p.1 

4.0 Entrainment and Source Water Results 

The Harbor Mouth, Ocean North, and Ocean South stations were not sampled in June, July, or 

August. Generally concentrations of undentified gobies were low at the Ocean Stations. The 

Ocean North Station had no unidentified gobies collected in September and October and 

concentrations of 73/1,000 m3 were reached in February 2000 during high tide. Unidentified 

gobies were collected at the Ocean South Station in low concentrations (less than 15/1,000 m3) 

during the September, October, November, and December surveys during high tide. In January 

and February 2000, concentrations increased at the Ocean South Station to a peak of 

209/1,000 m3 during a low tide on February 24, 2000. 

Data from the source water surveys show two seasonal peaks in unidentified goby 

concentrations. The highest concentration in the Elkhorn Slough stations occurred at Kirby Park 

in June 1999 (2,913/1,000 m3) during high tide. Other high concentrations occurred during a 

high tide at the Harbor Bridge Station in November 1999 (1,940/1,000 m3) and at a low tide 

(concentration = 1,721/1,000 m ) in February 2000. These distinct seasonal peaks may indicate 

spawning by two species of goby. The peak concentration at Kirby Park also coincided with a 

peak in bay goby concentrations. It is possible that these unidentified gobies may be bay goby 

that were too small to identify to species. Similarities in concentration increases between bay 

goby and unidentified gobies also occurred in November at the Harbor Bridge, Harbor Mouth, 

Ocean North, and Ocean South stations. 

Unidentified gobies were the second most abundantly entrained larval fishes collected in the first 

entrainment sampling program from November 1978 through March 1980 (PG&E, 1983). 

Taxonomic separations were not made within the Family Gobiidae except for longjaw 

mudsucker. It was thought that these unidentified gobies were probably arrow goby, bay goby, 

and yellowfin goby Acanthogobius flavimanus. Highest concentrations of 1,200/1,000 m3 were 

collected in January 1980 at Units 1 through 5 (PG&E, 1933). 

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4.0 Entrainment and Source Water Results 

4.4 Bay Goby 

Photographer: Neil McDaniel 

Lepidogobius lepidus 

Range: From Cedros Island. Baja California to 

Vancouver Island, British Columbia. 

Life History: Size: to 108 mm (4.25 in.); age at maturity: 

one to two years old; fecundity: limited information 

available; lifespan: seven plus years. 

Habitat: Intertidal mudflats, shallow pools. 

Fishery: None. 

Distribution Map for Bay Goby 

The bay goby Lepidogobius lepidus is a common bottom-dwelling inhabitant of bays and 

estuaries along the Pacific coast of North America. They range from Vancouver Island, British 

Columbia to Cedros Island, Baja California (Miller and Lea, 1972). Bay goby were the most 

abundant goby species collected between 1980 to 1992 during trawl surveys conducted in San 

Francisco Bay by the California Department of Fish and Game (CDFG). The bay goby is 

generally considered a shallow-water marine species but may occur on mud and mud-sand 

substrates down to depths of 61 m (200 ft.) (Miller and Lea, 1972). They are common on 

intertidal mudflats where they remain in invertebrate burrows and shallow pools when the tide is 

out (Grossman, 1979). Like many marine-estuarine species they are tolerant of variations in 

salinity and temperature. During population monitoring studies in the San Francisco BayE9-053.9 4-35 MLPP 316(b) Resource Assessment 

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4.0 Entrainment and Source Water Results 

Estuary bay goby occasionally (during periods of low Delta outflow) moved from marine waters, 

upstream through the Carquinez Straits into the lower salinity waters of Suisun Bay (CDFG, 

1999). 

The bay goby is a relatively small, elongate species that reaches a total length (TL) of about 

108 mm (4.25 in.) (CDFG, 1999). Bay goby vary from light olive-green to tan or brown in color 

with dark reddish-brown or brown dorsal mottling. Ventrally they have a uniform lighter 

coloration. They generally have a black-edged first dorsal fin. Scales are small and cover the 

body and posterior portions of the head (Hart, 1973). They have a moderate-sized terminal 

mouth and a blunt snout (Hart, 1973). As with other goby species their pelvic fins are fused, 

forming a hollow cone. Bay goby are reported to live for 7 years or more, which is considered 

unusual longevity for a small fish species (Grossman, 1979). Life span estimates of 2 to 3 years 

have been derived from length frequency data collected by CDFG. 

Based on differences in ova size/development from fish collected during April and May off 

Hunters Point Power Plant in San Francisco Bay and in Moss Landing Harbor, bay goby have 

been characterized as asynchronous multiple spawners (Wang, 1986). Female bay goby 

appeared to become reproductively mature at around 40 mm (1.6 in.) (Grossman, 1979). With 

the exception of a few gobies that mature within their first year, most individuals within a cohort 

do not become reproductively mature until their second year (Wang, 1986). Spawning occurred 

in Morro Bay from September through March, with peak activity occurring from January to 

March (Grossman, 1979). Grossman (1979) suggested that the timing of reproduction in bay 

goby may be highly variable. Little information about the details of bay goby spawning behavior 

exists in current literature. Because bay gobies use invertebrate burrows for predator avoidance 

and to stave-off dehydration during low tides it is thought that the 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, and spherical/elliptical in shape with 

an adhesive anchoring point (Wang, 1986). 

Newly hatched larvae are small (3 mm [0.12 in.] or less) and nearly transparent (Wang, 1986). 

Literature suggests that bay goby have a planktonic life phase of 3 to 4 months (Grossman, 1979; 

Wang, 1986). A 3 to 4 month estimate for the pelagic phase corresponded well with the 

recruitment models (based on gonadal maturity index data) for the species developed by 

Grossman (1979). This estimate also corresponded with the first appearance of settled larvae in 

Morro Bay, California during 1977. Bay goby larvae occur sympatrically with the larvae of 

arrow goby Clevelandia ios, cheekspot goby Ilypnus gilberti and yellowfin goby Acanthogobius 

flavimanus in San Francisco Bay and with arrow goby C. ios and shadow goby Quietula y-cauda 

in Morro Bay (Wang, 1986; Grossman, 1979). In a study by Wang (1986) most larval bay 

gobies were collected in San Francisco Bay from November through May, with peak numbers 

occurring in April and May. The greatest concentrations of larval bay gobies within the San 

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4.0 Entrainment and Source Water Results 

Francisco Bay system appeared to be concentrated between the Golden Gate Bridge and Angel 

Island (Wang, 1986). At about 25 mm TL (0.98 in.) bay goby larvae settle out of the plankton 

layers to begin a demersal existence. A leopard-spot-like pattern of melanophores forms above 

the lateral line in juveniles around the time they descend to the bottom (Grossman, 1979). In 

addition to this cryptic coloration, juveniles (and adults) occupy the burrows of blue mud shrimp 

Upogebia pugettensis, geoduck clams Panope generosa and other burrowing animals for shelter 

and predator avoidance (Grossman, 1979). 

No species-specific larval survivorship estimates were available for bay goby. However, 

Brothers (1975) calculated larval mortality over two-months, post-hatching for three sympatric 

gobiids (arrow goby, cheekspot goby, and shadow goby) from Mission Bay, California. These 

estimates were used to approximate bay goby mortality for early life stages as well as postsettlement juvenile and adult stages. Lack of species-specific fecundity data precluded 

estimation of FH for this species, but substituting survivorship from these closely related species 

for larval, juvenile, and adult stages allowed us to project future losses of equivalent adults. 

Juvenile bay goby feed on a variety of small crustaceans including copepods and amphipods, as 

well as some detrital material (Wang, 1986). Growth is initially rapid, with 50 percent of their 

total growth (length) occurring within the first 2 years (Grossman, 1979). Following this period 

of rapid growth, increases in length slow to about 6 mm (0.24 in.) per year (Grossman, 1979). 

The diet of adult bay gobies is not detailed in current literature but probably consists of many of 

the same items consumed by sympatric goby species, including small crustaceans, mollusks, 

larval fishes, and fish and invertebrate eggs. 

Bay goby are thought to be an important food item in the diet of a variety of vertebrate and 

invertebrate predators. Their abundance, small size, and long planktonic life 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. The Pacific staghorn sculpin Leptocottus armatus and California 

halibut Paralichthys californicus are among the many fish predators of adult bay goby (Brothers, 

1975). It is also assumed that many of the elasmobranch species (sharks and rays) that inhabit 

estuarine systems prey on bay gobies (Grossman, 1979). A predatory opisthobranch species 

Navanax intermis is also a documented predator (Paine, 1963). Wading and "probe feeding" 

birds are thought to regularly prey on bay gobies living on intertidal mudflats (Reeder, 1951). 

Bird species like marbled godwits Limosafedoa and willets Catoptrophorus semipalmatus are 

abundant on exposed tidal flats and probably consume a great number of bay goby. Tems Sterna 

spp. are also thought to be among the avian predators ofthe bay goby (Grossman, 1979). Due to 

their small size, bay goby are not harvested commercially for human consumption or targeted by 

recreational anglers (Wang, 1986). There is no mention in current literature of their harvest or 

use as bait, although they would probably be an effective bait for many species. 

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4.0 Entrainment and Source Water Results 

4.4.1 Bay goby results (30.4 percent) 

Bay goby comprised 30.4 percent of the total numbers of larval fishes collected in entrainment 

surveys at the new CC units intake (Figure 4-1). They were collected in all entrainment surveys 

from March 2,1999 through February 24, 2000 from in front of the intake of the CC units 

(Figure 4-9). Concentrations were typically below 200/1,000 m3 for from March 1999 through 

mid-October 1999. Peak concentration (2,668/1,000 m3) occurred on November 18, 1999 and the 

lowest concentration (22/1,000 m3) occurred on May 6, 1999. From November 22, 1999 through 

February 24, 2000, concentrations ranged from a low of 152/1,000 m3 to a high of 906/1,000 m3 

(Figure 4-9). 

The diel distributions were plotted for concentrations of bay goby collected in front of the new 

combined-cycle units intake from June 1999 through February 2000 (Figure 4-10). We analyzed 

only the entrainment surveys that coincided with the source water surveys. Bay gobies were 

typically collected (8 out of 9 surveys) in highest concentrations during the nighttime between 

1800 and 0300 hours PST. In February 2000 the peak diel concentration occurred at dawn at 

0627 hours. 

Bay Goby Entrainment Mean Concentration 

• ••••I-l , •••l.l.lllll l lllillhll 

• ' - --"":s8-3"°?""Sv"? 8ls ***: s,Lj ''* ," ? 2!!?58 " O -J * 

s a s — M O -J 8 8 s a 

Figure 4-9. Mean survey concentrations (#/1,000 m ) of larval bay goby at the Moss Landing Power 

Plant new combined-cycle units intake: March 1999 through February 2000. 

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4.0 Entrainment and Source Water Results 

Bay Goby Larval Entrainment Diel Mean Concentration 

| 6.000 

8 

c 

3 

3 .~ ^ 

1 . • _ R In • » l 

1 

11 If.. _ • • n I I __ _• 

B ? a «

 y tt 

Aug 12 

a $ 3 s ' 

Sep 16 

; : 3 

s a » 5 * a s -

Dec 29 

8:"*'aas; -

Jan 20 Feb 24 

Note: these entrainment surveys were conducted coincidentally with source water surveys. 

Figure 4-10. Concentrations (#/l,000 m3) of larval bay goby at the new combined-cycle units intake 

separated by sample collection time (PST): June 1999 through February 2000. 

Bay goby comprised 5.0 percent ofthe total fishes collected in the Elkhorn Slough area, 

30.5 percent in the Moss Landing Harbor area, and 4.1 percent in the Ocean area from June 1999 

through February 2000 (Figure 4-4). Bay goby were collected in all surveys (Figure 4-11). They 

were also collected at all stations in November. The highest concentrations occurred at high 

tides in September, October, November 1999, and January 2000. Generally peak concentrations 

occurred during high tides except in August and December. The highest concentration 

(509/1,000 m3) occurred at high tide in October at the Harbor Bridge station. 

E9-053.9 4-39 MLPP 316(b) Resource Assessment 

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4.0 Entrainment and Source Water Results 

Bay Goby Source Water Mean Concentration 

P.7 

E 100 

§ i 

c 

s 

• High 

• Low 

1 

I ooo 

OOO OOO 

! 

© 

i 

i 

. — ,—. 

°M§8 « 

Jun 16 Aug 12 Sep 16 

0

iiSS5 t , MSS5 0 MSS*5°8H84 , , M S S 

Oct 14 Nov 18 Dec 29 Jan 20 Feb 24 

. Key—KP: Kirby Park; D: Dairies; HB: Harbor Bridge; HM: Harbor Mouth; ON: Ocean North; OS: Ocean South 

<2> Stations not included in study design until September. 

© Samples voided due to improper preservation. 

Figure 4-11. Source water concentrations (#/l,000 m3) of larval bay goby at six stations near Moss 

Landing Power Plant: June 1999 through February 2000. 

Sub-samples of bay goby larvae collected from the source water surveys and the new combinedcycle intake surveys that corresponded to source water surveys (referred to as paired surveys) 

were measured. The first 50 specimens per sample were measured. The length frequency 

distribution of bay goby larvae varied among source water sampling locations. The largest 

numbers of small larvae were collected from sampling stations located in the harbor, as shown in 

Figure 4-12. Although our sample size of length-frequency varied with the number of larvae 

among source water sampling stations, the shorter bay goby larvae appear to be missing from 

both of the Elkhorn Slough sampling sites. Very few bay goby larvae were collected in the upper 

Elkhorn Slough (Kirby Park). This finding along with a pattern of increasing average larval size 

and concentration at the Dairies Station suggests that the source of bay goby larvae is somewhere 

in the direction of the harbor and Monterey Bay. The appearance of larger (possibly older stage) 

larvae collected in the mid-slough samples (Dairies Station) is consistent with a transport of 

larvae from a harbor/bay source up the slough. This pattern of shorter to longer larval length 

from the Monterey Bay to upper slough would point to the Moss Landing Harbor and Monterey 

Bay as a larval source. The strong pattern of decreasing concentration of bay goby larvae from 

the harbor-bay to the upper slough also points to the harbor-bay as a primary source of bay goby 

larvae. This conclusion is consistent with our knowledge ofthe species' preferred spawning 

habitat. 

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4.0 Entrainment and Source Water Results 

Bay Goby Vs Station 

Figure 4-12. Length frequency of all larval bay goby Lepidogobius lepidus lengths measured (n=l,lll*) 

by source water and intake sampling locations (June 1999 through January 2000). 

*CC Units intake: N = 862; source water survey: N = 249 

The length frequency of all bay goby larvae from the paired surveys is plotted in Figure 4-13 

along with the length frequency of source water specimens collected at high and low tide stages. 

The figure shows that more individuals were collected at high tide, particularly in the 3.0 to 3.1 

size classes. High tide water quality conditions or currents appear to favor hatching and 

distribution of bay goby larvae. The length of specimens ranged from 3 to 4.2 mm; the majority 

of individuals were between 3.3 and 3.6 mm. All of the bay goby lengths measured from both 

entrainment and source water sub-samples are plotted by survey in the Figure 4-14 scattergram. 

Inspecting the scattergram for periods of large numbers of smaller individuals followed by 

periods of fewer and larger individuals to indicate a hatching event, it is possible that a cohort of 

bay gobies hatched in July and November 1999. However the trends are slight, and the increase 

in average length between surveys appears to be less than expected based on the growth of 

individuals in a single cohort. It is more likely that hatching occurred several times during the 

summer and fall months, and the residual cohort of each hatching pulse blended in with new 

peaks of hatching larvae. 

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40 

35 

30 

25 

^ 20 

o 

E 

5 15 

10 

5 --

4.0 Entrainment and Source Water Results 

Bay Goby Length Frequency vs Tide 

• Low Tide 

D High Tide 

ffl I JL 

3 3.1 32 3.3 -3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 

Length (mm) 

Figure 4-13. Length frequency of all larval bay goby Lepidogobius lepidus measured (n=l,l 11*) by high 

and low tide stage (June 1999 through January 2000). 

*CC Units intake: N = 862; source water survey: N = 249 

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4.00 

3.50 

3.00 

2.50 

2.00 

1.00 

0.50 

0.00 

05/20/99 

4.0 Entrainment and Source Water Results 

Bay Goby Length by Date 

1 K 

1 j \ 1 

• * • 

< 

< 

} 

• 

* 

> 

t i 

1 

I 

* 

• 

• 

i 

i 

• 

» 

07/09/99 08/28/99 10/17/99 

Date 

01/25/00 03/15/00 

Figure 4-14. Scattergram plot of all larval bay goby Lepidogobius lepidus lengths measured (n=l,l 11*) 

by source water survey date (June 1999 through January 2000). 

*CC Units intake: N = 862; source water survey: N = 249 

Bay goby were not identified in the PG&E (1983) entrainment studies. It is likely that they were 

collected and that they were included in the general Family Gobiidae data analysis discussed in 

Section 4.3. 

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4.0 Entrainment and Source Water Results 

4.5 Blackeye Goby 

Coryphopterus nicholsi 

Photographer: Dan Dugan 

Range: From Point Rompiente, Baja California to 

Queen Charlotte Islands, British Columbia. 

Life History: Size: to 150 mm (6 in.); Age at maturity: 

two years, protogynous hermaphrodite; Fecundity: 3,300 

_ to 4,800 eggs; lifespan: five years. 

Habitat: Rocky reefs near sand-rock interface. 

Fishery: None. 

Distribution Map for Blackeye Goby 

The blackeye goby Coryphopterus nicholsi occurs commonly around nearshore reefs from 

Queen Charlotte Islands, British Columbia to Point Rompiente in Baja California (Miller and 

Lea, 1972). They are a marine species but will occasionally enter bays and estuaries (Wang, 

1986). Blackeye goby typically inhabit benthic substrates near the sand-rock interface. They 

live in crevices and burrows within small territories that they defend aggressively (Love, 1996). 

Blackeye goby are known to occur from the intertidal zone down to depths of 137 m (450 ft.) 

(Love, 1996). The species is reported to be largely diurnal (Love, 1996). Fossil blackeye goby 

otoliths have been identified from Pliocene deposits in California that are estimated have been 

formed between 8 and 12 million years ago (Ebert and Turner, 1962). Hart (1973) reported that 

"blackeye goby larvae have the ability to survive exposure to low salinities. 

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H 

1 

1 

1 

H 

I 

I 

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4.0 Entrainment and Source Water Results 

1 

The blackeye goby is an elongate, medium-sized goby that can be distinguished from other 

members of the family by their large scales, light coloration, and a fleshy ridge that extends 

dorsally from to just behind the eyes to the insertion of the first dorsal fin (Ebert and Turner, 

1962). Blackeye goby reach a maximum size of about 150 mm (6 in.) and have a life span of as 

much as 5 years (Love, 1996). With the exception of portions of their head, their body is 

covered with large, cycloid scales (Hart, 1973). Blackeye goby are pale tan to orange-olive in 

coloration with some brownish and green speckling (Miller and Lea, 1972; Hart, 1973). A small 

iridescent blue spot is present below each of the large black eyes and the distal margin of their 

first dorsal fin is tipped with black (Ebert and Turner, 1962; Miller and Lea, 1972; Hart, 1973; 

Love, 1996). Blackeye goby have a moderate-sized, terminal mouth that is directed forward 

(Hart, 1973). The joined pelvic fins of males become darker in color during breeding season 

(Ebert and Turner, 1962; Love, 1996). The species is hermaphroditic (protogynous) so all 

blackeye goby start life as females (Wiley, 1973; Love, 1996). They become reproductively 

mature within 2 years and at a total length (TL) of 38 to 51 mm (1.5 to 2 in.) (Love, 1996). 

Female blackeye goby transform into males at around 64 to 76 mm (TL) (2.5 to 3 in.). Males 

can be recognized by the presence of a protruding urogenital papilla (Wang, 1986; Love, 1996). 

Female blackeye goby are oviparous and based on examinations of ova by Wiley (1973) are able 

to spawn more than once during a season (Wang, 1986). The spawning season of blackeye 

gobies extends from February through October (Ebert and Turner, 1962; Wiley, 1973; Love, 

1996). Peak spawning activity occurs in the late spring and early summer (Love, 1996). Males 

prepare a nest by clearing (scraping) an area on the underside of ledges or underneath rocks for 

egg attachment (Love, 1996). Females deposit between 3,300 and 4,800 elongate/oblong eggs in 

the nest (Wiley, 1973; Love, 1996). Ebert and Turner (1962) calculated an average nest size of 

1,700 eggs. Eggs are demersal and adhesive at the point of attachment (Ebert and Turner, 1962; 

Wiley, 1973). Nests, formed by a single layer of eggf., are generally circular in shape and 

average about 100 mm (4 in.) in diameter (Ebert and Turner, 1962). Males guard the nest and 

tend the eggs until they hatch (Love, 1996). No information was available concerning incubation 

time. Newly hatched larvae are planktonic and about 3 mm (0.12 in.) in length (Ebert and 

Turner, 1962). Larvae can be carried great distances by currents and wind action. Juveniles 

have been found in surface waters far offshore as well as in the stomachs of albacore (Ebert and 

Turner, 1962). The duration ofthe planktonic larval phase is approximately 75 days (Steele, 

1997). Juveniles begin settling out of the water column at a length (TL) of 21 to 28 mm (0.83 to 

1.1 in.) and seek out rocky substrates to commence their demersal life phase (Wang, 1986). 

No species-specific larval survivorship estimates were available for blackeye goby. However, 

Brothers (1975) calculated larval mortality over two-months, post-hatching for three sympatric 

gobiids (arrow goby, cheekspot goby, and shadow goby) from Mission Bay, California. These 

estimates were used to approximate bay goby mortality for early life stages as well as postE9-053.9 4-45 MLPP 316(b) Resource Assessment 

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II 

1 

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H 

IE 

1 

1 

1 

1 

1 

1 

1 

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4.0 Entrainment and Source Water Results 

settlement juvenile and adult stages. Lack of species-specific fecundity data precluded 

estimation of FH for this species, but substituting survivorship from these closely related species 

for larval, juvenile, and adult stages allowed us to project future losses of equivalent adults. 

Blackeye goby consume a variety of small organisms and larval forms. The diet of juveniles 

includes crustaceans such as copepods and amphipods and their nauplii, as well as mollusk and 

echinoderm larvae, and bryozoans (Wang, 1986). The diet of adult blackeye goby consists 

mostly of small crustaceans (copepods and amphipods) and mollusks such as limpets and snails 

(Love, 1996). During their planktonic stage larval blackeye goby are probably consumed by a 

variety of species. Juveniles and adults develop predator avoidance behavior but still fall prey to 

numerous fish and bird species. Diving birds such as pelagic, Brandt's, and double-crested 

cormorants are among the reported avian predators of blackeye goby (Love, 1996). Blackeye 

goby are not targeted by commercial or recreational fishermen and are probably rarely, if ever, 

taken. 

4.5.1 BOsickeye goby results (3.0 percent) 

Blackeye goby comprised 3.0 percent of the total numbers of larval fishes collected in 

entrainment surveys at the new CC units intake (Figure 4-1). They were collected in all 

entrainment surveys from March 2, 1999 through December 9, 1999 from in front ofthe intake 

of the new CC units (Figure 4-15). They were collected again in low concentrations (below 

35/1,000 m3) in the December 21, December 29,1999 and January 13, February 3, February 10, 

and February 24,2000 surveys. Peak concentration (281/1,000 m3) occurred on November 11, 

1999 and the lowest concentration (1/1,000 m3) occurred on March 2,1999. Concentrations 

were typically below 50/1,000 m3 for most ofthe time period sampled. 

