasses 0.07 1 0.01 99.99

Halichoeres semicinctus rock wrasse 0.06 1 0.01 100.00

Total Larval Fish 1,072.90 14,025

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4.5.2.2 Shellfishes

A total of 6,942 larval target shellfishes representing 20 taxa (combined species designations) was

collected from HGS source water stations in the Harbor Complex during 12 monthly surveys in 2006

(Table 4.5-6 and Appendix C). The highest concentrations were collected during the May survey

(Appendix C). Megalops of kelp crabs, pea crabs, spider crabs, unidentified megalops, California spiny

lobster, and cancer crabs were the most abundant taxa and comprised over 90% of all specimens

collected. Data presented in Appendix C includes abundances for the uncombined species designations by

survey.

Table 4.5-6. Average concentration of larval target shellfishes in samples collected at HGS

source water stations in Los Angeles-Long Beach Harbor Complex in 2006.

Taxon Common Name

Avg. Conc.

(per 1,000 m3) Total Count

Percentage of

Total

Cumulative

Percentage

Pugettia spp. kelp crabs megalops 276.76 3,708 53.52 53.52

Pinnixa spp. pea crabs megalops 62.59 872 12.10 65.63

Majidae unid. spider crabs megalops 56.42 705 10.91 76.54

unidentified crab unidentified crab megalops 32.04 411 6.20 82.73

Panulirus interruptus California spiny lobster (larval) 24.40 351 4.72 87.45

Cancer spp. cancer crabs megalops 23.97 332 4.64 92.09

Grapsidae unid shore crabs megalops 10.69 149 2.07 94.15

Paguridae unid. hermit crabs megalops 9.37 130 1.81 95.97

Pinnotheres spp. pea crabs megalops 4.96 74 0.96 96.93

Loligo opalescens market squid 3.61 50 0.70 97.62

Brachyura unid. unidentified true crab megalops 3.33 44 0.64 98.27

Lophopanopeus spp. black-clawed crabs megalops 2.11 27 0.41 98.68

Diogenidae left-handed hermit crabs meg. 2.09 27 0.40 99.08

Pinnotheridae unid. pea crabs megalops 1.72 23 0.33 99.41

Porcellanidae unid. porcelain crabs megalops 0.94 12 0.18 99.59

Pachycheles rudis thickclaw porcelain crab meg. 0.85 13 0.16 99.76

Petrolisthes spp. porcelain crabs megalops 0.67 6 0.13 99.89

Pachycheles pubescens pubescent porcelain crab meg. 0.44 6 0.08 99.97

Petrolisthes cinctipes flat porcelain crab meg. 0.07 1 0.01 99.99

Petrolisthes eriomerus flattop crab megalops 0.07 1 0.01 100.00

517.11 6,942
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4.5.3 Results by Species for Cooling Water Intake Structure Entrainment

The following seven fish taxa were selected for detailed evaluation of entrainment effects based on their

abundance in entrainment samples. Together they comprised over 95% of the larvae entrained at HGS in

2006 (Table 4.5-1). In taxonomic order these are:

 anchovies (primarily Engraulis mordax);

 croakers (Sciaenidae unid.);

 white croaker (Genyonemus lineatus);

 combtooth blennies (Hypsoblennius spp.);

 unidentified gobies (mainly CIQ goby complex);

 yellowfin goby (Acanthogobius flavimanus); and

 bay goby (Lepidogobius lepidus).

The unidentified croakers are discussed along with the white croakers because a significant proportion of

these larvae were likely yolk-sac stage white croaker that could not be positively identified to the species

level. No shellfishes were included in the detailed evaluation because of the low numbers of larvae

relative to the fishes and the very low numbers of species with commercial or recreational importance.

This methodology was approved by the LARWQCB, SWRCB, EPA Region IX, NMFS, and CDFG

during a January 30, 2006 meeting at the LARWQCB offices.

4.5.3.1 Anchovies (Engraulidae)

Three species of anchovy (Family Engraulidae)

inhabit nearshore areas of southern California:

northern anchovy (Engraulis mordax), deepbody

anchovy (Anchoa compressa) and slough anchovy

(Anchoa delicatissima). This analysis of

entrainment effects on anchovies will concentrate

on life history aspects of the northern anchovy

because all of the Engraulid larvae collected that

were large enough to be positively identified were

northern anchovies. Seventy-five percent of the

specimens identified in the entrainment samples as

Engraulidae were northern anchovy. The remainder were very small specimens still in their recentlyhatched yolk-sac stage and some that were damaged to an extent that they could not be positively

identified to the species level.

Northern anchovy range from Cabo San Lucas, Baja California to Queen Charlotte Island, British

Columbia (Miller and Lea 1972), and the Gulf of California (Hammann and Cisneros-Mata 1989). They

are most common from Magdalena Bay, Baja California to San Francisco Bay within 157 km (98 miles)

of shore (Hart 1973; MBC 1987). Three genetically distinct subpopulations are recognized for northern

anchovy; (1) Northern subpopulation, from northern California to British Columbia; (2) Central

Mark Conlin
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subpopulation, from central California to northern Baja California; and (3) Southern subpopulation, off

southern Baja California (Emmett et al. 1991).

4.5.3.1.1 Life History and Ecology

The reported depth range of northern anchovy is from the surface to depths of 310 m (1,017 ft) (Davies

and Bradley 1972). Juveniles are generally more common inshore and in estuaries. Eggs are elliptical and

occur from the surface to depths of about 50 m (164 ft), while larvae are found from the surface to about

75 m (246 ft) in epipelagic and nearshore waters (Garrison and Miller 1982). Northern anchovy larvae

feed on dinoflagellates, rotifers, and copepods (MBC 1987).

Northern anchovy spawn throughout the year off southern California, with peak spawning between

February and May (Brewer 1978), although this may vary annually and geographically. Most spawning

takes place within 100 km (62 miles) of shore (MBC 1987). On average, female anchovies off Los

Angeles spawn every 7 to 10 days during peak spawning periods, approximately 20 times per year

(Hunter and Macewicz 1980; MBC 1987). Most spawning occurs at night and is completed by dawn

(Hunter and Macewicz 1980). Anchovies are all sexually mature by age two, and the fraction of the

population that is sexually mature at one year of age can range from 47100% depending on the water

temperature during development (Bergen and Jacobsen 2001). Love (1996) reported that they release

2,70016,000 eggs per batch, with an annual fecundity of up to 130,000 eggs per year in southern

California. Parrish et al. (1986) and Butler et al. (1993) stated that the total annual fecundity for one-year

old females was 20,00030,000 eggs, while a five-year old could release up to 320,000 eggs per year.

The northern anchovy egg hatches in two to four days, has a larval phase lasting approximately 70 days,

and undergoes transformation into a juvenile at about 3540 mm (1.41.6 in) (Hart 1973; MBC 1987;

Moser 1996). Larvae begin schooling at 1112 mm (0.40.5 in) SL (Hunter and Coyne 1982). Northern

anchovy on average reach 102 mm (4 in) in their first year, and 119 mm (4.7 in) in their second

(Sakagawa and Kimura 1976). Larval survival is strongly influenced by the availability and density of

phytoplankton species (Emmett et al. 1991). Storms and strong upwelling reduce larval food availability,

and strong upwelling may transport larvae out of the Southern California Bight (Power 1986). However,

strong upwelling may benefit juveniles and adults by increasing food resources. Growth in length is most

rapid during the first four months, and growth in weight is most rapid during the first year (Hunter and

Macewicz 1980; PFMC 1983). They mature at 78140 mm (3.15.5 in) in length, in their first or second

year (Frey 1971; Hunter and Macewicz 1980). Maximum size is about 230 mm (9.1 in) and 60 g (2.1 oz)

(Fitch and Lavenberg 1971; Eschmeyer and Herald 1983). Maximum age is about seven years (Hart

1973), though most live less than four years (Fitch and Lavenberg 1971).

Northern anchovy are very important in the trophic ecology of marine food webs. They are random

planktonic feeders, filtering plankton as they swim (Fitch and Lavenberg 1971). Juveniles and adults feed

mainly at night on zooplankton, including planktonic crustaceans and fish larvae (Fitch and Lavenberg

1971; Hart 1973; Allen and DeMartini 1983). Numerous fish and marine mammal species feed on

northern anchovy. Elegant tern and California brown pelican reproduction is strongly correlated with the

annual abundance of this species (Emmett et al. 1991).
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4.5.3.1.2 Population Trends and Fishery

Northern anchovy (Engraulis mordax) are one of four coastal pelagic species managed by the Pacific

Fisheries Management Council (PFMC). The other species include Pacific sardine, Pacific mackerel, and

jack mackerel. Northern anchovy in the northeastern Pacific is divided into three subpopulations, or

stocks: northern, central, and southern. Since 1978, the PFMC has managed northern anchovy from the

central and northern subpopulations. The central subpopulation includes landings from San Francisco to

Punta Baja, Baja California.

Three separate commercial fisheries target northern anchovy in California and Mexico waters: 1) the

reduction fishery, 2) the live bait fishery, and a 3) non-reduction fishery (Bergen and Jacobson 2001). In

the reduction fishery anchovies are converted to meal, oil, and protein supplements while the nonreduction fishery includes fish that are processed for human consumption, for animal food, or frozen for

use as fishing bait.

Northern anchovy populations began to increase following the collapse of the Pacific sardine (Sardinops

sagax) fishery in 1952. Landings remained fairly low throughout the 1950s, but increased rapidly in the

mid 1960s when reduction of anchovy without associated canning was permitted (Bergen and Jacobson

2001). The demand for this fishery was highly linked to the production and price of fish meal worldwide

(Mason 2004). A drastic decline of 40% in fish meal prices worldwide during the early 1980s (Durand

1998) and the decline in anchovy abundance nearly ended the anchovy reduction market by 1983.

Estimates of the central subpopulation averaged about 325 million kg (359,000 tons) from 1963 through

1972, increased to over 1.5 billion kilograms (kg) (1.7 million tons) in 1974, then declined to 325 million

kg (359,000 tons) in 1978 (Bergen and Jacobsen 2001). Anchovy biomass in 1994 was estimated at 391

million kg (432,000 tons). The stock is thought to be stable, and the size of the anchovy resource is

largely dependent on natural influences such as ocean temperatures related to a cold regime in the Pacific

Decadal Oscillation (Chavez et al. 2003).

Northern anchovy were one of the most abundant larvae in various surveys conducted in the Los AngelesLong Beach Harbor Complex in the 1970s (Brewer 1983; HEP 1976, 1979). Northern anchovy larvae

comprised 14% of the total catch in a survey conducted in the harbor area in 2000 (MEC 2002). Northern

anchovy was one of the most abundant species, along with topsmelt (Atherinopsis affinis), in purse seine

and beach seine sampling in the harbor complex in the early 1980s (Allen et al. 2006). Seasonally the

greatest population abundances typically occur in summer and early fall as a result of large numbers of

young-of-the-year. Northern anchovy were also the most abundant species collected by lampara net and

otter trawl in a survey of the harbor complex in 2000, and were more abundant in nighttime samples

(MEC 2002).

The earlier 316(b) study of the HGS in 19781979 (IRC 1981) measured average concentrations of

engraulid species complex larvae that were lowest from July through October and greatest from January

through June. Survey means for the near-field varied from 0 to 6,510 larvae/1,000 m3 (1,000 m3 =

264,172 gal) (average 265/1,000 m3) and from 1 to 12,500 larvae/1,000 m3 (average 1,116/1,000 m3) for

the far-field. These concentrations are approximately 20 times greater than the 2006 values. The annual
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mean nighttime concentration was significantly higher than the average daytime concentration. In

addition, the far-field mean abundance was significantly greater than the near-field value.

The California commercial fishery for northern anchovy varies substantially by region and year. There

have not been any landings of northern anchovy recorded from San Diego County since 1996 when

144,200 kg (318,000 pounds [lbs]) were landed (Pacific Fishery Information Network [PacFIN] 2007). In

2004, there were 147,400 kg (325,000 lbs) landed in the Los Angeles area as compared to 2.75 million kg

(6.07 million lbs) in the Santa Barbara area, and 3.89 million kg (8.58 million lbs) in the Monterey area,

for a total value of $750,000. Annual landings in the Los Angeles region since 2000 have varied from a

high of 3.66 million kg (8.1 million lbs) in 2001 to a low of 147,003 kg (0.3 million lbs) in 2004, with an

average of 1.35 million kg (3 million lbs) annually (Table 4.5-7).

Table 4.5-7. Annual landings and revenue for northern anchovy in the Los

Angeles region based on PacFIN data.

Year Landed Weight (kg) Landed Weight (lbs) Revenue

2000 1,279,437 2,820,677 $145,579

2001 3,656,509 8,061,223 $319,628

2002 1,205,307 2,657,247 $100,716

2003 327,468 721,944 $37,750

2004 147,003 324,087 $35,699

2005 1,979,989 4,365,130 $185,579

2006 865,971 1,909,139 $75,104

4.5.3.1.3 Sampling Results

Engraulid larvae (predominantly northern anchovy) was the seventh most abundant taxon at the

entrainment station with a mean concentration of 14 per 1,000 m3(1,000 m3= 264,172 gal) over all

surveys while engraulid eggs had an average concentration of 13 per 1,000 m3(Table 4.5-1). The seasonal

occurrence of larvae was divided between two periods of abundance, the greater being in MarchJuly and

a lesser peak in OctoberDecember (Figure 4.5-6). During periods of maximum abundance in late May

2006, anchovies were present in the entrainment samples at average concentrations of 75 per 1,000 m

3

.

They were absent from samples in JanuaryFebruary and AugustSeptember. Monthly source water

concentrations followed a similar seasonal pattern with maximum concentrations exceeding 200 per

1,000 m

3

in May 2006 (Figure 4.5-7). Anchovies were substantially more abundant in nighttime samples

than daytime samples, including 8 out of 13 surveys (62%) in which anchovies were collected in

nighttime samples (Cycle 3), but not daytime samples (Cycle 1) (Figure 4.5-8). The length frequency

distribution of measured northern anchovy larvae showed a bi-modal distribution with one peak

consisting of recently hatched larvae based on the reported hatch length of 23 mm (0.08-0.1 in) (Moser

1996), and another in the range of 1014 mm (0.4-0.6 in) (Figure 4.5-9). The lengths of the larvae from

the entrainment station samples ranged from 1.722.5 mm (0.07-0.9 in) with a mean of 10.6 mm (0.4 in)

notochord length (NL).
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Concentration (#/1000 cubic meters)

0

20

40

60

80

100

120

140

160

180

200

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-7. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of anchovy larvae collected at HGS entrainment Station E1 during 2006.

Concentration (#/1000 cubic meters)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-8. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of anchovy larvae collected at HGS source water stations during 2006.
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Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-0.2 -0.2 -0.2 -0.1 -0.1 -0.0 0.0 0.0 0.1 0.1 0.2 0.2 0.2

Note: Negative nighttime values are a plotting artifact

Figure 4.5-9. Mean concentration (#/1.0 m3[264 gal]) of anchovy larvae at

entrainment Station E1 during night (Cycle 3) and day (Cycle 1) sampling.

N = 96

Percent

0

10

20

30

Midpoint for

Length Category (mm)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Figure 4.5-10. Length (mm) frequency distribution for larval anchovy collected at

entrainment Station E1.
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4.5.3.1.4 Modeling Results

The following section presents the results for demographic and empirical transport modeling of

entrainment effects on Engraulidae (northern anchovy) larvae. FH modeling estimates for both egg and

larval stages were calculated separately, since the modeling approach was based on average ages of the

egg and larvae entrained. The two estimates were then added to obtain the total estimated adult female

losses. The FH model has the advantage that the eggs only need to be extrapolated back to the time at

which they are released from spawning females. An AEL estimate for anchovy eggs would require

extrapolating the number of eggs from the average age of entrainment to a mature adult increasing the

uncertainty of the estimate compared to FH. Therefore, only an FH estimate for anchovy eggs was

calculated. Total annual entrainment at HGS was estimated at 803,290 eggs (standard error of 23,311) and

940,784 larvae (standard error of 54,597) using measured cooling water flows during 2006 (Table 4.5-2).

Based on the design (or maximum) flows, total annual entrainment was estimated at 1,932,617 eggs

(standard error of 58,079) and 2,068,979 larvae (standard error of 105,000).

Fecundity Hindcasting (FH)

The entrainment estimates for northern anchovy eggs and larvae for the 2006 sampling period were used

to estimate the number of breeding females at the age of maturity needed to produce the estimated

numbers of eggs and larvae entrained. Butler et al. (1993) modeled annual fecundity and egg and larval

survivorshipfornorthernanchovy.Their“best”estimatecanbederivedbyfittingtherangeofmortality

estimates from field collections to the assumption of a stable and stationary population age structure.

Instantaneous daily mortality estimates from Butler et al. (1993) were converted, over their average stage

durations, to finite survivorship rates for each developmental stage (Table 4.5-8). These estimates were

used to calculate that the average age of the entrained anchovy eggs was 1.3 days. Fish at the mean age of

entrainment include yolk sac, early stage and late stage larvae. Therefore, survival estimates for all three

stages were combined to obtain a finite survival value of 0.002 up to the mean age at entrainment

(20.6 days). This was calculated by dividing a larval growth rate of 0.41 mm/day (0.02 in/day) into the

difference between the mean length (10.6 mm [0.42 in]) and the value of the 10th percentile (2.2 mm [0.09

in]), which was used to represent the size at hatching.

Table 4.5-8. Stage-specific life history parameters for northern anchovy

(Engraulis mordax) modified from Butler et al. (1993).

Stage Zbest

Stage

duration

(days) Age (days) Sbest CVbest

Egg 0.2310 2.9 0.512 0.142

Yolk-sac larva 0.3660 3.6 6.5 0.093 0.240

Early larva 0.2860 12 18.5 0.032 0.071

Late larva 0.0719 45 63.5 0.039 0.427

Early juvenile 0.0141 62 125.5 0.417 0.239

Late Juvenile 0.0044 80 205.5 0.703 0.033

Pre-recruit 0.0031 287 492.5 0.411 0.088

Z = instantaneous daily mortality; S = finite survival rate.
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Clark and Phillips (1952) reported age at sexual maturity as 1–2 years. Similarly, Leet et al. (2001)

reported that 47 to 100% of one-year olds may be mature in a given year, while all are mature by two

years. For modeling purposes, we used a value of one year. For longevity, Hart (1973) reported a value of

seven years, but Leet et al. (2001) stated that northern anchovy in the fished population rarely exceed four

years of age. The survivorship values in Table 4.5-9 were used to estimate an average annual fecundity of

163,090 eggs produced over a seven-year period using the data presented in Butler et al. (1993).

The estimated numbers of reproductive age adult female northern anchovies whose lifetime reproductive

output was entrained through the HGS CWIS for 2006, based on the total annual entrainment of anchovy

eggs, was seven using actual cooling water flows during the period or 16, based on the design cooling

water flows (Table 4.5-10). The estimated numbers of reproductive age adult female northern anchovies,

based on the total annual entrainment of larvae, was 5,746, based on the actual flows or 12,637, based on

the design flows. Combining the two estimates based on the actual flows increases the estimated numbers

of reproductive age adult female northern anchovies to 5,753 or 12,653, based on the actual and design

flows, respectively. The sensitivity analysis based on the 90% confidence intervals for both eggs and

larvae show that the variation in the estimates of entrainment had much less of an effect on the variation

of the FH estimate than the life history parameters used in the models.

Table 4.5-9. Survivorship table for adult northern anchovy (Engraulis mordax)

from Butler et al. (1993) showing spawners (Lx) surviving at the start of age

interval and numbers of eggs spawned annually (Mx).

Age (year) Lx Mx LxMx

1 1,000 22,500 22,500,000

2 468 93,500 43,800,000

3 216 195,000 42,000,000

4 102 280,000 28,600,000

5 48 328,000 15,700,000

6 22 328,000 7,210,000

7 10 328,000 3,280,000

TLF = 163,090

The total lifetime fecundity (TLF) was calculated as the sum of LxMx

divided by 1,000.
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Table 4.5-10. Results of FH modeling for anchovy larvae based on entrainment estimates

calculated using actual and design (maximum) CWIS flows.

Parameter Estimate Std. Error

FH

Lower

Estimate

FH

Upper

Estimate

FH

Range

Actual Flows

Eggs

FH Estimate 7 5 2 21 19

Total Entrainment 803,290 23,311 6 7 1

Larvae

FH Estimate 5,746 4,988 1,378 23,959 22,581

Total Entrainment 940,784 54,597 5,198 6,295 1,097

Design Flows

Eggs

FH Estimate 16 11 5 51 46

Total Entrainment 1,932,617 58,079 15 17 2

Larvae

FH Estimate 12,637 10,963 3,033 52,652 49,619

Total Entrainment 2,068,979 105,000 11,582 13,692 2,110

The upper and lower estimates are based on a 90% confidence interval of the mean. FH estimates were also

calculated using the upper and lower confidence estimates from the entrainment estimates.

Adult Equivalent Loss (AEL)

The parameters required for formulation of AEL estimates include larval survival from entrainment to

settlement and survival from settlement to the average age of reproduction for a mature female.

Instantaneous daily mortality estimates from Butler et al. (1993) were converted, over their average stage

durations, to finite survivorship rates for each developmental stage (Table 4.5-11). The early larval stage

survival was adjusted to the mean age at entrainment (20.6 days) and used to calculate a finite survival

through age 63.5 days of 0.174 using the daily survival rates for late stage larvae. The other finite survival

rates from Butler et al. (1993) were used to estimate the number of adults of age one year, the age of first

maturity when 50% of the females are sexually mature. The equivalent number of adult northern

anchovies calculated from the number of larvae entrained through the HGS CWIS for the sampling period

was 25,863 based on actual flows during the period. Based on design flows, the number of larvae

entrained increased to 56,879 (Table 4.5-11).
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Table 4.5-11. Results of AEL modeling for northern anchovy larvae based on entrainment

estimates calculated using actual and design (maximum) CWIS flows.

Parameter Estimate Std. Error

AEL

Lower

Estimate

AEL

Upper

Estimate

AEL

Range

Actual Flows

AEL Estimate 25,863 29,954 3,848 173,818 169,969

Total Entrainment 940,784 54,597 23,394 28,332 4,938

Design Flows

AEL Estimate 56,879 65,856 8,468 382,046 373,578

Total Entrainment 2,068,979 105,000 52,130 61,627 9,497

The upper and lower estimates are based on a 90% confidence interval of the mean. AEL estimates were also calculated

using the upper and lower confidence estimates from the entrainment estimates.

Empirical Transport Model (ETM)

A larval growth rate of 0.41 mm/day (0.02 in/day) for northern anchovies was estimated from Methot and

Kramer (1979) and used with the difference in the lengths of the 10th and 95th percentiles of the

measurements to estimate that the larvae were exposed to entrainment for a period of approximately

37.7 days. The average duration of the planktonic egg stage, 2.9 days, was added to the period for the

larvae to estimate a total period of exposure of 40.6 days.

The monthly estimates of PE for northern anchovies for 2006 ranged from 0 to 0.00067 using the actual

cooling water flows, and from 0 to 0.00157 using the design flows during the period (Table 4.5-12). The

largest estimate was calculated for the March survey, but the largest proportion of the source population

was present during the April survey (fi = 0.325 or 32.5%). The values in the table were used to calculate a

PM estimate of 0.0071 with a standard error of 0.0043 based on the actual cooling water flows and an

estimate of 0.0153 with a standard error of 0.009 based on the design flows.
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Table 4.5-12. ETM data and results for northern anchovy larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3.

Actual Flows Design Flows

Survey

Date

PE

Estimate

PE

Std. Err.

PE

Estimate

PE

Std. Err. fi

23-Jan-06 0 0 0 0 0.00099

21-Feb-06 0 0 0 0 0

20-Mar-06 0.00067 0.00045 0.00157 0.00104 0.02672

17-Apr-06 0.00010 0.00006 0.00022 0.00013 0.32493

15-May-06 0.00025 0.00024 0.00046 0.00043 0.20117

12-Jun-06 0.00014 0.00004 0.00030 0.00009 0.22969

10-Jul-06 0 0 0 0 0.02214

7-Aug-06 0 0 0 0 0.00774

5-Sep-06 0 0 0 0 0.01580

16-Oct-06 0.00029 0.00023 0.00074 0.00059 0.03038

13-Nov-06 0.00007 0.00007 0.00016 0.00016 0.07035

11-Dec-06 0.00043 0.00025 0.00101 0.00058 0.07009

PM 0.0071 0.0043 0.0153 0.0090 

4.5.3.2 White croaker (Genyonemus lineatus)

White croaker (Genyonemus lineatus) range from

Magdalena Bay, Baja California, north to

Vancouver Island, British Columbia (Miller and

Lea 1972). They are one of eight species of

croakers (Family Sciaenidae) found off California.

The other croakers include: white seabass

(Atractoscion nobilis), black croaker (Cheilotrema

saturnum), queenfish (Seriphus politus), California

corbina (Menticirrhus undulatus), spotfin croaker

(Roncador stearnsii), yellowfin croaker (Umbrina

roncador), and shortfin corvina (Cynoscion

parvipinnis).

4.5.3.2.1 Life History and Ecology

The reported depth range of white croaker is from near the surface to depths of 238 m (781 ft) (Love et al.

2005); however, in southern California, Allen (1982) found white croaker over soft bottoms between 10

and 130 m (32.8-426.5 ft), and it was collected most frequently at 10 m. It is nocturnally active, and is

considered a benthic searcher that feeds on a wide variety of benthic invertebrate prey. Adults feed on

polychaetes and crustaceans, while juveniles feed during the day in midwater on zooplankton (Allen

1982).

Illustration from NOAA
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White croakers are oviparous broadcast spawners. Detailed information on maturation, fecundity and

spawning of white croaker was provided in studies by Love et al. (1984) and Love (1996). They mature

between about 130 and 190 mm (5-7.5 in) TL, between their first to fourth year; approximately 50%

spawn at age one year. About one-half of males mature by 140 mm (5.5 in) TL, and one-half of females

by 150 mm (5.9 in) TL, and all fish are mature by 190 mm (7.5 in) TL in their third to fourth year. Off

Long Beach, white croakers spawn primarily from November through August, with peak spawning from

January through March. However, some spawning can occur year-round. Batch fecundities ranged from

about 800 eggs in a 155 mm (6.1 mm) female to about 37,200 eggs in a 260 mm (10.2 mm) female, with

spawning taking place as often as every five days. In their first and second year, females spawn for three

months for a total of about 18 times per season. Older fish spawn for about four months and about 24

times per season. The nearshore waters from Redondo Beach (Santa Monica Bay) to Laguna Beach are

considered an important spawning center for this species. A smaller spawning center occurs off Ventura.

Newly hatched white croaker larvae are 12 mm (0.04-0.08 in) SL and not well developed (Watson

1982). Larvae are principally located within 4 km (2.5 miles) from shore, and as they develop tend to

move shoreward and into the epibenthos (Schlotterbeck and Connally 1982). A larval growth rate was

derived from data on five species of Sciaenidae (croakers) that were raised in the laboratory by Southwest

Fisheries Science Center staff (Moser 1996). These were the black croaker (Cheilotrema saturnum),

corbina (Menticirrhus undulatus), spotfin croaker (Roncador stearnsii), queenfish (Seriphus politus), and

yellowfin croaker (Umbrina roncador). Hatch lengths and larval lengths at various numbers of days after

birth presented in Moser (1996) were used to calculate an average daily growth rate from hatching

through the flexion stage for Sciaenidae. The growth rate calculated from these data was 0.248 mm/day.

Although the species did not include white croaker this estimate was used for both white croaker and

unidentified croakers since the species that were measured all have larvae that are nearly indistinguishable

at small sizes (Moser 1996). Maximum reported size is 414 mm (16.3 mm) (Miller and Lea 1972), with a

life span of 1215 years (Frey 1971; Love et al. 1984). White croakers grow at a fairly constant rate

throughout their lives, though females increase in size more rapidly than males from age 1 (Moore 2001).

No mortality estimates are available for any of the life stages of this species.

White croakers are primarily nocturnal benthic feeders, though juveniles may feed in the water column

during the day (Allen 1982). Important prey items include polychaetes, amphipods, shrimps, and

chaetognaths (Allen 1982). In outer Los Angeles Harbor, Ware (1979) found that important prey items

included polychaetes, benthic crustaceans, free-living nematodes, and zooplankton. Younger individuals

feed on holoplankonic crustaceans and polychaete larvae. White croaker may move offshore into deeper

water during winter months (Allen and DeMartini 1983); however, this pattern is apparent only south of

Redondo Beach (Herbinson et al. 2001).

4.5.3.2.2 Population Trends and Fishery

White croaker is an important constituent of commercial and recreational fisheries in California. Prior to

1980, most commercial catches of white croaker were taken by otter trawl, round haul net (lampara), gill

net, and hook and line in southern California, but after 1980 most commercial catches were taken

primarily by trawl and hook and line (Love et al. 1984). Also, since then the majority of the commercial

fishery shifted to central California near Monterey mainly due to the increased demand for this species
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from the developing fishery by Southeast Asian refugees (Moore and Wild 2001). Most of the

recreational catch still occurs in southern California from piers, breakwaters, and private and sport boats.

Before 1980, state-wide white croaker landings averaged 310,700 kg (685,000 lbs) annually, exceeding

453,600 kg (1 million lbs) for several years (Moore and Wild 2001). High landings in 1952 probably

occurred due to the collapse of the Pacific sardine fishery. Since 1991, landings have averaged 209,100

kg (461,000 lbs) and steadily declined to a low of 64,640 kg (142,500 lbs) in 1998. Landings by

recreational fishermen aboard commercial passenger fishing vessels averaged about 12,000 fish per year

from 1990 to 1998, with most of the catch coming from southern California.

Annual relative abundance of white croaker in impingement samples at southern California power plants

showed decreases during the strong El Niño events of 1982-83, 1986-87, and 1997-98 as compared with

non-El Niño years (Herbinson et al. 2001). Additionally, the relative abundance of local populations have

been influenced by contamination from polychlorinated biphenyls and other chlorinated hydrocarbons

within bays and has lead to early ovulation, lower batch fecundities, and lower fertilization rates when

compared to non-contaminated areas (Cross and Hose 1988).

White croaker larvae predominantly occurred from November to early June in the earlier 316(b) study of

the HGS in 1978-1979 (IRC 1981). Highest concentrations were recorded for the period December to

March. Survey means varied from 0 to 700 larvae/1,000 m3(1,000 m3= 264,172 gal) at the near-field

station (average 260/1,000 m3) and from 0 to 6,200 larvae/1,000 m3(average 420/1,000 m3) at the farfield station. These concentrations are approximately twice the 2006 values for the near-field area.

Concentrations were significantly greater at the far field station indicating a larger population of spawning

adults in the outer harbor area.

White croaker larvae have been collected in abundance in the Los Angeles and Long Beach Harbor

complex in surveys conducted since the 1970s (HEP 1976, 1979; Brewer 1983; MBC 1984; MEC 1988).

White croaker larvae comprised 5% of the total catch in a survey of the harbor complex in 2000 and

exhibited peaks in abundance in May and again in November (MEC 2002). Sciaenid eggs collected in this

survey comprised 35% of the total catch; white croaker eggs were most abundant in February and

November trawls.

Annual commercial landings in the Los Angeles region since 2000 have varied from a high of 40,020 kg

(88,200 lbs) in 2000 to a low of 6,809 kg (15,011 lbs) in 2006, with an average of 19,690 kg (43,400 lbs)

and average net worth of $29,385 annually (Table 4.5-13). Sport fishery catch estimates of white croaker

in the southern California region from 2000 to 2006 ranged from 64,000 to 253,000 fish, with an average

of 189,400 fish caught annually (Recreational Fishery Information Network [RecFIN] 2007). In the Los

Angeles-Long Beach area in 2006, 13,680 kg (30,166 lbs) were landed for revenue of $26,630 according

to specific CDF&G catch block data from the area.
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Table 4.5-13. Annual landings and revenue for white croaker in the Los Angeles

region based on PacFIN data.

Year Landed Weight (kg) Landed Weight (lbs) Revenue

2000 40,020 88,240 $50,688

2001 23,390 51,560 $36,086

2002 25,880 57,056 $41,816

2003 21,770 48,000 $33,837

2004 8,894 19,608 $14,653

2005 11,180 24,652 $17,531

2006 6,809 15,011 $11,079

4.5.3.2.3 Sampling Results

White croaker larvae was the third most abundant taxon at the entrainment station with a mean

concentration of 125 per 1,000 m3(1,000 m3= 264,172 gal) over all surveys (Table 4.5-1). Unidentified

croaker (Sciaenidae), which consisted of a combination of newly-hatched white croaker, queenfish, and

several other croaker species, was the sixth most abundant taxon with a mean concentration of 19 per

1,000 m3. White croaker larvae were most abundant in late winter through spring, absent in summer and

fall, and began appearing again in NovemberDecember 2006 (Figure 4.5-10). During periods of

maximum abundance in early April 2006 white croaker was present in entrainment samples at average

concentrations of 800 per 1,000 m

3

. Source water abundances followed the same seasonal pattern, but the

peak average concentration in April was twice that of the entrainment samples (Figure 4.5-11).

