NOAA Technical Report NMFS 78 August 1989

Survey of Fishes and Water Properties

of South San Francisco Bay,

California, 1973-82

Donald E. Pearson

U.S. Department of Commerce
NOAA TECHNICAL REPORT NMFS

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34. Additions to a revision of the shark genus Carcharhinus: Synonymy of Aprionodon and Hypoprion, and description of a new species of Carcharhinus (Carcharhinidae),

by J. A. F. Garrick. November 1985, 26 p.

35. Synoptic review ofthe literature on the Southern oyster drill Thais haemasloma

j1oridana, by Philip A. Butler. November 1985, 9 p.

36. An egg production method for estimating spawning biomass of pelagic fish:

Application to the northern anchovy, Engraulis mordax, by Reuben Lasker (editor).

December 1985,99 p.

37. A histopathologic evaluation of gross lesions excised from commercially important North Atlantic marine fishes, by Robert A. Murchelano, Linda DespresPatanjo, and John Ziskowski. March 1986, 14 p.

38. Fishery atlas of the northwestern Hawaiian Islands, by Richard N, Uchida and

James H. Uchiyama (editors). September 1986, 142 p.

39. Survey of fish protective facilities at water withdrawal sites on the Snake and

Columbia Rivers, by George A. Swan, Tommy G. Withrow, and Donn L. Park. April

1986, 34 p.

40. Potential impact of ocean thennal energy conversion (OTEC) on fisheries, by

Edward P. Myers, Donald E. Hoss, Walter M. Matsumoto, David S. Peters, Michael

P. Seki, Richard N. Uchida, John D. Ditmars, and Robert A. Paddock. June 1986,

33 p.

41. A stationary visual census technique for quantitatively assessing community structure of coral reef fishes, by James A. Bohnsack and Scott P. Bannerol. July 1986, 15 p.

42. Effects oftemperature on the biology of the northern shrimp, Pandalus borealis,

in the Gulf of Maine, by Spencer Apollonio, David K. Stevenson, and Earl E. Dunton.

Jr. Septembec 1986, 22 p.

43. Environment and resources of seamounts in the North Pacific, by Richard N.

Uchida, Sigeiti Hayasi, and George W. Boehlert (editors). September 1986, 105 p.

44. Synopsis of biological data on the porgies, Calamus arctifrons and C. proridens

(Pisces: Sparidae), by George H. Darcy. September 1986, 19 p.

45. Meristic variation in Sebasles (Scorpaenidae), with an analysis of character

association and bilateral pattern and their significance in species separation, by Lochai Chen. September 1986, 17 p.

46. Distribution and relative abundance of pelagic nonsa1monid nekton eff Oregon

and Washington 1979-84, by Richard D. Brodeur and William G. Pearcy. December

1986, 85 p.

47. Reproduction, maturation, and seed production of cultured species: Proceedings

of the twelfth U.S.-Japan meeting on aquaculture, Baton Rouge, Louisiana, October

25-29, 1983, by Carl J. Sindennann (editor). February 1987, 73 p.

48. Widow rockfish: Proceedings of a workshop, Tiburon, California, December

11-12,1980, by William H. Lenarz and Donald R. Gunderson (editors). January 1987,

57 p.

49. Reproduction, movements, and population dynamics of the southern kingflsh,

MenJicirrhus americanus, in the northwestern Gulfof Mexico, by Stephen M. Harding

and Mark E. Chittenden, Jr. March 1987, 21 p.

50. Preparation of acetate peels of valves from the ocean quahog, Arctica islandica,

for age detenninations, by John W. Ropes. March 1987, 5 r.

51. Status, biology, and ecology of fur seals. Proceedings of an international

workshop, Cambridge, England, 23-27 April 1984, by John P. Croxall and Roger

L. Gentry (editors). June 1987,212 p.

52. Limited access alternatives for the Pacific groundfish fishery, by Daniel D.

Huppert (editor). May 1987, 45 p.

53. Ecology of east Florida sea turtles: Proceedings of the Cape Canaveral, Florida,

sea turtle workshop, Miami, Florida, February 26-27, 1985, by Wayne N. Witzell

(convener and editor). May 1987, 80 p.

54. Proximate and fatty add composition of 40 southeastern U.S. finfish species,

by Janet A. Gooch, Malcolm B. Hale, Thomas Brown. Jr., James C. Bonnet, Cheryl

G. Brand, and Lloyd W. Reiger. June 1987, 23 p.

55. Proximate composition, energy, fatty acid, sodium, and cholesterol content of

fmflsh, shellfish, and their products, by Judith Knynowek and Jenny Murphy. July

1987, 53 p.