The diel distributions were plotted for concentrations of blackeye goby collected in front of the 

new combined-cycle units intake from June 1999 through February 2000 (Figure 4-16). We 

analyzed only the entrainment surveys that coincided with the source water surveys. They were 

not collected in the January 2000 entrainment survey that coincided with the source water 

survey. Blackeye goby were typically collected in highest concentrations during the nighttime 

between 2200 and 2300 hours PST except in October when the highest concentration occurred 

after sunset at 1829 PST hours. 

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4.0 Entrainment and Source Water Results 

Blackeye Goby Entrainment Mean Concentration 

300 

250 

200 

150 

g 100 

o 2 

0 J ••••III - Jill • • I. X 

f I f i •? ? * -5 | i i i r i i i t t i i f | s s f f f i ? -? i ? if i i i. i i t t ? 

s is a s m a - i s s = s K 5 8 j • i * i j - • • • - s i • g - _ s B * i s j , 

Figure 4-15. Mean survey concentrations (#/1,000 m ) of larval blackeye goby at the Moss Landing 

Power Plant new combined-cycle units intake: March 1999 through February 2000. 

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4.0 Entrainment and Source Water Results 

Blackeye Goby Larval Entrainment Diel Mean Concentration 

700-i 

^50 0 

E entratlon { 

3 I 

Mean Cone 

0 TM 

1 

.1 . Ii B-S •. ' • 1 • II • En l m 

• 

m a 1 

s : i x 

X 8 »' 2 

Aug 12 Sep 16 

; ; : B 

8 s 5 a 

Oct 14 Jan 20 Feb 24 

Note: these entrainment surveys were conducted coincidentally with source water surveys. 

Figure 4-16. Concentrations (#/l,000 m3) of larval blackeye goby at the new combined-cycle units 

intake separated by sample collection time (PST): June 1999 through February 2000. 

Blackeye goby comprised 1.6 percent ofthe total fishes collected in the Elkhorn Slough area, 

2.9 percent in the Moss Landing Harbor area, and less than 1 percent in the Ocean area from 

June 1999 through February 2000 (Figure 4-4). Blackeye goby were collected in all months 

except December 1999 and January 2000 (Figure 4-17). They were only collected at low tides 

except at Kirby Park in June and November 1999 and the Dairies and Harbor Mouth in February 

2000. However, the peak concentration (280/1,000 m3) occurred at high tide in June at Kirby 

Park. Blackeye goby were not collected at the Ocean stations except at the Ocean North station 

during a low tide in October. 

Blackeye goby were not identified in the PG&E (1983) entrainment studies. It is likely that they 

were collected and that they were included in the general Family Gobiidae data analysis 

discussed in Section 4.3. 

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4.0 Entrainment and Source Water Results 

4.7 White Croaker 

Source: CDFG 

Genyonemus lineatus 

Range: From Todos Santos Bay, Baja California north 

to Barkley Sound, Vancouver Island, British Columbia. 

Life History: Size: up to 380 mm (15 in.) and 0.5 kg 

(1 lb); Age at maturity: one to four years; Fecundity: 

spawns 18 to 24 times a season, 800 to 37,000 eggs; Life 

span: twelve to fifteen years. 

Habitat: Near shore and offshore waters to 100 m 

(328 ft) in depth. 

Fishery: Recreational, small commercial market. 

Distribution Map for White Croaker 

The white croaker, also called drum, belongs to the Family Sciaenidae (Order Perciformes) 

which contains over 210 species. White croaker are found from southern Baja California to 

Vancouver Island, British Columbia. They are most abundant from southern California 

northward to about Monterey; they are uncommon north of San Francisco (Love, 1996). They 

are present in the Sacramento-San Joaquin Estuary, Tomales Bay, and the Moss Landing 

Harbor/Elkhorn Slough area. In North America, there are about 34 species of croaker, many of 

them important as sport and commercial fishes (Moyle and Cech, 1988). The white croaker has 

been given many names; in central California and in most fish markets, "kingfish" is most often 

used. 

White croaker are bottom-dwelling fishes found schooling and feeding along warm, shallow, 

nearshore coasts. White croaker are usually found in loose schools over sand or mud bottoms of 

bays and estuaries and in areas less than 30 m (98 ft) deep just outside the surf zone (Streamnet, 

1999). They may also, however, inhabit off-shore waters up to 100 m (328 ft) deep (Frey, 1971). 

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4.0 Entrainment and Source Water Results 

These fish seem to move inshore during summer months and offshore in winter. White croaker, 

silver in color, can reach 380 mm (15 in.) in length and can weigh over 0.5 kg (1 lb) (Streamnet, 

1999). These fish reach maturity in one to four years and may live from twelve to fifteen years 

(Frey, 1971). 

Although some spawning takes place throughout the year, most occurs between November and 

May (Skogsberg, 1939) with the heaviest concentration during the early spring months. Adults 

spawn in both near-shore shallow waters and the open waters of bays and estuaries. A large 

spawning center is located north and south ofthe Palos Verdes Peninsula, from Redondo Beach 

to Laguna Beach, and a smaller center is found north of Ventura (Love et al., 1984). Females lay 

from 800 to 37,000 eggs, and are able to spawn 18 to 24 times a season (Love et al., 1984). The 

fertilized eggs are pelagic and most drift into the shallow sand and gravel bottom regions ofthe 

bays and estuaries. 

The spherical eggs hatch in about one week, with the newly hatched larvae averaging about 

1.6 mm (0.06 in.) (Watson, 1982). The young larvae are pelagic and post-flexion larvae settle 

out to the sand and gravel bottom substrate as they develop (Love et al., 1984). There are no 

species-specific estimates of survivorship in the literature and therefore we assumed a 99 percent 

larval mortality through settlement. Length frequency analysis of white croaker larvae at the 

Diablo Canyon Power Plant in yielded mortality rates of approximately 99 percent (Tenera, 

2000). Murdoch et al. (1989) estimates a daily larval growth rate of 0.20 mm per day. The 

shallows of bays and estuaries are used as nursery grounds for the white croaker, but larvae are 

found in open water as well (Wang, 1986). While a few larvae have been taken as far as 150 

miles offshore, most larvae reside within 20 miles of the coast (Love, 1996). 

Early juveniles remain in the bays and estuaries; as they mature, the juveniles gradually migrate 

to deeper ocean waters, usually in the summer and fall (Wang, 1986). Juveniles are 

approximately 1.3 to 13 cm TL (Emmett et al., 1991). Both juveniles and adults favor cloudy 

water. 

The white croaker, although not of prime importance, has commercial value as bait and as a food 

fish. Commercial landing information for white croaker in the Monterey and Moss Landing area 

is shown in Figure 4-22a and b. In addition to man, white croaker are preyed upon by tuna, sea 

bass, dolphin, halibut, and sea lions. White croaker feed on just about anything, including crabs, 

shrimps, mollusks, and detritus. Since it is omnivorous and feeds in nearshore waters, the white 

croaker is susceptible to pollutants accumulating in its tissues. The white croaker fishery has 

been subject to occasional closures due to health threats to humans. 

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4.0 Entrainment and Source Water Results 

(a) 

1.2 -, 

s

 10

-

c 2 0.8 -

,§. 0.6 -

c 0.4 -

3 

o 

a 0.2 -

0.0 -

CO 

o> 

White Croaker Landings 

Q3 0) O »*• <V Ci 

QD QD O) 05 05 05 

05 O) 05 05 0> 05 

1987 to 1998 

1 State Total 

•jMonterey Area 

• Moss Landing 

v <o CO ^ 

O) 05 CO 0> 

O) O) O) O) 

53 

OS 

O) 

(b) White Croaker Landing Values 1987 to 1998 

pMonterey Area 

• Moss Landing 

Source: CDFG Landing Tables 

Figure 4-22. (a) White croaker California state-wide, Monterey area, and Moss Landing Harbor landings 

(1,000,000 lbs) and (b) White croaker California state-wide, Monterey area and Moss Landing Harbor 

landings values (dollars): 1987 to 1998. 

4.7.1 White Croaker Results (2.1 percent) 

White croaker comprised 2.1 percent of the total numbers of larval fishes collected in 

entrainment surveys at the new CC units intake (Figure 4-1). They were collected in four 

entrainment surveys in March 1999 and the first survey in April 1999 (Figure 4-23). A high 

concentration (197/1,000 m3) occurred on March 8, 1999. White croaker larvae were collected 

on June 24, 1999 in low concentrations (2/1,000 m3). Beginning in November 1999 they were 

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collected in each weekly survey except on January 21, 2000. The highest peak concentration 

(226/1,000 m3) occurred on December 21,1999. 

The diel distributions were plotted for concentrations of larval white croaker collected in front of 

the new combined-cycle units intake from June 1999 through February 2000 (Figure 4-24). We 

analyzed only the entrainment surveys that coincided with the source water surveys. During 

June through October 1999 and during January 2000 no white croaker larvae were collected in 

entrainment surveys that coincided with source water surveys. 

White Croaker Entrainment Mean Concentration 

8 

g 100 

50 

J 

JL 

I 

_ _ _ .Il a IB- I I 

| | II 

= N i. s a v. - m Z g = s 8 - * s » 3 j s 8 "''-'- "

 = 8 "•-'••'•"' -""*•*' * **'• 8 5 S 8 

Figure 4-23. Mean survey concentrations (#/1,000 m) of larval white croaker at the Moss Landing 

Power Plant new combined-cycle units intake: March 1999 through February 2000. 

In November 1999 larval white croaker were collected in highest concentrations before dawn 

(0636 PST). In December 1999 and February 2000 larval white croaker were collected in nearly 

equal peak concentrations during nighttime and daytime. 

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White Croaker Larval Entrainment Diel Mean Concentration 

5 80 

I 

tl 

C 

|j 60 

S 

c 

3 

s 

] 

1 

1 ll 11 

1 

« 

; = B -

Jul 12 

; 3 ; 

Aug 12 

5 s : 3 

? t 8 S 

Sep 16 

Note: These entrainment surveys were conducted coincidentally with source water surveys. 

Figure 4-24. Concentrations (#/1,000 m3) of larval white croaker at the new combined-cycle units intake 

separated by sample collection time (PST): June 1999 through February 2000. 

White croaker comprised less than 1 percent of the larval fish taxa collected in the Elkhorn 

Slough area, 0.9 percent in the Moss Landing Harbor area, and 4.4 percent in the Ocean area. 

White croaker larvae were collected only during the October, November, December 1999, and 

February 2000 surveys (Figure 4-25). They were collected from the Ocean South Station in 

October and November, from the Dairies Station in November, and from the Harbor Bridge 

Station in December. White croaker larvae were not collected at any stations in the January 

2000 source water survey. They were collected at all stations except Kirby Park in February 

2000. The peak high and low tide concentrations (155/1,000 m3 and 116/1,000 m3, respectively) 

occurred at Kirby Park in February 2000. 

White croaker larvae were entrained from August 1979 to March 1980 during the first 

entrainment study (PG&E, 1983). The peak concentration (400/1,000 m3) occurred at the Units 

1 through 5 intake in November and December 1979 (PG&E, 1983). 

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White Croaker Source Water Mean Concentration 

BHigh 

• Low 

O O O O O O O O O 

j 

i 

! 1 8 

Jun16 Jul 12 Aug12 Sep 16 Oct 14 Nov 16 Dec29 Jan 20 Feb24 

Key—KP: Kirby Park; D: Dairies: HB: Harbor Bridge; HM: Harbor Mouth; ON: Ocean North; OS: Ocean South 

O Stations not included in study design until September. 

© Samples voided due to improper preservation. 

Figure 4-25. Source water concentrations (#/l,000 m3) of larval white croaker at six stations near Moss 

Landing Power Plant: June 1999 through February 2000. 

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4.8 Blenniidae: Combtooth blennies 

Combtooth blennies are a prominent group among the fish fauna that inhabits inshore rocky 

habitats throughout much of the world. They are members of the Family Blenniidae within the 

Order Blennioidei, which also includes the clinids. Clinids are an extremely variable group of 

intertidal fishes that includes kelpfish Gibbonsia spp. and fringeheads Neoclinus spp. The 

Family Blenniidae, the combtooth blennies, contains around 345 species in 53 genera (Nelson, 

1994; Moser, 1996). They derive their common name from the arrangement of closely spaced 

teeth in their jaws. Four Blenniid species have been reported to occur in the CalCOFI study area, 

although one, Ophioblennius steindachneri, only ranges as far north as Bajia Sebastian Vizcaino 

in central Baja California (Moser, 1996). 

The Family Bleniidae is composed of species that vary widely in general appearance (Moser, 

1996). Despite this diversity in appearance the family shares several common external 

characteristics. 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 

elongate 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 ofthe same species-(Stephens et al., 1970). 

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. With the exception of the 

semi-pelagic sabertooth blenny Aspidontus taeniatus they tend to be demersal (Moser, 1996). 

Combtooth blennies are omnivores and eat both algae and a variety of invertebrates, including 

limpets, urchins, and bryozoa (Love, 1996). 

4.8.1 Hypsoblennius Spp. 

Combtooth blennies are represented along the California coast by three members of the genus 

Hypsoblennius; the bay blenny Hypsoblennius gentilis, rockpool blenny Hypsoblennius gilberti, 

and mussel blenny Hypsoblennius jenkinsi. These species co-occur throughout much of their 

range. The bay blenny H. gentilis is found along both coasts of Baja California and up the 

California coast to as far north as Monterey Bay, although it is absent from the Cape San Lucas 

area (Miller and Lea, 1972; Stephens et al., 1970). The distribution ofthe rockpool blenny 

H. gilberti extends from Magdalena Bay, Baja California to Pt. Conception, California (Miller 

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and Lea, 1972; Stephens et al., 1970). The range of the mussel blenny H. jenkinsi extends only 

as far north as Coal Oil Point in Santa Barbara County but occurs south to Puerta Marquis, 

Mexico (Miller and Lea, 1972; Stephens et al., 1970). Each species appears to have different 

habitat preferences. The mussel blenny H. jenkinsi is only found subtidally and inhabits mussel 

beds, the burrows of boring clams, or Serpulorbis spp. tubes (Stephens et al., 1970). They 

generally remain within one meter of their chosen refuge (Stephens et al., 1970). Rockpool 

blenny H. gilberti typically inhabit cobble in the intertidal and shallow subtidal zone and may 

regularly range as far as 15 m (49 ft) within their territories. Bay blenny H. gentilis are usually 

found subtidally but appear to have general habitat requirements and may inhabit a variety of 

intertidal and subtidal areas (Stephens et al., 1970). Bay blenny are commonly found in mussel 

Mytilis spp. beds and on encrusted floats, buoys, docks, and even fouled boat hulls (Stephens et 

al., 1970). H. gentilis are often found in bays and are tolerant of nearly estuarine conditions 

(Stephens et al., 1970). They are among the first fish species to colonize new or disturbed 

marine habitats such as new breakwaters (Stephens et al., 1970; Moyle and Cech, 1988). 

There are several morphological differences between the adults of three sympatric 

Hypsoblennius species. The head shape is different, as is the posterior extent of the lateral line 

(Stephens et al., 1970). In addition, the number of fin rays, coloration, and size may be 

distinguishing characteristics among adults (Stephens et al., 1970). Bay blenny are the largest of 

the three Hypsoblennius species inhabiting the California coast, reaching a size of 147 mm 

(5.8 in.) and living for at least 7 years (Stephens et al., 1970; Miller and Lea, 1972). The 

rockpool blenny attains a size of 140 mm (5.5 in.) and may live for 8 to 10 years (Stephens et al., 

1970; Miller and Lea, 1972). Stephens et al. (1970) stated that the rockpool blenny grew faster 

and attained a larger size than the bay blenny, however, Miller and Lea (1972) lists the bay 

blenny as growing larger. The smallest are mussel blenny which grow to 112 mm (4.4 in.) and 

have a life span 3 to 6 years (Stephens et al., 1970; Miller and Lea, 1972). Male and female 

growth rates are similar. Female rockpool blenny are 64 mm (2.5 in.) TL or more in size before 

they become reproductively mature (Love, 1996). Some individuals mature within their first 

year, however it is more common for blenny to become mature in their second (Love, 1996). 

The spawning season ofthe three California Hypsoblennius spp. 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). In Hypsoblennius 

spp., the responsibility for tending the nest resides with the male. Females spawn 3 to 4 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 (Stephens et al., 1970). The number of eggs a female produces varies 

proportionately with her size (Stephens et al., 1970). The smaller and shorter-lived H. jenkinsi 

carries relatively more eggs per length than H. gilberti (Stephens et al., 1970). A female mussel 

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blenny H. jenkinsi may carry 500 eggs in her first year and up to 2,900 eggs by her third year 

(Stephens et al., 1970). Female rockpool blenny H. gilberti may produce from 600 to 3,200 eggs 

per spawning (Love, 1996). Incubation time is temperature-dependent and eggs typically hatch 

in 4 to 18 days (Love, 1996). 

Larvae of all three species are pelagic and around 2.7 mm (0.11 in.) 2 days after hatching 

(Stephens et al., 1970). The planktonic phase for Hypsoblennius spp. larvae may last for 

3 months (Stephens et al., 1970; Love, 1996). Stephens et al. (1970) found that, although all 

Hypsoblennius spp. larvae were the same size at hatching, larvae ofthe rockpool blenny 

H. gilberti were larger at the time of settlement (18 to 21 mm [0.71 to 0.83 in.]) than either the 

mussel blenny or bay blenny (12 to 14 mm [0.47 to 0.55 in.]). He assumed that the size 

difference was the result of more rapid growth rather than a longer larval phase. The accelerated 

| growth rate of the rockpool blenny continued through the first post-larval year as individuals 

grew to a total length of between 65 and 80 mm (2.6 to 3.1 in.) (Stephens et al., 1970). Mussel 

| | and bay blenny of the same age averaged 45 mm (1.8 in.) in total length (Stephens et al., 1970). 

Rates of larval mortality were not available for blennids, but Brothers (1975) indicated that 

ll 99 percent larval mortality over two months is reasonable for three species of gobies that are 

ecological analogs in similar habitats. Daily survival was estimated as (1-0.99)1'

60

 = 0.926dl. 

A growth rate of 0.2 mmd_1 was estimated using the difference between transformation length 

(Moser, 1996; 10 - 22 mm) and hatch length (Moser, 1996; 2.3 - 3.0 mm) and 75 days to 

settlement (Fitch and Lavenberg, 1975). It was assumed that the age at entrainment was 

| approximately midway to flexion. The growth rate was used to estimate the age of entrainment 

as 7.8 days, i.e., one half age at flexion (flexion length minus hatch length divided by growth 

|) rate). Survival to entrainment was then estimated as 0.926 = 0.55. 

Larval survival from entrainment to settlement (75 days) was estimated as 0.926

 lo"' ° = 0.0057. 

Adult mortality was estimated from age groupings of three species in Stephens et al. (1970). 

Exponential instantaneous mortality rates (Z) were calculated from these age groupings using the 

relationship between log numbers at age In(Nt) and age t: 

In(Nt)= -Zt+b 

The average of the estimated instantaneous mortality rates (H. jenkinsi: Z=0.72; H. gilberti: 

Z=0.57; H. gentilis: Z=0.64) was used to estimate annual adult survival of 0.525 yr"1. Using this 

annual rate, the survival from settlement to age 3.67 year (average age used in fecundity 

hindcasting) was estimated as 0.11. 

Larval blennids are not difficult to distinguish from other larval fishes through a combination of 

myomere counts, pigmentation patterns and their elongated form (Moser, 1996). The northern 

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4.0 Entrainment and Source Water Results 

range of the bay blenny extends to Monterey Bay while the ranges of adult rockpool and mussel 

blenny do not extend north of Point Conception, Santa Barbara County (Miller and Lea, 1972). 

Larval Hypsoblennius spp. are not easily distinguished from each other. Because of the long 

pelagic life phase ofthe genus, and the corresponding potential for long-range dispersal, it is 

possible that larval rockpool and mussel blenny could occur in the Moss Landing/Elkhorn 

Slough area as well as within entrainment samples. For this reason identifications of 

Hypsoblennius spp. larvae were not made past the genus level. All Hypsoblennius larvae were 

combined in the Hypsoblennius spp. category. For assessment purposes in Section 6, we assume 

that the unidentified blennies in our samples are bay blenny. 

4.8.2 Blennies Hypsoblennius spp. Results (1.9 percent) 

Blennies comprised 1.9 percent ofthe total numbers of larval fishes collected in entrainment 

surveys at the new CC units intake (Figure 4-1). They were not collected in the entrainment 

surveys until April 29, 1999 and were present in every survey from May 13 through December 9, 

1999 (Figure 4-26). Larval blennies were not collected in the entrainment surveys from 

December 16, 1999 through February 17, 2000. They were collected in low concentrations 

(1.6/1,000 m3) during the February 24, 2000 survey. Peak concentration (272/1,000 m3) 

occurred on September 16, 1999. Concentrations were typically below 50/1,000 m3 for most of 

the time period sampled. 

Hypsoblennius spp. Entrainment Mean Concentration 

250 

100 

111 •.-.-. 

Imflliiiitfffm--.i_ttlltiti.llll1tlttitlli t 

j fc 5 sal s . •_ n =

s s "8

= i = g*is"ssB" s:: 88''i*i8*is 8 

Figure 4-26.. Mean survey concentrations (#/l,000 m3) of larval Hypsoblennius spp. at the Moss 

Landing Power Plant new combined-cycle units intake: March 1999 through February 2000. 

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The diel distributions were plotted for concentrations of larval blennies collected in front of the 

new combined-cycle units intake from June 1999 through February 2000 (Figure 4-27). We 

analyzed only the entrainment surveys that coincided with the source water surveys; no larval 

blennies were collected in the December 1999 and January 2000 entrainment surveys. The peak 

diel concentration of blennies occurred at nighttime between 1830 and 0230 hours PST between 

June and November 1999, except in August 1999 and February 2000, when the peak 

concentrations occurred at 0659 and 1452 hours PST, respectively. 

Blennies comprised 6.8 percent ofthe total larval fishes collected in the Elkhorn Slough area, 

5.1 percent in the Moss Landing Harbor area, and 3.0 percent in the Ocean area from June 1999 

through February 2000 (Figure 4-4). Larval blennies were collected in all surveys except 

December 1999 and January 2000 (Figure 4-28). In October 1999, they were collected at all 

stations except Ocean South. The highest concentrations occurred in June, July, and August 

during low tide. The highest peak concentration occurred in August (503/1,000 m3) at the 

Dairies station. 

Larval blennies were not identified in the PG&E (1983) entrainment studies nor have they been 

collected in other studies of Elkhorn Slough/Moss Landing Harbor (Nybakken et al., 1977; 

Yoklavich et al., 1992). Since Monterey Bay is the northern most boundary of the 

Hypsoblennius spp. range, it is possible that this is a new species for this area. 