Unidentified croaker larvae were also most abundant in spring samples at both the entrainment and source

water stations (Figures 4.5-12 and 4.5-13). There was no substantial difference in entrainment abundance

between daytime and nighttime samples for either white croaker or unidentified croaker larvae (Figures

4.5-14 and 4.5-15). With a sample size of 711 measured white croaker larvae, the length frequency plot

for larvae showed a strongly unimodal curve with over one-third of sampled larvae in the 2.0 mm (0.08

in) size class and a rapid decline in frequency of occurrence at larger size classes to 9.0 mm (0.35 in)

(Figure 4.5-16). Over 90% of the unidentified croakers were 2.0 mm (0.08 in) or smaller (Figure 4.5-17)

indicating that they were recently hatched and had not developed the pigmentation and other

characteristics necessary for positive identification to the species level. The mean length of specimens

from the entrainment station samples was 2.4 mm (0.09 in) NL for white croaker and 1.5 mm (0.06 in)

NL for unidentified croakers.
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Concentration (#/1000 cubic meters)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-11. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of white croaker larvae collected at HGS entrainment Station E1 during 2006.

Concentration (#/1000 cubic meters)

0

400

800

1200

1600

2000

2400

2800

3200

3600

4000

4400

4800

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-12. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of white croaker larvae collected at HGS source water stations during 2006.
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Concentration (#/1000 cubic meters)

0

40

80

120

160

200

240

280

320

360

400

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-13. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of unidentified croaker larvae collected at HGS entrainment Station E1 during 2006.

Concentration (#/1000 cubic meters)

0

25

50

75

100

125

150

175

200

225

250

275

300

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-14. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of unidentified croaker larvae collected at HGS source water stations during 2006.
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Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-1.2 -1.0 -0.8 -0.6 -0.4 -0.2 -0.0 0.2 0.4 0.6 0.8 1.0 1.2

Note: Negative nighttime values are a plotting artifact

Figure 4.5-15. Mean concentration (#/1.0 m3[264 gal]) of white croaker larvae at

entrainment Station E1 during night (Cycle 3) and day (Cycle 1) sampling.

Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-0.6 -0.5 -0.4 -0.3 -0.2 -0.1 -0.0 0.1 0.2 0.3 0.4 0.5 0.6

Note: Negative nighttime values are a plotting artifact

Figure 4.5-16. Mean concentration (#/1.0 m3[264 gal]) of unidentified croaker at

entrainment Station E1 during night (Cycle 3) and day (Cycle 1) sampling.
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Figure 4.5-17. Length (mm) frequency distribution for larval white croaker

collected at entrainment Station E1.

N = 98

P

ercent

0

10

20

30

40

50

Midpoint for

Length Category (mm)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Figure 4.5-18. Length (mm) frequency distribution for larval unidentified

croakers collected at entrainment Station E1.

N = 711

P

erce

nt

0

10

20

30

40

50

60

70

Midpoint for

Length Category (mm)

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0
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4.5.3.2.4 Modeling Results

The following section presents the results for demographic and empirical transport modeling of

entrainment effects on white croaker and unidentified croaker eggs and larvae. No age-specific estimates

of survival for larval and later stages of development were available from the literature for white croaker;

therefore, no estimates of FH or AEL were calculated, but enough information was available to estimate

FH for white croaker based on numbers of eggs entrained. Total annual entrainment of white croaker eggs

and larvae was 17,867,461 (standard error of 901,215) and 7,164,843 (standard error of 154,612),

respectively, based on the actual cooling water flows (Table 4.5-2). Based on the design, or maximum,

flows, a total of 43,114,182 white croaker eggs (standard error of 2,226,295) and 18,777,752 (standard

error of 401,199) white croaker larvae were entrained. A total of 14,562,519 (standard error of 607,258)

unidentified croaker eggs and 995,438 (standard error of 43,751) larvae was calculated using measured

cooling water flows during 2006 (Table 4.5-2). Based on the design cooling water flows, the total annual

entrainment was estimated at 41,351,239 unidentified croaker eggs (standard error of 1,519,856) and

2,856,932 (standard error of 173,898) for larvae.

Fecundity Hindcasting (FH)

The annual entrainment estimate for white croaker eggs was used to calculate the number of breeding

females at the age of maturity needed to produce the estimated number of larvae entrained. An estimate of

egg survival of 0.781 was based on egg stage duration of 2.17 days and an average age at entrainment of

0.97 days. A total lifetime fecundity of 2,294,250 eggs per female was calculated based on an average

number of eggs per batch of 19,000, an average number of 21 batches per year, and an average age in the

population of 5.75 years. Life history information presented in Love et al. (1984) is summarized in

Section 4.5.3.5.1Life History and Ecology. The estimated numbers of female white croakers whose

lifetime reproductive output was entrained through the HGS CWIS for the 2006 period was estimated at

10 fish based on the actual cooling water flows and at 24, based on the design cooling water flows (Table

4.5-14).

Table 4.5-14. Results of FH modeling for white croaker eggs based on entrainment estimates

calculated using actual and design (maximum) CWIS flows.

Parameter Estimate Std. Error

FH

Lower

Estimate

FH

Upper

Estimate

FH

Range

Actual Flows

FH Estimate 10 7 3 32 29

Total Entrainment 17,867,461 901,215 9 11 2

Design Flows

FH Estimate 24 17 7 77 70

Total Entrainment 43,114,182 2,226,29

5

22 26 4

The upper and lower estimates are based on a 90% confidence interval of the mean. FH estimates were also

calculated using the upper and lower confidence estimates from the entrainment estimates.
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Empirical Transport Model (ETM)

A larval growth rate 0.248 mm/day derived from data on five species of Sciaenidae (croakers) that were

raised in the laboratory by Southwest Fisheries Science Center staff (Moser 1996). A random sample of

200 lengths from the 711 measured white croaker larvae and all of the 98 measured unidentified croakers

were used to calculate a difference between the estimated hatch lengths and the 95th percentiles of the

measurements to estimate that white croaker and unidentified croakers were exposed to entrainment for

periods of approximately 15.2 and 6.1 days, respectively. The duration of the planktonic egg stage, 2.2

days, was added to the periods for the larvae to estimate total periods of exposure of 17.4 and 8.2 days,

respectively.

The monthly estimates of PE for white croaker for 2006 ranged from 0 to 0.00028 using the actual

cooling water flows during the period and from 0 to 0.00070 using the design flows (Table 4.5-15). The

largest estimate was calculated for the February survey, but the largest proportion of the source

population was present during the April survey (fi = 0.360 or 36.0%). The values in the table were used to

calculate a PM estimate of 0.0019 with a standard error of 0.0006 based on the actual flows and an

estimate of 0.0042 with a standard error of 0.0014 based on the design flows.

Table 4.5-15. ETM data and results for white croaker larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3.

Actual Flows Design Flows

Survey

Date

PE

Estimate

PE

Std. Err.

PE

Estimate

PE

Std. Err. fi

23-Jan-06 0.00009 0.00003 0.00021 0.00007 0.05264

21-Feb-06 0.00028 0.00008 0.00070 0.00020 0.10309

20-Mar-06 0.00012 0.00003 0.00029 0.00008 0.05394

17-Apr-06 0.00010 0.00003 0.00023 0.00007 0.35871

15-May-06 0.00018 0.00011 0.00032 0.00020 0.07015

12-Jun-06 0.00025 0.00031 0.00056 0.00068 0.00582

10-Jul-06 0 0 0 0 0

7-Aug-06 0 0 0 0 0.00064

5-Sep-06 0 0 0 0 0.00229

16-Oct-06 0.00001 0.00001 0.00004 0.00004 0.02081

13-Nov-06 0.00002 0.00001 0.00005 0.00001 0.19697

11-Dec-06 0.00008 0.00002 0.00019 0.00005 0.13494

PM 0.0019 0.0006 0.0042 0.0014 

The monthly estimates of PE for unidentified croakers for 2006 ranged from 0 to 0.00281 using the actual

cooling water flows and from 0 to 0.00663 based on the design flows (Table 4.5-16). The largest estimate

was calculated for the December 2006 survey, but the largest proportion of the source population was

present during the June survey (fi = 0.484 or 48.4%). The values in the table were used to calculate a PM

estimate of 0.0019 with a standard error of 0.0011 based on the actual cooling water flows and an

estimate of 0.0041 with a standard error of 0.0023 based on the design flows.
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Table 4.5-16. ETM data and results for unidentified croaker larvae based upon

actual and design (maximum) CWIS flow volumes and fixed source water volume of

431,694,503 m3.

Actual Flows Design Flows

Survey

Date

PE

Estimate

PE

Std. Err.

PE

Estimate

PE

Std. Err. fi

23-Jan-06 0.00016 0.00017 0.00037 0.00039 0.04196

21-Feb-06 0.00024 0.00029 0.00059 0.00072 0.04043

20-Mar-06 0.00006 0.00004 0.00013 0.00009 0.14532

17-Apr-06 0.00019 0.00013 0.00043 0.00029 0.22753

15-May-06 0.00137 0.00173 0.00251 0.00310 0.00395

12-Jun-06 0.00029 0.00010 0.00065 0.00021 0.48384

10-Jul-06 0.00000 0 0.00000 0 0.00856

7-Aug-06 0.00051 0.00062 0.00095 0.00112 0.00633

5-Sep-06 0.00000 0 0.00000 0 0.00803

16-Oct-06 0.00000 0 0.00000 0 0.00563

13-Nov-06 0.00019 0.00024 0.00042 0.00051 0.02706

11-Dec-06 0.00281 0.00401 0.00663 0.00938 0.00137

PM 0.0019 0.0011 0.0041 0.0023 

4.5.3.3 Combtooth blennies (Hypsoblennius spp.)

Combtooth blennies comprise a large group of

subtropical and tropical fishes that inhabit inshore

rocky habitats throughout much of the world. The

family Blenniidae, the combtooth blennies, contains

about 345 species in 53 genera (Nelson 1994, Moser

1996). They derive their common name from the

arrangement of closely spaced teeth in their jaws.

Three species of the genus Hypsoblennius occur in

the vicinity of HGS: bay blenny (H. gentilis),

rockpool blenny (H. gilberti), and mussel blenny

(H. jenkinsi). These species co-occur throughout

much of their range although they occupy different

habitats. The bay blenny is found along both coasts of Baja California and up the California coast to as far

north as Monterey Bay, (Miller and Lea 1972; Robertson and Allen 2002). The rockpool blenny occurs

from Magdalena Bay, Baja California to Point Conception, California (Miller and Lea 1972; Stephens et

al. 1970). The range of the mussel blenny extends from Morro Bay to Magdalena Bay, Baja California

and in the northern Gulf of California (Love et al. 2005).

Gerald Allen
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4.5.3.3.1 Life History and Ecology

Combtooth blennies are all relatively small fishes that typically grow to a total length of less than 200 mm

(7.9 in) (Moser 1996). Most have blunt heads that are topped with some arrangement of cirri (Moyle and

Cech 1988; Moser 1996). Their bodies are generally elongated and without scales. Dorsal fins are often

continuous and contain more soft rays than spines (Moyle and Cech 1988). Coloration in the group is

quite variable, even among individuals of the same species (Stephens et al. 1970).

The three species of Hypsoblennius found in California waters are morphologically similar as early larvae

(Moser 1996; Ninos 1984). For this reason, most Hypsoblennius identified in the HGS 316(b) plankton

collections were identified as Hypsoblennius spp. Certain morphological features (e.g., preopercular

spines) develop at larger sizes and allow taxonomists to identify some larvae to species.

Blennies inhabit a variety of hard substrates in the intertidal and shallow subtidal zones of tropical and

subtropical marine habitats throughout the world. They may occur to depths of 24 m (80 ft), but are more

frequently found in water depths of less than 5 m (15 ft) (Love 1996). Combtooth blennies are common in

rocky tidepools, reefs, breakwaters, and on pier pilings. They are also frequently observed on encrusted

buoys and boat hulls.

Summary of combtooth blenny distribution and life history attributes.

Range:

 Bay blenny—Monterey Bay to Gulf of California.

 Mussel blenny—Morro Bay to Magdalena Bay Baja California and the northern Gulf of California

 Rockpool blenny—Morro Bay to Magdalena Bay Baja California

Life History:

 Size: bay blenny to 14.7 cm (5.8 inches) TL, mussel blenny to 13 cm (5.1 inches), rockpool blenny to 17 cm (6.8

inches)

 Age at maturity: all species 0.5 years

 Life span: bay blenny 7 years, mussel blenny <6 years, rockpool blenny >8 years

 Fecundity: bay blenny 500–1,500 eggs, mussel blenny 200–2,000 eggs, rockpool blenny 700-1,700 eggs

Habitat:

 Bay blenny—soft bottom in bays and estuaries, associated with submerged aquatic vegetation and mussels on

mooring buoys; to 24 m (80 ft)

 Mussel blenny—empty worm tubes and barnacle tests on pilings, mussel beds, crevices in shallow rock reefs; to 21

m (70 ft)

 Rockpool blenny—under rocks, in crevices on shallow rock reefs; to 18 m (60 ft)

Fishery: None

The California blennies have different habitat preferences. The mussel blenny is only found subtidally

and inhabits mussel beds, the empty drill cavities of boring clams, barnacle tests, or in crevices among the

vermiform snail tubes Serpulorbis spp. (Stephens 1969; Stephens et al. 1970). They generally remain

within one meter of their chosen refuge (Stephens et al. 1970). The bay blenny is usually found subtidally,

but appears to have general habitat requirements and may inhabit a variety of intertidal and subtidal areas

(Stephens et al. 1970). They are commonly found in mussel beds and on encrusted floats, buoys, docks,

and even fouled boat hulls (Stephens 1969; Stephens et al. 1970). Bay blennies are also typically found in

bays as the common name implies and are tolerant of estuarine conditions (Stephens et al. 1970). They

are among the first resident fish species to colonize new or disturbed marine habitats such as new

breakwaters or mooring floats after the substrate is first colonized by attached invertebrates (Stephens et
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al. 1970; Moyle and Cech 1988). Rockpool blennies are mainly found along shallow rocky shorelines,

along breakwaters, and in shallow kelp forests along the outer coast.

Female blennies mature quickly and reproduce within the first year, reaching peak reproductive potential

in the third year (Stephens 1969). The spawning season typically begins in the spring and may extend into

September (Stephens et al. 1970). Blennies are oviparous and lay demersal eggs that are attached to the

nest substrate by adhesive pads or filaments (Moser 1996). Males tend the nest and developing eggs.

Females spawn three to four times over a period of several weeks (Stephens et al. 1970). Males guard the

nest aggressively and will often chase the female away; however, several females may occasionally

spawn with a single male. The number of eggs a female produces varies proportionately with size

(Stephens et al. 1970). The mussel blenny spawns approximately 500 eggs in the first reproductive year

and up to 1,500 eggs by the third year (Stephens et al. 1970). Total lifetime fecundity may be up to 7,700

eggs (Stephens 1969).

Larvae are pelagic and average approximately 2.7 mm (0.11 in) in length two days after hatching

(Stephens et al. 1970). The planktonic phase for Hypsoblennius spp. larvae may last for three months

(Stephens et al. 1970; Love 1996). Captured larvae released by divers have been observed to use surface

water movement and near-surface currents to aid swimming (Ninos 1984). After release, the swimming

larvae orient to floating algae, bubbles on the surface, or the bottoms of boats or buoys. The size at

settlement ranges from 12–14 mm (0.5–0.6 in). After the first year, mussel and bay blenny averaged 40

and 45 mm (1.6 and 1.8 in) total length, respectively (Stephens et al. 1970). Bay blennies grow to a

slightly larger size and live longer than mussel blenny, reaching a size of 15 cm (5.9 in) and living for 6–7

years (Stephens 1969, Stephens et al. 1970, Miller and Lea 1972). Mussel blennies grow to 13 cm (5.1 in)

and have a life span of 3–6 years (Stephens et al. 1970; Miller and Lea 1972). Male and female growth

rates are similar.

Juvenile and adult combtooth blennies are omnivores and eat both algae and a variety of invertebrates,

including limpets, urchins, and bryozoa (Stephens 1969; Love 1996). They are preyed on by spotted sand

bass, kelp bass, giant kelpfish, and cabezon (Stephens et al. 1970).

4.5.3.3.2 Population Trends and Fishery

Average concentrations of Hypsoblennius species complex larvae were lowest from mid-January through

the end of March and greatest from April through September in the earlier 316(b) study of the HGS in

19781979 (IRC 1981). Concentrations at the near-field station varied from 0 to 1,880 larvae per 1,000

m3 (average 70 per 1,000 m3) and from 1 to 1,800 larvae per 1,000 m3 (average 120 per 1,000 m3) at the

far-field station. The near-field concentrations were approximately three times greater than the 2006

values measured at the entrainment station while the far field station concentrations were about half of the

2006 values. There was no significant difference in concentration between day and night samples.

Combtooth blenny larvae have been collected in high abundance in surveys of the Los Angeles and Long

Beach Harbor Complex since the 1970s (HEP 1976, 1979; Brewer 1983; MBC 1984; MEC 1988).

Abundances of Hypsoblennius spp. larvae ranged from 5–20 % of the total catch. In a survey in the

harbor complex conducted in 2000, combtooth blenny larvae comprised 5% of the total catch (MEC

2002).
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There is no fishery for combtooth blennies and, therefore, no records on adult population trends based on

landings data.

4.5.3.3.3 Sampling Results

Combtooth blenny was the fifth most abundant taxon at the entrainment station with a mean concentration

of 30 per 1,000 m3 over all surveys (Table 4.5-1). They were most abundant in summer, peaking in June,

with a smaller peak in early fall (Figure 4.5-18). They were largely absent from winter samples. During

periods of maximum abundance in early June 2006, combtooth blennies were present in the entrainment

samples at average concentrations of 165 per 1,000 m3. Source water abundances followed the same

seasonal pattern, but the peak average concentration in June was much higher at 1,056 per 1,000 m3

(Figure 4.5-19). There was no substantial difference in entrainment abundance between daytime and

nighttime samples (Figure 4.5-20). The length frequency range for larvae was small, with over 95% in the

2.04.0 mm (0.08-0.16 in) size classes (Figure 4.5-21). The mean length of specimens from the

entrainment station samples was 2.7 mm (0.11 in) NL.
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Concentration (#/1000 cubic meters)

0

30

60

90

120

150

180

210

240

270

300

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-19. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of combtooth blenny larvae collected at HGS entrainment Station E1 during 2006.

Concentration (#/1000 cubic meters)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-20. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of combtooth blenny larvae collected at HGS source water stations during 2006.
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Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-0.30 -0.25 -0.20 -0.15 -0.10 -0.05 -0.00 0.05 0.10 0.15 0.20 0.25 0.30

Note: Negative nighttime values are a plotting artifact

Figure 4.5-21. Mean concentration (#/1.0 m3[264 gal]) of combtooth blenny larvae

at entrainment Station E1 during night (Cycle 3) and day (Cycle 1) sampling.

N = 221

Percent

0

10

20

30

40

50

60

Midpoint for

Length Category (mm)

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

Figure 4.5-22. Length (mm) frequency distribution for combtooth blenny larvae

collected at entrainment Station E1.
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4.5.3.3.4 Modeling Results

The following section presents the results for demographic and empirical transport modeling of CWIS

effects on combtooth blennies. There was very little species-specific life history information available for

combtooth blennies. Larval survival was estimated using data from Stephens (1969) and Stevens and

Moser (1982), and there was enough other information on reproduction to calculate both FH and AEL

estimates. Larval growth was estimated from information from Stevens and Moser (1982). Total annual

entrainment of combtooth blenny larvae at HGS was estimated at 2,255,907 (standard error of 55,768)

using actual cooling water flows during 2006 and using the design (or maximum) flows, annual

entrainment was estimated at 4,362,576 (standard error of 100,491) (Table 4.5-2).

Fecundity Hindcasting (FH)

The annual entrainment estimate for combtooth blenny larvae was used to estimate the number of females

at the age of maturity needed to produce this number of larvae over their lifetimes. No estimates of egg

survival for combtooth blenny were available, but because egg masses are attached to the substrate and

guarded by the male (Stephens et al. 1970), egg survival is probably high and was conservatively assumed

to be 100%. The mean length from a random sample of 200 combtooth blenny larvae was 2.7 mm (0.11

in). A larval growth rate of 0.20 mm/day (0.008 in/day) was derived from data in Stevens and Moser

(1982). The mean length and estimated hatch length of 2.2 mm (0.09 in) were used with the growth rate to

estimate that the mean age at entrainment was 2.3 days. A daily survival rate of 0.89 computed from data

in Stephens (1969) was used to calculate survival to the average age at entrainment as 0.892.3= 0.76. A

quadratic equation was used to estimate adult survival S at age in days x using Figure 17 in Stephens

(1969):

8 2 4 S x x 8.528 10 3.918 10 0.4602        (5)

An adult survivorship table (Table 4.5-17) was constructed using the survival equation based on Stephens

(1969) and information about eggs from Stephens (1969; Table 3) on H. gentilis, H. gilberti and H.

jenkinsi to estimate a lifetime fecundity of 2,094 eggs.

Table 4.5-17. Survivorship table for adult combtooth blenny from data in Stephens (1969)

showing spawners (Lx) surviving to the age interval and numbers of eggs spawned annually (Mx).

Age (year) Lx Mx LxMx

0.5 1,000 367 366,667

1.5 693 633 438,624

2.5 443 1,067 472,794

3.5 252 1,533 386,465

4.5 119 2,000 237,915

5.5 44 2,500 109,973

6.5 27 3,000 81,415

TLF = 2,094

The total lifetime fecundity was calculated as the sum of LxMx divided by 1,000.
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The estimated numbers of female combtooth blennies at the age of maturity (0.5 year) whose lifetime

reproductive output was entrained through the HGS CWIS during 2006 was 1,413 based on entrainment

estimates calculated using actual cooling water flows during the period and increased to 2,733 based on

the design flows (Table 4.5-18). The sensitivity analysis based on the 90% confidence intervals shows

that the variation in the estimate of entrainment abundance had much less of an effect on the variation of

the FH estimate than the life history parameters used in the model.

Table 4.5-18. Results of FH modeling for combtooth blenny larvae based on entrainment

estimates calculated using actual and design (maximum) CWIS flows.

Parameter Estimate Std. Error

FH

Lower

Estimate

FH

Upper

Estimate

FH

Range

Actual Flows

FH Estimate 1,413 1,225 340 5,878 5,538

Total Entrainment 2,255,90

7

55,768 1,356 1,471 115

Design Flows

FH Estimate 2,733 2,368 657 11,366 10,708

Total Entrainment 4,362,57

6

100,491 2,630 2,837 207

The upper and lower estimates are based on a 90% confidence interval of the mean. FH estimates were also

calculated using the upper and lower confidence estimates from the entrainment estimates.

Adult Equivalent Loss (AEL)

The parameters required for formulation of AEL include larval survival from entrainment to settlement

and survival from settlement to the average age of reproduction for a mature female. Larval survival from

entrainment through settlement at 50 days was estimated as 0.89(50-2.3)= 0.003 using the same daily

survival rate used in formulating FH. Juvenile and adult survival was calculated from observed age group

abundances in Stephens (1969). Daily survival through the age of 2.7 years for the three species was

estimated as 0.99 and was used to calculate a finite survival of 0.79 to the age at first maturity of 0.5

years.

The equivalent number of adult combtooth blennies calculated from the number of larvae entrained

through the HGS CWIS for the sampling period was 6,024 based on actual cooling water flows and

11,650 based on the design flows during 2006 (Table 4.5-19). The results of the sensitivity analysis show

that the model estimate was much more sensitive to the error associated with the life history estimates

than the entrainment estimates used in the model.
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Table 4.5-19. Results of AEL modeling for combtooth blenny larvae based on entrainment

estimates calculated using actual and design CWIS flows.

Parameter Estimate Std. Error

AEL

Lower

Estimate

AEL

Upper

Estimate

AEL

Range

Actual Flows

AEL Estimate 6,024 7,379 803 45,190 44,387

Total Entrainment 2,255,907 55,768 5,779 6,269 490

Design Flows

AEL Estimate 11,650 14,270 1,553 87,385 85,832

Total Entrainment 4,362,576 100,491 11,208 12,091 883

The upper and lower estimates are based on a 90% confidence interval of the mean. AEL estimates were also calculated

using the upper and lower confidence estimates from the entrainment estimates.

Empirical Transport Model (ETM)

A random sample of 200 lengths from the 221 measured larvae was used to calculate the difference

between the estimated hatch lengths and the 95th percentiles of the measurements. This value and a

growth rate of 0.20 mm/day (0.008 in/day) were used to estimate that blennies were exposed to

entrainment for a period of approximately 7.5 days.

The monthly estimates of PE for combtooth blennies for the 2006 period varied among surveys and

ranged from 0 to 0.00017 based on the actual flows and ranged from 0 to 0.00041 based on the design

flows (Table 4.5-20). The largest estimates were calculated for the April and December surveys, but the

largest proportion of the source population was present during the June survey (fi = 0.381 or 38.1%). As

the results for the JanuaryMarch surveys show, there were periods when combtooth blenny larvae were

collected at the source water stations, but not at the entrainment station (i.e., PEi=0 and fi > 0). The values

in the table were used to calculate a PM estimate of 0.0006 with a standard error of 0.0002 based on the

actual cooling water flows. Using the design flows, an estimate of 0.0012 with a standard error of 0.0004

was calculated.
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Table 4.5-20. ETM data and results for combtooth blenny larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3.

Actual Flows Design Flows

Survey

Date

PE

Estimate

PE

Std. Err.

PE

Estimate

PE

Std. Err. fi

23-Jan-06 0 0 0 0 0.00094

21-Feb-06 0 0 0 0 0.00327

20-Mar-06 0 0 0 0 0.00129

17-Apr-06 0.00017 0.00011 0.00038 0.00024 0.00904

15-May-06 0.00004 0.00001 0.00008 0.00002 0.21583

12-Jun-06 0.00008 0.00002 0.00018 0.00005 0.38149

10-Jul-06 0.00016 0.00003 0.00030 0.00006 0.12500

7-Aug-06 0.00005 0.00002 0.00009 0.00004 0.12077

5-Sep-06 0.00012 0.00004 0.00021 0.00006 0.08589

16-Oct-06 0.00004 0.00003 0.00010 0.00007 0.04028

13-Nov-06 0.00010 0.00007 0.00022 0.00014 0.01293

11-Dec-06 0.00017 0.00019 0.00041 0.00044 0.00326

PM 0.0006 0.0002 0.0012 0.0004 
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4.5.3.4 CIQ Goby complex (Clevelandia, Ilypnus, Quietula)

Gobies are small, demersal fishes that are found

worldwide in shallow tropical to temperate marine

environments. Many members of the family are

euryhaline and are able to tolerate very low salinities

and even freshwater. The family Gobiidae contains

approximately 1,875 species in 212 genera (Nelson

1994; Moser 1996). Twenty-one goby species from

16 genera occur from the northern California border to

south of Baja California (Moser 1996). In addition to

the three species comprising the CIQ complex (arrow goby Clevelandia ios [pictured above], cheekspot

goby Ilypnus gilberti, and shadow goby Quietula y-cauda), there are at least six other common species in

southern California: blackeye goby (Rhinogobiops nicholsii), yellowfin goby (Acanthogobius

flavimanus), longjaw mudsucker (Gillichthys mirabilis), blind goby (Typhlogobius californiensis), bay

goby (Lepidogobius lepidus), and bluebanded goby (Lythrypnus dalli).

Myomere counts, gut proportions, and pigmentation characteristics can be used to identify most fish

larvae to the species level. However, the arrow, cheekspot, and shadow gobies cannot be differentiated

with complete confidence at most larval stages (Moser 1996). Therefore, larval gobies collected during

entrainment sampling that could not be identified to the species level weregroupedintothe‘CIQ’goby

complex (for Clevelandia, Ilypnus and Quietula),orthefamilylevel‘Gobiidae’ifspecimenswere

damaged but could still be recognized as gobiids. Some larger larval specimens with well-preserved

pigmentation patterns could be identified to the species level (W. Watson, Southwest Fisheries Science

Center, pers. comm.), but those that were speciated in this study were subsequently combined into the

CIQ complex for analysis. The following section presents an overview of the family and life history

characteristics of each of the three species.

4.5.3.4.1 Life History and Ecology

All three species have overlapping ranges in southern California and occupy similar habitats. Arrow goby

is the most abundant of the three species in bays and estuaries from Tomales Bay to San Diego Bay,

including Elkhorn Slough (Cailliet et al. 1978), Anaheim Bay (MacDonald 1975) and Newport Bay

(Allen 1982). Arrow and cheekspot gobies were reported as abundant from the Cabrillo Beach area in

outer Los Angeles Harbor based on beach seine sampling (Allen et al. 1983). The life history of the arrow

goby was reviewed by Emmett et al. (1991) and the comparative ecology and behavior of all three species

were studied by Brothers (1975) in Mission Bay.

Arrow goby have the most northerly range of the three species, occurring from Vancouver Island, British

Columbia to southern Baja California (Eschmeyer and Herald 1983). The reported northern range limits

of both shadow goby Quietula y-cauda and cheekspot goby Ilypnus gilberti are in central California with

sub-tropical southern ranges that extend well into the Gulf of California (Robertson and Allen 2002).

Their physiological tolerances reflect their geographic distributions with arrow goby less tolerant of

warmer temperatures compared to cheekspot goby. When exposed to temperatures of 32.1C (89.8F) for

three days in a laboratory experiment, no arrow gobies survived but 95% of cheekspot goby did survive

Greg Goldsmith, USFWS
Harbor Generating Station CWIS Entrainment and

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(Brothers 1975). The species inhabits burrows of ghost shrimps (Neotrypaea spp.) and other burrowing

invertebrates, such as the fat innkeeper worm (Urechis caupo), and gobies exposed to warm temperatures

on mudflats can seek refuge in their burrows where temperatures can be several degrees cooler than

surface temperatures.

The reproductive biology is similar among the three species in the CIQ complex. Arrow goby typically

mature sooner than the other two species, attaining 50% maturity in the population after approximately 8

months as compared to 1618 months for cheekspot and shadow gobies (Brothers 1975). Mature females

for all three of these species are oviparous and produce demersal eggs that are elliptical in shape,

adhesive, and attached to a nest substratum at one end (Matarese et al. 1989; Moser 1996). Hatched larvae

are planktonic with the duration of the planktonic stage estimated at 60 days for populations in Mission

Bay (Brothers 1975). Arrow goby mature more quickly and spawn a greater number of eggs at a younger

age than either the cheekspot or shadow gobies. As with most fishes, fecundity is dependent on age and

size of the female. Fecundity of gobies in Mission Bay ranged from 225750 eggs per batch for arrow

gobies, 2251,030 eggs for cheekspot, and 3401,400 for shadow, for a mean value of 615 per batch for

the CIQ complex. Mature females of the CIQ complex deposit 25 batches of eggs per year.

Summary of CIQ goby distribution and life history attributes.

Range: Vancouver Island, British Columbia to Gulf of California

Life History:

 Size up to 57 mm (2.1 inches) (arrow goby); 64 mm (2.5 inches) (cheekspot goby); 70 mm (2.75 inches) (shadow

goby)

 Age at maturity from 0.71.5 years

 Life span ranges from <3 years (arrow goby) to 5 years (shadow goby)

 Spawns year-round in bays and estuaries; demersal, adhesive eggs with fecundity from 2251,400 eggs per female

and multiple spawning of 25 times per year

 Juveniles from 14.029.0 mm are < 1 year old

Habitat: Mud and sand substrates of bays and estuaries; commensally in burrows of shrimps and other invertebrates.

Fishery: None.

CIQ complex larvae hatch at a size of 23 mm (0.08-1.1 in) (Moser 1996). Data from Brothers (1975)

were used to estimate an average growth rate of 0.16 mm/day (0.006 in/day) for the approximately 60-day

period from hatching to settlement. Brothers (1975) estimated a 60-day larval mortality of 98.3% for

arrow goby larvae, 98.6% for cheekspot, and 99.2% for shadow. These values were used to estimate

average daily survival at 0.93 for the three species. Once the larvae transform at a size of approximately

1015 mm (0.4-0.6 in) SL, depending on the species (Moser 1996), the juveniles settle into the benthic

environment. For the Mission Bay populations mortality following settlement was 99% per year for arrow

goby, 6674% for cheekspot goby, and 6269% for shadow goby. Few arrow gobies exceeded 3 years of

age based on otolith records, whereas cheekspot and shadow gobies commonly lived for 4 years (Brothers

1975).

Gobies eat a variety of larval, juvenile, and adult crustaceans, mollusks, and insects. Many will also eat

small fishes, fish eggs, and fish larvae.
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4.5.3.4.2 Population Trends and Fishery

Average concentrations of gobiid species complex larvae were lowest from October through December

and greatest from February through June in the earlier 316(b) study of the HGS in 19781979 (IRC

1981). Average survey concentrations for the near-field station varied from 0 to 17,170 larvae per 1,000

m

3

(1,000 m3= 264,172 gal) (average 2,190 per 1,000 m3) and from 1 to 4,310 larvae per 1,000 m3

(average 320 per 1,000 m3) for the far-field station. The near-field concentrations were over 30 times

greater than the 2006 concentrations at the entrainment station, while the far field station concentrations

were only about 50% greater. There was no significant difference in abundance between day and night

samples at the near-field station.