56. Some aspects of the ecology of the leatherback turtle Dennochelys coriacea at

Laguna Jolova, Costa Rica, by Harold F. Hirth and Larry H. Ogren. July 1987, 14 p.

57. Food habits and dietary variability of pelagic nekton off Oregon and Washington,

1979-1984, by Richard D. Brodeur, Harriet V. Lorz, and William G. Pearcy. July

1987, 32 p.

58. Stock assessment of the Gulf of Menhaden, Brevoortia palronus, fishery, by

Douglas S. Vaughan. September 1987, 18 p.

59. Atlantic Menhaden, Brevoortia ryrannus, purse seine fishery, 1972-84, with a

brief discussion of age and size composition of the landings, by Joseph W. Smith,

William R. Nicholson, Douglas S. Vaughan, Donnie L. Dudley, and Ethel A. Hall.

September 1987, 23 p.

60. Gulf Menhaden, Brevoorria palronus, purse seine fishery, 1974-85, with a brief

di,cussion of age and size composition of the landings, by Joseph W. Smith, Eldon

J. Levi, Douglas S. Vaughan, and Ethen A. Hall. December 1987, 8 p.

61. Manual for starch gel electrophoresis: A method for the detection of genetic variation, by Paul B. Aebersold, Gary A. Winans, David J. Teel, George B. Milner, and

Fred M. Utter, December 1987, 19 p.

62. Fishery publication index, 1980-85; Technical memoradum index, 1972-85, by

Cynthia S. Martin, Shelley E. Arenas, Jacki A. Guffey, and Joni M. Packard.

December 1987, 149 p.

63. Stock assessment of the Atlantic Menhaden, Brevoortia ryrannus, fishery, by

Douglas S. Vaughan and Josepl:: W. Smith. January 1988, 18 p.

64. IDustIated key to penaeoid shrimps of commerce in the Americas, by Isabel Perez

Farfante. April 1988, 32 p.

65. History of whaling in and near North Carolina, by Randall R. Reeves and Edward

Mitchell. March 1988,28 p.

66. Atlas and zoogeography of common fishes in the Bering Sea and Northeastern

Pacific, by M. James Allen and Gary B. Smith. April 1988, 151 p.
NOAA Technical Report NMFS 78

Survey of Fishes and Water Properties

of South San Francisco Bay,

California, 1973-82

Donald E. Pearson

August 1989

u.s. DEPARTMENT OF COMMERCE

Robert Mosbacher, Secretary

National Oceanic and Atmospheric Administration

William E. Evans, Under Secretary for Oceans and Atmosphere

National Marine Fisheries Service

James Brennan, Assistant Administrator for Fisheries

CONTENTS

Acknowledgments iv

Introduction 1

Materials and Methods 2

Sampling 2

Analysis 3

Results 5

Physical characteristics 5

Temperature 5

Salinity 5

Substrate 5

Icthyological characteristics 6

General 6

Seasonal changes 6

Annual changes 6

Discussion 10

Life history 10

Distribution pattern 11

Species composition 11

Wet vs. dry years 12

Citations 13

iii

Appendix A: Trawl-effort distribution 14

Appendix B: Mean monthly water temperatures 14

Appendix C: Mean monthly salinities 14

Appendix D: Mean catch-per-trawl of fish species

Northern anchovy 15

English sole 15

Shiner surfperch 15

Gobies 15

Pacific herring 16

Sanddabs 16

Staghorn sculpin 16

Dwarf surfperch 16

Barred surfperch 17

White surfperch 17

Brown rockfish 17

Pile surfperch 17

Smelts 18

California tonguefish 18

Brown smoothhound sharks 18

Leopard sharks 18

Walleye surfperch 19

Bay pipefish 19

White croaker 19

Shad 19

Diamond turbot 20

Bat rays 20

Plainfin midshipmen 20

Bonyhead sculpin 20

Starry flounder 21

California halibut 21

Appendix E: Monthly species diversity 21
Acknowledgments _

I would like to express my sincere thanks to the staff of Marine Ecological

Institute for their assistance and access to their data. Special thanks are

also given to Dr. Ralph Larson of San Francisco State University for

his valuable critical review of this manuscript.