Hypsoblennius spp. Larval Entrainment Diel Mean Concentration 

i SOO 

I 

S 

S 

| 600 

S 

c 

i 

3 TM 

• R-i ...H i •••ni l 

• 

.1 • • 

1 

.In . - R -

5 5 : 3 "** 

Aug 12 Sep 16 Oct 14 

3*8S8S8S' ,-'SB3; * 

Dec 29 Jan 20 Feb 24 

Note: These entrainment surveys were conducted coincidentally with source water surveys. 

Figure 4-27. Concentrations (#/1,000 m3) larval Hypsoblennius spp. at the new combined-cycle units 

intake separated by sample collection time (PST): June 1999 through February 2000. 

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Hypsoblennius spp. Source Water Mean Concentration 

E 100 

• High 

• Low 

000 00^\ 000 

1 

® 

5 ° S i § S 5 ° i i i S 5 ° S i i S 5 ° ! i i 8 5 ° H ? 8 5 ° M S 8 5 ° i i S 8 5 ° i I I 8 5 ° i i 5 S 

Jun16 Jul 12 Aug12 Sep 16 Oct 14 Nov 18 Dec29 Jan20 Feb24 

Key—KP: Kirby Park; D: Dairies; HB: Harbor Bridge; HM: Harbor Mouth; ON: Ocean North; OS: Ocean South 

•0 Stations not included in study design until September. 

© Samples voided due to improper preservation. 

Figure 4-28. Source water concentrations (#/l,000 m3) of larval Hypsoblennius spp. at six stations near 

Moss Landing Power Plant: June 1999 through February 2000. 

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4.9 Longjaw Mudsucker 

Photographer Drew Talley 

^53 

Gillichthys mirabilis 

Range: From Bajia Magdalena, Baja California to 

Tomales Bay, California. In Arizona: the Salt River and 

the lower Colorado River. Introduced into the Salton 

Sea, California. 

Life History: Size: up to 210 mm (8.25 in.); Age at 

maturity: one year; Fecundity: spawns two to three times 

a season, 4,000 to 9,000 eggs; 8,000 to 27,000 eggs 

(Barlow, 1961); Lifespan: two years. 

Habitat: Tidal flats, shallow muddy waters. 

Fishery: Commercial and recreational: bait-fish fishery. 

Distribution Map for Longjaw Mudsucker 

The longjaw mudsucker Gillichthys mirabilis is a medium to large goby species that commonly 

inhabits bays, estuaries, tidal sloughs, and salt ponds along the Pacific coast of North America. 

The native distribution of longjaw mudsuckers extends along the Pacific Coast from Bajia 

Magdalena, Baja California to Tomales Bay, California (Love, 1996; Wang, 1986). They are 

most abundant from San Francisco Bay south. An isolated population has been documented in 

the upper reaches of the Gulf of Califomia and an introduced population has also become well 

established in the Salton Sea. The latter population is descended from 500 fish that were planted 

by CDFG during November 1930 (Barlow and De Vlaming, 1972). Longjaw mudsucker have 

also been reported in Arizona (Roosevelt Lake on the Salt River) and the lower Colorado River 

where they are commonly used as bait (Fuller, 1999). The occurrence of longjaw mudsucker in 

these systems is thought to have been derived from bait bucket releases (Fuller, 1999). 

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Longjaw mudsucker are able to tolerate a wide range of environmental conditions. The species 

are abundant on tidal flats and in shallow muddy backwaters (Love, 1996). They can live in 

water with salinities ranging from two and a half times that of seawater to nearly freshwater, and 

are able to withstand water temperatures as high as 35° C (95° F) (Love, 1996). Their preferred 

temperature range is between 9° C and 23° C (48° F and 73° F) (De Vlaming, 1971; Love, 

1996). Longjaw mudsucker are characterized as having bi-modal breathing capabilities (Moyle 

and Cech, 1988). In addition to extracting oxygen from the water with their gills, mudsuckers 

have the ability to absorb oxygen from air taken in (gulped) and held in their large and highly 

vascularized buccal cavity (Moyle and Cech, 1988; Love, 1996). They also have the ability to 

undergo limited cutaneous respiration through their fins (Barlow, 1961). They can survive 

extended periods of time out of the water and have been observed "walking" across tidal flats 

from one pool of water or burrow to the next (Moyle and Cech, 1988; Todd, 1968). Mudsuckers 

often retreat into holes and crab burrows when tidal flats are exposed during low tides (Love, 

1996). It has been reported that longjaw mudsucker can live out of the water for 6 to 8 days, if 

they are kept moist (Eschmeyer et al., 1983). 

Longjaw mudsucker are olive-brown to dark brown in color with yellowish bellies (Miller and 

Lea, 1972). Juveniles often have 8 dark bars down the length of their body and a dark blotch on 

their first dorsal fin (Walker et al., 1961; Love, 1996). Longjaw mudsucker reach a maximum 

size of about 210 mm (8.25 in.). They are readily distinguished from other similar-looking 

gobies by their disproportionately long upper jaw, which extends to near the margin of the gill 

opening. Their pelvic fins fuse to form a disc (Walker et al., 1961). 

The life span of longjaw mudsucker is about 2 years (Walker et al., 1961; Love ,1996). They 

become sexually mature and may spawn in their first year, when they are 25 to 51 mm (1 to 

2 in.) long. Longjaw mudsucker are multiple spawners and have been documented spawning 

2 to 3 times a year (Walker et al., 1961; Wang, 1986). Spawning activity peaks in the spring but 

may commence as early as November (in San Francisco and Tomales bays) and extends through 

July (Barlow and De Vlaming, 1961; Wang, 1986; Love, 1996). The timing of spawning is 

controlled by environmental cues such as seasonal changes in light and temperature (Moyle and 

Cech, 1988). Females are oviparous and lay from 4,000 to 9,000 adhesive, club-shaped eggs 

which are attached to the sides ofthe burrow with central stalks (Weisel, 1947). Barlow (1961) 

reported longjaw mudsucker laying between 8,000 and 27,000 eggs. The eggs are guarded by 

males during their 10 to 12 day incubation period (at 18° C [64° F]) (Weisel, 1947; Wang, 1986). 

Larvae are pelagic and 3 to 4 mm (0.12 to 0.16 in.) TL at hatching (Wang, 1986). They occur at 

all levels within the water column (Barlow, 1963; Wang, 1986). Because of heavy pigmentation 

observed in post-larvae as small as 8 to 12 mm (0.31 to 0.47) TL, the pelagic larval phase of the 

longjaw mudsucker is thought to be short in comparison to the pelagic phase of sympatric goby 

larvae (Barlow, 1963). Depending on local hydrographic conditions, larvae can be dispersed 

E9-053.9 4-69 MLPP 316(b) Resource Assessment 

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1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

H 

4.0 Entrainment and Source Water Results 

over a wide geographic area or remain relatively concentrated near their natal habitats. Larvae 

settle out at 8 to 12 mm in length (0.31 to 0.47 in.) and begin to develop dense pigmentation 

(Wang, 1986). 

The growth rate of young longjaw mudsucker is rapid but varies seasonally. Fitch and Lavenberg 

(1975) provided a growth rate for the first year of life of 12.7 cm/year (5 in.; or 0.338 mm/day). 

A 20 day larval duration was estimated based on a settlement size of 10 mm and hatch size of 3.5 

mm (Wang 1986) using the growth rate of 0.338 mm d-1 calculated from 127 mm growth in the 

first year (Fitch and Lavenberg, 1975). Larval mortality was assumed to be 99 percent over the 

larval period. Larval lengths ranged from 2.7 to 4.7 mm (mean 3.86 mm) using the center 98 

percent of measured lengths. Survival to entrainment was estimated using age 3.4 d, based on 

growth from the smallest ofthe 98 percent interval to mean length, as (1-0.99)3.4/20 = 0.455. 

Walker et al.(1961) found that the highest growth rates in the Salton Sea population occurred 

during the hot summer months. By August the modal size of the sampled young-of-the-year 

(YOY) population had reached a standard length (SL) of 60 to 80 mm (2.4 to 3.2 in.) (Walker et 

al., 1961). Growth rates had slowed by December with the modal size of yearling goby ranging 

from 80 to 115 mm SL (3.2 to 4.5 in.) (Walker et al., 1961). Males were observed to grow 

slightly faster than females (Walker et al., 1961). Longjaw mudsucker are carnivorous and 

juveniles feed on a variety of invertebrates and occasionally on small fishes. Their diet includes 

harpacticoids and other copepods, nematodes, and fly larvae of the Family Heliidae (Walker et 

al., 1961; Wang, 1986). Much of their diet as adults is composed of crustaceans such as crabs 

and ghost shrimp (Love, 1996). In the Salton Sea, the most important food of adult mudsucker 

was the pile worm Neanthes spp., although they also consumed barnacles, a variety of insect 

larvae, and an occasional Desert pupfish (Walker et al., 1961). Longjaw mudsucker are preyed 

upon by a variety of birds and fishes. 

Longjaw mudsucker are considered excellent bait and are used in a variety of recreational 

fisheries. They are considered one of the best baits to use for corvina Cynoscion xanthulus in the 

Salton Sea (Walker et al., 1961). Most mudsuckers used for bait are captured in cylindrical 

minnow traps. A small commercial bait fishery exists for longjaw mudsucker in the San 

Francisco Bay Estuary and Delta to supply the needs of striped bass fishermen. Annual landings 

of longjaw mudsuckers, reported in the CDFG CMASTER database, are generally small. 

Between 1987 and 1996, state-wide landings ranged from 10 pounds in 1994 to 557 pounds in 

1987. No landings were reported in 1990 or 1991. Other sources have reported mean annual 

catches for the live-bait industry to be around 14,000 pounds. 

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4.0 Entrainment and Source Water Results 

4.9.1 Longjaw Mudsucker Gillichthys mirabilis Results (1.2 percent) 

Longjaw mudsucker comprised 1.2 percent of the total numbers of larval fishes collected in 

entrainment surveys at the new CC units intake (Figure 4-1). They were collected in all 

entrainment surveys from March 2,1999 through February 24, 2000 (Figure 4-29). Peak 

concentration (43/1,000 m3) occurred on November 4,1999 and the lowest concentration 

(1.5/1,000 m3) occurred on March 8, 1999. 

Longjaw Mudsucker Entrainment Mean Concentration 

*£ 35 

C 30 

25 

a mm 

iifff«{«fjjff!;srfc££ f 

-r» w - N tt ^ i .1. <!, - -r* H li H 1* ' L • u» • 

iiiillltltiitiii i 

a 8 

3 » S 8 

S 2 8 -* a o» I - S : Iii B 8 

Figure 4-29. Mean survey concentrations (#/l,000 m3) of larval longjaw mudsucker at the Moss Landing 

Power Plant new combined-cycle units intake: March 1999 through February 2000. 

E9-053.9 4-71 MLPP 316(b) Resource Assessment 

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4.0 Entrainment and Source Water Results 

The diel distributions were plotted for concentrations of larval longjaw mudsucker collected in 

front of the new combined-cycle units intake from June 1999 through February 2000 (Figure 4-

30). We analyzed only the entrainment surveys that coincided with the source water surveys. 

The diel concentrations of larval longjaw mudsucker varied between night and day. The highest 

concentrations occurred at night in the September 1999 through January 2000 surveys (Figure 4-

30). The highest concentrations occurred in daylight hours during the June and August 1999 and 

February 2000 surveys. Concentrations were nearly equal between nighttime and daytime 

during the July 1999 survey. 

Longjaw Mudsucker Larval Entrainment Diel Mean Concentration 

J <o 

1 I II 1 ll. 

1 

1 1 

1 

I II 1 1 III. : « " 

s s " 

Jun 17 

3 3 3 ' 

Aug 12 

t a « " 

Sep 16 

= ; : » 

8 8 5 « 

~ i : a r 

= 8 8 S " 

Dec 29 Jan 20 

: : 3 

tt s : 

Feb 24 

Note: These entrainment surveys were conducted coincidentally with source water surveys. 

Figure 4-30. Concentrations (#/l,000 m3) of larval longjaw mudsucker at the new combined-cycle units 

intake separated by sample collection time (PST): June 1999 through February 2000. 

Longjaw mudsucker comprised 5.1 percent of the total larval fishes collected in the Elkhorn 

Slough area, 1.6 percent in the Moss Landing Harbor area, and less than 1 percent in the Ocean 

area from June 1999 through February 2000 (Figure 4-4). Longjaw mudsucker were collected in 

all surveys (Figure 4-31). The peak high tide concentration (272/1,000 m3) occurred at Kirby 

Park in July 1999. The peak low tide concentration (219/1,000 m3) occurred in February 2000 at 

Kirby Park. Longjaw mudsucker larvae were only collected twice (at Ocean South during high 

tide in November 1999 and at Ocean South during a low in January 2000) from the two stations 

located in Monterey Bay. 

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4.0 Entrainment and Source Water Results 

Longjnr MudsuclcerSoui'ce Watar Mean Concentration 

E 100 

5 10 

s 

• High 

• Low 

000 000 000 

I -

Jul 12 Aug 12 Sep 16 Oct 14 Nov 18 Dec 29 Jan 20 Feb 24 

Key—KP: Kirby Park; D: Dairies; HB: Harbor Bridge; HM: Harbor Mouth; ON: Ocean North; OS: Ocean South 

•$> Stations not included in study design until September. 

® Samples voided due to improper preservation. 

Figure 4-31. Source water concentrations (#/l,000 m3) of larval longjaw mudsucker at six 

stations near Moss Landing Power Plant: June 1999 through February 2000. 

All longjaw mudsucker larvae collected from the source water surveys and the new combinedcycle intake surveys that corresponded to source water surveys (referred to as paired surveys) 

were measured. The length frequency distribution of longjaw mudsucker larvae was similar 

throughout the source water study area. The generally uniform length of larvae among the 

various sampling locations, as shown in Figure 4-32, provides little insight into hatching sites 

based on larval stage. Although the sample size of length-frequency varied with concentrations 

of larvae among source water sampling locations, the shorter longjaw mudsucker larvae appear 

to be missing from samples collected both the at the Harbor Bridge and Harbor Mouth stations. 

This slight pattern of shorter to longer larval length from the upper slough to Monterey Bay 

would point to the inner slough and marshes as a larval source. A much stronger pattern of 

decreasing concentration of longjaw mudsucker larvae from upper slough to the Monterey Bay 

also points to the slough and marshes as a primary source of longjaw mudsucker larvae. This 

conclusion is consistent with our knowledge of the species' preferred spawning habitat. 

E9-053.9 4-73 MLPP 316(b) Resource Assessment 

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12 

10 

•o 

£ 6 

o 

V 

xt 

E 

• Kirby Park 

• Dairies 

• Harbor Bridge 

D Harbor Mouth 

• CC Units Intake 

£ u HI 

4.0 Entrainment and Source Water Results 

Longjaw Mudsucker Length Frequency 

II 1 u 

3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 

Length (mm) 

Figure 4-32. Length frequency of all larval longjaw mudsuckers Gillichthys mirabilis measured 

(n=180*) by source water and intake sampling locations (June 1999 through January 2000). 

, 1 

*CC Units intake: N = 47; source water surveys: N = 133 

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4.0 Entrainment and Source Water Results 

Longjaw Mudsucker Length Frequency Vs Tide 

Individual umber of 

0 -

• Low Tide 

D High Tide 

1 1 

nil i 11-

n 

n •" 

1 I ( j. .n , 

3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 

Length (mm) 

Figure 4-33. Length frequency of all larval longjaw mudsuckers Gillichthys mirabilis measured 

(n=180*) by high and low tide stage (June 1999 through January 2000). 

*CC Units intake: N = 47; source water surveys: N = 133 

The length frequency of all longjaw mudsucker larvae from paired surveys is shown in 

Figure 4-33 plotted along with length frequency of source water specimens collected at high and 

low tide stages. Tidal stage appears to have no relationship to larval stage. Differences in the 

individual length of specimens were slight ranging from 2.5 to 5.5 mm; the majority of 

specimens were between 3.4 and 4.5 mm. All of the individual lengths of longjaw mudsucker 

larvae collected in paired surveys are plotted by survey in the Figure 4-34 scattergram. Looking 

at Figure 4-34 for periods of large numbers of smaller individuals followed by periods of fewer 

and larger individuals to indicate a hatching event, it is possible that cohorts of longjaw 

mudsuckers hatched in July and September 1999. However the patterns are slight, and the 

increase in length between surveys appears to be less than expected based on growth rate in a 

single cohort. It is more likely that hatchings occurred throughout the summer and fall months, 

and the residual fraction of each previous pulse blended into the peaks of newly hatched larvae. 

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4.0 Entrainment and Source Water Results 

6.00 

5.00 

4.00 

3.00 

2.00 

1.00 

O.OO 

05/20/99 

Longjaw mudsucker Length Vs Time 

« 

( 

• 

) 

• 

• 

• 

• 

• 

• 

• 

• 

i 

• 

• 

• 

• 

i 

* 

• 

• 

• 

• 

• 

# 

I 

• 

r 

j i 

\ } 

07/09/99 08/28/99 10/17/99 12/06/99 01/25/00 03/15/00 

Figure 4-34. Scattergram plot of larval longjaw mudsuckers Gillichthys mirabilis lengths measured 

(n=180*) by source water survey date (June 1999 through January 2000). 

*CC Units intake: N = 47; source water surveys: N = 133 

Longjaw mudsucker larvae were entrained throughout the study period (November 1978 through 

March 1980) during the first entrainment study. The peak concentration (150/1,000 m3) 

occurred at Units 1 through 5 in September 1979. 

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4.0 Entrainment and Source Water Results 

4.10 Pacific Herring 

^4 

i'!' '^WWW'Wiiini-*! „. 

Clupea pallasi 

Range: From northern Baja Califomia to Toyama Bay, 

Japan, westward to the Yellow Sea. 

Life History: Size: Up to 46 cm (18 in.) and 550 g 11.2 

lb); Age at maturity: two to three years old; Fecundity: 

4.000 to 130,000 eggs; Life Span: Alaska- to nineteen 

years, California- to eleven years. 

Habitat: A schooling species found near shore to 

hundreds of miles off shore; spawns in intertidal and 

sub-tidal zones. 

Fishery: Commercial: valuable roe fishery; 

Recreational: small pier and shore angler fishery. 

Distribution Map for Pacific Herring 

Pacific herring belong to the Order Clupeiformes which contains some of the world's most 

numerous and economically important fishes (e.g., herring, sardine, anchovy). The overall 

distribution of the Pacific herring extends from Baja California to the north Pacific and westward 

to Japan and the Yellow Sea (Miller and Lea, 1972). In North America, Pacific herring range 

from Baja California north to arctic Alaska (PSMFC, 1999); they are most abundant off Alaska 

and British Columbia. In California, most of the populations are found in the San Francisco and 

Tomales bay areas (Fitch and Lavenberg, 1975). Pacific herring are found from very nearshore 

areas to hundreds of miles off the coast (Love, 1996). 

Pacific herring are small, streamlined marine fishes, measuring up to 46 cm (18 in.) in length and 

weighing up to 550 g (1.2 lb) (PSMFC, 1999). These slender fish are silvery below and bluishgreen to olive above (Love, 1996). Pacific herring stocks living in the waters off of Alaska and 

Canada tend to grow larger and live longer than the herring off California. In Alaska, herring 

have been aged to nineteen years old and can measure 38 cm (15 in.) in length. Pacific herring 

in California may live to eleven years of age and rarely exceed 30.5 cm (12 in.) in length (Fitch 

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1 

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• 

4.0 Entrainment and Source Water Results 

and Lavenberg,. 1975). California Pacific herring reach maturity at 2 to 3 years of age and at a 

length of 16.5 to 17.8 cm (6.5 to 7 in.) (Love, 1996). 

Pacific herring exhibit important behavioral characteristics such as schooling and diurnal (daily) 

vertical movement. A school starts to form when a young juvenile approaches the tail of another 

juvenile; both vibrate rapidly, and begin swimming together. The school increases in size as 

other fish join, and soon a steady schooling pattern emerges. A school behaves as an individual 

organism, tightening into a ball when threatened or spreading out when approaching shallow or 

surface waters. Single schools of herring have been estimated to include many millions of 

individuals (Svetovidov, 1963). There is a size limit for individuals within a school; the 

difference between the smallest and largest herring members is approximately 50 percent, The 

fishes above or below the size limit break away and form new schools. The depths at which 

herring swim are related to plankton movement, light intensity, temperature, and breeding 

condition (Svetovidov, 1963). Most herring are believed to stay in deeper water during the day 

and then make a vertical migration from 300 to 400 m (985 to 1,312 ft) toward the surface at 

night. These diurnal movements correspond to the movement of plankton and also to 

temperature, as the fish move from deep colder waters to warmer surface waters. 

The spawning activity of Pacific herring is largely influenced by their geographical location. In 

California, spawning is known to occur in San Diego Bay, San Luis River, Morro Bay, Elkhorn 

Slough, San Francisco Bay, Tomales Bay, Bodega Bay, Russian River, Noyo River, Shelter 

Cove, Humboldt Bay, and Crescent City Harbor (Leet et al., 1992). Fish begin entering 

protected coastal bays, estuaries, and shallow nearshore environments approximately two months 

prior to spawning (Eldridge, 1977). In the Moss Landing and Elkhorn Slough area, spawning 

takes place from November through July (Hardwick, 1973). Most spawning occurs during the 

winter, but a small, noticeable peak occurs from June to July. The southern Pacific herring 

populations are able to spawn in warmer water temperatures (18° C [64.4° F]) than the Canadian 

stocks (a maximum observed spawning temperature of 10° C [50° F]) (Alderdice and Velson, 

1971). 

The majority of spawning habitat is near vegetation in shallow waters ranging from the mean 

low-tide level to a depth of approximately 4 m (13 ft). The substrate of the spawning grounds 

tends to be clean, hard, and covered with gravel. Other substrate may include rocks, pilings, and 

jetties. A soft, muddy bottom may be used if a vegetative cover is available. Males and females 

spawn simultaneously over a period of 1 to 7 days (Miller and Schmidtke, 1956). The fertilized 

eggs, broadcast mostly at night, are adhesive and commonly attach to eelgrass, algae, and other 

intertidal vegetation (Hardwick, 1973). Thousands of females repeatedly deposit their eggs on 

the vegetation, which can result in egg masses from 10 to 15 layers thick (about 5 cm [2 in.]) 

(Love, 1996). In large spawning runs, a 9-m (30-foot) wide band of herring eggs may span a 

distance of 20 miles along the shoreline (Leet et al., 1992). In Elkhorn Slough, Pacific herring 

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4.0 Entrainment and Source Water Results 

are known to broadcast eggs on Salicornia spp. (pickleweed), a brackish marsh vegetation 

(Wang, 1986). Females are capable of spawning only once per season, and after producing 

between 4,000 and 130,000 eggs, they promptly return to the ocean, leaving the eggs to incubate 

and hatch. The rate of egg development varies with surrounding water temperature; Pacific 

herring eggs commonly hatch within 10 to 14 days at 11.8° to 13.5° C (53.2° to 56.3° F) (Wang, 

1986). Their salinity tolerance range is 8 to 18 ppt and seems to have no effect on egg 

development (Fitch and Lavenberg, 1975). 