Larval CIQ gobies have been one of the most abundant species collected in previous surveys of the Los

Angeles-Long Beach Harbor Complex area (HEP 1976; Brewer 1983; MEC 2002). In a survey conducted

in 2000, CIQ goby was the most abundant species group collected, comprising 33% of the total catch

(MEC 2002). In a 5-year study of fishes in San Diego Bay from 19941999, approximately 75% of the

estimated 4.5 million (standing stock) gobies were juveniles (Allen et al. 2002). Seasonal peaks in

population abundance generally occurred in summer and fall and were associated with settlement of

young-of-the-year although high abundances were also recorded in January and April of some years.

Population abundances vary among years and may be correlated to the severity of winter rainfall events

and urban runoff that may impact the water quality of seasonal estuaries in southern California. There is

no fishery for these goby species because of their small size.

4.5.3.4.3 Sampling Results

CIQ complex goby larvae were the most abundant taxon at the entrainment station with a mean

concentration of 516 per 1,000 m3(1,000 m3= 264,172 gal) over all surveys (Table 4.5-1). They were

present during all surveys, but tended to be most abundant in the MarchApril period and during June

(Figure 4.5-22). During periods of maximum abundance in early April 2006, CIQ complex gobies were

present in the entrainment samples at average concentrations of 1,750 per 1,000 m

3

. Gobies were also

present at the source water stations during all months of the year, with a peak average concentration in

May 2006 of 368 per 1,000 m

3

(Figure 4.5-23). The larvae tended to be more abundant in nighttime

samples, particularly from July through December (Figure 4.5-24). The length-frequency distribution for

a representative sample of CIQ goby larvae showed that the majority of the sampled larvae were recently

hatched based on the reported hatch size of 2–3 mm (0.08–0.12 in) (Moser 1996). The size classes of

most larvae were in the 2.05.0 mm (0.08–0.20 in) range with a small proportion in the 6.014.0 mm

(0.2–0.6 in) size classes (Figure 4.5-25). The mean length of specimens from the entrainment station

samples was 4.1 mm (0.16 in) NL.
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Concentration (#/1000 cubic meters)

0

400

800

1200

1600

2000

2400

2800

3200

3600

4000

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-23. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation (narrow

bars) of unidentified goby larvae (CIQ gobies) collected at HGS entrainment Station E1 during 2006.

Concentration (#/1000 cubic meters)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-24. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation (narrow

bars) of unidentified goby larvae (CIQ gobies) collected at HGS source water stations during 2006.
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Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-2.4 -2.0 -1.6 -1.2 -0.8 -0.4 -0.0 0.4 0.8 1.2 1.6 2.0 2.4

Note: Negative nighttime values are a plotting artifact

Figure 4.5-25. Mean concentration (#/1.0 m3[264 gal]) of unidentified goby larvae at

entrainment Station E1 during night (Cycle 3) and day (Cycle 1) sampling.

N = 1764

Percent

0

10

20

30

40

Midpoint for

Length Category (mm)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Figure 4.5-26. Length (mm) frequency distribution for unidentified goby

larvae collected at entrainment Station E1.
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4.5.3.4.4 Modeling Results

The following sections present the results for demographic and empirical transport modeling of CWIS

entrainment effects on CIQ goby populations. A comprehensive comparative study of the three goby

species in the CIQ complex by Brothers (1975) provided the necessary life history information for both

FH and AEL models. Total annual entrainment of CIQ goby larvae at HGS was estimated to be

33,290,815 (standard error of 869,904), using actual measured cooling water flows and using the design

flows was estimated at 75,938,007 (standard error of 1,933,837) during 2006 (Table 4.5-2).

Fecundity Hindcasting (FH)

The annual entrainment estimate for CIQ gobies was used to estimate the number of females at the age of

maturity needed to produce the number of larvae entrained during their lifetime. No estimates of egg

survival for gobies were available, but because gobies deposit demersal egg masses (Wang 1986) and

exhibit parental care, usually provided by the adult male, egg survival is generally high and was

conservatively assumed to be 100 percent. Estimates of larval survival for the three species from Brothers

(1975) were used to compute an average daily survival of 0.93. A larval growth rate of 0.16 mm/day

(0.006 in/day) was estimated from transformation lengths reported by Brothers (1975) for the three

species and an estimated transformation age of 60 days. The mean length (4.2 mm [0.16 in]) and the

estimated hatch length of 2.84 mm (0.11 in) from a random sample of 200 of the measured larvae were

used with the calculated growth rate to estimate that the mean age at entrainment was 8.4 days. Survival

to the average age at entrainment was then estimated as 0.938.4= 0.55. A survivorship table was

constructed using data from Brothers (1975) and was used to estimate a total lifetime fecundity of

1,400 eggs (Table 4.5-21). The age when at 50% of the female population was reproductive averaged 1.67

years.

The estimated numbers of female gobies at the age of maturity, whose lifetime reproductive output was

entrained through the HGS circulating water system for the 2006 period, was 43,360 based on the actual

cooling water flows and 98,906 based on the design flows (Table 4.5-22). The results of the sensitivity

analysis show that the greatest uncertainty associated with the estimate is related to the life history

parameters in the model and not the entrainment estimate.
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Table 4.5-21. Total lifetime fecundity estimates for three goby species

based on a life table in Brothers (1975).

Species Age N

%

Mature Fecundity Spawns

No.

Eggs

Eggs per

Spawner TLF

Clevelandia ios 0 500 0

1 100 81 450 1.5 54,675 547

2 4 100 700 2.0 5,600 56 603

Ilypnus gilberti 0 500 0

1 80 10 260 0 0

2 51 71 480 1.5 26,071 511

3 14 99 720 3.0 29,938 587

4 2 100 900 3.0 5,400 106 1,204

Quietula y-cauda 0 500 0

1 74 23 410 0 0

2 50 87 620 1.5 4,0455 809

3 26 99 840 2.5 54,054 1081

4 7 100 1,200 3.0 25,200 504 2,394

Mean 1,400

Table 4.5-22. Results of FH modeling for CIQ goby complex larvae based on entrainment

estimates calculated using actual and design (maximum) CWIS flows.

Parameter Estimate Std. Error

FH

Lower

Estimate

FH

Upper

Estimate

FH

Range

Actual Flows

FH Estimate 43,360 37,568 10,42

6

180,331 169,90

5 Total Entrainment 33,290,81

5

869,904 41,49

6

45,224 3,728

Design Flows

FH Estimate 98,906 85,692 23,78

2

411,330 387,54

8 Total Entrainment 75,938,00

7

1,933,83

7

94,76

3

103,049 8,287

The upper and lower estimates are based on a 90% confidence interval of the mean. FH estimates were also

calculated using the upper and lower confidence estimates from the entrainment estimates.

Adult Equivalent Loss (AEL)

The parameters required for formulation of AEL estimates include larval survival from entrainment to

settlement and survival from settlement to the average age of reproduction for a mature female. Larval

survival from entrainment through settlement was estimated as 0.9360-8.4= 0.02 using the same daily

survival rate used in formulating FH. Brothers (1975) estimated that mortality in the first year following

settlement was 99% for arrow, 66–74% for cheekspot, and 62–69% for shadow goby. These estimates

were used to calculate a daily survival of 0.995 that was used to estimate a finite survival of 0.21 for the

first year following settlement. Daily survival through the average female age of 2.21 years, from life

table data for the three species, was estimated as 0.994 and was used to calculate a finite survival over the

period of 0.21.
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The estimated number of adult CIQ gobies equivalent to the number of larvae entrained through the HGS

CWIS for the 2006 sampling period was 36,231 based on an entrainment estimate calculated using actual

CWIS flows and was 82,665 based on the design cooling water flows (Table 4.5-23). The results of the

sensitivity analysis show that the greatest uncertainty associated with the estimate is related to the life

history parameters in the model and not the entrainment estimate.

Table 4.5-23. Results of AEL modeling for CIQ goby complex larvae based on entrainment

estimates calculated using actual and design (maximum) CWIS flows.

Parameter Estimate Std. Error

AEL

Lower

Estimate

AEL

Upper

Estimate

AEL

Range

Actual Flows

AEL Estimate 36,231 40,708 5,711 229,972 224,261

Total Entrainment 33,290,815 869,904 34,682 37,798 3,116

Design Flows

AEL Estimate 82,665 92,855 13,027 524,564 511,537

Total Entrainment 75,938,007 1,933,837 79,202 86,128 6,926

The upper and lower estimates are based on a 90% confidence interval of the mean. AEL estimates were also calculated

using the upper and lower confidence estimates from the entrainment estimates.

Empirical Transport Model (ETM)

The larval duration used to calculate the ETM estimates for CIQ gobies was based on the lengths of

entrained larvae. The difference between the lengths of the 95th percentile (8.1 mm [0.32 in]) and the

estimated hatch length of 2.8 mm (0.11 in) was used with a growth rate of 0.16 mm/day (0.006 in/day) to

estimate that CIQ goby larvae were vulnerable to entrainment for a period of 32.7 days.

CIQ gobies larvae were present in the entrainment and source water samples throughout the year. The

monthly estimates of PE for the 2006 period ranged from 0.00023 to 0.00130 using the actual cooling

water flows (Table 4.5-24). Based on the design flows during the period, the estimates ranged from

0.00050 to 0.00292. The largest estimates occurred during the April survey with the largest proportion of

the source population occurring slightly later in the year in the June survey (fi = 0.143 or 14.3 percent).

The values in the table were used to calculate a PM estimate of 0.0265, with a standard error of 0.0112

based on the actual flows and an estimate of 0.0570 with a standard error of 0.0236 based on the design

flow volumes.
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Table 4.5-24. ETM data and results for CIQ goby larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3.

Actual Flows Design Flows

Survey

Date

PE

Estimate

PE

Std. Err.

PE

Estimate

PE

Std. Err. fi

23-Jan-06 0.00111 0.00047 0.00261 0.00107 0.04614

21-Feb-06 0.00056 0.00013 0.00138 0.00031 0.02558

20-Mar-06 0.00112 0.00065 0.00263 0.00151 0.07270

17-Apr-06 0.00130 0.00063 0.00292 0.00139 0.11825

15-May-06 0.00059 0.00020 0.00108 0.00036 0.13925

12-Jun-06 0.00114 0.00041 0.00254 0.00088 0.14297

10-Jul-06 0.00067 0.00023 0.00121 0.00040 0.05170

7-Aug-06 0.00061 0.00026 0.00112 0.00046 0.07611

5-Sep-06 0.00031 0.00016 0.00057 0.00028 0.07090

16-Oct-06 0.00062 0.00022 0.00155 0.00056 0.06600

13-Nov-06 0.00023 0.00010 0.00050 0.00021 0.08033

11-Dec-06 0.00103 0.00053 0.00242 0.00124 0.11007

PM 0.0265 0.0112 0.0570 0.0236 

4.5.3.5 Yellowfin Goby (Acanthogobius flavimanus)

Yellowfin goby (Acanthogobius flavimanus) is

native to Japan, South Korea, and China, where it

ranges from nearshore marine to coastal fresh

water habitats (Brittan et al. 1963; Haaker 1979).

This goby is catadromous in Japan, moving from

fresh water to saline mudflats to spawn (Herbold et

al. 1989). Yellowfin goby is an introduced (nonindigenous) species now common in many bays

and estuaries of California. The first documented

collection of a yellowfin goby in California

occurred in January 1963 in a midwater trawl from

the San Joaquin River (Brittan et al. 1963), and

they were first found in Los Angeles Harbor around 1977 (Moyle 2002). Explanations for its introduction

into California harbors include transport of adults in the fouled seawater system of ships, transport of eggs

or larvae in ballast water or on fouling organisms on ships’hulls,andimportofeggswithoysterspat

from Japan. Due to transport of their pelagic larval stage by nearshore currents they are now widespread

in bays and coastal lagoons in southern California (Schroeter and Moyle 2006).

4.5.3.5.1 Life History and Ecology

The early life history of yellowfin goby is similar to other members of the family Gobiidae. Females are

oviparous, laying demersal, adhesive eggs in burrows guarded by males until the planktonic larvae hatch

(Moser 1996). Spawning occurs mainly in winter and spring. Female yellowfin goby in Japan lay between

6,000 and 32,000 eggs and may be terminal spawners, with many dying after the eggs are released
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(Miyazaki1940,citedinWang1986).Wang’s(1986)fecundityestimateof18,000eggs per female falls

within the range reported by Miyazaki (1940).

Yellowfin goby larvae initially remain near the bottom before moving up into the water column (Jahn and

Lavenberg 1986; Moser 1996). The larvae hatch at 4.5 to 4.6 mm NL (approximately 0.18 in), begin to

have limited swimming ability between 6.7-8.5 mm (0.26-0.33 in), and transform at around 16-18 mm

(0.6-0.7 in) (Moser 1996). Upon transformation they settle to the benthos and begin their juvenile life

stage (Baker 1979).

Reported estimates for yellowfin goby longevity, age at maturity, and other demographic parameters vary

in the scientific literature. Hoshino et al. (1993) indicate that yellowfin goby in Japan live to three years

while Baker (1979) calculated an estimate of four years for populations in the San Francisco Bay Area.

Age at maturity was found to be less than one year (Baker 1979 [San Francisco Bay]) greater than one

year (Miyazaki 1940 [Japan]; Middleton 1982 [Australia]; Wang 1986 [California]); and as high as two to

three years (Brittan et al. 1970 [California]).

No estimates of larval growth or survivorship have been reported for yellowfin goby. Brothers (1975)

estimates a time period of 60 days from hatching to settlement for three sympatric gobies (i.e., arrow

goby, cheekspot goby, and shadow goby) from Mission Bay, California. Brothers (1975) calculated a

finite mortality estimate of 0.983 for arrow goby over the two-month time period from egg laying through

settlement, and this mortality estimate was used in the present study for calculating yellowfin goby

survivorship. The larval growth rate for arrow goby from Brothers (1975) and estimates of hatch size and

transformation length derived from Moser (1996) for yellowfin goby were used to estimate a larval

growth rate of 0.25 mm (0.01 in) per day.

4.5.3.5.2 Population Trends and Fishery

Yellowfin goby larvae have been collected in studies of the Los Angeles and Long Beach harbors since

1983 (MBC 1984) and ranked 8th in abundance in surveys conducted in 2000 (MEC 2002). Yellowfin

goby is commercially valuable in their native range more so than in California. Although small, this goby

is considered a delicacy in Japan (Eschmeyer and Herald 1983), but in California, particularly the San

Francisco Bay Area, it is used primarily as bait for striped bass (Cohen and Carlton 1995). There are no

recent records of commercial or recreational catches of this species for Los Angeles or Orange counties.

4.5.3.5.3 Sampling Results

Yellowfin goby larvae were the second most abundant taxon at the entrainment station with a mean

concentration of 263 per 1,000 m3 (1,000 m3 = 264,172 gal) over all surveys (Table 4.5-1). They were

mainly present at the entrainment station in JanuaryMarch and largely absent during all other months of

the year (Figure 4.5-26). During periods of maximum abundance in early March 2006 yellowfin goby

larvae were present in the entrainment samples at average concentrations of 4,385 per 1,000 m3.

Yellowfin gobies were far less abundant at the source water stations with a peak average concentration in

late February 2006 of 161 per 1,000 m3 for all stations combined (Figure 4.5-27). The larvae were

significantly more abundant in nighttime samples, except during early March when there was a high

abundance of recently-hatched larvae in the water column (Figure 4.5-28). The size classes of most larvae
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were in the 4.05.0 mm (0.16-0.2 in) range (Figure 4.5-29) and the mean length of 668 specimens was 4.7

mm (0.2 in) NL.
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C

oncentration (#/1000 cubic meters)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-27. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of yellowfin goby larvae collected at HGS entrainment Station E1 during 2006.

Concentration (#/1000 cubic meters)

0

50

100

150

200

250

300

350

400

450

500

550

600

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-28. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of yellowfin goby larvae collected at HGS source water stations during 2006.
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Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

Note: Negative nighttime values are a plotting artifact

Figure 4.5-29. Mean concentration (#/1.0 m3[264 gal]) of yellowfin goby larvae at

entrainment Station E1 during night (Cycle 3) and day (Cycle 1) sampling.

N = 668

P

ercent

0

10

20

30

40

50

60

Midpoint for

Length Category (mm)

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0

Figure 4.5-30. Length (mm) frequency distribution for yellowfin goby

larvae collected at entrainment Station E1.
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4.5.3.5.4 Modeling Results

The following sections present the results for demographic and empirical transport modeling of CWIS

entrainment effects on yellowfin goby populations. Total annual entrainment of yellowfin goby larvae at

HGS was estimated to be 15,407,999 (standard error of 1,744,298 using actual measured cooling water

flows during 2006 and 37,604,336 (standard error of 4,325,986) using the design (or maximum) cooling

water flows (Table 4.5-2).

Fecundity Hindcasting (FH)

The values required to estimate FH for yellowfin goby were substituted from reported life histories of

other species of gobies (Brothers 1975; Wang 1986). No estimates of egg mortality for gobies were

available, but goby egg masses are typically attached in burrows that are guarded by the male (Wang

1986; Moser 1996); therefore, egg survival is probably high and is conservatively assumed to be 100%

for the purpose of this analysis. Larval yellowfin goby survivorship estimates were also not available

from the literature. Therefore, we used an estimate of 98.3% larval arrow goby mortality over two months

from Brothers (1975) to calculate a daily survival estimate of 0.93 ([1-0.98]6 / 365.25 = 0.93) for yellowfin

goby. Survival to entrainment was then estimated using the average number of days to entrainment (2.5

days) as 0.932.5 = 0.85. The average age at entrainment was calculated by taking the difference between

the mean length (4.6 mm [0.18 in]) and the length of the 10th percentile (4.0 mm [0.16 in]) from a random

sample of 200 larvae and dividing this value by the estimated growth rate of 0.25 mm (0.01 in) per day.

The value of the 10th percentile was used as the length at hatch size rather than the calculated value due to

the length frequency distribution that approximated a normal curve. A batch fecundity estimate of 19,000

eggs was derived from Miyazaki (1940) and Wang (1986). This value was used as the estimate of lifetime

fecundity based on the observation by Miyazaki (1940) that yellowfin goby may be terminal spawners

and probably deposit a single egg batch per lifetime.

The estimated number of yellowfin goby larvae entrained over the one-year sampling period in 2006

(Table 4.5-2) was used to calculate the number of breeding females needed to produce the number of

larvae entrained. The number of adult females needed to produce the number of larvae entrained was 968

based on the actual cooling water flows and was 2,362 based on the design cooling water flows (Table

4.5-25). The results of the sensitivity analysis show that the greatest uncertainty associated with the

estimate is related to the life history parameters in the model and not the entrainment estimate.
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Table 4.5-25. Results of FH modeling for yellowfin goby larvae based on entrainment

estimates calculated using actual and design (maximum) CWIS flows.

Parameter Estimate Std. Error

FH

Lower

Estimate

FH

Upper

Estimate

FH

Range

Actual Flows

FH Estimate 968 845 230 4,072 3,842

Total Entrainment 15,407,999 1,744,298 788 1,148 361

Design Flows

FH Estimate 2,362 2,064 561 9,942 9,381

Total Entrainment 37,604,336 4,325,986 1,915 2,809 894

The upper and lower estimates are based on a 90% confidence interval of the mean. FH estimates were also

calculated using the upper and lower confidence estimates from the entrainment estimates.

Adult Equivalent Loss (AEL)

The formulation of AEL requires estimates of survival from settlement to maturity. No survival estimates

were available from the literature for these life stages of yellowfin goby. Therefore, we did not calculate

an AEL estimate for this species.

Empirical Transport Model (ETM)

The larval duration used to calculate the ETM estimates for yellowfin gobies was based on the lengths of

entrained larvae. The difference between the lengths of the 95th (5.6 mm [0.22 in]) and 10th percentile (4.0

mm [0.16 in]) was used with a growth rate of 0.25 mm/day (0.01 in/day) to estimate that yellowfin goby

larvae were vulnerable to entrainment for a period of 6.3 days.

Yellowfin goby larvae were present in entrainment and source water samples during the first half of the

year with the greatest proportion occurring during the February survey (fi = 0.52 or 52%). The monthly

estimates of PE for the 2006 period ranged from 0 to 0.00362 based on the actual flows and ranged from

0 to 0.00663 based on the design flows (Table 4.5-26). The values in the table were used to calculate a PM

estimate of 0.0065 with a standard error of 0.0044 using the actual flows and an estimate of 0.0154

(standard error of 0.0101) based on the design cooling water flow volumes.
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Table 4.5-26. ETM data and results for yellowfin goby larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3.

Actual Flows Design Flows

Survey

Date

PE

Estimate

PE

Std. Err.

PE

Estimate

PE

Std. Err. fi

23-Jan-06 0.00136 0.00071 0.00318 0.00163 0.26052

21-Feb-06 0.00073 0.00051 0.00180 0.00126 0.51765

20-Mar-06 0.00124 0.00091 0.00290 0.00211 0.19089

17-Apr-06 0.00294 0.00423 0.00663 0.00938 0.00111

15-May-06 0.00362 0.00233 0.00663 0.00419 0.01971

12-Jun-06 0 0 0 0 0

10-Jul-06 0 0 0 0 0

7-Aug-06 0.00044 0.00055 0.00080 0.00099 0.01012

5-Sep-06 0 0 0 0 0

16-Oct-06 0 0 0 0 0

13-Nov-06 0 0 0 0 0

11-Dec-06 0 0 0 0 0

PM 0.0065 0.0044 0.0154 0.0101 

4.5.3.6 Bay Goby (Lepidigobius lepidus)

The bay goby Lepidogobius lepidus is a common

bottom dweller of bays and estuaries along the

Pacific coast of North America. It ranges from

southeastern Alaska to Cedros Island, Baja

California (Love et al. 2005). It is generally

considered a shallow-water marine species, but

may occur on mud and sand substrata down to

depths of 305 m (1,000 ft) (Love et al. 2005).

4.5.3.6.1 Life History and Ecology

Bay gobies are common on intertidal mudflats

where they may remain in invertebrate burrows

and shallow pools when the tide recedes (Grossman 1979). Like many marine-estuarine species, they are

tolerant of variations in salinity and temperature. During population monitoring studies in the San

Francisco Bay-Delta, bay goby occasionally (during periods of low Delta outflow) moved from marine

waters upstream through the Carquinez Strait into the lower salinity waters of Suisun Bay

(Baxter et al. 1999).

Reports differ on the longevity of bay goby. They are reported to live for about seven years, which is

considered unusually long for a small fish species (Grossman 1979). Life span estimates of two to three

years have been derived from length-frequency data collected by CDFG in San Francisco Bay.

Neil McDaniel
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Bay goby have been characterized as asynchronous multiple spawners (Wang 1986). Most bay goby do

not become reproductively mature until their second year, but a few mature during their first year (Wang

1986). Because bay goby use invertebrate burrows for predator avoidance and protection against

dehydration during low tides, it is thought that this species, like many other goby species, may also use

burrows for spawning (Grossman 1979; Wang 1986). No fecundity information is available for bay goby.

Eggs are demersal, spherical/elliptical in shape, and have an adhesive anchoring point (Wang 1986).

Newly hatched larvae are small (3 mm [0.12 in] or less) and nearly transparent (Wang 1986) and may

have a planktonic life phase of 3 to 4 months (Grossman 1979; Wang 1986). McGowen (1993)

characterizedbaygobylarvaeaspartofthe“Stenobrachius”groupofthecoastalichthyoplankton

assemblage of the Southern California Bight since the larvae impinge upon the continental shelf.

Completion of the transformation stage (beginning of the juvenile phase) for bay goby larvae occur

around 29 mm (1.1 in) (Moser 1996). Juveniles (and adults) occupy the burrows of blue mud shrimp

(Upogebia pugettensis), geoduck clams (Panope generosa) and other burrowing invertebrates for shelter

and predator avoidance (Grossman 1979).

Juvenile and adult bay goby growth was described by Grossman (1979). Growth is initially rapid, with

50% of their total growth (length) occurring within the first two years. Following this period of rapid

growth, increases in length slow to about 6 mm (0.24 in) per year. Maximum length is reported to 10.2

cm (4 in).

Bay goby is thought to be an important food item in the diet of a variety of vertebrate and invertebrate

predators. Their abundance, small size, and extended planktonic duration make bay goby larvae an

important link in the food web of bay/estuarine systems (Wang 1986). Their abundance as juveniles and

adults suggests that they remain an important forage species throughout all life stages. Pacific staghorn

sculpin (Leptocottus armatus) and California halibut (Paralichthys californicus) are among the many fish

predators of other adult gobies (Brothers 1975) and it is assumed that these fishes, and sharks and rays

that inhabit estuarine systems, also prey on bay gobies (Grossman 1979). Bay goby are also a prey item

for birds (Reeder 1951; Grossman 1979).

4.5.3.6.2 Population Trends and Fishery

Bay goby larvae was the second most abundant species collected in a survey of Los Angeles and Long

Beach Harbors in 2000; comprising 16% of the total catch (MEC 2002). Larvae were more abundant in

the area of the ILAH nearest to HGS and in the deeper stations. Due to its small size, bay goby is not

harvested commercially for human consumption or targeted by recreational anglers. There is no reference

in the current literature of their harvest or use as bait. Bay goby occur commonly in beach seine and otter

trawl samples from Los Angeles-Long Beach Harbors (Allen and Pondella 2006a), but there is no specific

information available on long-term population trends.

4.5.3.6.3 Sampling Results

Bay goby was the fourth most abundant taxon at the entrainment station with a mean concentration of 34

per 1,000 m3(1,000 m3= 264,172 gal) over all surveys (Table 4.5-1). They were present in variable

concentrations during most surveys but tended to have lowest abundances in the OctoberDecember
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period (Figure 4.5-30). During periods of maximum abundance in early February 2006, bay gobies were

present in the entrainment samples at average concentrations of 95 per 1,000 m

3

. Bay gobies were also

present at the source water stations during all months of the year, except April with a peak average

concentration in August 2006 of 90 per 1,000 m

3

(Figure 4.5-31). The larvae tended to be more abundant

in nighttime samples although several surveys had greater numbers collected during daytime

(Figure 4.5-32). The length-frequency distribution for a representative sample of bay goby larvae

(Figure 4.5-33) showed that the majority of the sampled larvae were recently hatched based on the

reported hatch size of 2–3 mm (0.8-0.1 in) (Moser 1996). The mean length of specimens from the

entrainment station samples was 3.2 mm (0.13 in) NL.
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Concentration (#/1000 cubic meters)

0

20

40

60

80

100

120

140

160

180

200

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-31. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of bay goby larvae collected at HGS entrainment Station E1 during 2006.

Concentration (#/1000 cubic meters)

0

20

40

60

80

100

120

140

160

180

200

220

240

Survey

01-Jan

2006

01-Mar

2006

01-May

2006

01-Jul

2006

01-Sep

2006

01-Nov

2006

01-Jan

2007

Figure 4.5-32. Mean concentration (#/1,000 m3[264,172 gal]) wide bars) and standard deviation

(narrow bars) of bay goby larvae collected at HGS source water stations during 2006.
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Date

12/26/06

12/11/06

11/29/06

11/13/06

10/30/06

10/16/06

10/02/06

09/18/06

09/05/06

08/21/06

08/07/06

07/24/06

07/10/06

06/26/06

06/12/06

05/30/06

05/15/06

05/01/06

04/17/06

04/03/06

03/20/06

03/08/06

02/21/06

02/07/06

01/23/06

01/10/06

Nighttime Daytime

Mean Concentration/cubic meter

-0.24 -0.20 -0.16 -0.12 -0.08 -0.04 0.00 0.04 0.08 0.12 0.16 0.20 0.24

Note: Negative nighttime values are a plotting artifact

Figure 4.5-33. Mean concentration (#/1.0 m3[264 gal]) of bay goby larvae at entrainment

Station E1 during night (Cycle 3) and day (Cycle 1) sampling.

N = 283

Percent

0

10

20

30

40

50

60

70

80

Midpoint for

Length Category (mm)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Figure 4.5-34. Length (mm) frequency distribution for bay goby larvae

collected at entrainment Station E1.
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4.5.3.6.4 Modeling Results

The following sections present the results for the empirical transport modeling of CWIS entrainment

effects on bay goby populations. There were no published data on larval survival, or the reproductive

biology of bay goby that could be used in demographic modeling of entrainment effects. Bay goby are

also larger and occur over different habitats than the CIQ goby complex that was used as a source of life

history information for yellowfin goby. Based on these differences it was decided that the life history

information was not appropriate for use with bay goby. Total annual entrainment of bay goby larvae at

HGS was estimated to be 2,376,260 (standard error of 66,436) using actual measured cooling water flows

and was estimated at 5,070,071 (standard error of 138,207) using the design flows during 2006 (Table

4.5-2).

Empirical Transport Model (ETM)

The larval duration used to calculate the ETM estimates for bay gobies was based on the lengths of

entrained larvae. There are no reported larval growth rates for bay goby, but a growth rate of 0.23

mm/day (0.01 in/day) was calculated by using the size difference between hatch length (2.85 mm [0.1 in])

and transformation length (26.5 mm [1.0 in]) (Moser 1996; Wang 1986) divided by an average planktonic

duration of 3–4 months (105 days) from Grossman (1979). The difference between the lengths of the 95th

(4.1 mm [0.16 in]) and the estimated hatch length of 2.7 mm [0.11 in]) was used with the growth rate to

estimate that bay goby larvae were vulnerable to entrainment for a period of 6.3 days.

Bay goby larvae were present in entrainment and source water samples during most of the year except

during the fall and early winter months (Table 4.5-27) with the greatest proportion occurring during the

August survey (fi = 0.17 or 17%). As the results for the September, November, and December surveys

show, there were times when larvae were collected from the source water stations but not from the

entrainment stations (i.e., PEi=0 and fi > 0). The monthly estimates of PE for the 2006 period ranged from

0 to 0.00294 using the actual flow and ranged from 0 to 0.00663 using the design flows. The values in the

table were used to calculate a PM estimate of 0.0024 with a standard error of 0.0009 using the actual flows

and an estimate of 0.0050 (standard error of 0.0018) based on the design flows.
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Table 4.5-27. ETM data and results for bay goby larvae based upon actual and design

(maximum) CWIS flow volumes using the fixed source water volume of 431,694,503 m3.

Actual Flows Design Flows

Survey

Date

PE

Estimate

PE

Std. Err.

PE

Estimate

PE

Std. Err. fi

23-Jan-06 0.00013 0.00004 0.00029 0.00008 0.13704

21-Feb-06 0.00039 0.00028 0.00096 0.00068 0.06635

20-Mar-06 0.00036 0.00031 0.00085 0.00072 0.05346

17-Apr-06 0.00294 0.00129 0.00663 0.00286 0.02037

15-May-06 0.00056 0.00017 0.00102 0.00030 0.12701

12-Jun-06 0.00056 0.00022 0.00124 0.00047 0.11371

10-Jul-06 0.00076 0.00023 0.00138 0.00042 0.09277

7-Aug-06 0.00032 0.00014 0.00058 0.00025 0.17368

5-Sep-06 0 0 0 0 0.11997

16-Oct-06 0.00007 0.00008 0.00018 0.00019 0.03267

13-Nov-06 0 0 0 0 0.03421

11-Dec-06 0 0 0 0 0.02875

PM 0.0024 0.0009 0.0050 0.0018 
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5.0 IM P I N GE M EN T STU D Y

5.1 INTRODUCTION

The purpose of the impingement study was to determine the extent of potential impacts from the

operation of the CWIS of the HGS on fishes and selected invertebrates. Impingement occurs when

organisms larger than the traveling screen mesh size (9.5 mm [3/8 in]) become trapped against the

screens, either because they are too fatigued to swim against the intake flow at the screens or they are

dead. Normal operations impingement samples were collected over a 24-hour period to determine the

daily loss from operation of the CWIS. Data from these surveys were used to estimate annual

impingement at the HGS.

5.1.1 Species to be Analyzed

Several types of organisms are susceptible to impingement by the generating station. All fishes and

macroinvertebrates were processed (i.e., identified, enumerated, and where appropriate, measured) in

impingement samples. However, assessment of impingement effects was limited to the most abundant

fish taxa that together comprised 90% of all juveniles and adults collected at HGS. Assessment of

impingement effects on invertebrates was limited to those that were considered commercially or

recreationally important, and were collected in sufficient numbers to warrant analysis.

5.2 HISTORICAL DATA

Impingement sampling was conducted during the 1978–1979 316(b) demonstration (IRC 1981) and from

2003–2005 as required by the HGS NPDES permit (MBC 2007a). These data are summarized to provide

information on historical impingement at the HGS.