Shortly after hatching, and as the eyes become pigmented, the threadlike larvae move toward the 

surface waters. They tend to concentrate near the surface and remain for a long time in the area 

ofthe spawning grounds. Some larvae, however, have been found several miles out to sea, 

drifting with the currents (Fitch and Lavenberg, 1975). It takes about 70 days (Hay, 1985) (when 

larvae are approximately 26 mm TL [1.0 in.]) for the larvae to metamorphose. Metamorphosis is 

complete by 35 mm TL (1.38 in.) (Stevenson, 1962). Juveniles, depending on geographical 

region, range from 35 to 150 mm TL (1.38 to 5.9 in.) (Reilly, 1988). 

Herring usually reach maturity in 2 to 3 years in California and 3 to 4 years in Washington (Hart, 

1973). Pacific herring are pelagic, and while some may remain in the bays and estuaries, most 

leave and return to the ocean (Eldridge, 1977). At all life stages Pacific herring are plankton 

feeders, primarily selecting copepods, amphipods, fish larvae, and mollusks. They do not feed 

during the spawning season, but feed intensively in the summer after spawning. 

Pacific herring are a well described species with both age-and stage-specific mortality estimates 

available from the scientific literature. Egg mortality has been estimated to range from 20 

percent (Hourston and Haegele, 1980) to as high as 99 percent (Hardwick, 1973; Leet et al., 

1992). Larval mortality can also be derived from the literature and is assumed to be 99 percent 

through settlement (survivorship = 0.221). Data on larval age and growth (e.g., Stevenson, 1962; 

Alderdice and Hourston, 1985) are also important for estimating survivorship. Total adult 

mortality has been estimated as about 50 percent annually (z = 0.69) by Hourston and Haegele 

(1980). Estimates of natural adult mortality (m) are in close agreement from a variety of studies: 

m = 0.4 - 0.5 (Trumble and Humphreys, 1985), m = 0.39 (Fried and Wespestad, 1985), m = 0.36 

(Schweigert and Hourston, 1980), m = 0.56 (Gunderson and Dygert, 1988), and m = 0.31 - 0.71 

(Stocker et al., 1985). 

Pacific herring are an important species in the food chain and are fed upon, at all life stages, by 

many other species including ctenophores (comb jellies), chaetognaths (arrow worms), salmon, 

lingcod, sharks, seabirds, and marine mammals. Pacific herring are also sought after by man for 

food, bait, and roe. In addition to predation, they are also subject to being carried out of 

protective bays and estuaries into areas with little or no food supply. Despite the severe 

E9-053.9 4-79 MLPP 316(b) Resource Assessment 

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4.0 Entrainment and Source Water Results 

mortality rate, the recruitment of Pacific herring remains high due to their extremely high 

fecundity, their distribution, and early age of maturity. 

The harvest of Pacific herring is a multi-million dollar industry in the United States, with most of 

the fish coming from Alaska, Washington, and California. The Pacific herring fishing industry is 

highly regulated north of San Francisco Bay. There are small fisheries in the Monterey and San 

Francisco area that target Pacific herring for bait and food, but the more valuable fishery 

involves herring eggs (roe). There is a very lucrative export market for herring roe, especially 

for kazunoko kombu (roe-on-kelp) which is considered a delicacy in Japan. There are a limited 

number of permits issued for this fishery in San Francisco Bay. Large amounts of giant kelp, 

transported from the Channel Islands, are suspended from rafts, which are then anchored in the 

Pacific herring spawning grounds. At the end ofthe spawning period, divers collect the kelp and 

attached eggs, pack it in salt and export the high priced product to Japan. Commercial landing 

information on Pacific herring, sac-roe, and roe-on-kelp is shown in Figure 4-35a and b. 

(a) 

• ; 25 , 

| 20 -

1

 15" 

I 10 -

? 5 -

3 

° 0 Q.

 U H I 987 

Pacific Herring and Sac-Roe Landings 

llllh •ill. 

ooo>o<-c\ic*><'tn<or^c o flooocncno>o>c*oci>c,

oo)cn cncncooicDcbcAcnocnc n 

g Pacific Herring 

fl Herring Sac-Roe 

(b) 

a : 

•o 400 , 

c 

S 300 -

3 

| 200 -

» 100 -

3 0 -

o 

a 

1987 • 1988 j 1989 M 

Roe-on-Kelp Landings 

O v CM CO ^ w 

Oi Oi Oi Oi Oi Oi 

Oi Oi Oi Oi Oi Oi 

1 1996 1 1997 

• 1998 

gRo e on Kelp 

Source: CDFG Landing Tables. 

Figure 4-35. (a) Pacific herring, sac-roe and (b) roe-on-kelp California state-wide landings: 1987 through 

1998. 

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4.0 Entrainment and Source Water Results 

4.10.1 Pacific herring Clupea pallasi results (0.9 percent) 

Pacific herring comprised 0.9 percent of the total numbers of larval fishes collected in 

entrainment surveys at the new CC units intake (Figure 4-1). They were collected in all 

entrainment surveys from March 2, 1999 through June 24,1999 and again in August, October 

and December 1999 from the new CC units intake (Figure 4-36). They were collected in low 

concentrations in the August 31 (2/1,000 m3), October 28 (8/1,000 m3), and December 2, 1999 

(2/1,000 m3) entrainment surveys. No Pacific herring larvae were collected during the July, 

September, and November 1999 surveys. They were collected again each week beginning on 

January 20, 2000 through February 24, 2000. The highest concentration (110/1,000 m3) occurred 

on February 3, 2000. 

Pacific Herring Entrainment Mean Concentration 

120 

| 40 

S 

1.1,1,1.1,1,1, .L.lll ,—,—,—,_•.,—,—, A........... m ,I, M ,—T-B-JLTJ ill 

fftfi**1*ftfttitt**lm'tmt*i.f1t1111iiitiii i 

«

 s s ' B 8 r ti 8 = B « - 8 S i 5 j i 8 - m i jj - S 5 jj g - • 

= r. S 

8 S 8 

Figure 4-36. Mean survey concentrations (#/l,000 m ) of larval Pacific herring at the Moss Landing 

Power Plant new combined-cycle units intake: March 1999 through February 2000. 

The diel distributions were plotted for concentrations of Pacific herring larvae collected in front 

ofthe new combined-cycle units intake from June 1999 through February 2000 (Figure 4-37). 

Pacific herring larvae were not collected in the July 1999 through November 1999 entrainment 

surveys that coincided with the source water surveys. Peak concentrations occurred during the 

daytime in June 1999 and February 2000. In December 1999 peak concentration occurred at 

2224 hours PST, and in January 2000 they were only collected at 1830 hours PST. 

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4.0 Entrainment and Source Water Results 

Pacific Herring Larval Entrainment Diel Mean Concentration 

E 60 

1 

11 II 1 1 1 

III 

i - =* S 8 

Jun 17 Oct 14 

l!8K--SSKS B 3 «BSS» a 

Jul 12 Aug 12 Sep 16 Dec 29 Jan 20 Feb 24 

Note: these entrainment surveys were conducted coincidentally with source water surveys. 

Figure 4-37. Concentrations (#/l,000 m3) of larval Pacific herring at the new combined-cycle units 

intake separated by sample collection time (PST): June 1999 through February 2000. 

Pacific herring larvae comprised 10.9 percent ofthe larval fish taxa collected in the Elkhorn 

Slough area, less than 1 percent in both the Moss Landing Harbor and Ocean areas. They were 

not collected at any source water stations in August, September, October, and November 1999 

(Figure 4-38). The peak concentration occurred at Kirby Park during low tide in February 2000 

(1,815/1,000 m3). The peak high tide concentration (1,127/1,000 m3) also occurred at Kirby 

Park in February 2000. 

Entrainment data showed two spawning periods for Pacific herring during the first entrainment 

study (PG&E, 1983). Pacific herring larvae were entrained between May 1979 and early August 

1979 and again from December 1979 through March 1980 (Figure 4-38). The peak 

concentration (460/1,000 m3) occurred at Units 1 through 5 in January 1980 (PG&E, 1983). Peak 

concentrations from the previous entrainment study (PG&E, 1983) occurred at Units 1 through 5 

in January 1980. 

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f 

I 

m 

I 

1 

4.0 Entrainment and Source Water Results 

i 

4«HH R©©k Orab s FsiinnioDy Csionerodlaie 

Rock crab are decapod Crustacea belonging to the infraorder Brachyura and Family Cancridae. 

Four commercially important crab species, the dungeness crab Cancer magister, the Pacific or 

brown rock crab Cancer antennarius, the red rock crab Cancer productus, and the yellow rock 

crab Cancer anthonyi inhabit overlapping ranges along the Pacific Coast of North America. The 

four species occur sympatrically. However, the relative abundance of each differs 

geographically (Carroll and Winn, 1989; Jensen, 1995). Along the coast of California red rock 

crab and dungeness crab are more common in the north, yellow rock crab in the south, and the 

brown rock crab is generally more abundant in the central regions of the state (Carroll and Winn, 

1989; Parker, 1992). Rock crab inhabit a variety of substrata including rock, gravel, sand, sandysilt, and mud (Winn, 1985; Carroll and Winn, 1989). All four species occur in the low intertidal 

zone. However, the maximum depth range reported for each differs (Morris et al., 1980; Carroll 

and Winn, 1989; Jensen, 1995). The first stage zoeae of slender rock crab Cancer gracilis were 

collected in Elkhorn Slough and in offshore waters of Monterey Bay which suggested that adult 

females used the area for spawning (Hsueh, 1991). 

The carapaces of rock crab are broad and generally oval in shape, however the proportions and 

dorsolateral shape varies species to species. The margin of the anterior half of the carapace of 

each species is lined with an equal number of teeth (anterolateral teeth) on each side of the body. 

The characteristics (number, relative size, or appearance) of these teeth are different in each 

species (Schmitt, 1921; Carroll and Winn, 1989). The dorsal and ventral coloration of the 

exoskeleton also varies between the species (Carroll and Winn, 1989). All three species have 

dark-tipped claws. Adult rock crabs are sexually dimorphic with males attaining a larger size 

and growing larger, more robust chelae (claws). The shape of the abdominal flap of a rock crab, 

as with all brachyura, is the most definitive external sexual characteristic. In males the 

abdominal flaps are slender and narrow to a point while those of females are broad and rounded. 

Details of the reproductive behavior of rock crabs have not been well documented in literature, 

but are thought to follow a pattern similar to other cancrid crabs. Mating only occurs 

immediately after a female ecdysis (molt), when she is in a soft-shelled condition (Carroll and 

Winn, 1989). A male rock crab, stimulated by pheromones released from the female before she 

molts, will locate and "embrace" the female in a face-to-face position (Carroll and Winn, 1989; 

Jensen, 1995). This embrace continues through molting, insemination, and the initial hardening 

of her exoskeleton (Carroll and Winn, 1989). During the insemination phase, the male inserts his 

gonopod (paired pleopods) into the spermatotheca of the female and deposits a spermatophore 

(Carroll and Winn, 1989; Jensen, 1995). The sperm contained in the spermatophore can be 

viable for more than a year and may be used by the female for multiple spawnings (Carroll and 

Winn, 1989). Following mating the spermatophore hardens to form a plug that closes off the 

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spermatotheca and is thought to prevent further mating by the female (Carroll and Winn, 1989; 

Jensen, 1995). Fertilization occurs internally as the eggs are being extruded (Carroll and Winn, 

1989). Egg extrusion occurs about 11 weeks after mating and the female carries the egg mass 

under her abdominal flap (attached to setae on the endopodites of the pleopods) until the eggs 

hatch (Carroll and Winn, 1989). Ovigerous, or "berried" females are found throughout the year 

however their season of peak abundance varies somewhat from species to species (Toole, 1985; 

Winn, 1985; Reilly, 1987; Carroll and Winn, 1989). Variations in the size of a female's egg 

mass occur between individuals and species (Carroll and Winn, 1989). 

Information on the time required for egg development and hatching is not available for red rock 

crabs, however literature suggests that water temperature is an important variable for brown and 

yellow rock crabs (Anderson and Ford, 1976; Carroll, 1982). As with all decapod crustaceans, 

growth in rock crabs is an incremental process occurring only at the time of molting. Newly 

hatched larvae (prezoeal stage) molt to a first stage zoea in less than an hour (Carroll and Winn, 

1989). Larval rock crabs undergo a series of 5 zoeal molts (size changes) and one megalopal 

molt before they bear any resemblance to the adults. Zoea and megalops are pelagic and are 

widely dispersed by wind and currents over the continental shelf (Carroll and Winn, 1989). 

Juvenile crabs begin to settle out of the water column (following the megalopal molt) during the 

late spring and summer (Winn, 1985). 

Molting events separate the various post-larval stages, or instars, in the life of a crab. Because of 

their rigid exoskeleton, increases in the body dimensions of a crab can occur only after molting. 

Rock crab growth is characterized as indeterminate because molting and growth progress 

indefinitely (no terminal molt) until the animal dies. The period of time between molts 

(intermolt period) lengthens as the size of an animal increases and the proportional growth 

(width and weight increase) from each molt tends to decrease (Carroll, 1982; Carroll and Winn, 

1989). Water temperature is among the factors reported to have an effect on the growth rate of 

post-larval crabs (Anderson and Ford, 1976). While animals up to 76 mm (3 in.) carapace width 

(CW) may molt 2 or more times in a year, the intermolt periods of crabs in their later instars may 

last 16 months or longer (Carroll, 1982; Parker, 1992). The maximum age attained by each of 

the rock crab species is not well defined in literature but estimates (based on size and growth 

curves) suggest that some individuals may live for at least 6 years (Carroll, 1982; Carroll and 

Winn, 1989). 

Rock crabs are generalist carnivores and assume the role of both a predator and a scavenger. 

They actively forage for a variety of sessile and mobile animals including snails, clams, 

echinoderms, and crustaceans (Carroll and Winn, 1989). Because of their powerful chelae 

(claws), adult rock crabs have the ability to crush and consume a thick-shelled mollusks 

(gastropods and bivalves) like cockles Protothaca staminea (Boulding, 1984; Boulding and 

LaBarbera, 1986), mussels Mytilus spp. (Smith and Palmer, 1994; Dugan, pers. obs., 1997), and 

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4.0 Entrainment and Source Water Results 

abalone Haliotis spp. (Schiel and Welden, 1987). They also consume crustaceans such as hermit 

crabs (Morris et al., 1980; Ricketts et al., 1985), barnacles Balanus spp. (Ricketts et al., 1985), 

and a variety of crab species including smaller, or newly molted (soft), rock crabs. Cannibalism 

has been observed in the closely related dungeness crab (Gotshall, 1977). Food preferences 

during laboratory culture indicate that rock crabs are active planktivores during their larval 

stages (Rumrill et al., 1985). Rock crabs also have a highly developed ability to sense the 

presence of food in the vicinity (Carroll and Winn, 1989). Amino acid concentrations as low as 

10 " n moles/liter can be detected by the animals olfactory apparatus (Fuzessery and Childress, 

1975). 

Rock crabs are vulnerable to predation throughout their lives. However, the risk is greatly 

diminished in adult crabs. A host of planktivorous fishes and invertebrates consume pelagic rock 

crab larvae. As juveniles, rock crabs are preyed upon by a variety of fishes as well as some 

invertebrate species. The scorpionfish Scorpaena guttata, cabezon Scorpaenichthys 

marmoratus, barred sand bass Paralabrax nebulifer, and a number of rockfish species Sebastes 

spp. are among the many piscine predators ofjuvenile rock crabs (Turner et al., 1969; Roberts 

et al., 1984; Winn, 1985, Carroll and Winn, 1989). The sand star Astropecten verilli is known to 

prey on juvenile yellow rock crabs (Van Blaricom, 1978, 1982). One of the primary predators of 

adult rock crabs is the southern sea otter Enhydra lutris (Carroll, 1982; Benech, 1986). Rock 

crab are also a favored prey item of octopi (Ambrose, 1984) and are consumed by some shark 

species (Talent, 1982). Larger rock crabs are vulnerable to predation by fishes and to 

cannibalism during the "soft-shelled" period following a molt (Knowles and Carlisle, 1956; 

Carroll, 1982). 

Rock crabs have not been the focus of a dedicated commercial fishery until relatively recently. 

Historically they were considered bycatch in trap fisheries targeting more valuable species and 

were either thrown back into the sea or left on the shore to die (Dahlstrom and Wild, 1983; 

Winn, 1985). Small rock crab landings have been reported since at least the 1930's, however, a 

separate market category was not established for the group until 1950 (Parker, 1992). Annual 

rock crab landings of around 20,000 pounds were reported in 1950 (Heimann and Carlisle, 1970; 

Carroll and Winn, 1989; Parker, 1992). The fishery grew at an annual rate of about 10 percent 

from the late 1950s until 1971 (Parker, 1992). Landings nearly doubled in 1972 and by 1975 had 

surpassed 1 million pounds for the first time (Parker, 1992). State-wide landings from 1979 

through 1998 and landings from Monterey Bay ports from 1986 through 1998 are shown in 

Figure 4-39. During the past two decades rock crab landings have averaged over 1.3 million 

pounds annually (Figure 4-39) (CDFG Landing Summaries, 1979-1998). Commercial 

fishermen generally receive around $1.00 per pound for whole, live rock crab (Parker, 1992). 

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(a) 

Landing s of all Rock Crab Marke t Categorie s in California (1979 through 1998) 

2,000,000 

1,800,000 

M 1,200,000 

•o 

c 

0. 800,000 

600^000 

400,000 

200,000 

o> © •>- cy co •** m to h- ooo)0-*-wco^»ntDr-o o 

I

s- 00 CD COCOC O COCOC O CO CO OJ Oi O O Oi Oi Oi Oi Oi 

Oi Oi Oi Oi Oi O) Oi Oi O OiOiOiOlOiOiOiOiO i Oi Oi 

Year 

(b) 

Rock crab landings in Montere y Bay Ports (1986 through 1998) 

1 

1 

1 

i 

i 

40,000 , 

35,000 • 

30,000 -

25,000 -

•o 

§ 20,000 • 

o 

a 

15,000 -

10,000 • 5,000 -

•g Santa Cruz 

| Monterey 

QMOSS Landing 

11 Ll 

I ltl-"i i • M | • Bill—, J 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 

Year 

Source: CDFG Landing Summaries 1979-1998. 

Figure 4-39. (a) California state-wide landings (lbs) of rock crabs (includes the rock crab market 

categories of unspecified rock crabs, brown rock crab, red rock crab, and yellow crab): 1979 through 

1998. (b) Ports of Monterey Bay landings (lbs) ofthe market category "Unspecified Rock Crab": 1986 

through 1998. 

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In addition to landings of whole rock crab, rock crab claws are landed by gillnet fishermen who 

catch them incidentally, de-claw them and return them to the ocean. While rock crab claws were 

included in the crab claw market category, the majority of landings were composed of the claws 

of sheep crab Loxorhynchus grandis (D. Parker, CDFG, pers. comm.). Estimates of the 

percentage of rock crab claws in these landings are not available. Crab claw landings have 

declined significantly since the early 1990s when depth restrictions for gillnet use went into 

effect. 

The species composition of landings of whole rock crabs is not available because they have 

historically been landed in a combined market category (Unspecified Rock Crab) and not 

separated by species; some separation by species has occurred since 1995. However, the bulk of 

the landings are still grouped into the "Unspecified Rock Crab" market category. Trapping 

studies have provided some insight into variations in the seasonal abundance of each species and 

regional differences in species composition (Selby, 1980; Carroll, 1982; Carroll and 

Winn, 1989). 

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4.12 Hairy Rock Crab Cancer jordani 

Cancerjordani 

Picture to come 

Range: From Neah Bay, Washington to Bahfa de 

Tortuga, Baja California. 

Life History: Size: males up to 39.3 mm (1.5 in.); 

females to 19.5 mm (0.7 in.); Size at maturity: no 

information available; Fecundity: no specific 

information available; life span: no estimate available. 

Habitat: Under rocks in shallow bays, subtidally in kelp 

holdfasts; intertidally to depths of 104 m (340 ft). 

Fishery: No commercial or recreational fishery. 

Distribution Map for Hairy Rock Crab 

The hairy rock crab is one of the smallest members of the Family Cancridae. The species ranges 

from Bahfa de Tortuga, Baja California, Mexico to Neah Bay, Washington, although it is rare 

north of Coos Bay, Oregon (Jensen, 1995). Hairy rock crab occur from the intertidal zone down 

to depths of 104 m (340 ft) (Garth and Abbott, 1980). They are most often observed under rocks 

in the shallow waters of bays, but may also be found subtidally in the holdfasts of kelp. In 

Monterey Bay, up to 78 hairy rock crab have been documented per m2 of kelp holdfast (Garth 

and Abbott, 1980). 

The carapace of the hairy rock crab is similar in shape to other cancer crabs and has a smooth but 

somewhat irregular surface. The legs and dorsal surface of the carapace are covered with hair. 

The hairy rock crab may be confused with juvenile brown rock crab C. antennarius, which often 

have a hairy appearance (Carroll and Winn, 1989). Another small cancer crab, the furrowed rock 

crab Cancer branneri, also has hair covering its carapace and legs. Hairy rock crabs do not have 

the red ventral spotting present in juvenile C. antennarius (Carroll and Winn, 1989). The species 

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also has ten teeth lining the anterior margin of the carapace, instead of nine as in C. antennarius 

(Garth and Abbott, 1980). The anterolateral teeth of hairy rock crab are sharp and strongly 

curved, and are alternately large and small (Garth and Abbott, 1980; Carroll and Winn, 1989; 

Jensen, 1995). Dorsally, the carapace of the hairy rock crab is dark brown or reddish in color 

and often mottled in appearance (Jensen, 1995). Ventral surfaces are light and uniform in 

coloration. The fingers of the claws are dark-tipped (Jensen, 1995). The hairy rock crab is a 

small Cancer species with males measuring up to 39.3 mm (1.5 in.) and females to 19.5 mm (0.7 

in.) (Jensen, 1995). The life span of the species and the age/size at maturity is unknown. 

Information on the life history of the hairy rock crab is scarce. Reproductive behavior can be 

assumed to follow the pattern of other cancer crabs. Ovigerous females have been found in 

Monterey Bay during October and November. The eggs and larvae of hairy rock crab are similar 

in size to those of larger rock crab species (J. Carroll, Tenera, pers. comm.). Hairy rock crab 

larvae have been reported to be larger than those of C. antennarius in the same stage (J. Carroll, 

Tenera, pers. comm.). Because of the small size of adult female hairy rock crab, and the 

proportionally large size of individual eggs, it has been suggested that the species is probably 

less prolific than larger Cancer species (J. Carroll, Tenera, pers. comm.). Based on these 

observations, the fecundity would probably be on a scale of thousands or tens of thousands of 

eggs instead of the hundreds of thousands or millions typical of larger cancer crab species. It is 

likely that the larval, juvenile, and adult hairy rock crab are preyed upon by the same assemblage 

of fishes and invertebrates that consume the larvae and early crab stages of other Cancrid 

species. Because of their small size, adult hairy rock crab probably remain vulnerable to 

predation by fish species such as cabezon Scorpaenichthys marmoratus and rockfishes Sebastes 

spp., and small octopi Octopus spp. throughout their lives. The species is not harvested 

commercially or recreationally. 

4.12.1 Hairy Rock Crab Results (29.3 percent) 

Hairy rock crab comprised 29.3 percent of the total number of entrained megalops at the new CC 

units intake (Figure 4-1). They were collected in 12 ofthe 42 entrainment surveys (Figure 4-40). 

They were collected from the end of August 1999 through mid-October 1999 and again from 

mid-November 1999 through the beginning of December 1999. They were collected again in 

late December 1999, mid-January and mid-February 2000. The peak concentration 

(63/1,000 m3) occurred on September 30, 1999 all remaining concentrations were below 

11/1,000 m3. 

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Hairy Rock Crab Megalops Entrainment Mean Concentration 

•C50 

140 

8 30 

3 20 

• I 1 

I i i i i ? -j ? , | | i i r r § r 

2S:K*sJ?MS.;c;g«j;s*? s 

5 3 2 5S8ii ~ =S S 

S i i i i 8 s i i i f s? ? i ? r i * i i ? i i 

(0 — u — tfiK* — — NIMI D — wN*»rtH S O ~4 » 

if " J? ° - S 8 S Si 

Figure 4-40. Mean survey concentrations (#/l,000 m3) of hairy rock crab megalops at the Moss Landing 

Power Plant new combined-cycle units intake: March 1999 through February 2000. 

The diel distributions were plotted for concentrations of hairy rock crab megalops. We analyzed 

only the entrainment surveys that coincided with source water surveys from June 1999 through 

February 2000. Hairy rock crab megalops were collected only during the September through 

December 1999 surveys (Figure 4-41). Concentrations were highest during the early morning in 

September 1999, during the nighttime in October and November 1999, and in the afternoon in 

December 1999. 

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Hairy Rock Crab Megalops Entrainment Diel Mean Concentration 

j ~ 35 

E 

s 

S 15 

1 1 

Aug 12 

S £ 8 S " 

Sep 16 Oct 14 Feb 24 

Note: These entrainment surveys were conducted at the same time as the source water surveys. Data are preliminary. 

Figure 4-41. Concentrations (#/l,000 m3) of hairy rock rock megalops at the new combined-cycle units 

intake separated by sample collection time (PST): June 1999 through February 2000. 

Hairy rock crab megalops were collected in the September, October, December 1999, and 

February 2000 source water surveys (Figure 4-42). Peak concentrations occurred during the high 

and low tides (169/1,000 m3 and 79/1,000 m3, respectively) at the Ocean North Station on 

December 29, 1999. Hairy rock crab megalops were collected predominately at Ocean North, 

Ocean South, and Harbor Mouth stations. They were never collected at the Kirby Park, Dairies 

and collected only once in October 1999 at the Harbor Bridge. 

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Hairy Rock Crab Megalops Source Water Mean Concentration 

140 

E 120 I 

r 100 

s 

I 60 

3 

• High Tide 

• Low Tide 

000 000 000\ 

i 1 1 

1 

III j© | 

j 

i 1 

Jul 12 Aug 12 Sep 16 

Key—KP: Kirby Park; D: Dairies; HB: Harbor Bridge; HM: Harbor Mouth; ON: Ocean North; OS: Ocean South 

<3> Stations not included in study design until September. 

© Samples voided due to improper preservation. 

Figure 4-42. Source water concentrations (#/l,000 m3) of hairy rock crab megalops at six stations near 

Moss Landing Power Plant: June 1999 through February 2000. 

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4.13 Yellow Rock Crab Cancer anthonyi 

Cancer anthonyi 

Photographer: Dan Dugan 

Range: From Humboldt Bay, California to Bajia 

Magdalena, Baja California. 

Life History: Adult crabs sexually dimorphic; size: 

males to 176 mm (6.9 in.), females reach 144 mm (5.6 

in.); size at maturity: 90 to 100 mm (3.5 to 3.9 in.) for 

laboratory-reared animals; fecundity: 680,000 to 3.85 

million eggs; life span: no estimate available. 

Habitat: Soft substrates such as sand, sandy-silt, and 

mud; occur in the vicinity of rock reefs or artificial 

structures; the lower intertidal zone to depths exceeding 

130 m (427 ft). 

Fishery: Moderate commercial fishery, small 

recreational fishery. 

Distribution Map for Yellow Crab 

The yellow crab Cancer anthonyi Rathbun occurs along the Pacific Coast of North America from 

Humboldt Bay, California to Bajia Magdalena, Baja California (Jensen, 1995). Within this range 

their distribution is almost exclusively associated with sand substrata (Winn, 1985; Carroll and 

Winn, 1989). The species is most abundant on the expanses of open, sandy substrata that 

characterize much of the Southern Califomia Bight. It is, however, also commonly encountered 

near the rock-sand interface of natural and artificial reefs in the region (Morris, 1980; Carroll and 

Winn, 1989). Yellow crab are also common underneath and in the vicinity of offshore oil and 

gas platforms south of Point Conception (Page et al., 1999). In the northern parts of their range, 

where rocky benthic substrata predominate, their distribution appears to be confined more to 

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bays, sloughs, and estuaries (Jensen, 1995). Yellow rock crab occur from the lower intertidal 

zone to depths exceeding 130 m (427 ft) but are most commonly found in depths between 18 to 

55 m (59 to 180 ft) (Morris et al., 1980; Winn, 1985; Carroll and Winn, 1989; Jensen, 1995). 

They are the most abundant cancer crab species harvested in southem California, often 

composing 70 to 95 percent of the total crab catch in the region (Carroll and Winn, 1989). 

During diver surveys of yellow rock crab populations in Santa Monica Bay it was noted that the 

species was never seen during daylight hours in the vicinity of traps, but were often abundant in 

the traps the next morning (R. Hardy, CDFG, pers. comm.). These observations suggest that 

yellow rock crab are nocturnally active in shallow water and remain buried and inactive during 

daylight hours. 

The carapace of the yellow rock crab is similar in shape to that of the brown rock crab, but is 

proportionally larger and convex dorsolateral ly (domed). Its surface is smooth and there are ten 

anterolateral teeth extending along the anterior margin of each side of the body. The 

anterolateral teeth are wider and less acute than those of the brown rock crab. The carapace is 

widest between the ninth anterolateral teeth (Carroll and Winn, 1989). Dorsally, the yellow rock 

crab varies from light brown to yellow or orange in color (Carroll and Winn, 1989; Jensen, 

1995). Ventral surfaces are a uniform light yellow with no red speckling (Carroll and Winn, 

1989). The walking legs are also yellow or orange in color and generally do not have hair 

(Carroll and Winn, 1989; Jensen, 1995). The tips ofthe claws are dark (Carroll and 

Winn, 1989). 

Like the brown rock crab, adult yellow rock crab are sexually dimorphic, with males attaining a 

larger size and growing larger, more robust chelae (claws). Male crabs grow to a maximum size 

of 176 mm (6.9 in.) while females reach 144 mm (5.6 in.) (Jensen, 1995). No estimates ofthe 

life span of yellow rock crab were cited in the literature reviewed. A laboratory-reared female 

yellow crab became sexually mature after molting to the thirteenth instar (Anderson and Ford, 

1976). The molt occurred when the crab was 400 days old and had a post-molt carapace width 

of 98 mm (3.86 in.) (Anderson and Ford, 1976). 

Ovigerous female yellow rock crabs are found throughout the year (Toole, 1985; Winn, 1985; 

Reilly, 1987), however, they are most common during the winter and spring months (Reilly, 

1987). The size of a female's egg mass is variable and can contain from 680,000 to 3.85 million 

eggs (Carroll and Winn, 1989). The clutch size in yellow rock crabs is reported to average 2.6 

million eggs (Carroll and Winn, 1989). Development of the eggs and subsequent hatching takes 

7 to 8 weeks at ambient temperatures of 10° to 18° C (50° to 64° F) (Anderson and Ford, 1976; 

Carroll, 1982). Yellow rock crab eggs have hatched in 43 days at a constant temperature of 

17° C (63° F) (Carroll and Winn, 1989). Larval development was accelerated significantly by a 

water temperature increase of 4° C (7.2° F) from 18° to 22° C (64° to 72° F) (Anderson and 

Ford, 1976). Because of the shortened duration of each instar at 22° C (72° F), the total time 

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| required for larval development was cut to 33 days as compared with 45 days at 18° C (64° F) 

(Anderson and Ford, 1976). Differences in post-larval growth in yellow crabs have been 

I attributed to water temperature (Anderson and Ford, 1976). 

| 4.13.1 Yellow Rock Crab results (19.6 percent) 

Yellow rock crab comprised 19.6 percent of the total number of entrained Cancer spp. megalops 

• at the new CC units intake (Figure 4-1). They were collected in all CC units intake entrainment 

surveys from November 4, 1999 through December 21, 1999 and again in the January 13 and 20, 

m 2000 surveys (Figure 4-43). The highest concentrations occurred in December 1999 (peak 

• concentration, 16.3/1,000 m on December 16, 1999). All other concentrations were below 

3.4/1,000 m3. 

1 | 

Yellow Rock Crab Megalops Entrainment Muan Concentration 

1 6-

H 14 -

f g,2-H 

S 

8

 8 

• 5 6 

• 1 

4 

1

 2 

!• i •lli l ll 

• •? : ? M ' f M s f ? ' n ? ? f* J ! ? 8 f »

 ! ' • = ' » • • * ! * • ! ' ' • s

 «

 8 

• aS- i saf e s~ S =

 : s " 8 Sj ' j : 8 " ; i» ' ° i si " : ! s ' i : ii 

m Figure 4-43. Mean survey concentrations (#/l,000 m3) of yellow rock crab megalops at the Moss 

1 Landing Power Plant new combined-cycle units intake: March 1999 through February 2000. i 

i 

•: 1 The diel distributions were plotted for concentrations of yellow rock crab megalops. We 

B

 analyzed only the entrainment surveys that coincided with source water surveys from Jurie 1999 

H through February 2000. They were collected only in the November 1999 and January 2000 

; | surveys during one cycle at night (0236 and 1830 hours PST, respectively) (Figure 4-44). 

i: 

1 

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Yellow Rock Crab Megalops Entrainment Die! Mean Concentration 

12 

E 

§ 1 0 

5 

S 6 

S 

2 

4 

; 3 

B 11 5*i-"uI* ;

*58»5 :'*;S3* S 

Jul 12 Aug 12 Sep 16 

t! » 8 S * 

Dec 29 

Iiii ' 

Jan 20 

s « a : • 

Feb 24 

Note: These entrainment surveys were conducted at the same time as the source water surveys. Data are preliminary. 

Figure 4-44. Concentrations (#/l,000 m3) of yellow rock crab megalops at the new combined-cycle units 

intake separated by sample collection time (PST): June 1999 through February 2000. 

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Cancer anthonyi megalops were only collected at the Ocean South Station during a high tide 

(concentration = 8.4/1,000 m3) on December 29, 1999 (Figure 4-45). 

"E 6 

<B 4 

u * 

c 

u 

Yellow Rock Crab Megalops Source Water Mean Concentration 

• High Trie 

• Low Tide 

1 

i 

000\ 000 0O0 © 

£ Z Vt -0 m Z W T £ z w -o S Z « T <a m z w **3 

Aug 12 Sep 16 Nov 18 

Key—KP: Kirby Park; D: Dairies; HB: Harbor Bridge; HM: Harbor Mouth; ON: Ocean North; OS: Ocean South 

<3> Stations not included in study design until September. 

® Samples voided due to improper preservation. 

Figure 4-45. Source water concentrations (#/l,000 m3) of yellow rock crab megalops at six stations near 

Moss Landing Power Plant: June 1999 through February 2000. 

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4.14 Brown Rock Crab Cancer antennarius 

Cancer antennarius 

Photographer: Dan Dugan 

Range: From Queen Charlotte Sound, British Columbia 

to Cabo San Lucas, Mexico. 

Life History: Adult crabs sexually dimorphic; size: 

males to 178 mm (7 in.), females to 148 mm (5.8 in.); 

size at maturity: 60 to 80 mm (2.4 in. to 3.1 in.); 

fecundity: 410,000 to 2.79 million eggs; life span: 

estimated to be 5 to 6 years. 

Habitat: A variety of substrates including rock, gravel, 

sand, and sandy-silt. Occurs from the lower intertidal to 

depths exceeding 100 m (328 ft.) 

Fishery: Small recreational fishery; moderate 

commercial fishery. 

Distribution Map for Brown Rock Crab 

The Pacific or brown rock crab Cancer antennarius Stimpson is distributed in nearshore waters 

along the Pacific Coast of North America from Queen Charlotte Sound, British Columbia to 

Cabo San Lucas, Mexico (Jensen, 1995). Although it is reported to be abundant in Barkley 

Sound, British Columbia (Jensen, 1995), the species range of peak abundance extends from San 

Francisco Bay to coastal areas south ofthe U.S.-Mexico border (Carroll and Winn, 1989). 

Brown rock crab are a marine species that inhabit nearshore coastal regions but may also be 

found in sloughs and estuaries. They are, however, unable to osmoregulate and do not tolerate 

brackish conditions well (Garth and Abbott, 1980). Brown rock crab inhabit a variety of 

E9-053.9 4-99 MLPP 316(b) Resource Assessment 

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4.0 Entrainment and Source Water Results 

substrates including rock, gravel, sand, and sandy-silt (Winn, 1985). They occur from the lower 

intertidal zone to depths exceeding 100 m (328 ft) but are typically found near the rock-sand 

interface in depths of less than 55 m (180 ft) (Carroll and Winn, 1989). Juvenile brown rock 

crab inhabiting the intertidal zone survive exposure to the air during low tide by sheltering 

themselves under rocks and algae (Ricketts, 1985). 

The carapace ofthe brown rock crab is generally oval in shape and relatively flat dorsolateral ly 

with an irregular but otherwise smooth surface. Nine anterolateral teeth line the anterior margin 

of the carapace on each side of the body. The carapace is widest between the eighth anterolateral 

teeth (Carroll and Winn, 1989). The dorsal surface of the carapace is generally a mottled brown 

color but may range from orange-red to gray. Ventral surfaces are light (white to cream) in 

coloration with reddish speckling (Carroll and Winn, 1989). The red speckling on the ventral 

surfaces is a distinguishing characteristic of the species and is not present on other cancrid crabs. 

Another distinguishing characteristic of the species is the two pairs of antennae (one long, one 

short and stout) that originate between the retractable eye stalks (Carroll and Winn, 1989). The 

walking legs of brown rock crabs may be hairy, especially in juveniles and females (Carroll and 

Winn, 1989). Adult crabs are sexually dimorphic, with males attaining a larger size and growing 

larger more robust chelae (claws). Male crabs grow to a size (maximum carapace width [CW]) 

of 178 mm (7 in.) while females reach 148 mm (5.8 in.) (Jensen, 1995). The life span of brown 

rock crab is estimated to be 5 to 6 years (Carroll, 1982). 

Ovigerous female brown rock crabs are found throughout the year (Toole, 1985; Winn, 1985; 

Reilly, 1987) however, they are most common during the winter months (Carroll, 1982). The 

size of a female's egg mass is variable and can contain from 410,000 to 2.79 million eggs 

(Carroll and Winn, 1989). Development of the eggs and subsequent hatching takes 7 to 8 weeks 

at temperatures of 10° to 18° C (50° to 64° F) (Anderson and Ford, 1976; Carroll, 1982). Size 

(CW) increases in the brown rock crab range from 7 to 26 percent per molt, while increases in 

body weight of 50 to 70 percent have been measured (Carroll, 1982). The sexes undergo a molt 

to maturity (50 percent maturity value of population using Somerton, 1980 method) from 

between 60 mm and 80 mm (CW) (2.4 in. and 3.1 in.) (Carroll, 1982). Brown rock crabs are 

estimated to go through 10 to 12 molts before reaching sexual maturity (Parker, 1992). 

4.14.1 Brown Rock Crab Results (19.0 percent) 

Brown rock crab comprised 19.0 percent of the total number of entrained Cancer spp. megalops 

at the new combined-cycle units intake (Figure 4-1). They were collected in 14 of the 42 

entrainment collections at the new combined-cycle units intake (Figure 4-46). Highest 

concentrations occurred in two surveys in September 1999 (both concentrations were 

approximately 9/1,000 m3) and again in January 2000 (9.5/1,000 m3). All other concentrations 

from the new CC units intake entrainment surveys were below 5.1/1,000 m3. 

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4.0 Entrainment and Source Water Results 

Brown Rock Crab Megalops Entrainment Mean Concentration 

"E 7 

1 1 • I 1 , 1 11 

• > 

1 

iiifif?*f?illiriirst||»| » 

<*<-> - »(i o *^ s -• U , «W-*QS ; 

f f I f ? ? j? ? ? | I 5 I 

* — 3 S! " ? S - « • wo-- * 

tO (0 U ^IS> 0 *. — CB 

s s 

Figure 4-46. Mean survey concentrations (#/l,000 m ) of brown rock crab megalops at the Moss 

Landing Power Plant new combined-cycle units intake: March 1999 through February 2000. 

The diel distributions were plotted for concentrations or brown rock crab megalops. We 

analyzed only the entrainment survyes that coincided with source water surveys from June 1999 

through February 2000. They were collected in the August through November 1999 and the 

January 2000 entrainment surveys. The highest concentrations occurred at approximately 0240 

hours PST during the September through November 1999 surveys. In January 2000 they were 

only collected at nighttime at 1830 and 2219 hours PST (Figure 4-47). 

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4.0 Entrainment and Source Water Results 

Brown Rock Crab Megalops Entrainment Diel Mean Concentration 

P.61 

i 

a 15 

-

1 1 1 

j 

I I 

1 

S S * 5 ' 1 

Jul 12 Aug 12 

t t s e " 

Sep 16 

! 1 ( ! ' 

Dec 29 

858S"-SSt!*: -

Note: These entrainment surveys were conducted at the same time as the source water surveys. Data are preliminary. 

Figure 4-47. Concentrations (#/l,000 m3) of brown rock rock megalops at the new combined-cycle units 

intake separated by sample collection time (PST): June 1999 through February 2000. 

Brown rock crab megalops were predominately collected at the Ocean North and Ocean South 

stations (Figure 4-48). Peak concentration (25.1/1,000 m3) occurred on a low tide at the Ocean 

North station on December 29,1999. They were only collected at the Harbor Mouth Station 

during a low tide on February 24, 2000. They were never collected at the Kirby Park, Dairies, or 

Harbor Bridge stations from June 1999 through February 2000. 

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4.0 Entrainment and Source Water Results 

Brown Rock Crab Megalops Mean Source Water Concentration 

25 

• High Tide 

• Low Tide 

000 000 000 

• 

r 

i 

i 

!® 

Aug 12 Sep 16 

Key—KP: Kirby Park; D: Dairies; HB: Harbor Bridge; HM: Harbor Mouth; ON: Ocean North; OS: Ocean South 

O Stations not included in study design until September. 

© Samples voided due to improper preservation. 

Figure 4-48. Source water concentrations (#/l,000 m3) of brown rock crab megalops at six stations near 

Moss Landing Power Plant: June 1999 through February 2000. 

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4.0 Entrainment and Source Water Resulls 

4.15 Dungeness Crab Cancer magister 

Cancer magister 

Source: CDFG 

Range: From Pribilof Islands, Alaska to Point 

Conception, California. 

Life History: Size: males to 230 mm (9 in.), females to 

165 mm (6.5 in.); age at maturity: one and a half years; 

fecundity: 700,000 to 2.5 million eggs, spawns once a 

year; life span: to 8 years. 

Habitat: Common subtidally to 90 m (295 ft); as deep as 

230 m (750 ft). 

Fishery: Recreational, large commercial market. 

Distribution Map for Dungeness Crab 

Dungeness crab occur in Pacific coastal waters from Pribilof Islands, Alaska to Point Conception 

near Santa Barbara, California (Jensen, 1995). They are one of the largest and most 

commercially important crabs along the Pacific Coast. The northern coast of California, 

including the Bodega Bay and San Francisco area, supports a sizable dungeness crab population, 

while smaller populations occur in the Monterey Bay and Morro Bay/Avila Beach area 

(Dahlstrom and Wild, 1983). Five sub-populations are reported to exist in California waters in 

the following areas: 1) Avila Beach/Morro Bay, 2) Monterey Bay, 3) San Francisco, 4) Fort 

Bragg to Cape Mendicino, and 5) Eureka/Crescent City (Garth and Abbott, 1980). 

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1 

1 

B 

4.0 Entrainment and Source Water Results 

Dungeness crab are confined mainly to cold and temperate waters with annual mean 

temperatures ranging between 4° and 24° C (40° to 75° F) (Garth and Abbott, 1980). Adult 

dungeness crab commonly occur subtidally to 90 m (295 ft) residing on sandy bottoms and in 

eelgrass beds, but may be found as deep as 230 m (750 ft) (Jensen, 1995). Estuaries are 

important to their life cycle, and dungeness crab are thought to inhabit all estuaries from Morro 

Bay, California to Puget Sound, Washington (PSMFC, 1999). 

Dungeness crab are beige to light brown on top and light orange to cream below; coloration 

varies little between individuals except for a slight purple to blue contrast in their claws and legs 

(Jensen, 1995). Male dungeness crab can measure up to 230 mm (9 in.) in carapace width, 

however they are more commonly found measuring less than 190 mm (7.5 in.). Carapace width 

in females is approximately 165 mm (6.5 in.) (Garth and Abbott, 1980). 

Mating of dungeness crab, between hard-shelled males and soft-shelled (recently molted) 

females, occurs in the near-shore ocean in the vicinity of estuaries. On the central coast of 

California, mating occurs from March through May (Wild and Tasto, 1983). The females hold 

sperm internally until September to November at which time spawning begins and lasts through 

December (Garth and Abbott, 1980). The eggs are fertilized and the sponge-like mass of 

700,000 to 2.5 million eggs is carried on the female's abdomen until late-December (Wild and 

Tasto, 1983) through February (Garth and Abbott, 1980). Eggs start hatching in December and 

reach a peak in March (Garth and Abbott, 1980). 

After hatching, dungeness crab exist in a pre-zoeal stage for approximately 10 to 15 minutes 

(Reilly, 1983). During the next 105 to 125 days, larval development of dungeness crab 

progresses through five zoeal stages (approximately 80 to 95 days) to a megalopal stage 

(approximately 25 to 30 days) (Wild and Tasto, 1983). Sizes range from approximately 2.5 mm 

(0.25 in.) for stage one zoeae to 11.0 mm (0.43 in.) for megalopae (Poole* 1966). All larval 

stages are planktonic and the zoeae tend to make vertical diel migrations which keep them in the 

top 15 to 25 m (49 to 82 ft) ofthe water column by day and in surface waters by night (Reilly, 

1983). The surface currents carry the larvae offshore, causing more late stage zoeae to be 

distributed farther out to sea than the early stage zoeae (Wild and Tasto, 1983). 

In California waters, megalopae transform into juvenile dungeness crab in April through June. 

Young megalopae travel toward the coast with the aid of tidal currents and also by attaching 

themselves to the bells of jellyfish and the tentacles of Velella velella (Class Hydrozoa) (Garth 

and Abbott, 1980). The megalopae molt into first juvenile instars which then settle in shallow 

coastal waters, estuaries, and tidal flats. Living on eelgrass beds and other aquatic vegetation, 

the juveniles grow into adults through a series of molts; it takes approximately one and a half 

years and eleven to thirteen molts to reach maturity (Garth and Abbott, 1980; Wild and 

Tasto, 1983). After reaching maturity (at a carapace width of about 10 cm [4 in.]) dungeness 

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4.0 Entrainment and Source Water Results 

crab molt and mate only once a year. The life span for dungeness crab is about eight years 

(Butler, 1961). 