5.2.1 Summary of Historical Data

During 1978–1979, a total of 17,632 fish representing 41 taxa and weighing 311 kg (685 lbs) was

impinged during the 316(b) study at HGS (IRC 1981). Sampling was conducted for a total of 34 days

during the study. The mean cooling water flow rate at the generating station during sampling varied from

200,605 to 1,502,645 m3(53 to 397 mgd), with a total annual flow of approximately 327,977,820 m3

(86.652 billion gallons). The estimated annual impingement based on extrapolations of impingement rates

was 164,225 fish weighing 2,827 kg (6,234 lbs).

During the 1978–1979 year-long study, abundance and biomass peaked in December, January, and

February, although no samples were collected in April or May due to a maintenance outage (IRC 1981).

The most abundant species were Pacific pompano (Peprilus simillimus), white croaker, and queenfish,

which combined accounted for 76% of the total impingement abundance. Pacific pompano was the most

abundant species overall, accounting for 31% of the impingement abundance. A total of 17,632 fish

weighing 310.4 kg (684.3 lbs) was impinged during the year-long study. An estimated 1,080 fish were

impinged following an intake tunnel cleaning event in March 1979. It was hypothesized that when stop

logs were removed following an outage, the incoming rush of cooling water created velocity fields near

the intake that could not be avoided by fishes that were accustomed to the calmer waters.
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During the last two years of impingement monitoring at HGS (2003–2005), a total of 10 normal operation

impingement surveys was performed (MBC unpublished data). During these surveys, a total of 90 fish

weighing 11.6 kg (26 lbs) was collected. The most abundant fishes were round stingray (Urobatis

halleri), giant kelpfish (Heterostichus rostratus), and shiner perch (Cymatogaster aggregata), which,

when combined, accounted for 78% of impingement abundance. A total of 62 macroinvertebrates

weighing 5.3 kg (12 lbs) was also impinged. The most abundant invertebrates were tuberculate pear crab,

intertidal coastal shrimp (Heptacarpus palpator), and California two-spot octopus (Octopus

bimaculatus/bimaculoides), which together comprised 73% of the impingement abundance.

5.2.2 Relevance to Current Conditions

The historical impingement data presented in Section 5.4 is relevant for historical comparisons. During

the 1978–1979 study, the maximum cooling water flow of the HGS CWIS was 1,504,310 m3per day (397

mgd), and the average flow during the study year was 62% of maximum. From 1982 to 1995, cooling

water flow averaged 457,985 m3per day (121 mgd) (MBC 1997). Flow during the 2006 study averaged

about 185,296 m3per day (49 mgd), or 51% of current design flow, which is less than design flow in the

previous study due to the modifications to the CWIS.

5.2.3 QA/QC Procedures & Data Validation

The sampling program during the 1978–1979 study was conducted with the approval of the LARWQCB,

and detailed procedures and methodologies, as well as QA/QC methods, can be found in Appendices G

(Biological Field Procedures), H (Laboratory Procedures), and I (Statistical and Analytical Procedures) of

IRC (1981).

5.3 METHODS

The following sections provide information on the impingement sample collection and data analysis

methods. The impingement sampling program was designed to provide the necessary information for the

impingement mortality characterization and development of the calculation baseline. The impingement

sampling provided current estimates of the taxonomic composition, abundance, biomass, seasonality, and

diel periodicity of organisms impinged at the HGS. The sampling program also documented the size, sex,

and physical condition of fish and shellfish impinged. The abundance and biomass of organisms impinged

was used to calculate impingement rates (e.g., the number of organisms impinged per 1x106 m

3

[264,200,793 gallons] of cooling water flowing through the CWIS).

The HGS has one screening facility consisting of bar racks, traveling screens, and the circulating water

pumps. Seawater drawn into the HGS first passes through the bar racks, followed by the traveling screens,

and is then pumped to the condensers. All material that was impinged on the traveling screens during the

surveys was subsequently rinsed from the screens by a high-pressure wash system into a collection

basket. A more complete description of the CWIS is presented in Section 3.2.
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5.3.1 Field Sampling

Impingement sampling at the HGS was conducted over a 24-hour period one day per week from

January 5 to December 29, 2006. Surveys were performed at the HGS when at least one circulating water

pump was operating at the beginning of each survey. Before each sampling effort, the traveling screens

were rotated and washed clean of all impinged debris and organisms. The sluiceways and collection

baskets were also cleaned before the start of each sampling effort. The operating status of the circulating

water pumps was recorded on an hourly basis during the study year. During each survey, the 24-hour

sampling period was divided into four 6-hour cycles. Initiation of sample collection occurred as follows:

Cycle 1 (approx. 07001300 hr), Cycle 2 (approx. 13001900 hr), Cycle 3 (approx. 19000100 hr), and

Cycle 4 (approx. 01000700 hr). During this time, the traveling screens were stationary for a period of

approximately 5.75 hours and then they were rotated and washed for 15 minutes. This rinse period

allowed the entire screen to be rinsed of all material impinged since the last screen wash cycle. The

impinged material was rinsed from the screens into the collection baskets associated with each set of

screens. The collection baskets were fitted with 6.4 mm (0.25 in) mesh liners.

On some occasions, the screen wash systems were operated (automatically or manually) prior to end of

each cycle. The material that was rinsed on these occasions was combined with the material collected at

the end of each cycle. All debris and organisms rinsed from each unit was processed separately from other

units.

All fishes and macroinvertebrates collected at the end of each cycle were removed from any other

impinged debris, then identified, enumerated, and weighed. Depending on the number of individuals of a

given species present in the sample, one of two specific procedures was used, as described below. Each of

these procedures involved the following measurements and observations:

 The appropriate linear measurement for individual fish and shellfish was determined and

recorded. These measurements were recorded to the nearest 1 mm (0.04 in). The following

standard linear measurements were used for the animal groups indicated:

 Fishes - Total body length for sharks and rays and standard lengths for bony fishes.

 Crabs - Maximum carapace width.

 Shrimp & Lobsters - Carapace length, measured from the anterior margin of carapace

between the eyes to the posterior margin of the carapace.

 Octopus - Maximum“tentacle”spread,measuredfromthetipofonetentacletothetipofthe

opposite tentacle.

 Squid –Dorsal mantle length, measured from the edge of the mantle to the posterior end of

the body.

 The wet body weight of individual fish and shellfish was determined after shaking loose water

from the body. Total weight of all individuals combined was determined in the same manner. All

weights were recorded to the nearest gram (0.035 ounce).

 Determination of sex was made for fishes where such determination could be made by external

morphology (such as surfperches, sharks, and rays).
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 The qualitative body condition of individual fish and shellfish was determined and recorded,

using codes for decomposition and physical damage.

 Shellfishes and other macroinvertebrates were identified to species and their presence recorded,

but they were not measured.

 The amount and type of debris (e.g., Mytilus shell fragments, wood fragments, etc.) and any

unusual operating conditions in the screen well system were noted by writing specific comments

inthe“Notes”sectionofthedatasheet.Informationonweatherwasalsorecordedduringeach

collection.

The following specific procedures were used for processing fishes and shellfishes when the number of

individuals per species in the sample or subsample was less than 30:

 For each individual of a given species, the linear measurement, weight, and body condition codes

was determined and recorded.

The following specific subsampling procedures were used for fishes and shellfishes when the number of

individuals per species was greater than 30:

 The linear measurement, individual weight, and body condition codes for a subsample of 30

individuals was recorded individually on the data sheet. The individuals selected for measurement

were selected after spreading out all of the individuals in a sorting container, making sure that

they were well mixed and not segregated into size groups. Individuals with missing heads or other

major body parts were not measured.

 The linear measurements of up to 200 individuals of each taxon were recorded.

 The total number and total weight of all the remaining individuals combined was determined and

recorded separately.

5.3.2 QA/QC Procedures & Data Validation

During the NPDES impingement surveys (2003–2005), sampling was conducted in accordance with

specifications set forth by the LARWQCB in the NPDES permit for the plant. Specimens of uncertain

identity were cross-checked against taxonomic voucher collections maintained by MBC, as well as

available taxonomic literature. Occasionally, outside experts were consulted to assist in the identification

of species whose identification was difficult. Scales used to measure biomass (spring and electronic) were

calibrated every three months.

During the current study, QA/QC checks were conducted on a quarterly basis to verify compliance with

the field sampling procedures. QC surveys were conducted on February 9, April 13, August 3-4, and

October 12, 2006. Random cycles were chosen for QA/QC re-sorting to verify that all the collected

organisms were removed from the impinged material. If the count of any of individual taxon made during

the QA/QC survey varied by more than 5% (or one individual if the total number of individuals is less

than 20) from the count recorded by the observer, then the next three sampling cycles for that observer

would be checked. In all cases, impingement sampling was conducted properly following the written

procedures. All impinged materials were removed from the collection baskets and sorted properly, all

organisms were identified correctly and all length and weight measurements were recorded properly, and

the data sheets were filled out accurately and legibly. The survey procedures were reviewed with all

personnel prior to the start of the study and all personnel were given printed copies of the procedures.
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The following measures were employed to ensure accuracy of all data entered into the computer

databases and spreadsheets:

 Upon returning from the field, all field data sheets were checked by the Project Manager for

completeness and any obvious errors;

 Data were entered into pre-formatted spreadsheets;

 After data were entered, copies of the spreadsheets were checked against the field data sheets;

 In the prior studies, data were submitted annually to the LARWQCB, EPA Region IX, and the

CDFG.

5.3.3 Data Analysis

A log with hourly observations of each of the circulating water pumps for the entire study period was

obtained from LADWP. Impingement rates were calculated using the circulating water flow during each

of the cycles of each 24-hour survey. The total time for each cycle was multiplied by the known flow rate

of each of the circulating water pumps in operation during each cycle to determine CWIS flow during

each cycle.

The estimated daily impingement rate was then used to calculate the weekly and annual impingement.

The days between the impingement collections were assigned to a weekly survey period by setting the

collection day as the median day within the period and designating the days before and after the collection

date to the closest sampling day to create a weekly survey period. The total calculated flow for each

survey period was multiplied by the taxon-specific daily impingement rates for both abundance and

biomass. The estimated impingement rate for each survey period was summed to determine the annual

normal operation impingement estimates for each taxon. Annual impingement estimates are presented in

this report based on both (1) actual flow using flow volumes obtained from LADWP, and (2) design flow

volume based on the maximum permitted cooling water intake flow at the HGS (408,824 m3per day, or

108.0 mgd).

During impingement sampling, all fishes and invertebrates that were retained on the traveling screens

were rinsed from the screens, flowed along a water-filled sluiceway, and were deposited into the

impingement collection baskets for processing. Data are presented for all impinged taxa, but a subset of

species was selected for more detailed analysis. This included fish that comprised the top 90% or more of

the total abundance in impingement samples, and commercially or recreationally important invertebrates

that were also impinged in sufficient numbers to warrant analysis. This methodology was approved by the

LARWQCB, SWRCB, EPA Region IX, NMFS, and CDFG during a January 30, 2006 meeting at the

LARWQCB offices.

To put the impingement results in context, losses were compared against (1) known population estimates

where available, (2) commercial fishing landings for those species harvested commercially, and (3) sport

fishing landings for those species targeted by recreational anglers. Commercial landing data were derived

from three potential sources: (1) the PacFIN, which summarized all commercial landings in the Los

Angeles Area for the last seven years, (2) CDFG landing reports originating from Los Angeles area ports
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from 2005, and (3) CDFG catch block data from Long Beach area catch blocks in 2006. The five catch

blocks included in this analysis included: 718, 719, 738, 739, and 740. Sport fishing landings were

derived from the RecFIN, which included all marine areas in southern California.

5.4 SAMPLING SUMMARY

The following sections summarize results from the 2006 impingement weekly sampling at the HGS. The

study was designed to provide information necessary to characterize annual, seasonal, and diel variations

in impingement mortality as required by the §316(b) Phase II regulations. Annual variation was

characterized by comparison to previous impingement studies. Seasonal variation was characterized by

analysis of impingement rates during the yearlong study, and diel variation was characterized by analysis

of daytime (Cycle 1) and nighttime (Cycle 3) impingement collections.

During 2006, normal operation impingement surveys were performed during 50 of 52 weeks at the HGS

between January 5 and December 29, 2006, from the single screening facility. The two weeks with no

samples collected (in late April and early May) represent periods when no circulating water pumps were

operating due to a facility outage.

5.5 RESULTS

5.5.1 Impingement Results

A total of 1,290 fishes representing 25 species and weighing 188.85 kg (416.41 lbs) was collected during

impingement sampling in 2006. The estimated annual total impingement based on cooling water flow

volumes in 2006 was 8,851 individuals weighing 1,316 kg (2,903 lbs) (Table 5.5-1). Round stingray

(Urobatis halleri) was the most abundant species, with 877 individuals collected (68% of the abundance

total) and an estimated annual impingement of 6,150 individuals weighing 1,231 kg (2,715 lbs). The

annual impingement of round stingray represented 70% of the total impingement abundance and 94% of

the biomass. The next most abundant species in impingement samples were black perch (Embiotoca

jacksoni), specklefin midshipman (Porichthys myriaster), shiner perch (Cymatogaster aggregata), barred

sand bass (Paralabrax nebulifer), and giant kelpfish (Heterostichus rostratus). Combined these taxa

accounted for 91.2% of the sampled impinged fish abundance. When these estimates were calculated

using the design (maximum) cooling water flows, total projected numbers increased to 19,861 individuals

with a weight of 2,938 kg (6,479 lbs) (Table 5.5-2). Impingement results by survey are presented in

Appendix D. A list of all species collected during the study is presented in Appendix E.

A total of 1,014 macroinvertebrates representing at least 41 distinct taxa and weighing 37.3 kg (82.3 lbs)

was collected during impingement sampling in 2006. The estimated annual total impingement based on

cooling water flow volumes in 2006 was 6,753 individuals weighing 260 kg (573 lbs) (Table 5.5-3). The

nudibranch Hermissenda crassicornis was the most abundant species, with 271 individuals collected

(27% of the abundance total) and an estimated annual impingement of 1,840 individuals weighing 0.6 kg

(1.4 lbs). The next most abundant species in impingement samples were unidentified sea spiders

(Pycnogonida), tuberculate pear crab, California spiny lobster (Panulirus interruptus), intertidal coastal

shrimp, and California two-spot octopus. Combined these species accounted for 82.6% of the sampled

impinged macroinvertebrate abundance. When these estimates were calculated using the design

(maximum) cooling water flows, total projected numbers increased to 13,538 individuals with a weight of

575 kg (1,269 lbs) (Table 5.5-4).
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Table 5.5-1. Summary of HGS fish impingement from January through December 2006, and

estimated annual impingement based on actual cooling water flows.

Sampled

Impingement

Estimated Annual

Impingement % of Total

Taxa Common Name No. Wt.

(kg) No. Wt.(kg) No. Wt.(kg)

Urobatis halleri round stingray 877 176.577 6,150 1,231.676 69.5 93.5

Embiotoca jacksoni black perch 102 2.718 646 18.487 7.3 1.4

Porichthys myriaster specklefin midshipman 74 1.913 484 11.955 5.5 0.9

Cymatogaster aggregata shiner perch 65 0.559 390 3.359 4.4 0.3

Paralabrax nebulifer barred sand bass 31 1.113 209 7.513 2.4 0.6

Heterostichus rostratus giant kelpfish 27 2.204 192 15.731 2.2 1.2

Acanthogobius flavimanus yellowfin goby 23 0.442 163 3.146 1.8 0.2

Gibbonsia elegans spotted kelpfish 22 0.211 158 1.489 1.8 0.1

Phanerodon furcatus white seaperch 19 0.565 115 4.117 1.3 0.3

Porichthys notatus plainfin midshipman 9 0.034 62 0.234 0.7 <0.1

Tridentiger trigonocephalus chameleon goby 7 0.038 52 0.278 0.6 <0.1

Rhacochilus vacca pile perch 6 0.887 44 6.357 0.5 0.5

Pleuronichthys verticalis hornyhead turbot 5 0.581 34 3.974 0.4 0.3

Genyonemus lineatus white croaker 4 0.026 25 0.196 0.3 <0.1

Engraulis mordax northern anchovy 4 0.003 24 0.019 0.3 <0.1

Paralichthys californicus California halibut 3 0.885 23 7.452 0.3 0.6

Syngnathus leptorhynchus bay pipefish 3 0.011 20 0.072 0.2 <0.1

Leptocottus armatus Pacific staghorn sculpin 2 0.013 10 0.063 0.1 <0.1

Hyperprosopon argenteum walleye surfperch 1 0.006 8 0.051 0.1 <0.1

Atherinops affinis topsmelt 1 0.029 7 0.204 0.1 <0.1

Paralabrax maculatofasciatus spotted sand bass 1 0.022 7 0.154 0.1 <0.1

Icelinus quadriseriatus yellowchin sculpin 1 0.005 7 0.035 0.1 <0.1

Embiotocidae surfperch, unid. 1 0.004 7 0.028 0.1 <0.1

Gillichthys mirabilis longjaw mudsucker 1 0.001 7 0.007 0.1 <0.1

Gobiesox rhessodon California clingfish 1 0.001 7 0.007 0.1 <0.1

Total impinged fish 1,290 188.848 8,851 1,316.604 100.0 100.0
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Table 5.5-2. Estimated annual fish impingement at the HGS from January through December

2006 based on both actual and design (maximum) cooling water flows.

Estimated Annual Impingement

Sampled

Impingement Actual Flows Design Flows

Taxa Common Name No. Wt.

(kg) No. Wt.(kg) No. Wt.(kg)

Urobatis halleri round stingray 877 176.577 6,150 1,231.676 13,771 2,756.092

Porichthys myriaster specklefin midshipman 74 1.913 484 11.955 1,379 26.841

Embiotoca jacksoni black perch 102 2.718 646 18.487 1,371 41.034

Cymatogaster aggregata shiner perch 65 0.559 390 3.359 719 6.770

Paralabrax nebulifer barred sand bass 31 1.113 209 7.513 442 16.203

Heterostichus rostratus giant kelpfish 27 2.204 192 15.731 424 32.598

Acanthogobius flavimanus yellowfin goby 23 0.442 163 3.146 399 7.479

Gibbonsia elegans spotted kelpfish 22 0.211 158 1.489 354 3.235

Phanerodon furcatus white seaperch 19 0.565 115 4.117 221 7.799

Porichthys notatus plainfin midshipman 9 0.034 62 0.234 175 0.662

Tridentiger trigonocephalus chameleon goby 7 0.038 52 0.278 127 0.690

Rhacochilus vacca pile perch 6 0.887 44 6.357 83 12.520

Pleuronichthys verticalis hornyhead turbot 5 0.581 34 3.974 76 8.907

Paralichthys californicus California halibut 3 0.885 23 7.452 51 15.554

Genyonemus lineatus white croaker 4 0.026 25 0.196 48 0.426

Syngnathus leptorhynchus bay pipefish 3 0.011 20 0.072 48 0.196

Engraulis mordax northern anchovy 4 0.003 24 0.019 36 0.027

Atherinops affinis topsmelt 1 0.029 7 0.204 18 0.512

Gillichthys mirabilis longjaw mudsucker 1 0.001 7 0.007 18 0.018

Icelinus quadriseriatus yellowchin sculpin 1 0.005 7 0.035 18 0.089

Paralabrax maculatofasciatus spotted sand bass 1 0.022 7 0.154 18 0.386

Embiotocidae unid. surfperch unid 1 0.004 7 0.028 17 0.070

Hyperprosopon argenteum walleye surfperch 1 0.006 8 0.051 17 0.103

Leptocottus armatus Pacific staghorn sculpin 2 0.013 10 0.063 16 0.104

Gobiesox rhessodon California clingfish 1 0.001 7 0.007 15 0.015

Total impinged fish 1,290 188.848 8,851 1,316.604 19,861 2,938.330
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Table 5.5-3. Summary of HGS invertebrate impingement from January through December 2006, and

estimated annual impingement based on actual cooling water flows.

Sampled

Impingement

Estimated Annual

Impingement % of Total

Taxa Common Name No. Wt.

(kg) No. Wt.(kg) No. Wt.(kg)

Hermissenda crassicornis hermissenda 271 0.092 1,840 0.622 27.2 0.2

Pycnogonida sea spider, unid. 213 0.022 1,258 0.136 18.6 0.1

Pyromaia tuberculata tuberculate pear crab 124 0.166 801 1.086 11.9 0.4

Panulirus interruptus California spiny lobster 105 24.547 717 169.370 10.6 65.1

Heptacarpus palpator intertidal coastal shrimp 101 0.072 711 0.511 10.5 0.2

O. bimac./bimaculoides Calif. two-spot octopus 24 4.790 184 36.249 2.7 13.9

Heptacarpus paludicola Calif. coastal shrimp 19 0.017 138 0.122 2.1 <0.1

Diaulula sandiegensis ring-spotted dorid 18 0.021 128 0.145 1.9 0.1

Triopha maculata spotted triopha 16 0.012 116 0.083 1.7 <0.1

Polycera atra orange-spike polycera 14 0.007 111 0.053 1.7 <0.1

Parastichopus parvimensis warty sea cucumber 14 1.131 91 7.413 1.4 2.8

Leptopecten spp. scallop, unid. 11 0.011 70 0.065 1.0 <0.1

Dirona picta spotted dirona 7 0.003 57 0.023 0.8 <0.1

Parastichopus californicus California sea cucumber 6 0.232 38 1.617 0.6 0.6

Ammothea hilgendorfi sea spider 5 0.003 37 0.023 0.5 <0.1

Cancer antennarius Pacific rock crab 5 1.468 34 9.919 0.5 3.8

Heptacarpus spp. coastal shrimp, unid. 5 0.005 34 0.033 0.5 <0.1

Portunus xantusii Xantus swimming crab 5 0.150 31 0.972 0.5 0.4

Polycera hedgpethi Hedgpeth's polycera 3 0.002 24 0.015 0.4 <0.1

Flabellina trilineata threeline aeolis 3 0.003 22 0.021 0.3 <0.1

Pandalus danae dock shrimp 3 0.008 22 0.049 0.3 <0.1

Lysmata californica red rock shrimp 3 0.003 21 0.021 0.3 <0.1

Anisodoris nobilis Pacific sea-lemon 3 0.022 21 0.153 0.3 0.1

Parastichopus spp sea cucumber, unid. 3 0.003 21 0.021 0.3 <0.1

Aplysia californica California seahare 3 0.858 21 5.855 0.3 2.2

Hemigrapsus oregonensis yellow shore crab 3 0.015 20 0.093 0.3 <0.1

Cnidaria sea jelly, unid. 2 0.029 16 0.210 0.2 0.1

Crangon nigromaculata blackspotted bay shrimp 2 0.002 15 0.015 0.2 <0.1

Dendronotus frondosus leafy dendronotid 2 0.001 14 0.007 0.2 <0.1

Pisaster spp sea star, unid. 2 1.337 14 9.480 0.2 3.6

Holothuroidea sea cucumber, unid. 2 0.004 13 0.023 0.2 <0.1

Scrippsia pacifica giant bell jelly 1 0.044 8 0.346 0.1 0.1

Dendronotus iris giant-frond-aeolis 1 0.019 8 0.149 0.1 0.1

Ctenophora comb jelly, unid. 1 0.006 8 0.047 0.1 <0.1

Pinnixa spp pea crab, unid. 1 0.001 8 0.008 0.1 <0.1

Pleurobranchaea calif. California sea slug 1 1.778 7 12.779 0.1 4.9

Cancer anthonyi yellow crab 1 0.039 7 0.278 0.1 0.1

Discodorididae nudibranch, unid. 1 0.002 7 0.014 0.1 <0.1

Archidoris montereyensis Monterey sea-lemon 1 0.012 7 0.085 0.1 <0.1

Cuthona lagunae orange-faced nudibranch 1 0.001 7 0.007 0.1 <0.1

(table continued)
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Table 5.5-3 (continued). Summary of HGS invertebrate impingement from January through December

2006, and estimated annual impingement based on actual cooling water flows.

Sampled

Impingement

Estimated Annual

Impingement % of Total

Taxa Common Name No. Wt.

(kg) No. Wt.(kg) No. Wt.(kg)

Navanax inermis California aglaja 1 0.031 7 0.217 0.1 0.1

Gastropoda gastropod, unid. 1 0.007 7 0.049 0.1 <0.1

Farfantepenaeus calif. yellowleg shrimp 1 0.006 7 0.039 0.1 <0.1

Aplysia spp. seahare, unid. 1 0.310 6 1.744 0.1 0.7

Aurelia aurita moon jelly 1 0.010 6 0.056 0.1 <0.1

Pandalus stenolepis roughpatch shrimp 1 0.002 6 0.011 0.1 <0.1

Heptacarpus stimpsoni Stimpson coastal shrimp 1 0.001 5 0.005 0.1 <0.1

Mopalia muscosa mossy chiton 1 0.001 5 0.005 0.1 <0.1

Total impinged invertebrates 1,014 37.306 6,753 260.244 100.0 100.0

Note: Weights are only presented in kg.
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Table 5.5-4. Estimated annual invertebrate impingement at the HGS from January through

December 2006 based on both actual and design (maximum) cooling water flows.

Estimated Annual Impingement

Sampled

Impingement Actual Flows Design Flows

Taxa Common Name No. Wt.

(kg) No. Wt.(kg) No. Wt.(kg)

Hermissenda crassicornis hermissenda 271 0.092 1,840 0.622 3,625 1.244

Pycnogonida sea spider, unid. 213 0.022 1,258 0.136 2,139 0.248

Heptacarpus palpator intertidal coastal shrimp 101 0.072 711 0.511 1,600 1.15

Panulirus interruptus California spiny lobster 105 24.547 717 169.37 1,544 369.563

Pyromaia tuberculata tuberculate pear crab 124 0.166 801 1.086 1,535 2.25

O. bimac/bimaculoides Calif. two-spot octopus 24 4.79 184 36.249 428 85.961

Heptacarpus paludicola Calif. coastal shrimp 19 0.017 138 0.122 315 0.28

Diaulula sandiegensis ring-spotted dorid 18 0.021 128 0.145 267 0.310

Triopha maculata spotted triopha 16 0.012 116 0.083 234 0.172

Polycera atra orange-spike polycera 14 0.007 111 0.053 233 0.112

Parastichopus parvimensis warty sea cucumber 14 1.131 91 7.413 176 15.242

Leptopecten spp scallop, unid. 11 0.011 70 0.065 145 0.127

Dirona picta spotted dirona 7 0.003 57 0.023 111 0.042

Ammothea hilgendorfi sea spider 5 0.003 37 0.023 94 0.055

Heptacarpus spp coastal shrimp, unid. 5 0.005 34 0.033 79 0.079

Parastichopus californicus California sea cucumber 6 0.232 38 1.617 71 3.291

Portunus xantusii Xantus swimming crab 5 0.15 31 0.972 68 2.139

Cancer antennarius Pacific rock crab 5 1.468 34 9.919 67 18.929

Lysmata californica red rock shrimp 3 0.003 21 0.021 53 0.053

Anisodoris nobilis Pacific sea-lemon 3 0.022 21 0.153 52 0.387

Polycera hedgpethi Hedgpeth's polycera 3 0.002 24 0.015 52 0.035

Parastichopus sp sea cucumber, unid. 3 0.003 21 0.021 49 0.049

Aplysia californica California seahare 3 0.858 21 5.855 47 11.381

Hemigrapsus oregonensis yellow shore crab 3 0.015 20 0.093 45 0.203

Pandalus danae dock shrimp 3 0.008 22 0.049 44 0.094

Flabellina trilineata threeline aeolis 3 0.003 22 0.021 43 0.043

Dendronotus frondosus leafy dendronotid 2 0.001 14 0.007 36 0.018

Pisaster sp sea star, unid. 2 1.337 14 9.480 35 23.412

Crangon nigromaculata blackspotted bay shrimp 2 0.002 15 0.015 35 0.035

Cnidaria sea jelly, unid. 2 0.029 16 0.210 33 0.513

Holothuroidea sea cucumber, unid. 2 0.004 13 0.023 28 0.049

Archidoris montereyensis Monterey sea-lemon 1 0.012 7 0.085 18 0.212

Ctenophora comb jelly, unid. 1 0.006 8 0.047 18 0.105

Cuthona lagunae orange-faced nudibranch 1 0.001 7 0.007 18 0.018

Dendronotus iris giant-frond-aeolis 1 0.019 8 0.149 18 0.333

Pleurobranchaea calif. California sea slug 1 1.778 7 12.779 18 31.596

Scrippsia pacifica giant bell jelly 1 0.044 8 0.346 18 0.771

Cancer anthonyi yellow crab 1 0.039 7 0.278 18 0.695

Pinnixa sp pea crab, unid. 1 0.001 8 0.008 18 0.018

Discodorididae nudibranch, unid. 1 0.002 7 0.014 17 0.035

(table continued)
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Table 5.5-4 (continued). Estimated annual invertebrate impingement at the HGS from January through

December 2006 based on both actual and design (maximum) cooling water flows.

Estimated Annual Impingement

Sampled

Impingement Actual Flows Design Flows

Taxa Common Name No. Wt.

(kg) No. Wt.(kg) No. Wt.(kg)

Gastropoda Gastropod, unid. 1 0.007 7 0.049 17 0.122

Navanax inermis California aglaja 1 0.031 7 0.217 17 0.540

Aplysia spp seahare, unid. 1 0.310 6 1.744 11 3.367

Aurelia aurita moon jelly 1 0.010 6 0.056 10 0.099

Mopalia muscosa mossy chiton 1 0.001 5 0.005 10 0.010

Heptacarpus stimpsoni Stimpson coastal shrimp 1 0.001 5 0.005 10 0.01

Pandalus stenolepis roughpatch shrimp 1 0.002 6 0.011 10 0.02

Farfantepenaeus calif. yellowleg shrimp 1 0.006 7 0.039 9 0.056

Total impinged invertebrates 1,014 37.306 6,753 260.244 13,538 575.473

Note: Weights are only presented in kg.

Figures 5.5-1 and 5.5-2 present the fish impingement rates (based on abundance and biomass) during the

50 weeks of sampling during 2006. Impingement abundance was highest from August to November

(Figure 5.5-1), which corresponded with an increase in round stingray impingement. Biomass was

greatest during the same period (Figure 5.5-2). Invertebrate abundance was greatest from June through

August, with highest abundance recorded from late-June through early-August (Figure 5.5-3).

Invertebrate biomass was much more variable throughout the year, with peaks from January through

March (Figure 5.5-4), corresponding to the impingement of large individuals of certain species. Biomass

increased again from June through August, but in a steadier ascent than during the winter months. In

general, fish impingement abundance and biomass was greatest during nighttime (Figures 5.5-5 and

5.5-6). The same general trend was observed in invertebrate impingement (Figures 5.5-7 and 5.5-8).
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

100

200

300

400

500

600

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-1. Mean concentration (#/1,000,000 m3[264.2 million gallons] –wide bars) and standard error

(narrow bars) of fishes collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpingement Density (kg/1,000,000 cubic meters)

0

20

40

60

80

100

120

X

“X”denotesa two-week period of no sample collection.

Figure 5.5-2. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error (narrow

bars) of fishes collected in HGS impingement samples during 2006.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

200

400

600

800

1000

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-3. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of invertebrates collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpingement Density (kg/1,000,000 cubic meters)

0

5

10

15

20

25

30

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-4. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error (narrow

bars) of invertebrates collected in HGS impingement samples during 2006.
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Impingement Density (#/1,000,000 cubic meters)

-700 -600 -500 -400 -300 -200 -100 0 100 200 300 400 500 600 700

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Negative nighttime values are a plotting artifact.

Figure 5.5-5. Mean concentration (#/1,000,000 m3[264.2 million gal]) of fishes in impingement samples

during night (Cycle 3) and day (Cycle 1) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Negative nighttime values are a plotting artifact.

Figure 5.5-6. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of fishes in impingement samples

during night (Cycle 3) and day (Cycle 1) sampling.
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Impingement Density (#/1,000,000 cubic meters)

-1000 -800 -600 -400 -200 0 200 400 600 800 1000

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Negative nighttime values are a plotting artifact.

Figure 5.5-7. Mean concentration (#/1,000,000 m3[264.2 million gal]) of invertebrates in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-50 -40 -30 -20 -10 0 10 20 30 40 50

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Negative nighttime values are a plotting artifact.

Figure 5.5-8. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of invertebrates in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling.
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5.5.2 Fish Impingement Results by Species

Six fish taxa comprised 91.2% of the fishes in impingement samples and were selected for more detailed

analysis based on their total abundances in the samples. These taxa were: round stingray (68% of sampled

abundance), black perch (8%), specklefin midshipman (6%), shiner perch (5%), barred sand bass (2%),

and giant kelpfish (2%). A seventh species, northern anchovy (<1%), was also analyzed in further detail

due to its inclusion in the Coastal Pelagics Fishery Management Plan.

5.5.2.1 Round stingray (Urobatis halleri)

The round stingray, Urobatis halleri, is the most

common stingray found off the California coast. It is

distributed from Eureka, northern California to

Panama. It is most commonly found in shallow,

coastal water bodies (Love 1996; Zorzi et al. 2001).

Round stingrays are the single species belonging to

the family Urolophidae, which is one of eight families

in the order Myliobatiformes. Rays in this order are

all warm-water organisms found close to shore (Bond

1996).