Dungeness crab are carnivorous, eating smaller crustaceans, shrimps, molluscs, clams, worms, 

and occasionally fishes. Dungeness crab are also an important prey species. Adult dungeness 

crab are eaten by harbor seals, sea lions, and humans. Crab larvae are eaten by Pacific herring, 

Pacific sardines, rockfishes, and salmon. Juvenile dungeness crab are fed upon by starry 

flounder, lingcod, rockfishes, sturgeon, English and rock sole, sharks, and skates (PSMFC, 

1999). Marine worms, particularly Carcinonemertes errans, prey on the fertilized eggs of 

dungeness crab (Garth and Abbott, 1980). 

The central Califomia crab fishery began to decline in the early 1960's and the dungeness crab 

population still remains at low levels today. A number of factors have been investigated and 

suggested as to the cause of this decline. It is possible that pesticides, urban pollutants, and 

sewage have contributed to the mortality of larval and adult crabs (Garth and Abbott, 1980). 

Dungeness crab cannot tolerate conditions of low dissolved oxygen. Contaminants, even in low 

concentrations, are highly toxic to dungeness crab. Predation on megalopae by Columbia River 

salmon has been suggested as a cause for the reduction in recruitment of crab along the central 

coast (Wild and Tasto, 1983). As large numbers of Coho salmon began to be successfully 

introduced from the Columbia River hatcheries, the dungeness crab population began to decline. 

The change in the ocean climate, including higher sea levels, increased water temperatures, and 

greater intensity ofthe Davidson Current, appears to have contributed to the dungeness crabs' 

decline. Higher water temperatures reduce egg survival and hatching success, and may limit 

ovary development. With the increase in the force ofthe Davidson Current, many crab larvae 

may be drifting northward, leaving central California with decreased recruitment (Wild and 

Tasto, 1983). 

Dungeness crab landings throughout California have varied through the years. Landings were 

highest in the San Francisco area until the 1944 to 1945 season (Dahlstrom and Wild, 1983). 

Since that time, the majority of dungeness crab landings have been in northern California. The 

Morro Bay/A vila Beach and Monterey areas are in the southern part ofthe crab's range, and 

have never contributed significantly to the dungeness crab fishery. Figures 4-49a and b show 

reported commercial dungeness crab landings and values for the Monterey and Moss Landing 

areas from 1987 to 1998. 

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4.0 Entrainment and Source Water Results 

(a) 

Dungeness Crab Value s and Landings for the Monterey Area * 

1987 to 1998 

T $350 

-- $300 

- $250 

-- $200 

-- $150 

-- $100 

-- $50 

(A 

•a 

re (thou Value 

Im 

re 

•••Pound s Landed 

—•— Dollar Value 

$0 o 

a 

(b) 

Dungeness Crab Value s and Landings for Moss Landing 

1987 to 1998 

$140 

$120 

$100 

$80 

$60 

$40 

$20 

$0 

Dollar Value 

(thousands 

• • • Pounds Landed 

• Dollar Value 

Source: CDFG Landing Summaries 1987-1998. 

Figure 4-49. Dungeness crab landings (lbs) and value (dollars) of landings from 1987 through 1998 for 

(a) Monterey Bay ports* and (b) the port of Moss Landing. 

(•includes Monterey, Moss Landing, and Santa Cruz). 

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4.0 Entrainment and Source Water Results 

4.15.1 Dungeness Crab Results (14.7 percent) 

i 

Dungeness crabs comprised 14.7 percent of the total number of entrained Cancer spp. megalops 

collected in the new CC units intake surveys. They were collected in all surveys from mid-April 

1999 through June 3,1999 (Figure 4-50). Peak concentration (10.1/1,000 m3) occurred on May 

20,1999. The lowest concentrations (1.2/1,000 m3) occurred on April 29 and May 27,1999. 

Dungeness Crab Megalops Entrainment Mean Concentration 

1 ll III 1 

i n H. u J i i i 11 n n ^ n $ n 5 n H n n ? n !• s (* ! s 

.*?&£ > z N H ~ ^ *m --u S . ... . I " 8 <*> •*: 8 8 r 2 8 

Figure 4-50. Mean survey concentrations (#/l,000 m3) of dungeness crab megalops at the Moss Landing 

Power Plant new combined-cycle units intake: March 1999 through February 2000. 

Dungeness crab megalops were not collected at any source water stations from June 1999 

through February 2000. It is important to note that source water collections did not begin until 

June 16,1999 after the dungeness crab megalops were collected in entrainment surveys at the 

new combined-cycle units intake. 

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" 

4.0 Entrainment and Source Water Results 

4.16 Red Rock Crab Cancer productus 

Cancer productus 

Source: CDFG 

Range: From Kodiak Island, Alaska to Isla San Martin, 

Baja California. 

Life History: Adult crabs sexually dimorphic; size: 

males to 200 mm (7.8 in.), females to 158 mm (6.2 in.); 

fecundity: 560,000 to 1.01 million eggs. 

Habitat: Hard substrate such as rocky reefs, wellprotected boulder-strewn beaches, and gravel beds. 

Occur from the lower intertidal zone to depths of at least 

91 m (299 ft). 

Fishery: Recreational; small commercial fishery. 

Distribution Map for Red Rock Crab 

The red rock crab Cancer productus Randall occurs along the Pacific Coast of North America 

from Kodiak Island, Alaska to Isla San Martin, Baja California (Jensen, 1995). Based on the low 

densities of red rock crabs collected during trapping studies in San Diego County, it is commonly 

contended that southern California defines the southem extent ofthe species range (Winn, 1989). 

The abundance of red rock crab, relative to the other rock crab species, increases with latitude 

within the state. Red rock crab inhabit a variety of substrata including intertidal and subtidal 

rocky areas, gravel, coarse sand, and mud (Carroll and Winn, 1989). They are commonly found 

in close association with hard substratum such as rocky reefs, well-protected boulder-strewn 

beaches, and gravel beds (Morris, 1980; Carroll and Winn, 1989; Jensen, 1995). Red rock crab 

occur from the lower intertidal zone to depths of at least 91 m (299 ft) (Winn, 1985; Carroll and 

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4.0 Entrainment and Source Water Results 

0 

fl 

Q 

0 

0 

0 

Q 

Q 

0 

0 

8 

0 

0 

B 

0 

0 

Winn, 1989). Juvenile red rock crab inhabiting the intertidal zone survive exposure to the air 

during low tide by sheltering themselves under rocks and algae (Ricketts, 1895). Red rock crab 

are often collected in bays, estuaries, and sloughs, however, their distribution in these areas is 

affected by salinity gradients because the species lacks the ability to osmoregulate (Garth and 

Abbott, 1980). 

The carapace of the red rock crab is similar in shape but more laterally elongate than the 

carapace of brown rock crabs or yellow crabs. There are ten anterolateral teeth lining the 

anterior margins of the carapace along each side of the body. The carapace is widest between the 

eighth anterolateral teeth (Schmitt, 1921; Carroll and Winn, 1989). Anterolateral teeth are not 

equal in size in red rock crab and become larger and more acute posteriorly (Schmitt, 1921; 

Carroll and Winn, 1989). A shelf of 5 equally-spaced teeth protrudes between the eyes from the 

frontal margin of the carapace (Carroll and Winn, 1989). This shelf is one of the most 

distinguishing characteristics of the species at all sizes (Carroll and Winn, 1989). Adult red rock 

crabs are generally a uniform reddish color dorsally, but may also have a mottled appearance 

(Carroll and Winn; 1989, Jensen, 1995). Ventral surfaces are uniform in appearance and 

typically range from off-white to light yellow in coloration (Carroll and Winn, 1989). While 

there is no ventral speckling (red) in red rock crab, the dorsal surfaces of the walking legs may 

have a speckled appearance. The tips of the claws are dark (Carroll and Winn, 1989). Juvenile 

red rock crab are highly variable in dorsal coloration and display a wide array of patterns. The 

background dorsal coloration in juveniles may consist of variations of green, yellow, red, or 

white. Dorsal patterns include zebra-like stripes, multicolored bands, vermiculations, blotches, 

speckling, and uniform colors. Like the brown rock crab and yellow crab, adult red rock crab are 

sexually dimorphic, with males attaining a larger size and growing larger, more robust chelae 

(claws). Male crabs grow to a maximum size (CW) of 200 mm (7.8 in.), while females reach 

158 mm (6.2 in.) (Jensen, 1995). No estimates of the life span of red rock crab were cited in the 

literature reviewed. 

The size of a female's egg mass is variable and can contain from 560,000 to 1.01 million eggs 

(Carroll and Winn, 1989). No information about the development and subsequent hatching of 

red rock crab eggs was available in reviewed literature. Trask (1970) found that red rock crab 

larvae developed to the megalopal stage in 97 days at a temperature of 11° C (52° F), however, 

none of his laboratory-reared larvae survived to the first crab instar. 

4.116-1 Red R®ek Crab Resulte (9M p>ere®nt) 

Red rock crab comprised 9.8 percent of the total number of entrained Cancer spp. megalops at 

the new CC units intake (Figure 4-1). They were collected in 12 of the 42 entrainment surveys 

(Figure 4-51). The peak concentration (8.3/1,000 m3) occurred on May 20, 1999. 

Concentrations remained at or below 2.0/1,000 m3 for all remaining surveys. 

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Red Rock Crab Megalops Entrainment Mean Concentration 

1 1 1 1 I lll l II I 1 1 III I II I 

•ss:B8S?«?:?g!ii : 

5*8 - » « s ;2 g 

t S I I I I 8 g f I ! i jf jf jf F Sf | I I 

5 8 s f - s 5 Rj 8 

S S 

Figure 4-51. Mean survey concentrations (#/l,000 m3) of red rock crab megalops at the Moss Landing 

Power Plant new combined-cycle units intake: March 1999 through February 2000. 

The diel distributions were plotted for concentrations of red rock crab megalops. We analyzed 

only the entrainment surveys that coincided with source water surveys from June 1999 through 

February 2000. They were collected only at night in July and November 1999 during one cycle 

(2231 and 0236 PST, respectively) (Figure 4-52). 

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Red Rock Crab Megalops Entrainment Diel Mean Concentration 

P.71 

i 4 

m 

S 

i» 

s 

S 3 J = 

8 : = S i IS 

Aug 12 Sep 16 Jan 20 Feb 24 

Note: These entrainment surveys were conducted at the same time as the source water surveys. Data are preliminary. 

Figure 4-52. Concentrations (#/1,000 m3) of red rock rock megalops at the new combined-cycle units 

intake separated by sample collection time (PST): June 1999 through February 2000. 

Red rock crab megalops were not collected in any source water surveys from June 1999 through 

February 2000. It is important to note that the source water collections did not start until June 

16, 1999 after the peak concentration occurred at the new combined-cycle units intake. Ocean 

and Harbor Mouth stations were not added to the sampling design until September 1999. 

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4.17 Slender Rock Crab Cancer gracilis 

Cancer gracilis Photographer: MaGaw 

Range: From Prince William Sound, Alaska to Bahfa 

Playa Maria, Mexico. 

Life History: Size: males to 115 mm (4.5 in.), females to 

87 mm (3.4 in.); age at maturity: approximately 10 

months of age (post-settlement), about 60 mm (2.4 in.); 

fecundity: spawns once a season, 143,000 to one million 

eggs; life span: approximately 4 years. 

Habitat: Sandy and muddy bottoms of intertidal areas to 

174 m (571 ft), kelp and eelgrass beds, seasonally in 

bays and sloughs. 

Distribution Map for Slender Crab 

The slender crab, occasionally called graceful crab, are found from Prince William Sound, 

Alaska to Bahfa Playa Maria, Mexico (Jensen, 1995). They inhabit the sandy and muddy 

bottoms of intertidal areas and are found subtidally, often in kelp beds to depths of 174 m 

(571 ft) and in eelgrass beds (Garth and Abbott, 1980). Slender crab do not osmoregulate and 

therefore cannot tolerate low salinity brackish environments. They are usually not found in 

estuaries, but may be found seasonally in bays and sloughs (Jensen, 1995). 

Slender crab are often misidentified as dungeness crab, but are much smaller in size. Their 

carapace width measures up to 115 mm (4.5 in.) in males and up to 87 mm (3.4 in.) in females 

(Jensen, 1995). Their white-tipped claws lack the serrations belonging to dungeness crab and 

their purple walking legs are slender. 

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i 

I 

i 

i 

I 

§ 

i 

§ 

i 

i 

i 

i 

i 

i 

i 

i 

t 

I 

i 

4.0 Entrainment and Source Water Results 

In Monterey Bay, spawning of slender crab have been reported to occur in the spring and fall 

(Graham, 1989). In Elkhorn Slough, mating is common in November and ovigerous females are 

found in the slough during July and August (Garth and Abbott, 1980). Females produce one 

batch per year, although in a laboratory setting, some females produced a small second batch. 

The number of eggs extruded per female can range from 143,000 to one million. Females are 

able to spawn for at least two, and possibly three seasons, over their lifetime (Orensanz and 

Gallucci, 1988). 

After hatching, slender crab exist in a pre-zoeal stage for a very short time before molting to first 

stage zoeae. Slender crab progress through five zoeal stages to a megalops stage in an average of 

48.9 days at 17° C; each stage lasting approximately one week (Alley, 1975). All larval stages 

are planktonic and the crab larvae may become widely distributed. In Monterey Bay, 

concentrations of first stage zoeae have been found from 6 to 11 km (3.7 to 6.8 miles) offshore 

during the spring and late summer (Graham, 1989). Other larval stages, including megalopae, 

are found distributed offshore at all times of the year. It is estimated that slender crab mature at a 

size of about 60 mm (2.4 in.) carapace width and at approximately 10 months of age (postsettlement) (Orensanz and Gallucci, 1988). Slender crab molt approximately 11 to 12 times and 

live for about 4 years. 

In Monterey Bay, young slender crab are an important food source for the starry flounder 

Platichthys stellatus (Garth and Abbott, 1980). Slender crab feed on barnacles and bivalves, 

sometimes causing problems for the commercial oyster fishery. Some adults are occasionally 

taken in the sportfishery. 

4.17.1 Slender Rock Crab Results (7.1 percent) 

Slender rock crab comprised 7.1 percent of the total number of entrained Cancer spp. megalops 

(Figure 4-1). They were collected in the March 14,1999 survey and again in November 1999 

through mid-February 2000 surveys (Figure 4-53). Highest concentrations occurred on January 

20,2000 and February 3, 2000 (4.0/1,000 m3 and 3.2/1,000 m3, respectively). For all remaining 

surveys concentrations were at or below 2.0/1,000 m . 

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I 

I 

§ 

I 

I 

i 

-y 

I 

i 

I 

i 

i 

i 

i 

t 

i 

i 

i 

i 

4.0 Entrainment and Source Water Results 

Slender Rock Crab Megalops Entrainment Mean Concentration 

4.0 

3.5 

3.0 

2.5 -

2.0 

£ 1-5 

1.0 1 1 1 

1 1 

n 

:

 t : j ! s " s = s 

IWWWl l 

sSK?c:83*r' s 

i jj g " i it 8 " ; 

Figure 4-53. Mean survey concentrations (#/l,000 m3) of slender rock crab megalops at the Moss 

Landing Power Plant new combined-cycle units intake: March 1999 through February 2000. 

The diel distributions were plotted for concentrations of slender rock crab megalops. We 

analyzed only the entrainment surveys that coincided with source water surveys from June 1999 

through February 2000. They were collected in only one cycle per survey (Figure 4-54) in 

November (1236 hours PST), December (1534 hours PST) and January 2000 (1830 hours PST). 

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E 20 

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Slender Rock Crab Megalops Entrainment Diel Mean Concentration 

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Oct 14 Nov 18 Dec 29 

S8S-"3BEi -

Jan 20 Feb 24 

Note: These entrainment surveys were conducted at the same time as the source waler surveys. Data are preliminary. 

Figure 4-54. Concentrations (#/!,000 m3) of slender rock rock megalops at the new combined-cycle 

units intake separated by sample collection time (PST): June 1999 through February 2000. 

Slender rock crab megalops were predominately collected at the Ocean North and Ocean South 

stations in September, October, and December 1999 (Figure 4-55). They were collected at the 

Harbor Mouth Station only on October 14, 1999 during low tide. Peak concentration 

(11.2/1,000 m3) occurred during a low tide at the Ocean North Station on September 16, 1999. 

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Slender Rock Crab Megalops Source Water Mean Concentration 

E 8 

• High Tide 

• Low Tide 

000 000 000 

) 

© 

£ Z W T £ZW* 0 CD £ Z W "D £ Z (/> Tl O) £ Z D £ Z ffi D CO £ Z 

Jul 12 Aug 12 Sep 16 

Key—KP: Kirby Park; D: Dairies; HB: Harbor Bridge; HM: Harbor Mouth; ON: Ocean North; OS: Ocean South 

O Stations not included in study design until September. 

© Samples voided due to improper preservation. 

Figure 4-55. Source water concentrations (#/l,000 m3) of slender rock crab megalops at six stations near 

Moss Landing Power Plant: June 1999 through February 2000. 

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4.18 European Green Crab Carcinus maenas 

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Carcinus maenas 

Distribution Map for Green Crab* 

*Also introduced to South Africa and Australia; distribution unknown 

Photographer: McGaw 

Range: Native: along the Atlantic Coast of Europe and 

North Africa from Norway to Mauritania; introduced to 

South Africa, Australia and both coasts of North 

America. 

Life History: Size: males to 92 mm (3.6 in.) but rarely 

exceed 80 mm (3.1 in.); Fecundity: may spawn twice in 

a season, 185,000 eggs; Age at maturity: one to three 

years; Life span: to five years. 

Habitat: A variety of protected and semi-protected 

marine environments, including rocky shores, cobble 

beaches, sand/mud flats, and tidal marshes; intertidally 

to depths of 10 m (33 ft.) 

Fishery: No commercial or recreational fishery in U.S. 

The European green crab Carcinus maenas is an environmentally tolerant species that has 

become widely distributed outside ofits native range following unintentional introductions. The 

species is much maligned outside of its native range because of its voracious feeding habits. The 

green crab is a decapod crustacean belonging to the Infraorder Brachyura and Family Portunidae. 

Its native range extends along the Atlantic Coast of Europe and North Africa from Norway to 

Mauritania (Grosholtz, 1996). Introduced populations occur in South Africa, Australia, and 

along both coasts of North America (WDFW, 1999). The species has been documented on the 

Atlantic Coast of North America since the 1817 and now occurs from Nova Scotia to Virginia 

(Grosholtz, 1996). It was not found along the Pacific Coast until 1989/1990 when an established 

population was discovered in San Francisco Bay. Green crab were reported in Bodega Bay by 

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1993 and can now be found in every major bay and estuary between Monterey Bay and 

Humboldt Bay (Grosholtz, 1996). They have been reported to occur as far north as Willapa Bay, 

Washington and as far south as Morro Bay, California. The Willapa Bay population apparently 

did not persist (Jensen, 1995). Green crab occur in a variety of protected and semi-protected 

marine environments including rocky shores, cobble beaches, sand/mud flats, and tidal marshes 

(WDFW, 1999; Grosholtz, 1996; Cohen and Carlton, 1995). They are most often found in the 

intertidal and shallow subtidal regions of estuaries, typically in depths of less than 6 m (20 ft) 

(Jensen, 1995). They have been collected to depths of 10 m (33 ft) in San Francisco Bay (Cohen 

and Carlton, 1995). 

One of the reasons for the success of the green crab is tolerance of a wide range of environmental 

conditions. Adult green crab are euryhaline and tolerate salinities from 4 to 52 ppt (Cohen and 

Carlton, 1995). The species is also eurythermal and lives in water temperatures ranging from 5° 

to 30° C (41° to 86° F) but are reported to tolerate temperatures to 0° C (32° F) (WDFW, 1999). 

The species also achieves reproductive success under a wide range of environmental conditions. 

Successful embryonic development can occur at temperatures between 11° and 25° C (52° to 77° 

F) (WDFW, 1999). Survival of eggs and larvae is high in salinities ranging from 26 to 39 ppt, 

however, larval development is inhibited in salinities of less than 13 ppt (WDFW, 1999). 

Because ofthe species' wide environmental tolerances it has been suggested that it may 

eventually range along the Pacific Coast from Alaska to Baja California (Cohen and Carlton, 

1995). 

The dorsal surface of the green crab carapace is smooth but somewhat irregular. Five 

anterolateral teeth line the anterior margin of the carapace on each side of the body. The teeth 

are oriented forward and are relatively acute. The last pair of walking legs, although not highly 

modified for swimming as in many other Portunid crabs, are slightly flattened (Jensen, 1995). 

Green crab are often multicolored dorsally and range from a dark mottled greenish to orange 

(Jensen, 1995). Yellow patches are often present on the dorsal surface. Coloration varies 

individually and with the length of time since the last molt (WDFW, 1999). A recently molted 

individual is typically dark mottled green in coloration and gradually turns to orange and then 

red as the intermolt period progresses. The ventral coloration is similarly variable. Green crab 

can reach a size of 92 mm (3.6 in.) but rarely exceed 80 mm (3.1 in.) (Jensen, 1995). Males 

grow faster and attain a larger size than females. Individuals typically live for 3 to 5 years in 

California (Grosholtz, 1996). 

Mating in green crabs occurs immediately following the molt of a female. Much of the 

reproductive information available on the species has been collected in its native range. The 

timing of mating and settlement appears to vary geographically. In the North Sea, molting in 

females and subsequent mating occurs between April and November, but is most common from 

June to October (WDFW, 1999). Along the central coast of Maine mating occurs from July 

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through October (WDFW, 1999). Smaller females may molt and mate early in the season and 

then again in the fall (WDFW, 1999). Males molt in the Baltic Sea between May and June; 

along the central coast of Maine, mature males have completed molting by July (WDFW, 1999). 

Eggs are usually extruded in the spring, although ovigerous females can be found from midwinter to early summer (WDFW, 1999). Adult green crabs, particularly ovigerous females, are 

reported to migrate to deeper water during winter months (WDFW, 1999). It is thought that 

these females may move to deeper water to reduce variability in environmental factors such as 

salinity and temperature (WDFW, 1999). Female green crab can produce up to 185,000 eggs at 

a time under favorable conditions (Cohen and Carlton, 1995). Larvae are pelagic and aggregate 

in the upper layers of the water column at night during ebb tide. This behavior is thought to 

facilitate dispersal of the larvae into offshore waters where growth and development occur. 

Estimates of the period of time larvae spend in offshore waters vary from 2 weeks to as long as 

2 months (at 15° C [59° F]) (WDFW, 1999; Grosholtz, 1996). After larvae molt to megalopae 

they again aggregate in the surface waters at night and are carried inshore with the flood tide. 

They eventually molt to juveniles and settle out in the upper intertidal zone. Grosholtz (1996) 

states that green crab recruit during the spring and mature during the first year. Other sources 

suggest that juveniles settle out in late August and maturity occurs during the second or third 

year (WDFW, 1999). 

Green crabs are highly successful predators and consume a wide variety of invertebrates. The 

species is fast-moving and highly dexterous compared to other decapod crustaceans. It exhibits 

learning capabilities when handling prey, thereby reducing handling time during foraging 

(WDFW, 1999). Green crabs have been documented preying on organisms from more than 158 

genera in 104 families (Cohen et al., 1995). Analysis of stomach contents included plants and 

protists from 5 phyla, and animals from 14 phyla. Dominant prey species varied at different 

locations but included mussels, clams, snails, polychaetes, crabs, isopods, barnacles, and algae 

(Cohen et al., 1995). In their native range, green crabs prey heavily on mussels Mytilus edulis, 

dogwelks Nucella lapillus, and cockles Cerastoderma edule (WDFW, 1999). Green crab have 

been reported to greatly reduce the abundance ofits invertebrate prey populations, including 

commercially important species (Grosholtz, 1996). 

There is great concern over the expansion of the green crab along the Pacific Coast of North 

America. Green crab predation on quahogs Mercenaria mercenaria is thought to have been a 

factor in the collapse of soft-shell clam fisheries along the Atlantic seaboard in the 1950's 

(WDFW, 1999). The species has also become problematic for the east coast hard shell clam 

Mya arenaria fishery (Grosholtz, 1996). In California, significant reductions in populations of 

the small clams Nutricula spp. and Transennella spp., the cumacean Cumella vulgaris, and the 

amphipod Corophium spp. have been attributed to green crabs (Grosholz, 1996; Grosholz and 

Ruiz, 1995). The species has also been documented preying on other crab species up to its own 

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size. These include young Dungeness crab Cancer magister and the yellow shore crab 

Hemigrapsus oregonensis. Green crabs are voracious predators of young oysters Crassostrea 

gigas and frequently recruit into oyster culture bags (Grosholz, 1996). They are also a known 

intermediate host of an acanthocephalan worm Profilcollis botulus which has been known to 

cause heavy mortalities in seabirds (WDFW, 1999). 

There is a commercial fishery for green crabs in Europe where they are used for both food and 

bait, however, because of their small size, no commercial harvest or marketing of the species has 

occurred in the United States. The most likely avenue of its introduction into San Francisco Bay 

is from larvae and juveniles contained in the ballast water of large ships. Green crabs are also 

known to occur in discarded packing material (algae) used for seafood products shipped from the 

New England coast. The species expansion up and down the coast may be the result of natural 

dispersal of larvae but could also be from ballast water or seafood packing material. 

4.18.1 European Green Crab Carcinus maenas Results 

European green crab megalops (3 individuals) were collected in only two (April 15 and April 22, 

1999) entrainment surveys from the new combined-cycle units intake (Figure 4-56). 

Concentrations were 2.8/1,000 m3 on April 15, 1999 and 1.2/1,000 m3 on April 22, 1999. 

European Green Crab Megalops Entrainment Mean Concentration 

8 

!

 1*5 

C 8 % 

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ffffff«t«ffff**t»fcgiiff8ffif;*fFrFFF»»fr!ri?''; * 

££?B»£?8S S?8 3 £ S = S:*-;g5S ? Sl8r**:sS?fS23 ? = 35i?S;; K 

5 SSf e r » 5 > = = S" 8 = y3osS"sis"S*=B8* £ 28*i*i s 

5 B 

Figure 4-56. Mean survey concentrations (#/l,000 m3) of European green crab megalops at the Moss 

Landing Power Plant new combined-cycle units intake: March 1999 through February 2000. 

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5.0 IMPINGEMENT EFFECTS 

The use of raw water in power plant cooling water systems (CWS) requires that objects in the 

water larger than the diameter of the condenser tubes be screened to avoid plugging the 

condensers. Most CWS intakes employ 3/8 in. (0.953 cm) mesh traveling screens that rotate out 

of the water to clear debris and organisms from the mesh. Cooling water that flows through the 

traveling screens can impinge weakly mobile organisms against the screens or entangled them in 

screened debris. These organisms are typically juvenile and adult fishes and macroinvertebrates. 

The location ofthe intake and traveling screens, the approach velocities, and the quantity of 

debris in the water are all factors that can affect impingement rates. Impingement studies were 

previously conducted at MLPP in 1979 - 1980, and the results were presented in the Moss 

Landing Power Plant Cooling Water Intake Structures 316(b) Demonstration (PG&E, 1983). 

Most species of fish have the swimming capability to avoid impingement. Divers, swimming in 

front of the intake at the Diablo Canyon Power Plant, have documented young-of-the-year 

rockfish Sebastes spp., blackeye goby Coryphopterus nicholsi, and other small fishes swimming 

against the current just in front of the bar racks (Tenera, Inc., 1998). Other observations, 

recorded on video tape, showed a 15 cm (5.91 in.) painted greenling Oxylebius pictus swimming 

off of the traveling screen after apparently resting there (Tenera, Inc., 1998). However, it has 

been demonstrated that when there are large amounts of detritus (plant material) in the intake 

area, organisms strong enough to avoid the intake may become trapped in the detritus and 

become susceptible to impingement (PG&E, 1982). 

The common size screen mesh of 3/8 in. (0.953 cm) is designed both to prevent condenser tube 

from plugging and to minimize the approach and through-screen velocities for fish protection. 

As the mesh size is increased more larval and juvenile fish will enter the power plant's cooling 

water system (be entrained) and subjected to mechanical, chemical, and thermal stresses. A 

reduction in mesh size of traveling screens will increase the rate of impingement and the stress of 

through-screen velocities. Entanglement in debris also increases with through-screen-velocities. 

If there is no fish return system, these impingement effects decrease directly with reductions in 

through-screen-velocities. 

Consistent with the final study plan, impingement studies are not being conducted as a part of 

this 316(b) demonstration. Several ofthe modifications that will be made to the Units 1 

through 5 intake structure as part of the modernization project (Section 2.1) are expected to 

reduce the quantity of debris and the number of organisms impinged on the traveling screens at 

that location and are discussed below. It is important to note that the data from the prior 

impingement study showed the overall rate of impingement (standardized for differences in 

cooling water flow) was higher at the Units 1 through 5 intake than at Units 6 and 7 intake. This 

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was true for both fishes and macroinvertebrates (by a factor of 1.6 for fishes and 3.3 for 

macroinvertebrates) (PG&E, 1983). 

The cooling water volume pumped through the Units 1 through 5 intake structure will be reduced 

from 381,000 gpm (1,441 m3/min) to 250,000 gpm (946 m3/min) for the new combined-cycle 

units. As a result of the lower flows, approach velocities will decrease from 0.9 feet per second 

(fps; 0.27 meters per second [mps]) to 0.5 fps (0.15 mps). The new traveling screens will be 

inclined at an approximate angle of 73° from horizontal thus providing more surface screen area 

that will result in lower through-screen velocities. During screen rotation of the vertical 

traveling screens, debris has a tendency to fall back into the water at the air/water interface and 

create a large mass. These new angled screens will be more effective at removing debris than the 

conventional vertical traveling screens. The existing intake tunnel is approximately 350 ft 

(106.7 m) long (measured from the bar racks to the traveling screens). The new combined cycle 

(CC) forebay intake design places the traveling screens approximately 10 feet (3.1 m) behind the 

bar racks. The shortening of the tunnel may help to reduce impingement of schooling fishes that 

can become trapped in the tunnel and subsequently impinged. 

Data presented in this section are from impingement studies conducted at the Moss Landing 

Power Plant in 1979 - 1980 as part of the first 316(b) Demonstration program (PG&E, 1983). 

Data reported in PG&E (1983) were presented as numbers of organisms caught during each 

impingement collection. We have obtained the actual cooling water volumes for Units 1 

through 5 and Units 6 and 7 for the period of the impingement study and have calculated 

densities of the most abundantly impinged fishes and Cancer spp. crabs. 

The 1983 evaluation found that the power plant was employing BTA intake technology. The 

evaluation indicated that the existing cooling water intake system impinges small numbers of 

adult fishes and invertebrates on the intake screens. 

5.1 Impingement Study 

The impingement study (PG&E, 1983) was designed to quantify the composition and abundance 

of impinged organisms at both Units 1 through 5 and Units 6 and 7 of the MLPP. Lengths and 

weights of all fishes and selected macroinvertebrates impinged in 24-hour periods were recorded. 

Seasonal and diel (day and night) patterns of impingement were determined graphically. 

5.1.1 Methods 

Impinged fishes and macroinvertebrates were collected from weekly samples at the intakes of 

both Units 1 through 5 and Units 6 and 7. The impingement study began on January 20,1979 

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and continued through March 18, 1980. Samples were taken over a 24-hour period that was 

divided into either 3- or 6- hour cycles. This cycle-breakdown of sample collection allowed for 

the determination ofthe diel distribution ofthe impinged organisms. 

Before each sampling period all the traveling screens were rotated and rinsed to remove 

previously impinged organisms and debris. The screens remained stationary for 2.75 hours and 

then were rotated for 15 minutes while impinged organisms were rinsed into a collection basket 

lined with '/i-inch (0.635 cm) steel mesh. This procedure was repeated for the entire 24-hour 

sampling period. 

The impinged organisms were removed from the detritus. Fishes and macroinvertebrates were 

identified to species, counted, and measured. The fork length (tip of snout to fork in tail) of the 

fishes was measured for up to 50 individuals of each species, carapace widths measured for 

Cancer spp. and the mantle length was recorded for squids and octopus in every 24-hour 

collection. 

Gonads of the most commonly impinged fish were periodically examined to assess spawning 

condition. Gonads were dissected from the fish and classified as undeveloped, developing, 

mature, or spent. 

All samples were subjected to a Quality Control program that called for resorting sample debris 

and reidentification of the collected organisms. Sampling efficiency was also tested in various 

experiments. Marked dead fish were released directly in front of the intakes and the number of 

recovered fishes was recorded. Eighty-seven percent of the dead fish released into the Units 1 

through 5 intake were recovered in this test of sampling efficiency but only 35 percent were 

recovered from Units 6 and 7. The low recovery rate for Units 6 and 7 was attributed to a 

traveling screen design that was built to remove jellyfish, kelp, and algae. This system consists 

of L-shaped brackets or cylindrical projections attached to the traveling screens. These brackets 

interfered with the effectiveness ofthe spraywash system and some ofthe impinged material was 

carried over and bypassed the secondary sluiceway. It was observed that this "carry-over" 

occurred when there was insufficient water pressure. The differential collection efficiencies 

between the two intakes were taken into consideration when impingement characteristics were 

compared. 

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5.2 Life Histories of Abundantly Impinged Fishes 

5.2.1 Fishes 

Northern anchovy Engraulis mordax was the most abundant fish species collected from both 

intakes and constituted 61 percent of all fishes impinged. Shiner perch Cymatogaster aggregata 

ranked second in abundance at 9 percent, followed by topsmelt Atherinops affinis (9 percent) and 

Pacific herring Clupea pallasi (4 percent). These four species accounted for 83 percent of all 

fishes impinged during the entire study. Life histories for these species, except Pacific herring 

(discussed previously in Section 4.10), are presented below. 

Northern Anchovy Engraulis mordax 

Photographer: Mark Conlin 

The northern anchovy Engraulis mordax is a clupeoid fish (anchovy, sardine, and herring) 

belonging to the family Engraulididae (the anchovies). Engraulididae contains 139 species of 

anchovies that occur throughout the world (Moyle and Cech, 1988). Members of the family can 

be distinguished from other clupeids by their overhanging snout and long upper jaw (Moyle and 

Cech, 1988). Northern anchovy, one df the most prolific fishes in the coastal waters of the 

Pacific, contribute significantly to the economics ofthe world's fisheries. 

The northern anchovy population has been separated into three distinct sub-populations, based 

on morphological differences, and are represented geographically by the northern, central, and 

southern sub-populations (PFMC, 1990; Love, 1996). The northern sub-population is found 

from Vancouver Island, British Columbia to central California. The distribution of the central 

sub-population extends from central California to northern Baja California and the southern 

population is found along the southern coast of Baja. Considerable fluctuations in anchovy 

populations occur in response to cyclic variations in oceanographic conditions (Moyle and Cech, 

1988). 

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Northern anchovy are a pelagic marine species that occurs from surface waters down to depths of 

305 m (1,000 ft) (Love, 1996). They can be found in dense schools within bays and estuaries, 

and in ocean waters from just outside the surf zone to more than 300 miles offshore (Love, 

1996). They are most common within 100 miles of land (Love, 1996). Anchovies make 

extensive seasonal movements up and down the coast, as well as offshore and inshore (Love, 

1996). Their pattern of seasonal movement is moderately predictable, at best. Schools generally 

disperse and move toward the surface waters around sunset to feed. They re-form into larger, 

more consolidated schools later in the night (Love, 1996). 

Northern anchovy are elongate fishes with blue or green backs and silver bellies. They have 

been reported to reach a size of 229 mm (9 in.) but rarely exceed 178 mm (7in.) (Miller and 

Lea, 1972; Love, 1996). Northern anchovy may live to 7 years, but most do not live past 5 years 

of age. There are geographic differences between the time when individuals become 

reproductively mature. While all anchovy are mature by the time they reach 4 years in age, some 

may mature within their first year in the southern parts of their range (Love, 1996). 

Spawning occurs throughout the year (with peaks in December through May) in the southern end 

of the northern anchovy's range, but is seasonal in the northern locations. Near the Columbia 

River, off of the coast of Washington and Oregon, the fish spawn from mid-June through midAugust. Most spawning occurs within 150 miles from shore and typically takes place at night. 

Females are oviparous and can spawn 2 to 3 times a year, releasing from 2,700 tol6,000 eggs per 

batch (Brewer, 1978). Love (1996) indicates that females can release from 2,700 to 16,000 eggs 

per batch, with annual fecundity as high as 130,000 eggs in southern California. The number of 

eggs produced varies geographically. Eggs are pelagic and are broadcast into the water column 

(Bolin, 1936; Wang, 1986). The eggs hatch in 2 to 4 days and larvae begin their pelagic phase at 

approximately 3 mm TL (Wang, 1986; Love, 1996). The larval phase lasts for approximately 70 

days (Wang, 1986; Love, 1996). Larvae begin schooling at 11 to 12 mm (0.43 to 0.47 in.) and 

transform into juveniles at 35 to 40 mm (1.38 to 1.57 in.) (Hart, 1973). Survival of juveniles is 

thought to be greatest during calm ocean conditions (Love, 1996). 

Northern anchovy are primary consumers and filter-feed on plankton. They feed on zooplankton 

such as krill, copepods, and arrow worms, and on phytoplankton, small fishes, and pelagic fish 

eggs (Love, 1996). Anchovy are undoubtedly one of the major forage fishes within their range. 

Marine mammals, sea birds, fishes, and invertebrates all prey on anchovy at some stage of their 

life. 

Northern anchovy in the central sub-population are harvested commercially in Mexico and 

Califomia for reduction, human consumption, live bait, dead bait, and other non-reduction 

commercial uses (PFMC, 1998). Landings of northern anchovy in California between 1916 and 

1997 varied from a low of 72 metric tons (MT) in 1926 to a high of 143,799 MT in 1975 

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(PFMC, 1998). This historical variation in landings generally reflects changes in both anchovy 

populations and the interest of fisherman to fish for them. The most recent stock assessment for 

northern anchovy estimated spawning biomass at 388,000 MT during the middle of February 

1995 (Jacobson et al., 1995). Although no more recent stock assessments have been made, a 

qualitative analysis of the available data indicates that this remains the best estimate of current 

spawning biomass (Jacobson et al., 1997). 

Shiner perch Cymatogaster aggregata 

Shiner perch Cymatogaster aggregata belong to the small (23 species) family Embiotocidae 

which are found abundantly in sub-tropical and temperate waters along the Pacific coast of North 

America and Asia (Moyle and Cech, 1988). Shiner perch range from San Quintin Bay, Baja 

Califomia to Port Wrangell, Alaska (Miller and Lea, 1972). They are abundant from British 

Columbia south (Love, 1996). Shiner perch and striped surfperch Embiotoca lateralis are the 

two most widely distributed embiotocid species (Odenweller, 1975). 

Shiner perch inhabit a wide variety of habitats including estuaries and quiet bays, eelgrass beds 

Zostera marina, and open coast areas around kelp beds. They are also frequently found in the 

vicinity of piers, jetties, and oil platforms. Shiner perch occur commonly in schools and 

aggregations from the intertidal zone down to depths 61 m (200 ft) (Love, 1996). They are most 

often found in depths of less than 15 m (50 ft) but have been collected as deep as 210 m (690 ft) 

(Love, 1996). They are euryhaline and can also be found in lower salinity areas of coastal 

streams and even occasionally in freshwater (Fierstine et al., 1973; Love, 1996). They are also 

reported to be eurythermal and live in water ranging from 4° C to 21° C (39° F to 70° F) 

(Odenweller, 1975; Love, 1996). 

Shiner perch are small fishes that are silvery in overall appearance but have black spots on their 

scales. The black spots form a background pattern of thin horizontal stripes along the sides of 

the fish (Humann, 1996; Love, 1996). There are several (usually 3) vertical yellow bars overlaid 

on the pattern along the mid-body (Humann, 1996; Love, 1996). There is often a dusky patch on 

the snout below the nostril (Humann, 1996; Love, 1996). Shiner perch reach a size of 178 mm 

(7in.) and may live for 8 years (Love, 1996). They become reproductively mature after 1 year 

(Love, 1996). 

Spawning in shiner perch occurs during the spring and summer. Odenweller (1975) related the 

timing of spawning to the temperature and productivity of the environment. In the southern 

portions of its range spawning begins in April-May, while in British Columbia it begins in JuneAugust. Females are ovoviviparous and young are bom during the winter months. Females 

store sperm for a period of time before embryo development begins. Thirty-six embryos may 

develop in a single female (Love, 1996). Because of their greatly enlarged and highly 

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vascularized dorsal, pelvic, and anal fins, embryos are able to obtain nutrients from the mother 

(and develop) in uterus-like sacs within the ovary. When bom they may be greater than 3 cm in 

length (Moyle and Cech, 1988). 

Shiner perch feed primarily on planktonic organisms such as copepods, amphipods, arrow worms 

and fish eggs (Love, 1996). When zooplankton abundance is low they will feed heavily on 

. benthic organisms such as pelecypods, gastropods, polychaetes, tunicates, and fish eggs 

(Odenweller, 1975). 

Shiner perch are preyed upon by a wide variety of marine mammals, birds, and fishes. Oxman 

(1995) determined that shiner perch composed 2.87 percent ofthe prey items consumed by 

harbor seals Phoca vituUna in the Moss Landing/Elkhorm Slough area. California sea lions 

Zalophus californianus are also reported to feed on shiner perch (Love, 1996). They have a 

variety of avian predators including: great blue herons Ardea herodias, western gulls Larus 

occidentalis, bald eagles Haliaeetus leucocephalus, least tems Sterna antillarum and Brandt's 

Phalacrocorax penicillatus and double-crested cormorants Phalacrocorax auritus (Love, 1996). 

Shiner perch are also consumed by a number of piscivorous fishes. Califomia halibut 

Paralichthys californicus, kelp bass Paralabrax clathratus, and barred sand bass Paralabrax 

nebulifer are among their many piscine predators (Love, 1996). Although small landings are 

made, shiner perch have little commercial value. They are caught by recreational anglers in bays 

and from piers and are considered a good baitfish for a number of gamefish. 

Topsmelt Atherinops affinis 

Topsmelt, along with jacksmelt and grunion, belong to the family Atherinidae (silversides). 

These schooling fish are found from the Gulf of California to Vancouver Island, British 

Columbia (Miller and Lea, 1972), occasionally extending as far north as Queen Charlotte 

Islands, British Columbia (Humann, 1996). They are most commonly found from Tillamook 

Bay, Oregon southward and are very abundant in California waters (Love, 1996). 

Topsmelt usually aggregate in shallow waters and tend to school near the surface, although they 

may be seen as deep as 9 m (30 ft)(Love, 1996). Topsmelt are often the most abundant fishes in 

estuaries. They are also found in kelp canopies, along sandy beaches, and at times, offshore. 

The San Francisco topsmelt {Atherinops affinis affinis), is distinctive because it is the only one of 

the three subspecies in this range to be found in the Sacramento-San Joaquin estuary. Topsmelt 

commonly live in the salt ponds near the southern end of San Francisco Bay, withstanding 

salinity concentrations three times greater than that of ocean water. Topsmelt are tolerant to a 

wide range of salinities, as they also live in fresh and brackish water (Carpelan, 1955). 

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Topsmelt are silvery green along their backs with a silver stripe midline along their side. They 

can reach up to 368 mm (14.5 in.) (Love, 1996) and may live six to nine years (Wang, 1996). 

These fishes mature between two and three years of age (Love, 1996) although Carpelan (1955) 

reported that the topsmelt of the salt ponds near Alviso spawned when they were one year old. 

Topsmelt spawn along the Pacific coast and in estuaries. In San Francisco Bay, spawning 

generally occurs between April and October, with a peak in May and June (Wang, 1996). 

Females probably spawn more than once (Wang, 1986) and produce between 200 to 1,000 eggs 

per season (Love, 1996). Spawning takes place primarily at night. Topsmelt eggs form large 

clusters as they become entangled in the variety of marine plants used as spawning substrate. 

Topsmelt larvae of the estuaries tend to swim in schools near the surface of shallow and open 

water, whereas pelagic larvae along the coast remain in the top few inches ofthe kelp canopies. 

Topsmelt feed on plankton, algae, crustaceans, detritus, amphipods, and insect larvae. This 

species is targeted by California sealions, harbor seals, least tems, and Brandt's and doublecrested cormorants. Topsmelt are also used as food and bait (Love, 1996). 

Bocaccio Sebastes paucispinis 

Bocaccio are one of the most wide-ranging and commercially important rockfish species. They 

belong to the family Scorpaenidae that is composed rockfishes and scorpionfishes and is 

represented by more than 310 species worldwide (Moyle and Cech, 1988). Bocaccio are one of 

the more than 60 species in the genus Sebastes that occur off the Pacific Coast of North America 

(Moyle and Cech, 1988). The range of bocaccio extends from Stepovak Bay, Alaskan Peninsula 

to Pt. Blanca, Baja California (Miller and Lea, 1972; Love, 1996). They are most abundant from 

British Columbia and southern Alaska to central Baja California (Love, 1996). Bocaccio often 

form large aggregations and tend to occur near the bottom. Though generally associated with 

hard benthic substrates, they may be found over mud and sand bottoms or high in the water 

column (Love, 1996). Bocaccio occur from the surface down to depths exceeding 457 m 

(1,500 ft). Adult bocaccio are generally found in deeper, offshore waters and are most common 

in depths from 46 m (150 ft) to 305 m (1,000 ft) (Love, 1996). Juveniles may be found in 

surface waters under drifting mats of kelp or around inshore reefs and kelp beds (Love, 1996). 

Huge aggregations ofjuvenile bocaccio invade shallow nearshore waters during certain years. 

Bocaccio gravitate into deeper water as they grow and are thought to move about extensively as 

adults. Tagged juveniles have been recaptured 60 and 80 miles from their release site (Love, 

1986). 