5.5.2.1.1 Life History and Ecology

The habitat distribution of the round stingray is fairly limited. They can be found off beaches and in

protected bays and channels, where they inhabit soft, loose sand or muddy bottoms. They are commonly

found in shallow coastal areas at depths of 130 m (398 ft), but are more commonly found in waters less

than 15 m (49 ft) deep. Mature females are more common further offshore, usually occurring in waters

1218 m (3959 ft) deep, whereas males prefer waters less than 12 m (39 ft) deep. Adults are not

commonly found in very shallow waters in the winter months (Love 1996; Zorzi et al. 2001).

Round stingrays bear live young, with a gestation period of approximately three months (Babel 1967). In

June, females move to shallow, inshore waters just for the time required to breed with males. They return

to these same waters to spawn in August and September. A female can produce up to eight young per

litter with an average of three per litter. Individuals measure about 100 mm (3.9 in) in length at birth

(Love 1996).

There is not much information on age and growth for the round stingray due to the absence of bony

otoliths or scales. They can reach a maximum length of 558 mm (22 in), and are considered mature at

254–266 mm (10.0–10.5 in) in length. At birth, the young remain in water shallower than about 4 m (13

ft) until they reach approximately 152–177 mm (6–7 in) in length (Love 1996). The round stingray uses

its stinging spine in defense against predators. Due to the shallow nature of their coastal habitat, they

often incidentally sting beach goers that wade in these shallow waters (Love 1996; Zorzi et al. 2001).

Stingrays shed and regenerate their spines each year during fall, but can also regenerate a spine that is lost

during other times of years (Johansson et al. 2004).
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Due to the limited habitat where round stingrays are found, their food source is also limited. Smaller

stingrays will feed on invertebrates such as worms, shrimps, crabs, and amphipods. Larger stingrays

primarily feed on clams (Love 1996).

5.5.2.1.2 Population Trends and Fishery

Round stingrays are incidentally caught by pier and shore anglers. There is currently not a market for this

speciesinCalifornia.In2005,“stingray”landingsintheLosAngelesareatotaled649kg(1,430lbs)ata

value of $292 (CDFG 2006). All of the landings were reported in the spring and summer (April–August

2005).Commerciallandingsof“stingray”reportedfromcatchblocksintheLongBeachareatotaled9.1

kg (20 lbs) in 2006, with an estimated value of less than one dollar (CDFG 2007). During 1978-79, a total

of 163 round stingrays was impinged at HGS, equivalent to about five individuals per day (IRC 1981). It

comprised only 0.9% of impingement abundance, and abundance was highest from July through

September. From 2003 through 2005, a total of 57 round stingrays were collected in 10 impingement

samples (MBC 2006). Average annual impingement ranged from 1 to 21 stingrays per survey, and

averaged about 6 stingrays per survey (MBC 2006).

5.5.2.1.3 Sampling Results

Round stingray was the most abundant species impinged, with an estimated 6,150 individuals calculated

using actual cooling water flow volumes, or 69.5% of the annual total, weighing 1,231.68 kg

(2,715.85 lbs) (Table 5.5-1). Impinged sporadically throughout the first half of the year, round stingrays

were very abundant in impingement surveys during the second half of the year, with individuals collected

in nearly every survey (Figure 5.5-9). Biomass followed a pattern consistent with that seen in abundance

(Figure 5.5-10). Overall, generally higher abundance and biomass was recorded during nighttime

impingement surveys (Figures 5.5-11 and 5.5-12).

Length frequency analysis of 817 measured individuals indicated a mean disc width (DW) of 161 mm

(6.3 in) (Figure 5.5-13). (Disc width is reported here since rays without tails are sometimes collected).

Individuals ranged in size from 110 mm (4.3 in) DW to 250 mm (9.8 in) DW in a nearly normal

distribution peaking with the 160 mm (6.3 in) DW size class, or approximately 3 years old (Babel 1967).

A total of 817 individuals were sexed, with 42% female, 58% male, and less than 1% of undetermined sex

due to the physical condition of the animal. Of the 784 individuals that were evaluated for condition

factor, 67% were alive, 30% were dead, and 3% were mutilated.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

100

200

300

400

500

600

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-9. Mean concentration (#/1,000,000 m3[264.2 million gal]) and standard error of round

stingray collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpingement Density (kg/1,000,000 cubic meters)

0

20

40

60

80

100

120

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-10. Mean biomass (kg/1,000,000 m3[264.2 million gal]) and standard error of round stingray

collected in HGS impingement samples during 2006.
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Impingement Density (#/1,000,000 cubic meters)

-700 -600 -500 -400 -300 -200 -100 0 100 200 300 400 500 600 700

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact

Figure 5.5-11. Mean concentration (#/1,000,000 m3[264.2 million gal]) of round stingray in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact

Figure 5.5-12. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of round stingray in impingement

samples during night (Cycle 3) and day (Cycle 1) sampling.
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Length category (mm DW)

80 100 120 140 160 180 200 220 240 260 280

P

ercent

0

5

10

15

20

25

30

N = 817

Mean = 161

Figure 5.5-13. Disc width (mm) frequency distribution for round stingray

collected in impingement samples.

5.5.2.2 Black perch (Embiotoca jacksoni)

Black perch (Embiotoca jacksoni) range from Pt.

Abreojos, Baja California, Mexico to Fort Bragg,

California in depths from 0 to 50 m (0 to 164 ft)

(Miller and Lea 1972, Allen 1982). Nineteen

species of perch are common to the nearshore

waters of southern California, with 10 of these

species commonly observed in central and

southern California (Miller and Lea 1972; Allen

and Pondella 2006b). Allen and Pondella (2006b)

included black perch in their southern California

shallow rock sand group. Black perch have been

frequently observed in impingement sampling

throughout southern California since 1990, albeit in greatly reduced abundances in comparison to more

abundant perch species, such as walleye surfperch (Hyperprosopon argenteum) (MBC unpub. data).

5.5.2.2.1 Life History and Ecology

Quast (1968a) included black perch in his Zone II classification as a bottom microcarnivore, typically

patrolling the areas of coralline red algae. Stephens et al. (2006) further confirmed this habitat affinity,

noting a stronger presence in the southern portion of the Southern California Bight. Within this zone,

Quast (1968b) reported their primary prey items reflect this habitat preference, with the principal

Jay Carroll
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composition including polychaete worms, amphipods, spider crabs, etc. Allen (1982) determined

gammaridean amphipods and reptantian decapods comprised the majority of prey items, although

polychaetes were also important. Black perch ranked higher in abundance along the mainland (14th) than

at Santa Catalina Island (30th) in fish assemblages sampled by gillnet from 1996 to 1998, indicating

preference for the mainland, which may be attributed to the greater overall frequency of the rocky-reef,

sandy-bottom ecotone they prefer (Pondella and Allen 2000; Allen and Pondella 2006b). Along the Los

Angeles Federal Breakwater, black perch represented nearly 12% of all fishes, or the second most

abundant species observed (Froeschke et al. 2005).

Like all surfperch, black perch are viviparous, producing free-swimming, fully developed young. Young

surfperches are often larger than the typical 9.5 mm (3/8 in) screen mesh at most generating stations,

preventing their entrainment and transport throughout the CWIS. Froeschke et al. (in press) reported that

black perch exhibit a general 1:1 sex ratio, with a peak spawning period in southern California from July

through October. These authors noted that gestating females were capable of carrying between 4 and 17

embryos, with larger females carrying more embryos.

Froeschke et al. (in press) reported black perch to reach a maximum age of seven years old, with the

predominance of individuals less than five years old. The authors noted that, as with most fish, growth

was fastest during the early part of their life, with maximum growth between ages 0 and 2 before slowing.

5.5.2.2.2 Population Trends and Fishery

Surfperch commercial landings, overall, steadily declined from the peak in 1982, with some research

indicating the decline may partially be attributable to increased water temperature that dominated the

northeast Pacific Ocean throughout much of the 1980s and 1990s (Fritzsche and Collier 2001). The

NMFS Los Angeles Times recreational fishing database recorded an annual mean landing of 50 black

perch from all landings ranging from Paradise Cove on the northwestern edge of the Santa Monica Bay

south to San Diego, California over the period 1991–2003 (NMFS 2007). Due to the random nature of the

recreational fishing data, no real population trends can be determined for black perch. Total statewide

recreationallandingsof“surfperches”were489,000fishin1999,withmostofthecatchincentraland

northern California (Fritzche and Collier 2001). Commercial landings in the Los Angeles area have

fluctuated between about 136 and 1,361 kg (300 and 3,000 lbs) per year since 2000 (Table 5.5-5). In

2005,“surfperch”landingsintheLosAngelesareatotaled21.3kg(47lbs)withavalueof$86(CDFG

2006).Commerciallandingsof“surfperches”in2006reportedfromcatchblocksintheLongBeacharea

totaled 74.9 kg (165 lbs), at an estimated value of $660 (CDFG 2007).

During 1978-79, a total of 77 black perch were impinged at HGS, equivalent to about two black perch per

survey (IRC 1981). They were present year-round, but highest impingement occurred in February (10

individuals during February 1, 1979). From 2003 through 2005, only four black perch were collected in

10 impingement samples at the HGS (MBC 2006). Average annual impingement ranged from 0 to 1 black

perch per survey, and averaged 0.4 fish per survey (MBC 2006).
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Table 5.5-5. Annual landings and revenue for surfperches in the Los Angeles region

based on PacFIN data.

Landed Weight

Year kilograms pounds Revenue

2000 1,278 2,817 $3,085

2001 239 526 $1,315

2002 972 2,143 $6,455

2003 414 913 $1,743

2004 164 362 $689

2005 161 354 $403

2006 497 1,095 $2,624

5.5.2.2.3 Sampling Results

Black perch was the second most abundant species impinged with an estimated 646 individuals calculated

using actual cooling water flow volumes, or 7.3% of the annual total, weighing 18.49 kg (40.76 lbs)

(Table 5.5-1). Black perch were impinged consistently during the late-spring/early-summer, although

impingement occurred throughout the year (Figure 5.5-14). Lowest impingement occurred from late-July

through mid-November. Highest biomass occurred during the second half of the year during a more

sporadic period (Figure 5.5-15). This was due to impingement of larger individuals during surveys when

impingement abundance was relatively low. Black perch were impinged with greater frequency during the

nighttime, but the greatest single-survey impingement rates were observed during the daytime (Figure

5.5-16). Conversely, biomass was more consistent and often greater during nighttime surveys than was

recorded during daytime surveys (Figure 5.5-17).

Length frequency analysis of 98 measured individuals was used to calculate a mean standard length of 75

mm (Figure 5.5-18). Individual lengths were recorded in a wide range of sizes, ranging from 50200 mm

SL (2.0 to 7.9 in). Despite the widespread distribution, the majority of recorded lengths were spread

between the 50 to 70 mm (2.0 to 2.8 in) size classes, with peak abundance in the 60 mm (2.4 in) size

class, corresponding to young-of-the-year. Ninety-nine individuals were sexed, with 10% female, 6%

male, and 69% juvenile. Sexes of the remaining 15% could not be determined. The disposition of 102

individuals was evaluated for condition factor: 6% were alive, 89% were dead, and 5% were mutilated.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

20

40

60

80

100

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-14. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of black perch collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpingement Density (kg/1,000,000 cubic meters)

0

1

2

3

4

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-15. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of black perch collected in HGS impingement samples during 2006.
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Impingement Density (#/1,000,000 cubic meters)

-160-140-120-100 -80 -60 -40 -20 0 20 40 60 80 100 120 140 160

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-16. Mean concentration (#/1,000,000 m3[264.2 million gal]) of black perch in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-17. Mean biomass (kg/1,000,000 m

3

[264.2 million gal]) of black perch in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.
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Length category (mm SL)

60 80 100 120 140 160 180 200

P

ercent

0

10

20

30

40

50

N = 98

Mean = 75

Figure 5.5-18. Length (mm) frequency distribution for black perch collected in

impingement samples.

5.5.2.3 Specklefin midshipman (Porichthys myriaster)

The specklefin midshipman, Porichthys myriaster,

is one of two species of midshipman found off the

California coast (the other being plainfin

midshipman [Porichthys notatus]). The specklefin

midshipman is most commonly found in muddy

and sandy areas ranging from Point Conception,

California, to Magdalena Bay, Baja California

(Hubbs and Schultz. 1939; Fitch and Lavenberg 1975). Specklefin midshipman belongs to the family

Batrachoididae, which is in the order Batrachoidiformes. Fish in this order are usually broad-headed, bigmouthed, benthic organisms of tropical and temperate waters (Bond 1996).

5.5.2.3.1 Life History and Ecology

The common habitat of the specklefin midshipman is typically found to be muddy and sandy bays, and

along the open shore to depths of 126 m (413 ft). Although the range of the specklefin midshipman and

the plainfin midshipman overlap, the specklefin prefers to live in shallower waters than the plainfin

(Hubbs et al. 1939).

Thespecklefin’sprimary habitat is muddy and sandy bottoms; except, during April to June when they

will move to rocky areas for spawning. Females will attach their eggs, 200-400, to the underside of rocks

and remain with the eggs for a day or two along with the male to guard the eggs. The male will stay with
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the eggs for the month or more it takes them to hatch. During this time the male does not feed, and can

become emaciated and diseased. Many males may succumb to the stress and die before or after the eggs

hatch (Fitch and Lavenberg 1975).

There is not much documentation on the growth rate of the specklefin midshipman, but it is estimated

they can grow to 508 mm (20 in) in length (Allen 1982). Males will grow much larger than females.

There is no information on their maximum age, but a 457 mm (18 in) male weighing about 0.9 kg (2 lbs)

was reported to be eight years old (Fitch and Lavenberg 1975).

Midshipmen in general are not selective feeders, and will eat anything they come across that they can get

their mouth around, both alive and dead. Crustaceans, octopus, squid, and small fish make up the majority

of their diet. Giant seabass, sea lions, and porpoises have been known to feed on midshipmen. During

daylight hours when in muddy areas they bury themselves and emerge to feed at night (Fitch and

Lavenberg 1975). At night they use photophores to display light for use in courtship (Bond 1996). They

are most active at night and have been known to make humming and grunting sounds (Eschmeyer and

Herald 1983).

5.5.2.3.2 Population Trends and Fishery

There is currently no market for midshipmen. Anglers catch midshipmen incidentally, probably due to the

fact that they will eat anything. No specklefin midshipman landings were reported in the commercial

fishing databases queried (CDFG 2006, 2007). During 1978-79, a total of 29 specklefin midshipman was

impinged at HGS, equivalent to less than one individual per survey (IRC 1981). They were impinged

throughout the year, with highest numbers occurring in February and March. During 10 impingement

surveys at the HGS from 2003 through 2005, only one individual was impinged (MBC 2006).

5.5.2.3.3 Sampling Results

Specklefin midshipman was the third most abundant species impinged with an estimated 484 individuals

calculated using actual cooling water flow volumes, or 5.5% of the annual total, weighing 12.0 kg (26.4

lbs) (Table 5.5-1). The majority of specklefin midshipman was collected during the May 11-12, 2006

survey, with a mean impingement rate of greater than 200 individuals per 1,000,000 m3(Figure 5.5-19).

This was the first survey after the maintenance outage. During the rest of the year, impingement densities

were consistently less than 25 individuals per 1,000,000 m3. Biomass exhibited a different pattern, with

highest biomass occurring on the July 14th survey (Figure 5.5-20). This was due to impingement of larger

individuals during that survey. During periods of peak impingement, higher abundance and biomass was

generally observed during daylight hours (Figures 5.5-21 and 5.5-22), with the exception of Survey 28.

Length frequency analysis of 74 measured individuals was used to calculate a mean standard length of 99

mm (3.9 in) (Figure 5.5-23). Although individuals were collected representing size classes up to 330 mm

SL (13 in), the majority of recorded lengths were in the 40170 mm (1.66.7 in) size classes. Peak

abundance was recorded in the 60 mm SL (2.4 in) size class. Of the 73 individuals that were evaluated for

condition factor, 79% were alive and 21% were dead.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

50

100

150

200

250

300

350

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-19. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of specklefin midshipman collected in HGS impingement samples during 2006

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpingement Density (kg/1,000,000 cubic meters)

0

1

2

3

4

5

6

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-20. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of specklefin midshipman collected in HGS impingement samples during

2006.
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Impingement Density (#/1,000,000 cubic meters)

-420 -400-30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-21. Mean concentration (#/1,000,000 m3[264.2 million gal]) of specklefin midshipman

in impingement samples during night (Cycle 4) and day (Cycle 2) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-22. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of specklefin midshipman in

impingement samples during night (Cycle 4) and day (Cycle 2) sampling.
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Length category (mm SL)

40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340

Percent

0

5

10

15

20

25

N = 74

Mean = 99

Figure 5.5-23. Length (mm) frequency distribution for specklefin midshipman

collected in impingement samples.

5.5.2.4 Shiner perch (Cymatogaster aggregata)

Shiner perch ranges from San Quintin Bay, Baja

California, to Port Wrangell, Alaska (Miller and

Lea 1972). There are 19 species of Pacific

nearshore surfperches (Family Embiotocidae) that

occur off southern California (Miller and Lea

1972). Most inhabit nearshore waters, bays, and

estuaries, though some are found further offshore.

5.5.2.4.1 Life History and Ecology

Shiner perch occurs primarily in shallow-water

marine, bay, and estuarine habitats (Emmett et al.

1991), and is demersal on sandy and muddy bottoms. On the southern California shelf, shiner perch are

found at depths to 90 m (295 ft), and Allen (1982) reported most occur at about 70 m (230 ft). It has been

reported to depths of 146 m (480 ft) (Miller and Lea 1972). Juveniles and adults occur in oligohaline to

eurohaline waters, and even occasionally in fresh water. This species forms schools or aggregations

during the day (Fitch and Lavenberg 1975), but solitary individuals are found on the bottom at night.

Important prey items for this species off southern California include calanoid copepods and chaetognaths

(Allen 1982). It is a predominantly diurnal visual plankton picker, but larger individuals may engage in

nocturnal epibenthicsearching(Allen1982).Shinerperch,alongwithwhitecroaker,formedAllen’s

(1982)“nearshoreschoolers”recurrentgroup;thetwospeciesoccurcommonlyoffsouthernCalifornia

even though shiner perch is considered a cold-temperate, outer-shelf species, while white croaker is a

temperate, inner-shelf species.
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Eggs of the shiner perch are fertilized internally, and females give birth to live young. Mating occurs

primarily in the spring and summer in California (Bane and Robinson 1970). The reproductive capacity of

this species is directly related to female size; smaller females produce as few as 5 young, while larger

females can produce over 20 young (Wilson and Millemann 1969). Shiner perch have no larval stage. At

birth, fully developed young are about 34 to 78 mm in length (Wilson and Millemann 1969; Hart 1973).

Shiner perch live for about eight years and reach about 180 mm in length (Miller and Lea 1972; Hart

1973).

5.5.2.4.2 Population Trends and Fishery

This species is not commercially important, but some shiner perch are landed for bait and human

consumption (Emmett et al. 1991). Shiner perch are fished recreationally, especially from piers and in

baysandestuaries.Totalstatewiderecreationallandingsof“surfperches”were489,000fishin1999,with

most of the catch in central and northern California (Fritzche and Collier 2001). Commercial landings in

the Los Angeles area have fluctuated between about 136 and 1,361 kg (300 and 3,000 lbs) per year since

2000.In2005,“surfperch”landingsintheLos Angeles area totaled 21.3 kg (47 lbs) at a value of $86

(CDFG2006).Commerciallandingsof“surfperches”reportedfromcatchblocksintheLongBeacharea

totaled 74.9 kg (165 lbs) in 2006, at an estimated value of $660 (CDFG 2007). Numbers of shiner perch

in southern California waters declined after the mid-1970s, and this is likely related to warming ocean

temperature, decreased zooplankton biomass, and reduced upwelling (Stull and Tang 1996, Beck and

Herbinson 2003, Allen et al. 2004). During 1978-79, a total of 1,873 shiner perch were impinged at HGS,

equivalent to about 55 shiner perch per survey (IRC 1981). It was the fourth most abundant species during

the yearlong study, and abundance was highest in February. From 2003 through 2005, six shiner perch

were collected in 10 impingement samples (MBC 2006). Average annual impingement ranged from 0 to 5

shiner perch per survey, and averaged about 0.6 fish per survey.

5.5.2.4.3 Sampling Results

Shiner perch was the fourth most abundant species impinged with an estimated 390 individuals calculated

using actual cooling water flow volumes, or 4.4% of the annual total, weighing 3.4 kg (7.4 lbs) (Table

5.5-1). The majority of shiner perch was impinged consistently during the first nine months of the year,

with peak impingement during the late-spring/early-summer period (Figure 5.5-24). This species only

occurred in one impingement survey during the fourth quarter of the year. Biomass generally followed a

pattern consistent with that seen in abundance (Figure 5.5-25). Shiner perch were impinged with greater

frequency during the daytime than during nighttime (Figure 5.5-26). This same pattern was more

pronounced with biomass (Figure 5.5-27).

Length frequency analysis of 64 measured individuals was used to calculate a mean standard length of 61

mm SL (2.4 in) (Figure 5.5-28). A wide range of size fishes were collected, ranging from the 30 to 130

mm (1.2 to 5.1 in) size classes. Despite the wide range of sizes, the majority of recorded lengths were in

the 40 mm SL (1.6 in) size class, corresponding to young-of-the-year. Fifty-seven individuals were sexed,

with 19% female, 12% male, and 51% juvenile. Sexes of the remaining 18% could not be determined.

These same 57 individuals were evaluated for condition factor: 98% were dead and 2% were mutilated.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

20

40

60

80

100

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-24. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of shiner perch collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpingement Density (kg/1,000,000 cubic meters)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-25. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of shiner perch collected in HGS impingement samples during 2006.
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Impingement Density (#/1,000,000 cubic meters)

-100 -80 -60 -40 -20 0 20 40 60 80 100

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-26. Mean concentration (#/1,000,000 m

3

[264.2 million gal]) of shiner perch in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-1.50 -1.25 -1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-27. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of shiner perch in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.
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Length category (mm SL)

40 60 80 100 120 140

Percent

0

10

20

30

40

50

60

N = 64

Mean = 61

Figure 5.5-28. Length (mm) frequency distribution for shiner perch collected in

impingement samples.

5.5.2.5 Barred sand bass (Paralabrax nebulifer)

The barred sand bass (Paralabrax nebulifer) range

from Bahia Magdalena, Baja California, Mexico

to Santa Cruz, California in depths from the

surfzone to 183 m (600 ft) (Miller and Lea 1972).

In addition to barred sand bass, two other species

of the genus Paralabrax are commonly observed

in central and southern California, including kelp

bass (P. clathratus) and spotted sand bass (P.

maculatofasciatus) (Miller and Lea 1972; Allen

and Pondella 2006b). Allen and Pondella (2006b) included barred sand bass in their shallow rock sand

species group, along with kelp bass. Barred sand bass have been frequently observed in impingement

sampling throughout southern California since 1990 (MBC unpubl. data).

5.5.2.5.1 Life History and Ecology

The more cosmopolitan of the three, barred sand bass are frequently taken by recreational anglers in

widely varied habitats ranging from bays and harbors to nearshore low-relief hard bottom to sand-reef

ecotone throughout southern California (Allen and Hovey 2001; Hovey et al. 2002). Contrary to their

name, barred sand bass have been more frequently been reported in association with bottom structures,

than over featureless, sandy bottoms, outside of the spawning season (Allen and Hovey 2001). During

spawning season, however, barred sand bass frequently form large aggregations, often over low-relief
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sandy bottom, such as offshore of Huntington Beach, California (Hovey et al. 2002). Regardless of the

season, barred sand bass have been noted to rarely venture more than 3 m (10 ft) above the bottom (Love

et al. 1996), with the possible exception of short duration vertical spawning rushes, similar to what has

been observed in the other two Paralabrax species (Miller and Allen 2006; Erisman and Allen 2006).

Although they have been taken as deep as 183 m (600 ft), the greatest density of individuals has typically

been observed at less then 30 m (98 ft) water depth (Allen and Hovey 2001).

In trawl sampling of Alamitos Bay, California, Valle et al. (1999) reported that nearly all collections of

barred sand bass occurred in eelgrass beds. Furthermore, all individuals were juveniles, with the average

individual less than 40 mm SL (1.6 in), ranging from 1692 mm SL (0.63.6 in). Similar surveys by

Allen and Herbinson (1990) designed to determine the distribution of juvenile California halibut

(Paralichthys californicus) reported nearly 114 barred sand bass per hectare within bay habitats of

southern California, but less than one individual per hectare in semi-exposed and fully exposed nearshore

habitat in water depths less than 15 m (49 ft). By targeting California halibut, soft bottom sandy habitat

was primarily sampled, which may have resulted in a programmatic bias against late juvenile/adult barred

sand bass, which would be more associated with structures in the exposed areas. A mean length of 46 mm

SL (1.8 in) recorded during these surveys suggested the majority of individuals collected were juveniles,

which would be consistent with the bay collections made by Valle et al. (1999). Further emphasizing the

use of bay habitat as nursery grounds for barred sand bass, Allen et al. (2002) indicated that 97% of all

individuals taken in San Diego Bay, California were juveniles.

All three Paralabrax species common to southern California have been characterized as broadcast

spawners (Love et al. 1996; Erisman and Allen 2006; Miller and Allen 2006), meaning they produce

pelagic eggs that are carried by ocean currents rather than being attached to benthic substrate. Barred sand

bass, specifically, spawn from April to November, with a peak in July (Allen and Hovey 2001).

Typically, they form dense breeding aggregations over sandy bottoms in depths from 15 to 30 m during

the summer months (Hovey et al. 2002). Based on histological examination of the gonads Oda et al.

(1993) reported that barred sand bass were capable of daily spawning, while in season. Unfortunately,

batch fecundity for barred sand bass could not be determined during this study due to an insufficient

sample size.

Each sex reaches maturity at slightly different rates in barred sand bass, with one half of all males

reaching maturity by 219 mm TL (8.6 in), while females were delayed until 239 mm TL (9.4 in), or two

and three years, respectively (Love et al. 1996). Initially believed to be gonochoric (1:1 sex ratio, no sex

change), Oda et al. (1993) hypothesized that barred sand bass may in fact be a protogynous

hermaphrodite, similar to spotted sand bass (Hastings 1989). Hovey et al. (2002) further investigated this

and identified two transitional individuals, supporting the notion that hermaphroditic biology was

possible, but concluded that barred sand bass were functioning gonochores with the potential to change

sex. These data, and recent studies by Sadovy and Domier (2005), suggest these hermaphroditic

possibilities were more representative of passing through a non-functional bisexual juvenile stage than

changing sex from a functional female to functional male.
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Age and growth of barred sand bass suggest they grow at a faster rate over the first five years than the

remaining years of life (Love et al. 1996). These authors noted that the average barred sand bass grow

from approximately 100 mm TL (3.9 in) at less than one year to approximately 300 mm TL (11.8 in) by

age 5. Barred sand bass were aged to 24 years by these authors, but they noted the predominance of

individuals were less than 15 years old.

5.5.2.5.2 Population Trends and Fishery

Since 1953, only recreational fishing, with no commercial take, has been allowed for Paralabrax species

by the CDFG (Allen and Hovey 2001). Dotson and Charter (2003) reported that the complex of barred

sand bass and kelp bass has ranked among the top two recreationally landed groups in an area ranging

from Goleta, California to the U.S.-Mexico border for the period 1959–1998. For the period 1993–2003,

an annual mean recreational landing of 344,014 barred sand bass was reported (NMFS 2007). In southern

California, annual recreational landings have ranged between 139,000 and 1,130,000 fish per year, with a

declining trend since 2002 (Table 5.5-6). During 1978-79, a total of 49 barred sand bass was impinged at

HGS, equivalent to about 1.4 individuals per survey (IRC 1981). It was most abundant in February 1979.

From 2003 through 2005, one barred sand bass was collected in 10 impingement samples (MBC 2006).

Table 5.5-6. Annual recreational landings (numbers) of barred sand bass

in southern California based on RecFIN data.

Year Landings

2000 1,130,000

2001 806,000

2002 1,062,000

2003 892,000

2004 704,000

2005 307,000

2006 139,000

5.5.2.5.3 Sampling Results

Barred sand bass was the fifth most abundant species impinged with an estimated 209 individuals

calculated using actual cooling water flow volumes, or 2.4% of the annual total, weighing 7.5 kg (16.6

lbs) (Table 5.5-1). Barred sand bass was more frequently impinged from spring through fall (Figure 5.5-

29). Biomass exhibited a similar pattern with definitive peaks in impingement occurring during the

summer months (Figure 5.5-30). This was due to larger individuals impinged during this period in

comparison to the rest of the year. During periods of peak impingement, higher abundance and biomass

were consistently recorded during nighttime hours (Figures 5.5-31 and 5.5-32).

Length frequency analysis of 31 measured individuals was used to calculate a mean standard length of

106 mm SL (4.2 in) (Figure 5.5-33). Although size classes as high as 270 mm SL (10.6 in) were

represented, the majority of individuals were in the 70100 mm (2.8 to 3.9 in) size classes with a peak

centered at 7080 mm SL (2.83.1 in), indicating a principally juvenile assemblage, or approximately

one-year old based on Love et al. (1996). Of the 31 individuals that were evaluated for condition factor,

55% were alive and 45% dead.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

5

10

15

20

25

30

35

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-29. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of barred sand bass collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpingement Density (kg/1,000,000 cubic meters)

0

1

2

3

4

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-30. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard

error (narrow bars) of barred sand bass collected in HGS impingement samples during 2006.
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Impingement Density (#/1,000,000 cubic meters)

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-31. Mean concentration (#/1,000,000 m3[264.2 million gal]) of barred sand bass in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-32. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of barred sand bass in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.
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Length category (mm SL)

60 80 100 120 140 160 180 200 220 240 260 280

P

ercent

0

5

10

15

20

25

N = 31

Mean = 106

Figure 5.5-33. Length (mm) frequency distribution for barred sand bass collected

in impingement samples.

5.5.2.6 Giant kelpfish (Heterostichus rostratus)

Giant kelpfish (Heterostichus rostratus) ranges

from Cape San Lucas, Baja California, Mexico to

British Columbia, Canada from the surface to

depths of 40 m (131 ft) (Miller and Lea 1972).

Allen and Pondella (2006b) included giant kelpfish

in their southern nearshore reef and soft bottom

species group. Giant kelpfish have been frequently

observed in low abundances during impingement

sampling throughout southern California since

1990 (MBC unpubl. data).

5.5.2.6.1 Life History and Ecology

Quast (1968a) included giant kelpfish in his Zone I

classification for their common occurrence in and about the kelp fronds. Within this zone, Quast (1968a)

reportedgiantkelpfishcommonlyfeedonsmall“microscopic”preyitemssuchasvariousplanktonic

organisms (copepods, mysids, and crustacean eggs). Giant kelpfish were only reported for collections

made along the mainland, in relatively low abundances, in fish assemblages sampled by gillnet from 1996

to 1998, suggestive of a greater distribution along the mainland than at Santa Catalina Island (Pondella

and Allen 2000). Stephens et al. (2006) further noted that giant kelpfish have been recorded throughout

Jay Carroll
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much of the nearshore waters of California, typically around the lower depths of the kelp bed near the

stipes.

Giant kelpfish lay eggs in closely guarded nests created by the males, often interspersed among red and

brown algae (Stepien 1986). The author confirmed previous behavioral observations noting that once the

eggs are laid, the female is chased off while the male continues to guard the nest. Giant kelpfish were

reported to appear in large numbers in the spring and summer months, consistent with a principal

spawning season of January through May.

Stepien (1986) confirmed a previously reported maximum age of 5+ years (Feder et al. 1974). Giant

kelpfish grow at a relatively consistent rate throughout their life span, reaching approximately 180 mm

TL (7.1 in) by age one (Stepien 1986). Larval individuals reach flexion by nine days after hatch with

settlement by 60 days after hatch.

5.5.2.6.2 Population Trends and Fishery

There were no recent landings of giant kelpfish in the PacFIN or RecFIN databases (PacFIN 2007;

RecFIN 2007). Anecdotally, giant kelpfish are incidentally taken by recreational anglers while targeting

otherkelpbedassociatedspecies.In2005,“kelpfish”landingsintheLosAngelesareatotaled34.0kg

(75 lbs) at a value of $75 (CDFG 2006). Commercial landings of giant kelpfish reported from catch

blocks in the Long Beach area totaled 79.4 kg (175 lbs) in 2006, at an estimated value of $175 (CDFG

2007).

During 1978-79, a total of 69 giant kelpfish was impinged at HGS, equivalent to about two individuals

per survey (IRC 1981). It was collected in relatively low numbers year-round, with a strong peak during a

February 1979 survey with 26 individuals. From 2003 through 2005, a total of seven giant kelpfish were

impinged during 10 normal operation surveys (MBC 2006).

5.5.2.6.3 Sampling Results

Giant kelpfish was the sixth most abundant species impinged with an estimated 192 individuals calculated

using actual cooling water flow volumes, or 2.2% of the annual total, weighing 15.7 kg (34.7 lbs)

(Table 5.5-1). The majority of giant kelpfish was impinged sporadically throughout the first three quarters

of the year, with a slight seasonal increase during late spring through summer (Figure 5.5-34). Biomass

generally followed a pattern consistent with that seen in abundance, except peak biomass rates were seen

in early winter and late summer (Figure 5.5-35). This was due to larger individuals impinged during

surveys when abundance was relatively low. Overall, generally higher abundances were recorded during

nighttime, with the exception of a single survey in February (Figures 5.5-36). Biomass was generally

greater during nighttime hours, with the exception of the first two surveys (Figure 5.5-37).

Length frequency analysis of 27 measured individuals was used to calculate a mean standard length of

182 mm (7.2 in) (Figure 5.5-38). Although individuals were collected representing size classes as small as

30 mm SL (1.2 in), the majority of recorded lengths were in the 100330 mm SL (3.913.0 in) size

classes. Peak abundance was recorded in the 190 mm SL (7.5 in) size class, representing individuals oneyear old. Of the 27 individuals that were evaluated for condition factor, 70% were alive and 30% were

dead.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

10

20

30

40

50

X

“X”denotes a two-week period of no sample collection.

Figure 5.5-34. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of giant kelpfish collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpingement Density (kg/1,000,000 cubic meters)

0

1

2

3

4

5

6

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-35. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of giant kelpfish collected in HGS impingement samples during 2006.
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Impingement Density (#/1,000,000 cubic meters)

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-36. Mean concentration (#/1,000,000 m3[264.2 million gal]) of giant kelpfish in

impingement samples during night (Cycle 4) and day (Cycle 2) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-37. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of giant kelpfish in

impingement samples during night (Cycle 4) and day (Cycle 2) sampling.
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Length category (mm SL)

30 100 120 140 160 180 200 220 240 260 280 300 320 340

P

ercent

0

2

4

6

8

10

12

14

16

N = 27

Mean = 182

Figure 5.5-38. Length (mm) frequency distribution for giant kelpfish collected in

impingement samples.

5.5.2.7 Northern anchovy (Engraulis mordax)

Information on the life history, ecology, population trends, and fishery for northern anchovy is

summarized in Section 4.5.3.1.

During 1978-79, a total of 48 northern anchovy was impinged at HGS, equivalent to about 0.3% of the

estimated annual abundance (IRC 1981). During that study 79% of the individuals were impinged in June

and August 1979. From 2003 through 2005, only one northern anchovy was collected at the HGS in 10

impingement samples (MBC 2006).

5.5.2.7.1 Sampling Results

Northern anchovy was the fourteenth most abundant species impinged with an estimated 24 individuals

calculated using actual cooling water flow volumes, or 0.3% of the annual total, weighing 0.02 kg (0.04

lbs) (Table 5.5-1). A total of four individuals was collected during the study, all between June 30 and July

21, 2006. The four individuals ranged in length from 32 to 38 mm SL, with an average of 34 mm, the

approximate length of transformation (Moser 1996). All four individuals were dead when collected.

5.5.3 Shellfish Impingement Results by Species

Two shellfish taxa were impinged in sufficient numbers, and considered commercially/recreationally

important, to warrant further analysis. These taxa were: California spiny lobster (10% of total sampled

macroinvertebrate abundance), and California two-spot octopus (2 percent). Combined, these taxa

comprised nearly 13% of the macroinvertebrates in impingement samples, and 79% of the biomass.
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5.5.3.1 California spiny lobster (Panulirus interruptus)

California spiny lobster ranges from Monterey

Bay, California, to Manzanillo, Mexico, and there

is also a small population along the northwestern

shore of the Gulf of California (MBC 1987). They

are the only representative of the spiny lobster

family (Palinuridae) in southern California.

5.5.3.1.1 Life History and Ecology

During the first two years, juveniles inhabit

surfgrass beds from the lower intertidal to depths

of about 5 m (16 ft). Juveniles and adults are

considered benthic, though they have been

observed swimming near the surface, and occur

from the intertidal zone to about 80 m (262 ft). Preferred habitats include mussel beds, rocky areas, and in

kelp beds (Morris et al. 1980; Barsky 2001).

California spiny lobster is oviparous, the sexes are separate, and fertilization is external. With few

exceptions, adult females spawn every year. Barsky (2001) reported that mating occurs from November

through May, and Wilson (1948) indicated the primary spawning season was from March to August.

Mating takes place on rocky bottoms in water depths of 1030 m (3398 ft) (Mitchell et al. 1969).

Spawning occurs from the Channel Islands off southern California to Magdalena Bay, Baja California,

including other offshore islands and banks, such as Cortez and Tanner (MBC 1987). Females move

inshore to depths less than 10 m (33 ft) to extrude and fertilize the eggs. At San Clemente Island, females

carried between 120,000 eggs (66 mm [2.6 in] CL) and 680,000 eggs (91 mm [3.6 in] CL) (Barsky 2001).

Hatching occurs from March to December. Larvae are pelagic and are found from the surface to depths of

137 m (449 ft), and within 530 km (329 miles) of shore (MBC 1987). Upon hatching, transparent larvae

(phyllosoma) go through 12 molts, increasing in size in each subsequent molt. Phyllosoma larvae are

infrequently collected in the Southern California Bight (Johnson 1956; MBC 1987). After five to ten

months, the phyllosoma transforms into the puerulus larval stage that resembles the adult form but is still

transparent. The puerulus actively swims inshore where it settles in shallow water. At La Jolla, puerulus

appeared in nearshore waters in late May and occurred there through mid-September (Serfling and Ford

1975). It is estimated that the puerulus stage of California spiny lobster lasts approximately two to three

months (Serfling and Ford 1975).

A 6.1 mm CL (0.2 in) juvenile specimen molts 20 times to reach 45.7 mm CL (1.8 in) at the end of its

first year (Barsky 2001). Spiny lobsters molt four times during the second year, and three times during the

third year. Mitchell et al. (1969) found adult spiny lobsters (larger than 41 mm CL (1.6 in) molt once

yearly. Both sexes reach maturity at approximately 5–6 years at a mean size of 63.5 mm CL (2.5 in)

(Barsky 2001). It takes a spiny lobster 7–11 years to reach the legal fishery size of 83 mm CL (3.3 in).

Females grow faster (4.4 mm/year [0.2 in/year]) than males (3.7 mm/year [0.1 in/year]) (Mitchell et al.

1969). Males may live up to 30 years, and reach a maximum length of 91 cm TL [35.8 in] and weight of

Courtesy of NOAA Central Library Photo Collection
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15.8 kg (34.8 lbs). Females may live up to 17 years, and reach a maximum size of 50 cm TL (19.7 in) and

5.5 kg (12.1 lbs) (MBC 1987).

Lobsters are nocturnal, seeking crevices in which to hide during the day, and moving about the bottom at

night (Wilson 1948). Panulirus is an omnivorous bottom forager, feeding on snails, mussels, urchins,

clams, and fish (Tegner and Levin 1983; Barsky 2001). A large portion of the population makes seasonal

migrations stimulated by changes in water temperature, with an offshore migration in winter, and an

inshore migration in late-spring and early summer (Mitchell et al. 1969, Barsky 2001). By the end of

August, berried females and juveniles comprise the bulk of the shallow-water population. Warmer water

temperatures shorten the development time of lobster eggs. By late September, the thermocline breaks

down and lobsters move to deeper water (1030 m) where they remain for the winter (MBC 1987).

5.5.3.1.2 Population Trends and Fishery

California spiny lobsters have been fished commercially in southern California since the late 1800s

(Barsky 2001). They are fished with traps, most of which are constructed of wire mesh. Most traps are

fished in shallow rocky areas in waters shallower than 31 m (100 ft) deep. Commercial landings in the

Los Angeles area have fluctuated and ranged between 43,084 kg and 62,585 kg (95,000 lbs and 138,000

lbs) per year since 2000 (Table 5.5-7). In 2005, commercial landings of spiny lobster in the Los Angeles

area totaled 101,324 kg (223,420 lbs) at a value of $1,771,864 (CDFG 2006). Commercial landings from

Long Beach area catch blocks in 2006 totaled 21,875 kg (48,225 lbs) at an estimated value of $448,844

(CDFG 2007). From 2003 through 2005, no spiny lobsters were collected in 10 impingement samples at

the HGS (MBC 2006).

Table 5.5-7. Annual landings and revenue for California spiny lobster in the Los Angeles

region based on PacFIN data.

Landed Weight

Year kilograms pounds Revenue

2000 47,879 105,574 $715,355

2001 49,333 108,779 $707,831

2002 43,429 95,761 $653,172

2003 54,654 120,512 $858,713

2004 62,419 137,634 $997,151

2005 55,946 123,362 $977,519

2006 52,902 116,650 $1,086,553

5.5.3.1.3 Sampling Results

California spiny lobster was the second most abundant shellfish species impinged with an estimated 717

individuals calculated using actual cooling water flow volumes, or 10.6% of the annual total count,

weighing 169.4 kg (373.5 lbs) (Table 5.5-3). Impinged sporadically throughout the first six months of

2006, California spiny lobsters were more abundant and consistent in surveys from summer into early

fall, with a distinct peak during late summer (Figure 5.5-39). Biomass followed a pattern consistent with

that seen in abundance, except the survey on February 3, when the impingement sample was comprised of

relatively small numbers of large individuals (Figure 5.5-40). Abundance was relatively equal between
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daytime and nighttime samples (Figure 5.5-41). A similar pattern was generally observed for biomass,

although peak biomass was recorded during a survey in early February due to the larger individuals

collected (Figure 5.5-42).

Length frequency analysis of 105 measured individuals was used to calculate a mean carapace length of

62 mm (2.4 in). Individuals predominantly ranged in size from 50 mm to 90 mm (2.0 in to 3.5 in)

carapace length (CL), with individuals also representing the 110 and 150 mm CL (4.3 and 5.9 in) size

classes (Figure 5.5-43). Nearly 61% of the individuals measured were in the 60 mm CL (2.4 in) size class,

and the majority of individuals impinged were smaller than the legal size limit. A total of 105 individuals

were sexed, of which 33% were female, 51% were male, and 15% were juvenile. Of the 105 individuals

that were evaluated for condition factor, 99% were alive and the remaining 1% was dead.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

20

40

60

80

100

120

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-39. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of California spiny lobster collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpinge

m

ent D

ensity (kg/1,0

0

0,0

0

0 cubic m

eters)

0

5

10

15

20

25

30

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-40. Mean biomass (kg / 1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of California spiny lobster collected in HGS impingement samples during 2006.
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Impingement Density (#/1,000,000 cubic meters)

-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-41. Mean concentration (#/1,000,000 m3[264.2 million gal]) of California spiny lobster

in impingement samples during night (Cycle 3) and day (Cycle 1) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-42. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of California spiny lobster in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.
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Length category (mm CL)

50 60 70 80 90 100 110 120 130 140 150

P

ercent

0

10

20

30

40

50

60

70

N = 105

Mean = 62

Figure 5.5-43. Length (mm) frequency distribution for California spiny lobster collected in

impingement samples.

5.5.3.2 California two-spot octopus (Octopus spp.)

There are two similar octopus species that occur in

southern California: Octopus bimaculatus and O.

bimaculoides. Both are referred to as the two-spotted

octopus since they are difficult to distinguish, and for

more than 60 years were thought to represent a single

species (Morris et al. 1980). O. bimaculoides ranges

from San Simeon, California, to Bahia San Quintin,

Baja California, and is found in a variety of habitats

to depths of 20 m (66 ft) (Lang and Hochberg 1997).

The sibling species O. bimaculatus has a similar

geographic distribution, occurring from Santa

Barbara, California, south to Punta Eugenia, Baja

California, and in some locations within the Gulf of California. It also occurs in slightly deeper depths (to

50 m or 164 ft) (Morris et al. 1980; Lang and Hochberg 1997).

5.5.3.2.1 Life History and Ecology

Both octopus species occur in a variety of habitats, including mudflats, intertidal zones, reefs, crevices,

and kelp beds. O. bimaculoides females lay their eggs under rocks from late winter to early summer, and

brood them continuously for two to four months (Morris et al. 1980). Females lay between 200 and 800

eggs, depending on female size and condition (Lang and Hochberg 1997). The young remain on the

bottom after hatching, and often move toward the intertidal. Adults feed on mollusks, crustaceans, and

Photo: J. Forsythe
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fishes. In the rocky intertidal zone, O. bimaculoides drills and feeds principally on limpets (Collisella and

Notoacmea), snails (Tegula spp.), Pacific littleneck, and hermit crabs (Pagurus spp.) (Morris et al. 1980).

They also feed on mussels (Mytilus spp.) and the Pacific calico scallop (Argopecten ventricosus) (Lang

and Hochberg 1997).

O. bimaculatus spawns throughout most of the year, though there is a distinct seasonal peak from April

through July (Lang and Hochberg 1997). Hatching takes place in a relatively short time-frame since there

is an inverse relationship between development time and water temperature (Ambrose 1981). Ambrose

(1981) also reported an average clutch size of about 20,000 eggs for a female weighing about 260 g

(0.57 lbs). After hatching, young octopuses are planktonic for several months, and then settle to the

bottom (Lang and Hochberg 1997). Juvenile O. bimaculatus feed on small crustaceans, while adults

consume a wide variety of motile benthic invertebrates.

5.5.3.2.2 Population Trends and Fishery

Most California landings of octopus result from incidental catches in other fisheries (Lang and Hochberg

1997). In 2005, commercial landings of octopus in the Los Angeles area totaled 182.7 kg (403 lbs) at a

value of $558 (CDFG 2006). Commercial landings from Long Beach area catch blocks in 2006 totaled

17.7 kg (39 lbs) at an estimated value of $105. From 2003 through 2005, a total of six two-spot octopus

was impinged at the HGS, and annual impingement ranged from 0 to 0.8 individuals per survey,

averaging about 0.5 individuals per survey (MBC 2006).

5.5.3.2.3 Sampling Results

California two-spot octopus was the fourth most abundant shellfish species impinged with an estimated

184 individuals calculated using actual cooling water flow volumes, or 2.7% of the annual total, weighing

36.3 kg (79.9 lbs) (Table 5.5-3). Peak abundance and biomass were recorded from winter through spring,

with occurrences during only two surveys after April (Figures 5.5-44 and 5.5-45). Overall, California

two-spot octopus was impinged more frequently during daytime surveys, but the highest abundance and

biomass were recorded during the first nighttime survey (Figures 5.5-46 and 5.5-47).

Length frequency analysis of 22 measured individuals was used to calculate a mean of 384 mm (15.1 in)

arm spread (AS) (Figure 5.5-48). Although measurements varied widely from 190630 mm AS (7.524.8

in), the predominance of individuals had maximum arm spans between 290440 mm (11.417.3 in). A

total of 22 individuals were sexed, of which 32% were female, 27% were male, and 41% could not be

determined. Of the 22 individuals that were evaluated for condition factor, 86% were alive, 5% were

dead, and 9% were mutilated.
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Survey Date

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 Impingement Density (#/1,000,000 cubic meters)

0

10

20

30

40

50

60

70

80

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-44. Mean concentration (#/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of California two-spot octopus collected in HGS impingement samples during 2006.

Survey Date

I

Jan-06 Mar-06 May-06 Jul-06 Sep-06 Nov-06 Jan-07 mpinge

m

ent D

ensity (kg/1,0

0

0,0

0

0 cubic m

eters)

0

2

4

6

8

10

12

14

16

X

“X”denotesatwo-week period of no sample collection.

Figure 5.5-45. Mean biomass (kg/1,000,000 m3[264.2 million gal] –wide bars) and standard error

(narrow bars) of California two-spot octopus collected in HGS impingement samples during 2006.
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Impingement Density (#/1,000,000 cubic meters)

-140-130 -20 -10 0 10 20 30

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-46. Mean concentration (#/1,000,000 m3[264.2 million gal]) of California two-spot octopus in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.

Impingement Density (kg/1,000,000 cubic meters)

-30 -25-10 -8 -6 -4 -2 0 2 4 6 8

Survey Date

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

Nighttime Daytime

X

“X”denotesatwo-week period of no sample collection.

Note: Negative nighttime values are a plotting artifact.

Figure 5.5-47. Mean biomass (kg/1,000,000 m3[264.2 million gal]) of California two-spot octopus in

impingement samples during night (Cycle 3) and day (Cycle 1) sampling.
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Length category (mm AS)

200 240 280 320 360 400 440 480 520 560 600

Percent

0

2

4

6

8

10

N = 22

Mean = 384

Figure 5.5-48. Arm spread (mm AS) length frequency distribution for California

two-spot octopus collected in impingement samples.
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6.0 IM PA C T AS SE S SM E N T

6.1 IMPACT ASSESSMENT OVERVIEW: DATA AND APPROACH

Section 316(b) of the Clean Water Act regulates cooling water intake systems at electrical generating

facilities, and requires the location, design, construction, and capacity of cooling water intake structures

reflect the best technology available (BTA) for minimizing adverse environmental impacts (AEI). In

2004, EPA published Phase II 316(b) regulations for existing power plants, which established

performance standards for reducing entrainment by 60 to 90% and impingement mortality by 80 to 95%.

However, the Phase II regulations were suspended by EPA in 2007. On May 20, 2007, EPA transmitted a

memorandum to regional administrators informing them that the Phase II rule should be considered

suspended,andthat“all permits for Phase II facilities should include conditions under Section 316(b) of

the Clean Water Act developed on a Best Professional Judgment basis. See 40 CFR 401.14.”Aswritten,

the Clean Water Act does not specify required cooling water intake system (CWIS) technologies or

methods by which EPA must make its determinations under Section 316(b).

PriortothepublicationofthePhaseIIregulationsin2004,regulatorsreliedonEPA’s(1977)draft

guidelines for evaluating adverse impacts of cooling water intake structures to determine compliance with

Section 316(b). At the HGS, the previous 316(b) demonstration evaluated entrainment and impingement

impacts using several methods, including:

1. Evaluation of IM&E losses relative to known source populations, and

2. Assigning a relative level of impact for each taxon analyzed.

Under the 19781979 316(b) evaluation, impact analyses were conducted using several techniques.

Entrainment losses were compared to source water populations, and estimates of ichthyoplankton

entrainment were evaluated using an equivalent adult model. Impingement losses were compared with

source populations calculated from demersal fish surveys, and also compared to recreational and

commercial fishing landings. Lastly, impingement mortality was compared with instantaneous mortality

rates for three fish species. In summary, there were no significant effects from the HGS on the standing

crop and natural mortality rates of the taxa analyzed. The ultimate conclusion of the HGS 316(b)

demonstration was that there were no significant adverse impacts on nearshore fish populations in the

Southern California Bight from the operation of the HGS, and the configuration of the intakes represented

BTA for minimizing AEI.

Since the suspended Phase II regulations were based on performance standards for reducing entrainment

and impingement and did not explicitly rely on determining whether existing levels represented an AEI,

EPA determinedthe“...performance standards reflect the best technology available for minimizing

adverse environmental impacts determined on a national categorical basis.”AlthoughAEIwasnot

intended to be used in assessing compliance under the new regulations, the potential for AEI was still

considered in determining the types of plants and water body where the new performance standards

would apply. Plants with low capacity factors and low cooling water volumes were considered to be BTA

since their cooling systems had a low potential for AEI.
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In its 1977draftguidancedocument,EPA indicated“Adverse aquatic environmental impacts occur

whenever there will be entrainment or impingement damage as a result of the operation of a specific

cooling water intake structure. The critical question is the magnitude of any adverse impact.”EPAalso

clarifiedintheguidancedocument:“Regulatory agencies should clearly recognize that some level of

intakedamagecanbeacceptableifthatdamagerepresentsaminimizationofenvironmentalimpact.”

In the 2006 IM&E study, entrainment and impingement losses were measured by collecting samples at

theHGSunit’sscreensforimpingementsamplingandinthevicinityoftheintakeswithinSlip5inILAH

for entrainment sampling. The purpose of this impact assessment is to put the measured losses into

context, and to evaluate the potential for AEI due to the CWIS.

6.1.1 CWIS impacts

There are three general types of effects associated with cooling water intake structures: (1) thermal

effects, (2) impingement effects, and (3) entrainment effects. Thermal effects are regulated under Section

316(a) of the Clean Water Act and the Water Quality Control Plan for Control of Temperature in the

Coastal and Interstate Waters and Enclosed Bays of California (California Thermal Plan). The recent

NPDES permit for the HGS indicated that the generating station continues to operate in compliance with

the California Thermal Plan. Entrainment occurs when organisms are drawn into a cooling water intake

structure and subsequently pass through the HGS. Organisms large enough to become trapped on the

traveling screens are impinged.

In discussing the potential effects of the HGS CWIS on fish and shellfish populations the first thing that

needs to be considered is the life history of the species in the communities. First of all, several fish

species in the nearshore coastal areas around HGS have early life stages that are not susceptible to

entrainment. Live-bearers, such as surfperches, and some sharks and rays, produce young that are fully

developed and too large to be affected by entrainment. In addition, for fishes with entrainable life stages,

the period of time that they are vulnerable to entrainment may be relatively short. As the results for HGS

show, many species are only vulnerable to entrainment for a few days when they are newly hatched since

their swimming ability increases rapidly with age and development. Gobies, which comprised almost half

of the total estimated fish larvae entrained, have demersal eggs, which are not subject to entrainment.

Also, with increased age young post-larval fishes begin searching for adult habitat, usually on the bottom,

where they are less susceptible to entrainment. From the standpoint of impingement effects, one of the

most abundant groups of species in protected bays and estuaries, gobies, are generally not susceptible to

impingement after transformation to the juvenile life stage because they are bottom-dwelling species that

typically do not move up into the water column. This is also true of many flatfishes, which are bottomdwellers and also tend to be strong swimmers. Even fish species that swim in the water column are

generally not susceptible to impingement effects as they mature because they are able to swim against the

slow approach velocity of the cooling water inflow.

6.1.2 Review of IM&E Sampling Approach

ThesuspendedPhaseII316(b)regulationsrequiredthatIM&Estudiesinclude“Documentation of

current impingement mortality and entrainment of all life stages of fish, shellfish, and any protected

species identified previously and an estimate of impingement mortality and entrainment to be used as the
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calculation baseline.”Forthepurposesofthisstudytheterm ‘shellfish’wasinterpretedasincluding

commercially and recreationally important species of crustaceans (crabs, lobsters, shrimp, etc.) and

mollusks (squid and octopus) that are harvested on a regular basis from the coastal areas surrounding the

HGS. This definition does not include organisms such as clams, mussels, and other crustaceans and

mollusks that may only be harvested occasionally for recreational purposes, although the entrainment

processing was expanded, at the request of the LARWQCB staff, to include all crab megalops stage

larvae, and the impingement sampling quantified all of the organisms. This definition was used because

‘shellfish’couldalsobeconsideredasincludingallspeciesofshelledinvertebrates,including

zooplankton, and clarification of the term was not provided in the regulations.

ThesuspendedRule’sentrainmentperformancestandard focused on addressing impacts to fish and

shellfish rather than lower trophic levels such as phyto- and zooplankton. EPA recognized the low

vulnerability of phyto- and zooplankton in its 1977 draft 316(b) guidance (EPA 1977). There were several

reasons why there is a low potential for impacts to phyto- and zooplankton and why it made sense for the

EPA to focus on effects on fish and shellfish. The reasons included the following:

 The extremely short generation times; on the order of a few hours to a few days for

phytoplankton and a few days to a few weeks for zooplankton;

 Both phyto- and zooplankton have the capability to reproduce continually depending on

environmental conditions; and

 The most abundant phyto- and zooplankton species along the California coast have populations

thatspantheentirePacificorinsomecasesalloftheworld’soceans.Forexample,Acartia tonsa,

one of the common copepod species found in the nearshore areas of California is distributed

along the Atlantic and Pacific coasts of North and South America and the Indian Ocean.

Relative to the large abundances of phyto- and zooplankton, larval fishes make up a minute fraction of the

total numbers of organisms present in seawater. The EPA has correctly focused on potential impacts on

fishes and shellfishes because they are more susceptible to entrainment effects for the following reasons:

 They have much shorter spawning seasons relative to phyto- and zooplankton. In many species,

spawning occurs only once during the year;

 Unlike phyto- and zooplankton that may be distributed over large oceanic areas, most fishes are

restricted to the narrow shelf along the coast and in some cases have specific habitat requirements

that further restrict their distribution; and

 Unlike many phyto- and zooplankton, there is a greater likelihood of mortality due to entrainment

in larval fishes, since many lower trophic level organisms are not soft bodied as is the case for

finfish and are better able to tolerate passage through the cooling system.

The impingement and entrainment sampling was therefore focused on fishes and shellfishes as required in

the suspended 316(b) Phase II regulations. All of the fishes and shellfishes collected during the

impingement sampling were counted and identified, while fish eggs and larvae, megalops stages of crabs,

phyllosome larvae of spiny lobster, and squid larvae were identified and counted from the entrainment

samples. The suspended 316(b) Phase II regulations provided latitude for focusing on the set of species
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that could be accurately quantified and that provided the necessary detail to support development of other

aspects of the CDS, and therefore, allowed for negotiating an acceptable compromise between the

regulating agency and the discharger. The target group of organisms that were included in the entrainment

sample processing was finalized at a January 12, 2006 meeting with staff from the LARWQCB and other

resource agencies.

The specific taxa (species or group of species) that were included in the assessment were limited to the

taxa that were sufficiently abundant to provide reasonable assessments of impacts. For the purposes of

this study plan, the taxa analyzed in the assessment were limited to the most abundant taxa that together

comprised 9095% of all larvae entrained and/or juveniles and adults impinged by the generating station.

The most abundant taxa were used in the assessment because they provided the most robust and reliable

estimates for the purpose of assessing impacts. Since the most abundant organisms may not necessarily

have been the organisms that experienced the greatest effects on the population level, the data were also

examined to determine if additional taxa should have been included in the assessment. For example, this

might include commercially or recreationally important taxa, taxa with limited habitats, and any

threatened or endangered fish or shellfish species. No listed species were entrained or impinged at the

HGS during the study and no additional taxa beyond the taxa selected based on sampling abundance were

included in the assessment.

Results for individual taxa from the impingement and entrainment sampling need to be combined, where

possible, to evaluate the combined effects of the CWIS. This is done by extrapolating the numbers of

adult and juvenile fishes impinged to the same age used in the adult equivalent loss (AEL) and fecundity

hindcasting (FH) models for the entrainment data. The age used in the AEL and FH modeling was the

average age of reproductive females in the population. Unfortunately, the life history information

necessary for the modeling was unavailable for most species so combined assessments were only possible

for CIQ gobies, combtooth blennies, and northern anchovy. No EAM (equivalent adult modeling) was

done on impingement estimates due to the low numbers of fishes collected and the lack of necessary life

history parameters for most species.

6.1.3 Approaches for assessment of CWIS impacts

Due to the suspension of the 316(b) Phase II rule, state and federal permit writers have been directed to

implement Section 316(b) on a case-by-casebasisusing“bestprofessionaljudgment”.Inthecaseofthe

HGS,thepermitapplicantisobligatedtoprovidetheLARWQCBwiththe“bestinformationreasonably

available”toassistitinfulfilling its decision-making responsibility. To make Section 316(b) decisions,

permitwritershavereliedonprecedentfrom othercasesandonEPA’s(1977)draft“Guidancefor

Evaluating the Adverse Impact of Cooling Water Intake Structures on the Aquatic Environment: Section

316(b) P.L. 92-500.”

As is clear from the statute, the permit writer must consider two basic issues in making a finding that an

intake technology employs the BTA for minimizing AEI:

1. Whether or not an AEI is caused by the intake and, if so,

2. What intake structure represents BTA to minimize that impact?
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The usual approach for a 316(b) demonstration would be to consider the question of BTA only if a

determination has been made that a facility is causing an AEI.

6.1.3.1 Adverse Environmental Impact (AEI) Standard

SincetherewerenoregulationsdefiningAEI,permitdecisionsmustbebasedontheEPA’sAEI

interpretationsprovidedinguidancedocumentsissuedsincethe1970’s.Inthosedocuments,theEPAhas

indicated that assessment of AEI should be based on an evaluation of population level effects, not just

lossesofindividualorganisms.Inits1977DraftBTA Guidelines,theEPA statedthat“[a]dverse

environmental impacts occur when the ecological function of the organism(s) of concern is impaired or

reducedtoalevelwhichprecludesmaintenanceofexistingpopulations...”.Additionally,inthe1976

DevelopmentDocument,releasedinconjunctionwiththeEPA’spreviousSection316(b)draftguidelines,

theEPA saidthat“[t]hemajorimpactsrelated to cooling water use are those affecting the aquatic

ecosystems.Seriousconcernsarewithpopulationeffectsthat...mayinterferewiththemaintenanceor

establishment of optimum yields to sport or commercial fish and shellfish, decrease populations of

endangeredorganisms,andseriouslydisruptsensitiveecosystems.”

The EPA (1977) draft guidelines acknowledge that the determination of the extent of AEI when it is

occurringisdifficulttoassess.Theystatethat“Adverseaquaticenvironmentalimpactsoccur whenever

there will be entrainment or impingement damage as a result of the operation of a specific cooling water

intake structure. The critical question is the magnitude of any adverse impact. The exact point at which

adverse aquatic impact occurs at any given plant site or water body segment is highly speculative and can

only be estimated on a case-by-casebasis...”

Due to the obvious difficulties with determining the extent of AEI, the document (EPA 1977) provides

some general guidelines. These involvedeterminingthe“relativebiologicalvalueofthesourcewater

body zone of influence for selected species and determining the potential for damage by the intake

structure”basedonthefollowingconsiderationsofthevalueofagivenareatoaparticular species:

 principal spawning (breeding) ground;

 migratory pathways;

 nursery or feeding areas;

 numbers of individuals present; and

 other functions critical during the life history.

Following this general approach provided by the EPA (1977), additional criteria can be evaluated that are

specific to the marine environment around HGS that are directly applicable to the present 316(b) study:

 distribution (pelagic, subtidal, nearshore subtidal & intertidal);

 range, density, and dispersion of population;

 population center (source or sink);

 magnitude of effects;

 long-term abundance trends (e.g., fishery catch data);

 long-term environmental trends (climatological or oceanographic); and

 life history strategies (e.g., longevity and fecundity).
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By assessing the relative value of each of these criteria for a particular taxon, the extent of the impact that

the loss of these animals has on the local environment and the population as a whole could be better

assessed.

6.1.4 Relating measured impacts to source populations

The potential magnitude of the losses due to entrainment and impingement depend on many factors

including the physical characteristics of the source water body, and the biological characteristics of the

affected populations including the following:

 Reproductive biology that affects the vulnerability of certain life stages, such as surfperches and

sharks and rays with no planktonic larval phase,

 Distribution and habitat preferences that affect vulnerability, and

 Duration of time that larval and juvenile stages are vulnerable due to behavior, mobility, and

habitat preferences.

The criteria used to evaluate the potential for AEI need to be placed into a larger context using the

characteristics of the source water and the biological community. This assessment focuses on a set of

species that were collected during the study in adequate abundances to provide reasonable confidence in

the estimates of entrainment and impingement effects. These species were also selected to be broad

enough to include representatives from the different habitats and species groups present in the source

water. As previously discussed (Section 6.1.1), not all of the fishes and shellfishes in the source water are

subject to entrainment or impingement, and only a few species occur in high abundance in both

entrainment and impingement samples. These differences in the vulnerability to entrainment and

impingement occur due to different life histories of the species, and the differences in habitat preferences

and behavior that may occur at different life stages. The potential magnitude of the losses due to

entrainment and impingement depends on many factors, as listed above, but specifically we will focus on

the distribution of the species and their habitats to determine which species are at greatest risk. The

extreme case of highest risk would occur for a rare or endangered species with a distribution that was

limited to the area around the HGS intake in the Los AngelesLong Beach Harbor Complex (Harbor

Complex). Species at least risk are those such as northern anchovies that are widely distributed in

offshore habitats and produce larvae that are primarily distributed in offshore waters.

The focus of the assessment will be on species with adult populations in the nearshore areas of the Harbor

Complex that are directly affected by entrainment and impingement at the HGS CWIS. Therefore the

following criteria from the list in the previous section can be used to focus the assessment on species with

adult and larval distributions that would place them at greatest risk to entrainment and impingement

effects:

 distribution (pelagic, subtidal, nearshore subtidal & intertidal),

 range, density, and dispersion of population; and

 population center (source or sink).
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These criteria relate directly to the habitats associated with the fish and shellfish potentially affected by

entrainment and impingement. This approach to classification has been taken in recent studies of marine

fishes of California (Horn and Allen 1978; Allen 1985; Allen and Pondella 2006b) and will be used to

organize the taxa included in this assessment. We have simplified the more detailed categorization of

habitats used by Allen and Pondella (2006b) which included several habitats used to define deeper

offshore areas (Figure 6.1-1). These deeper offshore habitat types can be combined for the purposes of

our assessment since the taxa associated with those habitats are generally not at risk due to entrainment

and impingement and were collected in very low numbers. The habitats defined by Allen and Pondella

(2006b) have been simplified for this assessment to the following habitat types:

 bays, harbors, and estuaries;

 subtidal and intertidal rocky reefs and kelp beds;

 coastal pelagic;

 continental shelf and slope; and

 deep pelagic including deep bank and rocky reefs.