Bocaccio are an elongate, moderately compressed species of rockfish with a square to slightly 

indented tail. They are readily distinguished from other rockfish species of similar body shape 

by their coloration and large mouth, in which the maxillary extends beyond the rear margin of 

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the eye orbit, while in chilipeppers Sebastes goodei and silvergray rockfish Sebastes brevispinis 

the maxillary only extends to the middle or rear of the orbit. The lower jaw of bocaccio projects 

upward, ending with a prominent symphyseal knob. Adults are a dark, rusty-brown to gray color 

dorsally, gradating to a silvery belly. There is scattered spotting on the back and sides of 

juveniles and most adults. In adults, the spotting is largely confined to areas above the 

prominent lateral line. Chilipeppers and silvergray rockfish do not have spotting. Melanistic 

(black) blotches are also present on a small proportion ofthe adult bocaccio population. The 

size, shape, location, and number of these blotches varies with affected individuals. Melanistic 

blotches occur on several other schooling, deepwater rockfish species. 

Bocaccio are ovoviviparous or primitively viviparous with fertilization and embryonic 

development taking place within the body prior to larval extrusion (Phillips, 1964; Love, 1996). 

Fecundity varies proportionately with the size of the female. A 381 mm (15 in.) fish may 

produce 20,000 eggs per season while a 762 mm (30 in.) fish can produce many as 2.3 million 

eggs in a season (Phillips, 1964; Love, 1996). When embryonic development is complete a 

female extrudes her "eyed" larvae into the surrounding water, which activates them (Morris, 

1956; Phillips, 1964). Larvae range from 3.7 mm (0.15 in.) to 5.4 mm (0.21 in.) in length at 

extrusion. 

Spawning season varies somewhat with latitude. In southern California spawning peaks in 

January but may occur in during most other months of the year (October through July) 

(Love, 1996). In central and northern California spawning occurs from January to May and 

peaks in February (Love, 1996). Further north spawning takes place from January through 

March (Love, 1996). Larval bocaccio are pelagic planktivores and typically occur in the top 100 

feet of the water column (Thomas and Bence, 1992). They are widely distributed over the 

continental shelf and have been collected in plankton nets as far as 300 miles offshore (Thomas 

and Bence, 1992; Love, 1996). When larvae reach a size of 38 to 64 mm (1.5 to 2.5 in.) they 

begin settle out of the water column and orient to bottom substrates (Thomas and Bence, 1992). 

Settlement generally occurs by late May or early June (Thomas and Bence, 1992). 

Bocaccio are relatively large rockfishes at adulthood and grow rapidly compared to many ofthe 

deepwater rockfish species. Bocaccio grow to over 910 mm (36 in.) reaching a weight of 

15 pounds (Thomas and Bence, 1992; Love, 1996). They live for at least 35 years and possibly 

as long as 40 (A. Andrews MLML pers. comm.). At 8 to 10 years of age a bocaccio is around 

610 mm (24 in.) in length and may weigh 2.3 kg (5 lbs) (Thomas and Bence, 1992; Love, 1996). 

Females grow significantly faster than males and are larger when they mature (Phillips, 1964; 

Love, 1996). Females are also thought to have a longer lifespan (Love, 1996). Size at maturity 

varies geographically, with individuals in southern California maturing between 356 and 

457 mm (14 to 18 in.) and individuals to the north maturing between 559 and 610 mm (22 to 

24 in.) (Love, 1996). 

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The rapid growth of young bocaccio is fueled by their diet of small fishes. Other young rockfish 

Sebastes spp., surfperch (Family Embiotocidae), jack mackerel Trachurus symmetricus, and a 

variety of small inshore fishes compose the bulk of their diet by the end of their first year 

(Phillips, 1964). As bocaccio grow and move to deeper water they continue to prey primarily on 

fishes, however, they will also consume invertebrate species such as market squid Loligo 

opalescens and pelagic red crabs Pleuroncodes planipes. Small rockfishes Sebastes spp., 

sablefish Anoplopoma fimbria, northern anchovies Engraulis mordax, and lanternfish (Family 

Myctophidae) are among the fishes frequently consumed by adult bocaccio (Phillips, 1964; 

Love, 1996). Pinnipeds such as harbor seals Phoca vituUna and northern elephant seals 

Mirounga angustirostris are among the predators of bocaccio (Love, 1996). Juveniles also fall 

prey to a variety of seabirds. 

Historically bocaccio have been a major component of commercial rockfish landings in 

California. In addition to being the dominant rockfish species in California's early longline 

fishery, it was the most abundant rockfish harvested in the otter trawl fishery from Morro Bay to 

Fort Bragg until the mid-1980s (Thomas and Bence, 1992). Bocaccio have also been a 

prominent species in set gillnet and hook and line rockfish fisheries. Since the mid-1980s 

chilipepper have replaced bocaccio as the dominant rockfish species in the trawl fishery (Thomas 

and Bence, 1992). Federal management of bocaccio began in 1982 and because of its continued 

decline in abundance an annual harvest guideline of 4 million pounds was established for the 

species in 1991 (Thomas and Bence, 1992). Biomass estimates for the species fell from 

150 million pounds in 1978 to 20 million pounds in 1989 (Thomas and Bence, 1992). Landings 

of bocaccio have continued to decline in the 1990s and quotas have become increasingly 

restrictive. Declines in landings can be the result of a number of factors including the species' 

abundance, more restrictive quotas, and market forces. 

Commercial bocaccio landings in California were first accurately estimated in 1978 when they 

averaged around 4 million pounds annually (Thomas and Bence, 1992). Accurate landing data 

for bocaccio are not available from 1981-1990 (in CDFG Landing Summary) because the 

majority of bocaccio were landed in a combined bocaccio/chilipepper market category (Figure 

5-1 and Figure 5-2). From available CDFG data, landings of bocaccio peaked at over 10 million 

pounds by 1980 and then began a slow but steady decline until 1990 when landings were again 

about 4 million pounds (CDFG Landing Summary). Beginning in 1991, when a quota for the 

species was established, landings declined from over 2 million pounds (in 1991, 1992, and 1993) 

to less than 300,000 pounds in 1998 (Figure 5-3). The ex-vessel price for bocaccio since 1986 

has averaged 39 cents a pound and ranged from a low of less than 33 cents in 1986 to a high of 

around 50 cents in 1998 (CDFG). Virtually all bocaccio are processed (filleted) and sold fresh as 

rock cod or red snapper fillets. 

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600,000 

500,000 

400,000 

•o 

§ 300,000 

o 

0. 

200,000 

100,000 

I Monterey 

I Moss Landing 

3 Santa Cruz 

1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 

Year 

Figure 5-1. Bocaccio landings from Monterey Bay ports. Includes market category 253 (bocaccio). 

2,500,000 

2,000,000 

cn 

•O 

c 

3 

O 

Q. 

1,500,000 

1,000,000 

500,000 

I Monterey 

I Moss Landing 

I Santa Cruz 

1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 

Year 

Source: CDFG Landing Summaries 1986-1998. 

Figure 5-2. Landings of combined market category for bocaccio/chilipepper. Includes market category 

956 (bocaccio/chilipepper). 

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12,000,000 -| 

10,000,000 • 

8,000,000 

co 

§ 6,000,000 

o 

0. 

4,000,000 

2,000,000 

I Bocaccio 

I Bocaccb/Chilipepper 

j?> cS> oP <&&c&<&&c&<&<$>cX> dp dfi d? dp dp dp d? 

Year 

N<SP N < ^ N«SP NSP NcJP NcjP NcjP Nc*p ,£P Ncsp g> N c^ N c^ ^ ^ jp ^ $> $ 

Source: CDFG Landing Summaries 1986-1998. 

Figure 5-3. Bocaccio landings from California including the combined category for bocaccio and 

chilipepper. 

Bocaccio are also an important species in recreational catches along the coast of California and 

Oregon (Love, 1996). A majority of party boat landings of the species occur from Mendocino 

County, northern California to southern California (Love, 1996). In southern California 

bocaccio may account for as much as 14 percent of the total recreational catch (Thomas and 

Bence, 1992; Love, 1996). They are generally caught in greater abundance in the southern 

California fishery than in the northern California fishery (Thomas and Bence, 1992; Love, 1996). 

Recreational catches of bocaccio by the party boat fleet are typically made in depths of 76 m 

(250 ft) to 229 m (750 ft) of water (Thomas and Bence, 1992). Since 1984 recreational landings 

ofthe species have followed the same trend as commercial landings (Thomas and Bence, 1992). 

Beginning in 1999 the recreational take of bocaccio was restricted to 3 fish per day. 

Pacific herring Clupea pallasi 

The life history ofthe Pacific herring is discussed in Section 4.10 of this report. 

5.2.2 Macroinvertebrates 

A majority (62 percent) of the total macroinvertebrates impinged by both MLPP intakes was 

collected from Units 1 through 5. Cancer spp. crabs constituted 37 percent of the total number 

of macroinvertebrates impinged at Units 1 through 5 and 9 percent at Units 6 and 7. Crangon 

spp. shrimps constituted 19 percent of the total number impinged at Units 1 through 5 and 31 

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percent at Units 6 and 7. The species composition of impinged organisms was generally similar 

between the two intakes. 

Rock Crabs Family Cancridae 

The life history ofthe rock crab is discussed in Section 4.11 of this 316(b) Demonstration 

Report. 

Hairy Rock Crab Cancer jordani 

The life history of the hairy rock crab is discussed in Section 4.12 of this 316(b) Demonstration 

Report. 

Yellow Rock Crab Cancer anthonyi 

The life history ofthe yellow rock crab is discussed in Section 4.13 of this 316(b) Demonstration 

Report. 

Brown Rock Crab Cancer antennarius 

The life history of the brown rock crab is discussed in Section 4.14 of this 316(b) Demonstration 

Report. 

Dungeness Crab Cancer magister 

The life history of the dungeness crab is discussed in Section 4.15 of this 316(b) Demonstration 

Report. 

Red Rock Crab Cancer productus 

The life history of the red rock crab is discussed in Section 4.16 of this 316(b) Demonstration 

Report. 

Slender Rock Crab Cancer gracilis 

The life history of the slender rock crab is discussed in Section 4.17 of this 316(b) 

Demonstration Report. 

European Green Crab Carcinus maenas 

The life history of the European green crab is discussed in Section 4.18 of this 316(b) 

Demonstration Report. 

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Oregon cancer crab Cancer oregonensis 

The Oregon cancer crab ranges from St. George Island, Pribilof Islands, Alaska to Palos Verde, 

California, although they are uncommon south of Point Arena, California (Jensen, 1995). They 

are found in holes, crevices, empty barnacle shells, under rocks, and on pilings. Although they 

occur in the intertidal zone, they are more plentiful subtidally to depths of 435 m (1427 ft) (Garth 

and Abbott, 1980). 

Oregon cancer crabs are usually reddish-brown or orange above and lighter below, with darkcolored claws. The carapace color can vary, however, and in some areas white, mottled, or 

striped crabs are common (Jensen, 1995). It is a stout, small crab with a carapace width of 31.9 

mm (1.3 in.) in males and 47.1 mm (1.9 in.) in females (Garth and Abbott, 1980). (Jensen [1995] 

reports a size to 53 mm [2.1 in.]). The Oregon crab has ten teeth; the carapace is widest at the 

seventh and eighth tooth. 

In Washington populations (Puget Sound) molting and mating of the Oregon cancer crab occurs 

from April to June. One brood a year is typical and ovigerous females are most often seen from 

November through February. The ovigerous females that are occasionally found from April to 

June are most likely carrying a second brood. The average number of eggs per female is 

approximately 20,540, with a range between 10,000 and 33,000 (Garth and Abbott, 1980). 

Oregon cancer crabs live among beds of barnacles and mussels. Although they feed mainly on 

these crustaceans and molluscs, polychaete worms, smaller crustaceans, and algae are also 

consumed. They are primarily carnivores and tend to be more active at night. 

The most abundantly impinged shrimp species were three species of bay shrimp: Crangon 

nigricauda (17 percent ofthe total macroinvertebrates impinged), Crangon nigromaculata (7 

percent), and Lissocrangon stylirostris (7 percent). All three species were collected throughout 

the year with peak abundance during the winter that was associated with storms. They were 

impinged primarily at night. Other species of shrimp such as Pandalus danae, Upogebia 

pugettensis, and Peneus californiensis were impinged in relatively low numbers. 

Seven species of cancer crabs were impinged in the following order of abundance: 1) Cancer 

antennarius, C. anthonyi, C. productus, C. gracilis, C. magister, C. jordani, and C. oregonesis. 

All of these crab species were impinged in substantially higher numbers at Units 1 through 5. 

Three species {Cancer antennarius, C. anthonyi, C. productus) were collected in the greatest 

numbers and accounted for 37 percent of the catch at Units 1 through 5 but only 9 percent were 

collected at Units 6 and 7. Cancer antennarius was the most abundant (21 percent) of all 

macroinvertebrates impinged. The frequency of collection of small Cancer antennarius 

suggested that Moss Landing Harbor/Elkhom Slough provide a nursery habitat for juvenile 

crabs. C. anthonyi constituted approximately 4 percent of all macroinvertebrates impinged. The 

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peak abundance in April was composed ofjuvenile crabs. C. productus constituted less than 2 

percent of the total number of macroinvertebrates impinged. Again, the peak (June) in 

abundance was represented by the presence of small crabs. Dungeness crab were collected in 

low numbers (24 crabs from Units 1 through 5 and 27 crabs from Units 6 and 7) throughout the 

year. 

Squid constituted less than 5 percent of the total number of macroinvertebrates impinged at the 

Units 1 through 5 intake and 3 percent at Units 6 and 7. They were collected in every month and 

did not display a seasonal pattern. The peak number of crabs and squid were impinged in June 

(68 individuals) at Units 1 through 5 and in October at Units 6 and 7 (70 individuals). 

Bay shrimps Crangon spp. 

Crangon nigricauda, black-tailed shrimp, Crangon nigromaculata, black-spotted shrimp and 

Lissocrangon stylirostris, smooth shrimp, commonly known as "bay shrimp" belong to the 

Family Crangonidae. Shrimp families are easily differentiated from each other by their claw 

characteristics; crangonids are the only shrimp family to have subchelate claws. These shrimp 

tend to bury in the sand or mud and are more flattened than other shrimp. 

In California today, bay shrimp are fished commercially primarily in San Francisco Bay (Figure 

5-4) and are sold mainly as bait. However, in the 1940's and 1950's, annual bay shrimp catches 

for human consumption averaged 704,000 pounds with peaks as high as nearly 3,000,000 pounds 

(Chace and Abbott, 1980). Crangon franciscorum, Franciscan bay shrimp, were the vast 

majority of bay shrimp caught commercially until the early 1980's. The black-tailed bay shrimp 

is currently the most commonly caught species, and the spotted bay shrimp has also increased in 

abundance since the 1980's (SEW, 1999). Smooth bay shrimp are rarely taken in large numbers 

(Chace and Abbott, 1980). 

Black-tailed shrimp Crangon nigricauda 

The black-tailed bay shrimp are found from Prince William Sound, Alaska to Isla San Geronimo, 

Baja California, Mexico. They are commonly found in estuaries, embayments, and in the 

nearshore ocean environment, ranging from the intertidal zone down to 57 m (187 ft) (Jensen, 

1995). Black-tailed shrimp live on sandy and muddy bottoms and are also found around eelgrass 

beds. 

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E 

XZ 

a 

o 

•o 

c 

o 

a. 

San Francisco, Monterey and Moss Landing Contribution 

to California Bay Shrimp Landings 

1986 to 1998 

| Total 

|San Francisco 

I Monterey 

I Moss Landing 

CM co -*r m co i*- oo 

Ol Oi O O) O* O) o 

Ol Or Or Or Oy O) Or 

Source: CDFG Landings Summaries 1986-1998. 

Figure 5-4. Reported commercial bay shrimp landings in San Francisco, Monterey, and Moss Landing 

areas from 1986 to 1998. 

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I 

Crangonids can only be identified to species once they reach a length greater than 10 mm (0.4 

in.). Black-tailed shrimp usually become mature after one year, when females are approximately 

33mm (1.3 in.) and males are approximately 28 mm (1.1 in.) (CDFG, 1999). Males generally 

reach a total length of 40 mm (1.6 in.) and females 60 mm (2.4 in.), although greater lengths 

have been reported in San Francisco Bay and some offshore populations (FWIE, 1999). Females 

may live two years, while most males die after one year (CDFG, 1999). 

The spawning season of black shrimp appears to occur year-round along the California coast, 

with peaks in winter-spring and summer-fall (FWIE, 1999). The females, carrying eggs under 

their abdomen, remain partly buried in the sand or mud during the day. The eggs hatch at night, 

at which time the females emerge and beat their pleopods, creating currents to release the newly 

hatched larvae. By dawn, most of the larvae have been freed from the female. Fecundity is 

directly related to the female's size, with an average-sized female producing approximately 

3,700 eggs (Krygier and Horton, 1975). Early-stage larvae, found in the surface waters, 

generally occur in near shore locations while late-stage larvae, found near the bottom of the 

water column, are more likely to be found in onshore and upstream locations (FWIE, 1999). The 

planktonic stage lasts from two to five months (Krygier and Horton, 1975). 

Black shrimp tend to migrate from concentrations of lower to higher salinity as they mature. As 

egg stage development in ovigerous females advances from stage one to stage four, the shrimp's 

occurrence in more saline waters also increases (salinity average of 24.6 ppt for females with 

stage four eggs) (FWIE, 1999). Higher temperatures lead to larger sizes of bay shrimp, 

presumably due to faster growth and longer growing seasons Annual abundance of the blacktailed shrimp increased during the drought years (1987 to 1992) and has remained high despite 

increased freshwater flows and decreased salinities. 

Black-spotted shrimp Crangon nigromaculata 

The black-spotted shrimp is found from the Farallon Islands in northem California to Turtle Bay, 

Baja California, Mexico (CDFG, 1999). It inhabits shallow coastal waters and is typically found 

on sand bottoms from 5 to 174 m (16 to 565 ft) (Jensen, 1995). It is more commonly found in 

nearshore ocean environments than in estuaries. The black-spotted shrimp is migratory and 

capable of swimming, however it tends to be more epibenthic, remaining in areas of sand and 

mud. 

The black-spotted shrimp is easily recognized by the eyespots on either side of their abdomen. 

These shrimp can reach approximately 70 mm (2.7 in.) in size (Jensen, 1995). The spawning 

season of bay shrimp is long, with reports of ovigerous females being found during 9 to 12 

months ofthe year (FWIE, 1999). Periods of peak abundance of black-spotted juveniles in the 

Bay-Delta area have been highly variable, ranging from late spring to winter. It has been 

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5.0 Impingement Effects 

hypothesized that the Bay serves as a continuation of the nearshore nursery area for the blackspotted shrimp (CDFG, 1999). 

Since the mid-1980's, the abundance of black-spotted shrimp has steadily increased. It was the 

second most abundant species of shrimp caught in San Francisco Bay from 1991 through 1993 

(CDFG, 1999). 

Smooth shrimp Lissocrangon stylirostris 

The smooth shrimp ranges from Chrikof Island, Alaska to San Luis Obispo Bay, near Avila 

Beach, California. It occurs most commonly in the subtidal area to about 80 m (262 ft) (Jensen, 

1995). Smooth shrimp inhabit the surf zone on wave swept beaches (Jensen, 1995) and are 

sublittoral in regions of hard sand or mixed rock bottoms (Chace and Abbott, 1980). 

Smooth shrimp reach approximately 61mm (2.4 in.) in length (Jensen, 1995). They are the least 

abundant species of bay shrimp caught by fishermen in San Francisco Bay. Smooth shrimp have 

been caught in water temperatures ranging from 8.7° to 16° C (47.7° to 60.8° F) and at salinities 

ranging from 52 to 100 percent seawater (Chace and Abbott, 1980). Smooth shrimp are faster 

moving than other bay shrimp, probably due to their more challenging environment. They feed 

on other small cmstaceans and clams (Jensen, 1995). 

Market squid Loligo opalescens 

The market squid is a member of the class Cephalopoda; squids and octopuses. Cephalopods are 

highly organized and the most intelligent of the invertebrates (Hochberg and Fields, 1980). The 

giant nerve fibers of the market squid are used in neurophysiological research, adding much to 

our understanding of nerve impulses. Market squid range from southern Alaska to Isla 

Guadalupe, Mexico, but are more common from British Columbia southward (Hochberg and 

Fields, 1980). Market squid are pelagic, living in coastal waters but returning to shallow inshore 

waters to spawn. It is the only species of squid that is abundant inshore (Hochberg and Fields, 

1980). 

Market squid are translucent blue in color, but vary from a mottled gold and brown to a dark 

brown or red. They have an ability to change color; this "social signaling" is used for courtship, 

schooling, feeding, and for camouflage when frightened. Squid have elongated bodies and swim 

by jet propulsion. Male market squid reach 275 mm (11 in.) in size (not including tentacles) and 

females approximately 200 mm (8 in.) (UCLA, 1999). Female and male market squid may reach 

maturity at dorsal mantle lengths (DML) as small as 72 to 81 mm (2.8 to 3.2 in.) (FWIE, 1999). 

At 15 mm (0.6 in.) DML squid are reported to be approximately 50 days old. 

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Market squid spawn year-round from San Francisco to Baja, but exhibit biannual spawning 

peaks (Starr et al, 1998). The majority of spawning activity in southern California squid 

populations occurs from December through March, but may also occur in July. Squid 

populations in Monterey Bay spawn mainly in May and June, and to a lesser extent in November 

(Hochberg and Fields, 1980). Adults migrate from areas over the continental shelf to nearshore 

sandy and rocky bottom bays, often near submarine canyons, to spawn. Both male and female 

squid are terminal spawners and die after spawning. Starr et al. (1998) state market squid have a 

life span of one to two years, while Hochberg and Fields (1980) report most spawners appear to 

be three years old. 

The female produces from 180 to 300 eggs encased in a cylindrical capsule and may extrude 20 

to 30 capsules during a spawning event (Starr et al, 1998; FWIE, 1999). The first egg cases to be 

laid are attached with thin stalks to the bottom substrate. Subsequent layers (approximately 20 to 

30 capsules) are then deposited until large clusters are formed (Starr et al, 1998). Egg cases have 

been observed in depths ranging from 3 to 180 m (10 to 590 ft) (FWIE, 1999). The eggs hatch in 

15 to 90 days, depending on water temperature. 

Squid do not have a true larval stage; young squid are called hatchlings. The hatchling squid 

look like miniature adults and have a mantle length of 2.7 mm (0.1 in.) (Starr et al, 1998). 

Hatchlings live off their yolk sac for several days. They are weak swimmers until they are 

around 15 mm (0.59 in.) DML, and therefore, can be widely dispersed by currents (FWIE, 1999). 

At 70 to 80 days old hatchlings have become stronger swimmers and begin to form schools 

(FWIE, 1999). Juveniles grow rapidly and school for approximately 4 to 8 weeks in semiprotected nearshore areas before beginning to disperse into deep water (Starr et al., 1998). 

Squid are carnivores and feed using their tentacles, preying on small cmstaceans (euphausiids, 

mysids, etc.) fishes, polychaete worms, and their own young. Hatchling squid feed on small 

planktonic cmstaceans including crab larvae, copepods, and penaeid shrimp myses (FWIE, 

1999). Squid are consumed by many species of fishes, birds, and marine mammals. 

Market squid are fished commercially, marketed for human consumption or sold as bait. Figure 

5-5 shows the reported Monterey area contribution to the commercial landings for market squid 

in California from 1986 through 1998. Historically, the squid fishery has been important to the 

central California coast. 

E9-053.9 5-19 MLPP 316(b) Resource Assessment 

4-28-2000