The taxa included in this assessment were categorized into these habitat types (Table 6.1-1). Taxa that

occur in more than one habitat were included in the habitat group that best reflected the primary

distribution for the taxa and if a primary habitat could not be identified, the one where they are at greatest

risk to the effects of entrainment and impingement. For example, silversides occur in both bay and harbor,

and coastal pelagic habitats but since their occurrence in bay and harbor habitats places them at greater

risk to power plant effects they will be treated along with other taxa specific to that habitat. This raises an

important point in regards to impact assessment. Taxa that occupy several different habitats will be at less

risk from power plant impacts especially if at least one of the habitats is not directly affected by

entrainment and impingement. For example, white croakers occur in bays and harbors where they are

directly at risk to impingement and entrainment at HGS but also in sandy shallow nearshore areas where

they are not at risk.

This approach to assessing AEI is consistent with a recent trend in fisheries management to ecosystem

based management (Larkin 1996; Link 2002; Mangel and Levin 2005). This approach recognizes that

commercial fishing stocks can only be protected if the habitats and other components of the ecosystem are

protected. An ecosystem-based approach also addresses other human activities in addition to fishing and

the environmental factors that affect an ecosystem, the response of the ecosystem, and the outcomes in

terms of benefits and impacts on humans. In this context it will help identify the habitats most at risk to

CWIS effects and help identify a broader context for the effects relative to the entire ecosystem. If

restoration were to be allowed as a compliance alternative, this approach to assessment would focus the

restoration scaling with the appropriate species from the identified habitats.
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Figure 6.1-1. Marine habitat types in California (from Allen and Pondella [2006b]).
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Table 6.1-1. Habitat associations for taxa included in assessment of CWIS effects at the HGS.

Primary habitat in bold, upper case and secondary habitat in lower case.

Fishery Habitats

Scientific name Common name

S-Sport,

C-Comm.

bays,

harbors

reefs,

kelp

beds

coastal

pelagic shelf

Fishes

Acanthogobius flavimanus yellowfin goby X

Cymatogaster aggregata shiner perch S X x

Embiotoca jacksoni black perch S, C x X

Engraulidae unid. anchovies C X

Genyonemus lineatus white croaker S, C x X x

Gobiidae unid. CIQ goby complex X

Heterostichus rostratus giant kelpfish X

Hypsoblennius spp. combtooth blennies X x

Lepidogobius lepidus bay goby X

Paralabrax nebulifer barred sand bass S x X

Porichthys myriaster specklefin midshipman X x x

Sciaenidae unid. croakers S, C X x

Urobatis halleri round stingray X

Shellfishes

Octopus spp. two-spot octopus C x X

Panulirus interruptus California spiny lobster S X

6.2 SUMMARY OF ENTRAINMENT AND IMPINGEMENT RESULTS

The following section summarizes the combined results of the entrainment and impingement studies at

HGS to provide an overview of annual impacts to marine life that are directly attributable to operations at

the generating station. Earlier sections of the report provide greater detail and explanation of the results

on individual species, and the information in this section provides an overview of the major results. In

addition, for those species such as northern anchovy that were affected by both entrainment of eggs and

larvae and impingement of juveniles and adults, the data are summarized together for all life stages. In

later sections, the information on calculated losses is compared to long-term population trends and then

discussed in terms of adverse environmental impacts.

6.2.1 Taxa Composition

Data from the bi-weekly entrainment surveys conducted at the HGS cooling water intakes were used to

calculate that an estimated 65.3 million fish larvae and 99.9 million fish eggs were entrained through the

generating station CWIS in 2006 (Table 6.2-1). If all circulating water pumps had been in operation

during the entire year, larval entrainment would have increased by 135% to 153.3 million, and egg

entrainment would have increased by 170% to 269.4 million. Approximately 51% of the larvae were CIQ

gobies, 24% were yellowfin gobies, 11% were white croakers, 4% were bay gobies, 3% were combtooth

blennies and forty-three other species combined contributed nearly 8% of the annual total. Larvae from 48

taxa were represented in the collections. Many of the larvae and eggs could not be positively identified to
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the species level, and this added some uncertainty to the estimates of annual entrainment for individual

species. The most abundant taxonomic group of fish eggs in the samples were unidentified eggs (49%),

followed by white croaker eggs (18%), and unidentified croaker eggs (15%). Eggs of approximately 10

fish taxa were represented in the collections. A complete listing of all of the taxonomic categories

identified during the study is presented in Appendix E.

There were an estimated 18.9 million target shellfish larvae entrained represented by 16 taxa (Table

6.2-1). Kelp crab megalops comprised 64% of the annual entrainment of target shellfish larvae and spider

crab megalops comprised about 19% of the total. Species with commercial fishery value included market

squid with approximately 26,676 paralarvae (hatchlings) entrained under actual flow (62,179 for design

flows) while cancer crabs had 15,625 megalops entrained under actual flows (35,225 for design flows).

Data from the weekly normal operations sampling were used to estimate that annual fish impingement at

the HGS from a total of 25 taxa groups was 8,851 individuals weighing 1,317 kg (2,903 lbs) based on

actual cooling water flow, and 19,861 individuals weighing 2,938 kg (6,479 lbs) based on design cooling

water flow (Table 6.2-2). The most abundant species impinged by number and biomass were round

stingray and black perch.

Annual macroinvertebrate impingement estimates at the HGS were 6,753 individuals weighing 260 kg

(573 lbs) based on actual cooling water flow, and 13,538 individuals weighing 575 kg (1,269 lbs) based

on design cooling water flow (Table 6.2-3). The most abundant species impinged by numbers included

the nudibranch hermissenda, sea spiders, tuberculate pear crab, California spiny lobster, and intertidal

coastal shrimp. The remaining 43 species each comprised less than 3% individually to the total. The

species contributing most to impingement biomass California spiny lobster, California two-spot octopus,

and the California sea slug.
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Table 6.2-1. Rank and estimated annual entrainment of common fish larvae, fish eggs and target shellfish

larvae at HGS in 2006.

Rank Taxon

Est. Annual

Entrainment

(actual flows)

Est. Annual

Entrainment

(design flows)

% Comp.

(actual flows)

Cumulative

% Comp.

(actual flows)

Fish Larvae

1 gobies 33,290,815 75,938,007 50.98 50.98

2 yellowfin goby 15,407,999 37,604,336 23.60 74.58

3 white croaker 7,164,843 18,777,752 10.97 85.55

4 bay goby 2,376,260 5,070,071 3.64 89.19

5 combtooth blennies 2,255,907 4,362,576 3.45 92.65

6 croakers 995,438 2,856,932 1.52 94.17

42 Other taxa 3,806,737 8,721,337 5.83 100.00

65,297,999 153,331,011

Fish Eggs

1 unidentified fish eggs 49,261,253 130,894,994 49.32 49.32

2 white croaker eggs 17,867,461 43,114,182 17.89 67.21

3 croaker eggs 14,562,519 41,351,239 14.58 81.79

4 sand flounder eggs 8,780,223 30,684,631 8.79 90.58

6 Other taxa 9,413,438 23,379,179 9.42 100.00

99,884,894 269,424,225

Target Shellfishes

1 kelp crabs megalops 12,009,598 26,357,647 63.54 63.54

2 spider crab megalops 3,520,320 7,285,587 18.62 82.16

3 pea crabs megalops 1,810,300 4,467,908 9.58 91.74

13 Other taxa 1,561,119 3,233,933 8.26 100.00

18,901,337 41,345,075
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Table 6.2-2. Rank and estimated annual impingement of top ten most common fish taxa at

HGS in 2006 by estimated abundance and weight for actual and design flows.

Rank Common Name

Total No.

Actual Flows

Total No.

Design Flows

% Total

Actual Flows

Cumulative

% Total

Actual Flows

1 round stingray 6,150 13,771 69.48 69.48

2 black perch 646 1,371 7.30 76.78

3 specklefin midshipman 484 1,379 5.47 82.25

4 shiner perch 390 719 4.41 86.66

5 barred sand bass 209 442 2.36 89.02

6 giant kelpfish 192 424 2.17 91.19

7 yellowfin goby 163 399 1.84 93.03

8 spotted kelpfish 158 354 1.79 94.81

9 white seaperch 115 221 1.30 96.11

10 plainfin midshipman 62 175 0.70 96.81

15 Other taxa 282 606 3.19 100.00

8,851 19,861

Total Wt. (kg)

Actual Flows

Total Wt. (kg)

Design Flows

% Total

Actual Flows

Cumulative

% Total

Actual Flows

1 round stingray 1,232 2,756 93.55 93.55

2 black perch 18 41 1.40 94.95

3 giant kelpfish 16 33 1.19 96.15

4 specklefin midshipman 12 27 0.91 97.06

5 barred sand bass 8 16 0.57 97.63

6 California halibut 7 16 0.57 98.19

7 pile perch 6 13 0.48 98.68

8 white seaperch 4 8 0.31 98.99

9 hornyhead turbot 4 9 0.30 99.29

10 shiner perch 3 7 0.26 99.55

15 Other taxa 6 14 0.45 100.00

1,317 2,938
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Table 6.2-3. Rank and estimated annual impingement of top ten most common invertebrate

taxa at HGS in 2006 by estimated abundance and weight for actual and design flows.

Rank Common Name

Total No.

Actual Flows

Total No.

Design Flows

% Total

Actual Flows

Cumulative

% Total

Actual Flows

1 hermissenda 1,840 3,625 27.24 27.24

2 sea spider, unid. 1,258 2,139 18.62 45.86

3 tuberculate pear crab 801 1,535 11.86 57.71

4 California spiny lobster 717 1,544 10.61 68.32

5 intertidal coastal shrimp 711 1,600 10.52 78.85

6 Calif. two-spot octopus 184 428 2.72 81.57

7 Calif. coastal shrimp 138 315 2.04 83.61

8 ring-spotted dorid 128 267 1.89 85.51

9 spotted triopha 116 234 1.72 87.23

10 orange-spike polycera 111 233 1.64 88.87

38 Other Taxa 752 1,618 11.13 100.00

6,756 13,538

Total Wt. (kg)

Actual Flows

Total Wt. (kg)

Design Flows

% Total

Actual Flows

Cumulative

% Total

Actual Flows

1 California spiny lobster 169 370 65.00 65.00

2 Calif. two-spot octopus 36 86 13.85 78.85

3 California sea slug 13 32 5.00 83.85

4 Pacific rock crab 10 19 3.85 87.69

5 sea star, unid. 9 23 3.46 91.15

6 warty sea cucumber 7 15 2.69 93.85

7 California seahare 6 11 2.31 96.15

8 seahare, unid. 2 3 0.77 96.92

9 California sea cucumber 2 3 0.77 97.69

10 tuberculate pear crab 1 2 0.38 98.08

38 Other taxa 5 10 1.92 100.00

260 574
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6.2.1.1 Temporal Occurrence

The greatest concentrations of larval fishes occurred during March 2006 and the fewest occurred in

September (Figure 4.5-1). Fish eggs had a peak in abundance in late February prior to the peak abundance

of fish larvae (Figure 4.5-2). They also had increased abundances in early June that did not appear to be

reflected in larval concentrations. Larvae tended to be more abundant in samples collected at night than

those collected during the day, although daytime collections occasionally yielded higher concentrations

(Figure 4.5-3).

Impingement abundance was highest from August to November (Figure 5.5-1), which corresponded with

an increase in round stingray impingement. Biomass was greatest during the same period as the peak

abundance (Figure 5.5-2). Invertebrate abundance was greatest from June through August, with highest

abundance recorded from late-June through early-August (Figure 5.5-3). Invertebrate biomass was much

more variable throughout the year, with peaks from January through March (Figure 5.5-4), corresponding

to the impingement of large individuals of select species. Biomass increased again from June through

August, but in a steadier ascent than during the winter months. In general, fish impingement abundance

and biomass was greatest during nighttime (Figures 5.5-5 and 5.5-6).

6.2.2 Combined Analysis and Modeling Results for Selected Species

Several species of fishes and shellfishes that were abundant in either the entrainment or impingement

samples, had recreational or commercial fishery value, or were federally managed species were analyzed

in detail in Sections 4 and 5. Some of the larval taxa had sufficient information available on their life

history to estimate losses based on conversion to adult equivalents. The results of these analyses are

summarized using actual flow rates for the CWIS at HGS in 2006 (Table 6.2-4) and design flow rates for

the CWIS (Table 6.2-5).
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Table 6.2-4. Summary of HGS entrainment and impingement sampling results and model output for common fish and shellfish species

based on actual CWIS flows in 2006. Model estimates indicate whether the number was based on eggs (E), larvae (L), or both

combined (C).

Species Common Name

Est. Annual

Larval Ent.

(millions)

Est. Annual

Egg Ent.

(millions)

ETM

PM 2*FH AEL

Annual

Imping.

Estimate

Imping.

Weight

(kg)

Fishes

Gobiidae unid. gobies 33.29 0 2.65 86,720L36,231L0

Acanthogobius flavimanus yellowfin goby 15.41 0 0.65 1,936L163 3.15

Genyonemus lineatus1 white croaker 7.16 17.87 0.19 20E25 0.20

Lepidogobius lepidus bay goby 2.38 0 0.24 0

Hypsoblennius spp. combtooth blennies 2.26 0 0.06 2,826L6,024L0

Engraulis mordax northern anchovy 0.94 0.8 0.71 11,506C25,863L24 0.02

Urobatis halleri round stingray   6,150 1,231.68

Embiotoca jacksoni black perch   646 18.49

Porichthys myriaster specklefin midshipman   484 11.96

Cymatogaster aggregata shiner perch   390 3.36

Paralabrax spp.2sand bass 0.12  209 7.51

Heterostichus rostratus giant kelpfish 0  192 15.73

Shellfishes

Panulirus interruptus spiny lobster 0.22  717 169.37

Octopus spp. two-spot octopus   184 36.25

1

larval entrainment estimate includes white croaker and unidentified croakers combined

2

only barred sand bass collected in abundance in impingement sampling
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Table 6.2-5. Summary of HGS entrainment and impingement sampling results and model output for common fish and shellfish species

based on design CWIS flows in 2006. Model estimates indicate whether the number was based on eggs (E), larvae (L), or both

combined (C).

Species Common Name

Est. Annual

Larval Ent.

(millions)

Est. Annual

Egg Ent.

(millions)

ETM

PM 2*FH AEL

Annual

Imping.

Estimate

Imping.

Weight

(kg)

Fishes

Gobiidae unid. gobies 75.94 0 5.70 197,812L82,665L0

Acanthogobius flavimanus yellowfin goby 37.60 0 1.54 4,724L399 7.48

Genyonemus lineatus1 white croaker 18.78 43.11 0.42 48

E

48 0.43

Lepidogobius lepidus bay goby 5.07 0 0.50 0

Hypsoblennius spp. combtooth blennies 4.36 0 0.12 5,466L11,650L0

Engraulis mordax northern anchovy 2.07 1.93 1.53 25,306C56,879L36 0.03

Urobatis halleri round stingray   13,771 2,756.09

Embiotoca jacksoni black perch   1,371 41.03

Porichthys myriaster specklefin midshipman   1,379 26.84

Cymatogaster aggregata shiner perch   719 6.77

Paralabrax spp.2sand bass 0.27  442 16.20

Heterostichus rostratus giant kelpfish 0  424 32.60

Shellfishes

Panulirus interruptus spiny lobster 0.36  1,544 369.56

Octopus spp. two-spot octopus   428 85.96

1

larval entrainment estimate includes white croaker and unidentified croakers combined

2

only barred sand bass collected in abundance in impingement sampling
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6.3 ASSESSMENT OF TAXA BY HABITAT TYPE

The following sections present assessments for taxa from the five habitat types simplified from Allen and

Pondella (2006b). A general discussion of the habitat and the potential risk to the habitat due to HGS

operation will be followed by discussion of the specific impacts to the fishes and shellfishes included in

the assessment for each habitat type (Table 6.1-1).

6.3.1 Background on Oceanographic Setting and Population Trends

Water temperatures and current patterns have a significant effect on marine faunal composition.

Understanding the nature of the variability in these physical factors is essential for explaining long-term

population trends for many marine species. The Southern California Bight, defined as the nearshore

coastal area from Point Conception south into Baja California, is a transition zone between the cool

temperate Oregonian fauna, to the north and the warm temperate San Diegan fauna to the south. This

transition is caused by the geology and oceanic current structure of the region. The source of cold water is

the California Current, the eastern branch of the North Pacific Gyre. The strength of the California

Current varies on many time frames. On a multi-decadal scale it oscillates between a warm and cold

phase referred to as the Pacific Decadal Oscillation (PDO). During the warm phase the PDO is relatively

weaker than average, while during the cold phase it is stronger than average. This multi-decadal

oscillation has had a significant effect on the Southern California Bight (SCB) and the most pertinent

debate concerns when it will switch back to a cold phase (Bograd et al. 2000; Durazo et al. 2001; LluchBelda et al. 2001). During the cold phase, the bight is colder than average and dominated by the

Oregonian fauna. The opposite is the case for the warm phase; the bight is warmer than average and

dominated by the San Diegan fauna. There have been three transitions in the PDO over the last century.

The most recent oscillation of the PDO caused a regime shift starting in the late 1970s that was completed

by the end of the 19821984 El Niño, the largest El Niño recorded at that time (Stephens et al. 1984;

Holbrook et al. 1997).

The strength of the PDO varies annually and the most important phenomenon with respect to this

variation is the El Niño Southern Oscillation (ENSO). This oscillation consists of two components, El

Niño and La Niña periods. El Niño causes the California Current to weaken and move offshore as warm

subtropical water moves into the bight. The rebound from this event is the shift to La Niña, which in

effect is manifested as a strengthening of the California Current and generally cooler water in the bight.

Either phase of an ENSO generally lasts 12 years, depending upon their strength, and are particularly

important for understanding fish dynamics in the SCB for a variety of reasons. First, in the El Niño phase,

the bight is warmed and mobile warm-water fishes and invertebrates immigrate or recruit into the region

(Lea and Rosenblatt 2000; Pondella and Allen 2001). Cold water forms migrate out of the region, move

into deeper (cooler) water, or are extirpated. During the La Niña phase, the SCB usually, but not always,

is cooler than normal, and we observe an increase in cold temperate (Oregonian fauna) organisms through

the same processes. Highly mobile organisms will immigrate or emigrate from the bight during these

periods; and on smaller spatial scales less mobile organisms may exhibit offshore versus onshore

movements. However, the resident fauna tends not to be altered on such short time frames when

compared to the magnitude of the PDO.
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In the decade prior to this study there were three major events that affected the California Current System

that need to be explained in order to understand the oceanographic setting of this study period. The first

was the 199798 El Niño, the strongest recorded event of its kind (Figure 6.3-1). This was followed by a

series of four cold water years (19992002) including the strongest La Niña on record (Schwing et al.

2000, Goericke et al. 2005). The possible return to the cold water phase of the PDO did not occur since

20032004wasdescribedasa‘normal’year(Goerickeetal.2005).Thisnormalyearturned out to be the

beginning of an extended warm phase that has persisted through 2006 (Peterson et al. 2006). Thus, the

oceanographic context for this study can best be described as a warm phase of the PDO that has persisted

for three years. Prior to this warm phase were four unusually cool years.

Newport Pier Sea Surface Temperature

1970197119721973197419751976197719781979198019811982198319841985198619871988198919901991199219931994199519961997199819992000200120022003200420052006

T

e

m

p

erature

D

e

viatio

n (°C)

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5 El Niño

La Niña

Warm Phase

PDO Transition

Figure 6.3-1. Sea surface temperature anomalies for Newport Pier, California. Values are ± the longterm average (19252006).

To determine the current population status of fishes and invertebrates in the SCB requires placing this

data into an appropriate long-term context. From an oceanographic standpoint, the influences that were

associated with change over time are the PDO, the ENSO, and the associated ocean temperature changes.

These oceanographic metrics are interconnected with each other and have effects in the SCB on varying

time scales. In order to understand the responses of organisms in the SCB to these various environmental

metrics, it is important to realize the general trends for the region (Brooks et al. 2002) and that each taxon

may have a unique response to these metrics based upon its life history characteristics and evolution.

In addition to the real time responses these organisms have to oceanographic parameters, anthropogenic

influences also have significant effects. Currently, the most extensively studied anthropogenic effects are
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related to over-fishing and the various management actions associated with fishing. In the SCB, all of the

top-level predators (with the exception of marine mammals) were over-fished during the last seven

decades (Ripley 1946; Love et al. 1998; Allen et al., in press; Pondella and Allen, in review). The effects

of fisheries were also species specific, as the effort, type of fishery and associated management actions

vary by species. Some fishes were reserved for recreational anglers (e.g. kelp bass, barred sand bass, etc.)

as they were historically over-fished by commercial fishers (Young 1963); others were primarily

commercial species (e.g. anchovies); while others are extracted by both fisheries (e.g. California halibut).

Fishery data may or may not reflect actual population trends due to socioeconomic considerations such as

market value, effort, management actions, etc. Fishery independent monitoring programs produce the best

population time series metrics and also allow non-commercial species to be evaluated.

6.3.1.1 Habitat Associations and Fisheries

Entrained larvae were categorized in terms of the habitat types typically utilized by juveniles and adults,

and the type of fishery, if any, that the species supports. Most larval taxa were from species typically

found associated with the types of habitats in close proximity to the intake: bay, rocky reef, and shelf sand

bottom. Species primarily associated with the bays and harbors habitat (e.g., gobies, blennies) had the

highest number of taxa entrained and impinged (48.89% and 72.00% respectively; Table 6.3-1). Over

95% of the total number of larval fish entrained and impingement biomass was associated with the bays

and harbors habitat. Sport fishery species accounted for approximately 13.8% of the total number of

larvae entrained and commercial fishery species accounted for 14.8%, while species with no direct fishery

value comprised the majority (84.7%) of the larvae entrained. (Note that some species such as white

croaker were classified as both a sport and commercial fishery species). Approximately 96% of the

impinged biomass was from fishes and rays that have no direct fishery value.

Table 6.3-1. Percent of larvae entrained (abundance) or adults/juveniles impinged (biomass)

associated with general habitat types and fisheries.

Attributes

Entrained %

of taxa

Entrained %

of abundance

Impinged %

of taxa

Impinged %

of biomass

Habitat Association

Continental shelf / slope 35.56 13.95 32.00 1.79

Bays, Harbors 48.89 95.65 72.00 98.20

Rocky reef, Kelp 46.67 3.22 44.00 4.34

Coastal pelagic 20.00 17.86 16.00 0.04

Deep pelagic 4.44 0.02 0.00 0.00

Fishery

Sport 40.00 13.84 48.00 3.94

Commercial 26.67 14.76 12.00 2.32

None 51.11 84.65 48.00 96.06

Note: Percentages do not total 100% because species may have more than one associated habitat and fishery.

The percentages of taxa associated with different habitats are very similar for both entrainment and

impingement with the largest percentage of the taxa being associated with the bay and harbor habitat

where the intake is located (Table 6.3-1). The percentages for bay and harbor taxa increase for abundance

and biomass since these taxa were entrained and impinged in much higher numbers than taxa from other

habitats. As the percentages show, many of these are not targeted by sport or commercial fishing.
Harbor Generating Station

IM&E Final Report Impact Assessment

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Although fishes and shellfishes from other habitats occur in bay and harbors, the taxa with the greatest

potential for CWIS impacts will be the taxa that only occur in that habitat such as three taxa of gobies and

round stingray (Table 6.1-1).

6.3.2 Bay and Harbor Habitats

This habitat type includes bays, harbors and estuaries that are either entirely marine and largely

influenced by tidal movement of seawater, or estuarine areas where seasonal freshwater input lowers

salinities in some areas of the habitat. Much of the nearshore habitat in the vicinity of HGS is of the bay

and harbor type. Although no undisturbed wetland areas still exist within the highly developed Harbor

Complex, shallow water habitats have been created near Cabrillo Beach and Piers 300 and 400. There is a

small, natural wetlands area, Los Cerritos Wetland, inside the nearby Alamitos Bay, and extensive salt

marsh areas within Anaheim Bay, located approximately two kilometers downcoast of Alamitos Bay.

Characteristic fishes from these habitats in the Harbor Complex would include deepbody anchovy, bay

pipefish, bay blenny, round stingray, and diamond turbot (Allen and Pondella 2006a). Approximately

two-thirds of the fish species and almost all of the entrained fish larvae collected during the IM&E

sampling had some dependency on bay and harbor habitats during at least some stage of their life, and it

is considered the primary habitat for seven fish taxa included in this assessment: CIQ gobies, combtooth

blennies, shiner perch, yellowfin goby, bay goby, round stingray, and specklefin midshipman (Table 6.1-

1). While CIQ gobies yellowfin goby, and bay goby occur almost exclusively in these habitats, two

species of combtooth blennies, the rockpool blenny (Hypsoblennius gilberti) and mussel blenny

(Hypsoblennius jenkinsi), also inhabit shallow intertidal and subtidal rocky reef habitats, and specklefin

midshipman, round stingray, and shiner perch also occur on the outer coast.

Annual entrainment of CIQ goby larvae was estimated to be 33.3 million larvae based on actual flow

volumes and 75.9 million larvae based on design flow volumes (Tables 6.2-4 and 6.2-5). No goby eggs

were entrained because eggs are attached in burrows and are not vulnerable to entrainment until they

hatch as larvae. The entrainment and source water data on larval concentrations were used to estimate that

approximately 3% of the larval CIQ goby population in the Harbor Complex source waters were

potentially lost due to entrainment based on actual flows (Table 6.2-4). Based on the design flows, this

estimate increases to about 6% (Table 6.2-5). The entrainment losses were also used to estimate that the

annual larvae entrained would have resulted in the production of 36,231 and 86,720 adult CIQ gobies

based on actual and design flow volumes, repectively. Two other species of gobies, the yellowfin and the

bay goby were common in the entrainment samples in 2006. The estimated annual larval entrainment at

HGS was 15.4 million and 37.6 million yellowfin goby based on actual and design flows, respectively

(Tables 6.2-4 and 6.2-5). These numbers were used to estimate that 1,936 and 4,724 adult equivalent

yellowfin gobies would be lost due to entrainment at HGS based on actual and design flows, respectively.

The estimated annual larval entrainment at HGS in 2006 was 2.4 million and 5.1 million bay gobies, with

an estimated 0.24% and 0.50% of the larval bay goby population potentially lost due to entrainment in

2006. Gobies were not common in impingement sampling because they generally occur on the bottom

and not in the water column where they would be subject to impingement. The estimated annual

impingement at HGS in 2006 was 163 and 399 yellowfin gobies based on actual and design flows,

respectively (Table 5.5-2). No CIQ gobies were collected in the impingement sampling at HGS.
Harbor Generating Station

IM&E Final Report Impact Assessment

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Annual entrainment of combtooth blenny larvae was estimated at 2.3 million based on actual flows and

4.4 million based on design flows. Using the actual flows, the estimated adult equivalents lost due to

entrainment at HGS was 2,826 and 6,024 adult equivalents based on the FH and AEL model results,

respectively, and approximately 0.06% of the larval blenny populations were lost due to entrainment.

Using the design flow volumes, an estimated 5,466 and 11,650 adult equivalents were lost due to

entrainment, and approximately 0.12% of the larval populations were lost due to the CWIS at HGS.

Combtooth blennies are similar to gobies in that they have adhesive demersal eggs that are not vulnerable

to entrainment. No combtooth blennies were impinged at HGS in 2006. Blennies, especially mussel

blennies, utilize submerged artificial substrates (pier pilings, dock floats, breakwater material) and their

associated fouling communities for shelter and spawning habitat. The extensive development within the

Harbor Complex in support of shipping (piers, pilings, etc.) provides abundant habitat for a large

population of blennies and this explains why their larvae were entrained in relatively large numbers. Most

blenny larvae that were captured were recently hatched, based on size frequency distributions, and

reached peak concentrations during summer months.

Round stingray was the most abundantly impinged species with an estimated 6,150 individuals weighing

1,232 kg (2,716 lbs) based on actual flows and 13,771 individuals weighing 2,756 kg (6,076 lbs) based on

design flows. Impingement occurred primarily from August through December. There was no

entrainment mortality because stingrays give birth to live young and individuals measure about 100 mm

(3.9 in) in length at birth. Round stingrays are very common in bays and harbors throughout southern

California and there is no directed fishery for the species, only incidental take while fishers target other

bottom fishes. Most of the impinged rays were juveniles. Because round stingrays are so common in

shallow, soft bottom habitats, it is unlikely that the numbers impinged at HGS have any adverse impact

on the population.

Two additional bay and harbor species that were commonly collected in the impingement sampling, but

were absent in entrainment sampling, included specklefin midshipman (no larvae entrained) and shiner

perch (not susceptible to entrainment). Estimated annual impingement of specklefin midshipman was 484

and 1,379 individuals, based on actual and design flow, respectively. Biomass of specklefin midshipman

was 11.955 kg (26.36 lbs) and 26.841 kg (59.18 lbs), based on actual or design flow, respectively. Shiner

perch was also relatively abundant in the impingement sampling, with 390 and 719 individuals impinged

using actual and design flows, respectively. While round stingray has been infrequently captured during

regular NPDES otter trawl surveys within the Harbor Complex, specklefin midshipman and shiner perch

frequently appear during the surveys (MBC 2007a, b). Both specklefin midshipman and shiner perch have

shown recent increases in population levels based on these otter trawl sampling programs.

Bay and harbor species clearly have the highest risk of AEI of all habitat groups represented in the HGS

IM&E sampling. Most of these organisms are affected through entrainment since the juveniles and adults

of species such as gobies and blennies occupy benthic habitats within the bay where they are less

susceptible to the effects of impingement. However, there is uncertainty regarding the magnitude of the

impacts in relation to environmental variables and other stressors that can cause population changes. The

earlier 316(b) study in 197879 documented average entrainment densities of goby larvae at 4,705 per

1,000 m

3

, but in 2006 the average densities were only 516 per 1,000 m

3

. Combtooth blenny densities, on
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IM&E Final Report Impact Assessment

6-22

the other hand, were comparatively stable ranging from 3050 per 1,000 m

3

between the two study

periods. In the case of gobies and blennies, habitat loss could reduce the reproductive output of the

population by increasing the density dependent competition for viable substrate to attach their demersal

eggs (Cowan and Shaw 2002). There are no long-term historical data available on blenny and goby

populations within the Harbor Complex, although the higher larval density of gobies from the earlier

study suggests a substantially greater spawning biomass in the late 1970s as compared to 2006.

Harbor construction projects, effects of pollution and continued loss of remaining wetland habitats in the

vicinity have contributed to changes in the available habitat and water quality and undoubtedly has led to

changes in the composition of the biological communities, including the possible decline in larval

abundances. Stephens et al. (1994) and Stephens et al. (2006) noted a substantial decline in fish

populations in King Harbor, Redondo Beach, California in association with the destruction and

subsequent rebuilding of the breakwall, activities which included dredging the harbor. Although these

authors concentrated on the impact to reef associated species, even greater impacts may occur to demersal

soft-bottom species since they are directly affected by loss of habitat and mortality due to dredging and

other activities associated with harbor expansion. Overall trends in trawl data from the Harbor Complex

indicate a decline in total demersal fish abundance in 2000 near the HGS (Figure 6.3-2), coinciding with

major dredging activities in 1994 and 2000. These data show abundances near HGS declined sharply after

1994 and remained low through 2004. In sampling near the Long Beach Generating Station, abundances

declined after 1992, rebounded slightly in 1999 and 2000 before declining again and remaining low

through 2003. The timing of actual dredging has varied throughout the Harbor Complex, indicating these

patterns may, in fact, be coincidental at best. Insufficient data exist to conclusively evaluate the role

dredging played in harbor-wide fish population trends. Abundance of fishes at both locations in 2005 and

2006 was similar to or greater than that measured at the onset of monitoring in 1980 (Figure 6.3-2).

The small fraction of the source larval production cropped by power plant entrainment (fractional losses

below 3% for gobies) would not be expected to have any substantial effect on a population that is not

targeted by any fishery take (Newbold and Iovanna 2007). The bay habitat continues to sustain a thriving

population of gobies and blennies, as evidenced by their abundant larval concentrations. In a constructed

harbor configuration such as the ILAH where HGS is located that is significantly affected by tidal

exchange, many of the larvae are also inevitably lost to the system due to export by outgoing tidal

currents, despite behavioral adaptations that cause larvae to migrate toward the bottom or move to areas

with less current and minimize export (Barlow 1963; Pearcy and Myers 1974; Brothers 1975). Larvae that

are transported into coastal waters can provide genetic exchange between estuarine areas along the coast

by moving back into bays with incoming tidal currents (Dawson et al. 2002), but most of these exported

larvae experience much higher mortality rates in the open ocean and deeper outer harbor areas than those

that are retained in the ILAH.
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IM&E Final Report Impact Assessment

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0

20

40

60

80

100

120

140

160

180

200

1980 1985 1990 1995 2000 2005

Year

H

G

S

# per total minute fished

0

20

40

60

80

100

120

140

160

LB

G

S

# per total minute fishe

HGS d

LBGS

Figure 6.3-2. Abundance per minute fished for fish collected in HGS and LBGS NPDES monitoring

otter trawl surveys, 1980-2006. Northern anchovy was excluded from this analysis.

Demographic-based estimates of projected losses assume that there is available habitat to support the

additional production in the source water area, which is not usually the case in the example of substrateoriented or territorial taxa like gobies. In contrast, species that live in open water environments, such as

white croaker, are generally not limited by habitat availability but by other factors such as food

availability, oceanographic conditions, or predation. , Density–dependent mortality may be a substantial

factor affecting post-settlement recruits where there is a limited amount of benthic habitat (Brothers 1975;

Steele and Forrester 2005), as in the Harbor Complex. Therefore, projections of adult equivalents based

on larval entrainment likely overestimate actual adult losses. For example, much higher levels of

entrainment mortality were estimated for the South Bay Power Plant in south San Diego Bay (Tenera

Environmental 2004). It was estimated that the South Bay Power Plant entrained 2227% of the CIQ

gobies from the available source water population. However. data from a previous entrainment study and

long-term data on adults indicated that the population in south San Diego Bay was stable and not affected

by the additional larval mortality due to entrainment. Situations such as this further illustrate the

complexity in estimating the overall impact to habitat-reliant species through demographic modeling. In

K-strategy species (e.g., gobies that invest significant energy into maintaining territories and guarding

nests), density-dependent forces can act upon the adult spawning population to limit the overall larval

production (Cowan and Shaw 2002; Fuiman 2002). This, in itself, may artificially suggest reduced

population abundances, while in fact, the habitat may be at or near its carrying capacity for the species in

question, as may have occurred in the south San Diego Bay goby populations. Furthermore, the effect of

unmeasured compensatory mechanisms naturally acting upon these early life stages help to regulate

recruitment and population levels (Houde 2002). Unfortunately, complementary data on adult abundances

in the HGS source waters are not available.
Harbor Generating Station

IM&E Final Report Impact Assessment

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In terms of potential economic losses resulting from IM&E of bay and harbor associated species, there are

no direct impacts because they have no fishery value, except for the occasional use of larger specimens as

fishing bait or incidental sport catches. Larval reductions could have some effect on the trophic structure

of the source water through the loss of available forage for predators. However, any potential effects

would not be directly measurable due to the high natural variation in the system and the unknown

compensatory response of other species present in the bay and nearshore environment.

6.3.3 Rocky Reef and Kelp Bed Habitats

Physical structure and food resources are essential factors in promoting fish abundance and diversity.

Shallow rocky reefs and the giant kelp (Macrocystis spp.) forests often associated with them provide both

factors. Much of the shoreline of the Los Angeles-Long Beach Harbor Complex consists of hard intertidal

and subtidal substrates, such as concrete bulkheads and piers, and there is a limited attachment area for

macrophytes such as giant kelp. Some of the common species in typical kelp bed habitats include kelp

bass, black perch, opaleye, halfmoon, California sheephead, señorita, garibaldi, salema and zebraperch

(Stephens et al. 2006). Although the presence and extent of giant kelp affects the abundance of some reef

fishes, many other factors can also affect their distributions, and it is not unusual to find many of the

species characteristic of kelp bed habitats in other shallow water locations. Common species of fishes and

target invertebrates that are typically associated with rocky reef habitats that were impinged at HGS

included the black perch, giant kelpfish, barred sand bass, octopus, and California spiny lobster (Table

6.1-1). Of these, only sand bass and California spiny lobster were entrained. Impacts to representative

species from this habitat are briefly discussed.

Black perch was the second most abundant species impinged with an estimated 646 individuals calculated

using actual cooling water flow volumes, or 7.3% of the annual total, weighing 18.49 kg (40.76 lbs). Like

all species of surfperch, black perch are viviparous, producing free-swimming, fully developed young and

are therefore not susceptible to entrainment. The majority of impinged individuals were in the 50 to 70

mm (2.02.8 in) size classes, which indicates that they were less than one year of age. The low levels of

impingement would not be expected to have any adverse impacts on the populations of black perch which

is much more abundant in other habitats outside the ILAH where they are not subject to the effects of the

HGS CWIS.

An estimated 120,000 sand bass larvae (Paralabrax spp.) were entrained at HGS in 2006 based on actual

flows, although they were not identified to species and may have been a mix of kelp bass, spotted sand

bass and barred sand bass. An estimated 0.12% and 0.27% of the sea bass population in the HGS source

water was lost due to entrainment at HGS, based on the actual and design flow entrainment estimates,

respectively. No sand bass eggs were collected during the entrainment sampling perhaps indicating that

the HGS intake is not near any areas were these fishes are spawning. The larvae may be transported into

the ILAH where they are subject to entrainment. The total annual fecundity for this group, which can be

as high as 4.1 million eggs depending on the species (Cailliet et al. 2000), indicates a low potential for

adverse impacts to the population due to entrainment. Barred sand bass were the 5th most abundant

species impinged at HGS in 2006 with an estimated 209 individuals weighing 7.5 kg (16.5 lbs), based on

actual flows. The majority of individuals were 70100 mm (2.8 to 3.9 in) in length, indicating a

principally juvenile assemblage, or approximately one-year old based on Love et al. (1996). Since 2000
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IM&E Final Report Impact Assessment

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the recreational fishery for barred sand bass in southern California has averaged 720,000 fish exceeding

the minimum size limit of 30.5 cm (12 in). The low levels of impingement would not be expected to have

any adverse impacts on the populations of sand basses which are much more abundant in other habitats

outside the ILAH where they are not subject to the effects of the HGS CWIS.

Giant kelpfish was one of the impinged species that is usually associated with rocky reef habitat that also

contains kelp or other macrophytes, although it may also occur in seagrass beds over soft substrates. It

was the sixth most abundant species impinged with an estimated 192 individuals calculated using actual

cooling water flow volumes, or 2.2% of the annual total, weighing 15.7 kg (34.7 lbs). Peak abundance

was recorded in the 190 mm SL (7.5 in) size class, representing individuals approximately one-year old.

The absence of larvae in the samples indicated that the few impinged individuals probably migrated from

elsewhere in the Harbor complex and were spawned in areas outside of the intake vicinity.

California spiny lobster was one of the target shellfish larvae selected for analysis because of its

importance in commercial and sport fisheries in southern California, and the fact that it is a common

macroinvertebrate in the rocky reef and kelp bed habitats. Estimated annual entrainment based on actual

flows and design flows was 220,000 and 360,000 phyllosome larvae, respectively. However, it comprised

such a small fraction of the entrained larvae that no demographic or ETM modeling was performed.

California spiny lobster was the second most abundant shellfish species impinged with an estimated 717

individuals weighing 169 kg (373 lbs) based on actual flows and 1,544 individuals weighing 370 kg (816

lbs) based on design flows (Tables 6.2-4 and 6.2-5). The mean carapace length of 105 impinged lobsters

was 62 mm (2.4 in), which is smaller than the legal minimum fishery size limit of 83 mm (3.25 in). In

2005, combined commercial landings of spiny lobster in the Los AngelesLong Beach areas totaled

101,324 kg (223,420 lbs) at a value of $1,771,864 while landings from CDFG catch blocks in the

immediate vicinity of the Harbor Complex in 2006 totaled 21,875 kg (48,225 lbs) at an estimated value of

$448,844 (CDFG 2007). The estimate of impinged biomass based on actual flows represents

approximately 0.8 percent of the 2006 landings from the local catch blocks with a value of $3,500.

The intake structure at HGS is located in a primarily mud bottom habitat with constructed hard substrate

material around the perimeter of the basin. Species associated with rocky reef and kelp habitats can

migrate between areas and occasionally find suitable habitat in bays and harbors due to the presence of

algae and eelgrass, rock jetties, and other structures that provide shelter, especially for juveniles that may

recruit into these habitats after being transported into the Harbor Complex as larvae. While some

individuals may recruit and grow within small habitat patches it is more likely that most adults take up

temporary residence when they encounter such habitat patches during their movements. Taxa such as

barred sand bass, California spiny lobster, and others that occur across a number of habitats will be less

susceptible to CWIS impacts than species with more specific associations with habitats directly affected

by the CWIS. Fishes identified with the rocky reef and kelp bed habitats are not at risk of AEI from

entrainment or impingement at HGS.
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6.3.4 Coastal Pelagic Habitats

Two species entrained and impinged at HGS, northern anchovy and white croaker, are characteristic of

the coastal pelagic zone (Table 6.1-1). Both species can be considered habitat generalists because they are

also found in bays and a variety of other shallow water locations (Allen and Pondella 2006a). Juveniles

tend to be more abundant in the shallower depths of the habitat range.

The estimated annual loss of northern anchovy due to operation of the HGS CWIS included 0.9 million

larvae based on actual flow volumes, and 2.1 million based on design flow volumes (Tables 6.2-4 and

6.2-5). An estimated 0.8 million eggs were entrained using the actual flow volumes, or 1.9 million based

on the design flow volumes. These estimates were used to calculate the estimated losses of age one

equivalents, the age at which 50 percent of the adults are mature, was 11,506 and 25,863 adult equivalent

using actual flows and 25,306 and 56,879 adult equivalents using design flows based on the FH and AEL

model results, respectively. Annual impingement of northern anchovy was negligible. They are

considered an important part of the marine food webs in California because of their use as a forage

species by numerous species of fishes, birds, and marine mammals.

The evidence suggests that large-scale oceanographic phenomena, and not localized perturbations such as

intake effects, are responsible for the population-wide changes seen in anchovies. Northern anchovy is

one of two indicator organisms for the PDO in the California Current System, (Chavez et al. 2003; Norton

and Mason 2005; Horn and Stephens 2006). Northern anchovy dominates during the cold water phase and

Pacific sardine during the warm water phase. Scale deposition of these two species in the anoxic Santa

Barbara basin is one tool used for reconstructing the phases of the PDO over the past 2,000 years

(Baumgartner et al. 1992; Finney et al. 2002). The commercial catch of northern anchovy follows this

pattern and by 1983 the catch of northern anchovy had basically disappeared in California (Mason 2004).

The faunal switch associated with the PDO at the end of the 1970s was really completed in the Southern

California Bight with the 19821984 El Niño (Stephens et al. 1984; Holbrook et al. 1997), the largest El

Niño recorded at that time. During the strong La Niña years (19992002) there was resurgence in catch of

this stock. However, a return in catch of northern anchovy and a corresponding stock increase in Southern

California will undoubtedly be delayed until the next cold phase of the PDO.

The difference in source water concentrations of northern anchovy between the 19781979 (IRC 1981)

and the 2006 studies probably reflects changes in the oceanographic environment. Concentrations

dropped from approximately 256 per 1,000 m3in the earlier study to only 14 per 1,000 m3in the 2006

study (0.5% of earlier concentrations), and the estimated annual entrainment dropped from 100 million to

approximately 2 million eggs and larvae combined in the 2006 study. This reduction is similar to the large

decrease in the landings from Los Angeles area ports over the same period which were 38,383,362 kg

(84,620,828 lbs) in 1981 (data before 1981 was not available from PacFIN) and averaged only 1,351,669

kg (2,979,921 lbs) from 20002006 (Table 4.5-7), or 2% of the 1981 landings. The total estimated losses

from entrainment in the 2006 study were extrapolated using the FH model results to 11,506 and 25,306

fishes at the age of 50% maturity based on actual and design flows, respectively. The length at that age,

95 mm (3.7 in), was used to predict a weight of 5.0 g (0.18 oz) using a best fit model

(Weight=0.0005e

0.0242*Length) derived from length and weight data for the northern anchovy collected from

the impingement samples. The total predicted weight of the CWIS losses amounted to approximately

0.01% of the average landings at Los Angeles area ports from 20002006 (Table 4.5-7), with a total value
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IM&E Final Report Impact Assessment

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of $6 to $12. These values do not represent AEI to northern anchovy, especially since this species has a

broad distribution extending well beyond the SCB.

White croaker is a common member of the croaker family that is found in the Harbor Complex and also

in the nearshore sand bottom habitats as a bottom-associated species. White croaker was the third most

abundant larvae entrained with 7.2 to 18.8 million larvae entrained based on actual and design flows,

respectively. An estimated 17.9 to 43.1 million white croaker eggs were also entrained at HGS in 2006.

An estimated 25 to 48 individuals weighing 0.20 to 0.43 kg (0.40-0.95 lbs) were impinged in 2006 based

on actual and design flows, respectively. Using the egg entrainment data, an estimated 20 to 48 adult

equivalents were lost due to entrainment at HGS (Tables 6.2-4 and 6.2-5). Proportional mortality due to

entrainment to the HGS source water population of larvae was less than 1% using either actual or design

flows in the calculations.

Recreational and commercial catch data for white croaker indicating a declining fishery were not

consistent with the fishery independent data. Recreational and commercial catches both declined from

1980-2006 (Figure 6.3-3a). Overall, the declines in white croaker recreational and commercial catch,

especially in the late 1990s, show the same patterns from impingement data at southern California plants

described by Herbinson et al. (2001). The impingement of white croaker at the Huntington Beach

Generating Station (HBGS) just south of Alamitos Bay shows low impingement throughout the 1990s

(Figure 6.3-3b). The impingement of white croaker in 2005 was similar to levels recorded during the early

1980s. Based on the analysis of long-term patterns of change in croakers relative to ocean warming events

by Herbinson et al. (2001), the increase in white croaker may be in response to the prolonged cooler water

temperatures that have persisted in the southern portion of the California current since 1999 (Peterson et

al. 2006). In contrast to the fishery and impingement data, trawls collected as part of NPDES monitoring

programs for the Huntington Beach Generating Station (HBGS) and the Haynes, Harbor, and Alamitos

Generating Stations show fluctuations in abundance without any clear trends (Figure 6.3-3c). The Harbor

trawls are collected in the ILAH, while the Haynes and Alamitos trawls are collected just outside

Alamitos Bay, and show an increasing trend from 2003-2005. This increase is consistent with recent

impingement data from HBGS that also show an increase over the same period.

The results from both the fishery and fishery-independent studies (Figure 6.3-3) indicate higher numbers

of adult white croaker in the period when the previous 316(b) study was conducted (IRC 1981). The

potentially larger population of spawning adults in the outer harbor area may explain why the

concentrations from that study were much higher at the near-field and far-field stations.

In summary, the coastal pelagic habitat is extensive within the southern California bight, and most of the

common fish species that are part of this assemblage are wide-ranging. Most have a directed commercial

or sport fishery and their populations are generally sensitive to large-scale oceanographic influences.

Since the HGS is located in the Harbor Complex, it does not affect this habitat directly and given the wide

distributions of most of the component species, including distributions in other habitats where they are

not as susceptible to CWIS effects, there is very low potential for any adverse impacts to these

populations.
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IM&E Final Report Impact Assessment

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a) Recreational and Commercial Catch

0

500

1000

1500

2000

2500

3000

1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006

Year

R

ecreational Catch

(1000s of Fish)

0

100

200

300

400

500

600

700

800

900

C

o

m

m

ercial Catch

(1000s of lbs.)

Recreational

Commercial

b) HBGS Impingement

0

500

1,000

1,500

2,000

2,500

1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

Year

Impingement (kg)

c) Huntington Beach and LA Harbor-Alamitos Trawls

0

10

20

30

40

50

60

70

80

1978 1982 1986 1990 1994 1998 2002 2006

Year

Fish per Trawl Minute

Harbor-Alamitos

Huntington Beach

Figure 6.3-3. White croaker fishery and population trends

a) Recreational and commercial landings for Los Angeles area ports from RecFIN and PacFIN

databases; b) Huntington Beach Generating Station (HBGS) impingement average annual biomass; and

c) NPDES trawl data with average number of fish per trawl minute for HBGS and Harbor, Haynes and

Alamitos Generating Stations, collected off Huntington Beach and inside the Los Angeles-Long Beach

Harbor breakwaters, respectively.
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IM&E Final Report Impact Assessment

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6.3.5 Shelf Habitats

Shelf habitats include several different habitats from Allen and Pondella (2006b) including inner, middle,

and outer shelf, and shallow slope habitats. The abundance, biomass, and other population attributes of

the fish assemblages in these habitats increase from the inner to outer shelf (Allen 2006). This gradient is

attributed to the increased variability in ocean conditions on the inner shelf due to runoff and pollution

among other factors. A variety of flatfishes and other species dominate the fish assemblages on the soft

mud and sandy bottoms in these habitats. Fishes characteristic of the inner and middle shelf include

California halibut, bay goby, California tonguefish, bigmouth sole, hornyhead turbot, and California skate

(Allen and Pondella 2006b). Fishes characteristic of the outer shelf and slope include plainfin

midshipman, Pacific sanddab, pink seaperch, curlfin turbot, Dover sole, longspine thornyhead, and

California rattail (Allen and Pondella 2006b).

While species from this habitat comprised 16 out of 45 (36%) species collected in the entrainment

samples and 8 out of 25 (32%) species collected in the impingement samples, none was selected for the

assessment because their overall abundances were low (<14% of total larvae and <2% impinged

biomass). Entrainment was very low for shelf species since the larvae would have to be transported from

offshore areas into the Harbor Complex. Although this did occur for several species, the total numbers of

shelf species entrained was very low relative to all of the other habitat assemblages that occur in closer

proximity to the Harbor Complex (Table 6.3-1). Due to the location of the HGS intake the percentage of

the total impingement biomass for the fishes from this habitat was much lower than the percentage for

entrainment. As a result none of the species included in the assessment were primarily associated with

this habitat type. Due to the low numbers fishes associated with shelf habitats that were entrained or

impinged, there is very little risk of any adverse impacts to fish species from this habitat type.

6.3.6 Deep Pelagic Habitats

Deep pelagic habitats include several different habitats described by Allen and Pondella (2006b)

including deep slope, deep bank, and deep rocky reef habitats. This category also includes open ocean

pelagic habitats. Some of these habitats are extremely productive and the fishes inhabiting these areas are

the basis of large commercial fisheries. The fisheries in the areas outside the three-mile limit of California

state waters are federally managed by the PFMC. Fishes characteristic of the deep shelf, bank and slope

habitats include Pacific hake, splitnose rockfish, rex sole, sablefish, blackgill rockfish, and shortspine

thornyhead. Several different species of rockfishes dominate the fish assemblages on the deep reef, shelf

and canyon habitats including bocaccio, chilipepper, and greenspotted, greenstripe, rosethorn, and

pinkrose rockfishes. Fishes characteristic of open ocean pelagic habitats include swordfish, striped marlin,

several species of shark, albacore, and bluefin, bigeye, and yellowfin tunas. Although the fishes

characteristic of these habitats occasionally occur closer to shore their primary habitats are offshore in

open water or at deep ocean depths. Only two larval fishes associated with the deep pelagic habitat

(Bathymasteridae, 0.01%; Bathylagidae, 0.01%) were collected in this study, and no species from this

habitat were collected in impingement sampling; therefore, there is a very low probability that CWIS

impacts from HGS would affect species from this habitat type.
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6.4 CONCLUSIONS AND DISCUSSION

Impacts to SCB fish and invertebrate populations caused by the entrainment of planktonic larvae through

the HGS CWIS can only be assessed indirectly through modeling. The estimates from these models can

be added to impingement losses of juveniles and adults to estimate the total losses due to the HGS CWIS.

Three taxa (CIQ goby complex, yellowfin goby, and white croaker) comprised 86% of all entrained fish

larvae. Of the ten most abundant fish species entrained at HGS, only two (white croaker and anchovies)

have any direct commercial or recreational fishery value. All of the abundantly entrained species can be

considered forage species for larger predatory fishes, sea birds, or marine mammals. Approximately half

of the 48 different fish taxa entrained and the 25 taxa impinged belonged to species with some direct

fishery value (e.g., anchovies, silversides, croakers, sea basses, California halibut) even though most of

those (except white croaker and anchovies) were collected in very low abundance (less than 1% of the

total abundance or biomass [Tables 5.4-1 and 5.5-1]) in the samples and, as a result, were not assessed for

potential impacts. Only 15% and 4% of the total entrainment abundance and impingement biomass,

respectively, were from fishes and rays that have some direct fishery value.

The ETM procedure estimates the annual probability of mortality due to entrainment (PM). It puts the

entrainment estimate into context by comparing it with a known source population at risk of entrainment.

The greatest PM estimate was for the CIQ goby complex with a predicted fractional larval loss of 2.65%.

The next greatest probabilities of mortality were for northern anchovy (0.71%) and yellowfin goby

(0.65%). The spatial extent of the habitats potentially affected by entrainment is directly proportional to

the estimate of time that the larvae are exposed to entrainment. The two goby groups had local

populations primarily located in the habitats of the Harbor Complex, while the anchovies are widely

distributed and probably originated from eggs spawned in the outer harbor area or in nearshore areas of

San Pedro Bay. Most larvae were entrained at sizes that indicated they were recently hatched. The

modeled species with primarily nearshore (non-bay) distributions included white croaker and northern

anchovy, and these had PM estimates well below 1%. These levels of additional mortality would be

considered low, especially when the populations of these species extend over a much larger geographic

range than the extrapolated source water bodies. No invertebrate taxa were modeled for entrainment

impacts due to the low abundance of the target taxa (e.g., spiny lobsters, Cancer crabs).

Changes in total impingement and entrainment through time were affected not only by natural changes in

biological and oceanographic factors but also by changes in cooling water flow. Compared to the IM&E

study conducted at HGS in 19781979 (IRC 1981), concentrations of northern anchovy, unidentified

gobies, and queenfish larvae were an order of magnitude less abundant in 2006 than in 1978-1979 while

combtooth blennies and white croaker were approximately the same (Table 6.4-1). Anchovy larvae in

particular were significantly more abundant in the earlier study, due in part to the cooler water climatic

regime in the SCB that favored anchovy populations at that time. The most abundantly impinged species

in 19781979 were Pacific pompano (Peprilus simillimus), white croaker, and queenfish, which

combined accounted for 76% of the total impingement abundance. In the 2006 samples, the most

abundant species were round stingray, black perch and specklefin midshipman with round stingray

accounting for 75% of all impinged fishes. Annual fish impingement (normal operations and heat

treatments) was 2,827 kg (6,232 lbs) in 19781979 compared to 1,317 kg (2,903 lbs) in 2006. In the

1978-79 study HGS was operating Units 15 with a combined flow of 86,652 MG (62% of maximum
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design flows), whereas in 2006 only Unit 5 was operational with an annual flow of 17,885 MG (51% of

maximum design flows) resulting in an 80% reduction in flows between studies.

Declines of numerous juvenile/adult fish stocks have been documented in southern California since the

1970s. Holbrook et al. (1997) estimated a 69% decrease in populations of 75 fish species at King Harbor

and off Palos Verdes, California, between 1975 and 1993. Brooks et al. (2002) examined impingement

data from four coastal generating stations in southern California, and determined that the abundance of 37

fish species declined an average of 41% from 1978 to 1992 which they attributed to a regional decline in

productivity. From 1951 through the mid-1990s, macrozooplankton biomass in waters off southern

California decreased by 80%, coinciding with a temperature increase in the oceanic surface layer

(Roemmich and McGowan 1995). A combination of these natural temperature increases, reduced nutrient

supplies, and changes in ocean circulation resulted in overall declines of phytoplankton and zooplankton

in the southern California bight. Most of the fish species analyzed in the present study feed on

zooplankton with the decrease possibly affecting overall fish abundance.

Shifts in species composition over the long term can also be attributed, in part, to regime shifts. For

example, Hsieh et al. (2005) examined long-term larval abundance off southern California and its

relationship with several factors. The Pacific Decadal Oscillation (PDO) is a pattern of Pacific climate

variability that affects ocean surface temperatures, shifting phases on a 20-30 year time scale. When

abundances between the cold period (1951-1976) and the warm period (1977-1998) of the PDO were

compared, larval densities of Pacific sardine and Pacific chub mackerel increased significantly, while

densities of northern anchovy larvae decreased slightly. Sand bass larvae increased significantly, and

were positively correlated with shifts in the PDO. Allen et al. (2004) found a significant positive

correlation in the abundance of several species, including spotted kelpfish, and shifts in the PDO. Other

fish species, including combtooth blennies, northern anchovy, and deepbody anchovy, correlated

negatively with the PDO.

Table 6.4-1. Comparison of larval fish densities and total annual entrainment at HGS from studies in

19781979 and studies in 2006.

Mean Average Annual

Density (#/1,000 m3)

Actual Annual

Entrainment

(millions)

Species Common Name 197879 2006 197879 2006

Larval Fishes

Engraulidae anchovies 265 14 100 1

Gobiidae gobies 4,705 516 520 33

Hypsoblennius spp. combtooth blennies 50 30 19 2

Genyonemus lineatus white croaker 135 125 52 7

Seriphus politus queenfish 15 1 a <0.1

Pleuronichthys guttulatus diamond turbot 1 <1 a <0.1

Fish Eggs

Engraulis mordax northern anchovy <1 13b a <1b

Anchoa spp. bay anchovies <10 

b a b

Sciaenid complex croakers 1,075 284 390 14

a Annual estimate not calculated due to low densities of larvae or eggs.

bCombined into Engraulidae and includes both northern anchovy and bay anchovies.
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6.4.1 IM&E Losses Relative to 1977 EPA AEI Criteria

EPA (1977) providedsomegeneralguidelinestodeterminethe“relativebiologicalvalueofthesource

waterbodyzoneofinfluenceforselectedspeciesandthepotentialfordamagebytheintakestructure”

based on the following considerations of the value of a given area to a particular species:

 principal spawning (breeding) ground;

 nursery or feeding areas;

 migratory pathways;

 numbers of individuals present; and

 other functions critical during the life history.

Fishes in the vicinity of the HGS intake structure are characteristic to some extent of the fish assemblages

found in other bays and harbors in southern California, although the unique position of HGS in the back

reaches of the Harbor Complex affect the assemblage structure. The structural complexity of the Harbor

Complex contributes to the habitat value of the area as a spawning and nursery ground for several species

even though it is a highly modified, dredged embayment that was once part of a natural wetland system.

However, the results indicate that there was a limited diversity of species in the samples compared to

other bay/estuary areas in southern California. Two taxa (CIQ goby complex and yellowfin goby)

comprised 75% of all entrained larvae, and both use embayments as their primary habitat. Yellowfin goby

is an introduced species that may be out-competing native goby species, while CIQ gobies are abundant

in quiet-water areas with soft substrates where they inhabit burrows and lay their eggs. Because these

species have short life spans and their populations are likely limited by the availability of adult habitat,

the additional mortality due to entrainment would not be expected to substantially affect their local

populations. There was no evidence of population declines in gobies at the South Bay Power Plant in

south San Diego Bay (Tenera Environmental 2004) where entrainment mortality levels were substantially

higher. For the abundantly impinged species, size-frequency distributions indicated that most of the round

stingrays and black perch were small, young-of-the-year fishes. Both of these fishes are not susceptible to

entrainment impacts.

The issue in the EPA guidelines of fish migratory pathways relative to intake location primarily concerns

anadromous fishes and situations where power plant intake locations are on or near rivers that may

function as narrow migratory corridors for certain species. Because the HGS intake is not located in such

a corridor, this issue is not of concern for any of the species that were impinged.

The other points of concern relative to intake location and fish distribution are numbers of individuals

present and other functions critical during the life history (i.e., high concentrations of individuals present

in the area for reasons other than spawning, recruitment or migration). This may include a circumstance

where, for example, prevailing currents or the proximity to certain bathymetric features attracts prey items

for a predatory species and thus results in high concentrations of a species that may subsequently be at

risk of impingement. None of the data collected during this study suggests that there are any species that

are especially vulnerable to impingement or entrainment due to their behavior at any stage in their life
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history. This includes all common species as well as any special status species designated for protection

under state or federal statutes.

No federal/state threatened or endangered fish/shellfish species were identified in entrainment and

impingement samples collected from HGS. This is consistent with past entrainment and impingement

sampling conducted at HGS. Off southern California, species managed under the Magnuson-Stevens

Fishery Conservation and Management Act are listed in the Coastal Pelagic Fishery Management Plan

(FMP) and the Pacific Groundfish FMP. EFH includes all waters off southern California offshore to the

Exclusive Economic Zone. Five species covered under the two FMPs that occurred in entrainment and/or

impingement samples at the HGS are shown in Table 6.4-2.

Table 6.4-2. Fish and shellfish species under NMFS federal management or with CDFG special status

entrained and/or impinged at HGS in 2006 based on actual flow volumes.

Species Common Name

Management

Group

Estimated No.

Larvae (based on

Entrainment

Samples)

Juveniles/Adults

(based on

Impingement

Samples)*

Citharichthys sordidus Pacific sanddab Pacific Groundfish 13,740 –

Engraulis mordax northern anchovy Coastal Pelagics 940,784 24

Loligo opalescens market squid Coastal Pelagics 26,676 –

Merluccius productus Pacific hake Pacific Groundfish 8,421 –

Sardinops sagax Pacific sardine Coastal Pelagics 11,836 –

*

Includes estimated numbers from normal impingement, and actual numbers from marine growth control surveys.

6.4.2 IM&E Losses Relative to Other AEI Criteria

Additional criteria that were evaluated because they were specific to the marine environment around HGS

included:

 distribution (pelagic, subtidal, nearshore subtidal & intertidal);

 range, density, and dispersion of population;

 population center (source or sink);

 magnitude of effects;

 long-term abundance trends (e.g., fishery catch data);

 long-term environmental trends (climatological or oceanographic); and

 life history strategies (e.g., longevity and fecundity).

The criteria of distribution, range, habitat, and population center all need to be considered relative to the

magnitude of the effects.

The magnitudes of the CWIS losses were all relatively low, as expected, for taxa that are primarily

associated with habitats not directly affected by HGS. Not only were the estimated effects low for these

taxa, the broad geographic distributions throughout the SCB for fishes such as northern anchovy and

white croaker further reduce the potential for any AEI. The Harbor Complex is not the source or primary
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habitat for many of the taxa and is not critical to these populations. Data on these fishes from other studies

support the conclusion that there is very low risk of AEI due to the HGS CWIS.

This low risk of AEI to these taxa is supported by fish impingement data that has been routinely measured

for decades at several coastal power plants in southern California. The same core group of fish species

continues to be impinged at these power plants, and there is no measurable effect on fish populations from

the operation of the cooling water systems. For species that are harvested commercially, such as northern

anchovy, the biomass of fish impinged is orders of magnitude less than annual commercial landings.

These taxa seem to be responding to factors other than power plant impacts. Anchovies disappeared from

the commercial fishery after the regime shift and were essentially absent during the last two decades. Any

time series data that extends to before or during this regime shift has evidence of this change. Other

fisheries were declining (white croaker) while catch in the fishery independent monitoring programs

found them to be either increasing or extremely variable in abundance over time. After the faunal shift

(i.e., post 19821984 El Niño), fishes that would be negatively affected by warming conditions were

essentially extirpated from the nearshore environment of the San Pedro Bay area. This period was marked

by general low fish productivity (Brooks et al. 2002) until the La Niña of 1999 and the following fouryear cool water period.

The low potential for AEI for all of the taxa entrained and impinged at HGS is consistent with a recent

review on population level effects of IM&E on harvested fish stocks (Newbold and Iovanna 2007). They

modeled the potential effects of IM&E on populations of 15 East Coast fish stocks that are targeted by

either commercial or recreational fisheries using empirical data on entrainment and impingement, life

history, and stock size. For 12 of the 15 species, the effects of removing all of the sources of power plant

entrainment and impingement were very low (less than 2.5%). For the other three species, the effects

ranged from 22.3% for striped bass to 79.4% for Atlantic croaker. Their overall conclusions were that

population level effects were negligible for most fish stocks but could be severe for a few. They attributed

the absence of large effects for most species to compensatory mechanisms that are probably acting on the

populations at some level. If there is strong density dependence acting on these populations during the life

stages from the period when they are vulnerable to entrainment as larvae through the age of maturity, then

they concluded that there should be very little potential for population level effects due to entrainment and

impingement.

Although it seems clear that there is very low risk of AEI to taxa that are not primarily distributed in the

Harbor Complex, the potential risk to the fishes included in the assessment that are primarily associated

with bay and harbor habitats was also low, particularly compared to other power plants situated in

embayments in southern California. This is a reflection of both the lower abundances of these fishes in the

ILAH and the low cooling water volumes of HGS relative to other facilities. Data on adult populations

available from south San Diego Bay indicated that much higher entrainment losses did not represent a

significant risk to the population. Although no data on adult populations of these resident fishes are

available for the Harbor Complex, the much lower entrainment losses would indicate that there is very

low risk of adverse population impacts. This risk is reduced by the abundance of bay and harbor habitat in

the areas surrounding the Harbor Complex. Larvae potentially lost due to entrainment at small sizes near
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IM&E Final Report Impact Assessment

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the plant may be replaced by larvae transported into the ILAH that were spawned in similar habitats

throughout the Harbor Complex area.
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