The National Marine Fisheries Service (NMFS) does not approve, recommend

or endorse any proprietary product or proprietary material mentioned in this

publication. No reference shall be made to NMFS, or to this publication furnished

by NMFS, in any advertising or sales promotion which would indicate or imply

that NMFS approves, recommends or endorses any proprietary product or proprietary material mentioned herein, or which has as its purpose an intent to cause

directly or indirectly the advertised product to be used or purchased because of

this NMFS publication.

iv
Survey of Fishes and

Water Properties of

South San Francisco Bay,

California, 1973-82

DONALD E. PEARSON

Tiburon Laboratory

Southwest Fisheries Center

National Marine Fisheries Service, NOAA

3150 Paradise Drive

Tiburon, CA 94920

ABSTRACT

The objective of this study was to describe the physical and

ichthyological changes occurring seasonally and annually in the

south San Francisco Bay, based on the results of 2,561 otter

trawl and water samples obtained between February 1973 and

June 1982. Temperature varied predictably among seasons in

a pattern that varied little between years. Salinity also underwent predictable seasonal changes but the pattern varied substantially between years. The most abundant species offish were

northern anchovy (Engraulis mordax), English sole (Parophrys

vetulus), and shiner surfperch (Cymatogaster aggregata). The

majority of the common fish species were most abundant during wet years and least abundant in dry years. Numeric diversity was highest during the spring and early summer, with no

detectable interannual trends. Species composition changed extensively between seasons and between years, particularly years

with extremely high or extremely low freshwater inflows. All

the common species exhibited clustered spatial distributions.

Such spatial clustering could affect the interpretation of data

from estuarine sampling programs. Gobies (Family Gobiidae)

were more abundant during flood tides than during ebb tides.

English sole were significantly more abundant in shallower

areas. Shiner surfperch showed significant differences in abundance between sample areas.

Introduction _

With approximately 3.5 million people living in the area,

the San Francisco Bay (also known as the San Francisco

Estuary) is heavily impacted by man's activities. One of the

most critical environmental issues for this estuary is the role

of freshwater inflow. As increasing demands are placed on

the freshwater sources to the estuary, it becomes increasingly important to understand the estuary as it is affected by

freshwater inflow.

San Francisco Bay has four distinct sections: the delta,

north bay, central bay, and the south bay (Fig. 1). The delta

is formed by the confluence of the Sacramento and San Joaquin Rivers and is a region of freshwater. The north bay includes the null zone (tidal wedge) which varies in location

depending on river outflows (Rozengurt et al. 1987). Most

freshwater entering the estuary comes from the delta and

passes through the north bay (Conomos 1979). The central

bay connects the Pacific Ocean, the north bay, and south bay.

Generally quite deep, the cental bay is probably the most

diverse region of the estuary based on habitat types,

hydrology, and geography. The south bay is shallow, with

a mean depth of only 3 meters (McCulloch et al. 1970), and

obtains most of its freshwater from the north bay (Conomos

1979). Flushing of the south bay is generally poor.

Two major ecological studies have been conducted on large

portions of the San Francisco Bay. One, an ongoing study

by the California Department of Fish and Game (DFG), is

a long-term sampling program of the entire estuary with the

specific goal of determining the effects of freshwater inflow

on the estuary. As part of the study, they hope to obtain

baseline data and achieve a more complete understanding of

the ecology of the estuary (Perry Herrgesell, Calif. Dep. Fish

Game, Wilson Way, Stockton, CA 95211, pers. commun.

Sept. 1988). To accomplish these goals, DFG samples 42

stations throughout the estuary. Each station is sampled once

a month using an otter trawl, a midwater trawl, and a water

sampler. They have found that most fish species within the

estuary show a mixed response to delta outflows (DFG 1987).

The other important ecological study of San Francisco Bay

was done by Aplin (1967), in which he examined six stations in south San Francisco Bay from 1963 to 1966. Each

station was sampled once a month using a midwater trawl,

an otter trawl, a water sampler, and a sediment sampler.

Results were tabulated with little attempt to interpret the data.

One of Aplin's sampling stations was located near one of

the stations used in the present study, and specific details

of his results are compared with those of this study in the

"Species Composition" section.

This study was undertaken to examine the spatial and temporal variation ofselected elements of the fish fauna and of

water characteristics ofthe estuarine habitat in the south San

Francisco Bay. By intensively examining a small portion of

the estuary from February 1973 to June 1982, it was possible to determine relative abundances by month and year of

the most common fish species. Patterns of distribution were

also examined. In addition, it was possible to test for the
10

I

N

r

Figure 1

Locations of five sampling stations in south San Francisco Bay, California, used in this study.

effects of tide, time, depth, and location on fish catches.

Sampling was done by Marine Ecological Institute (MEl),

a private, nonprofit, educational organization, as part oftheir

marine science education program.

This study differs from the Aplin and DFG studies in

several respects: its more limited geographic scale, its

reliance on a larger number ofsamples each month (Appendix A) and on longer-term sampling, and the fact that it was

conducted as part of an education program. An intensive examination of a small region of the estuary is useful because

it reveals some of the small-scale biological characteristics

of the environment.

An additional characteristic of this study which makes it

valuable is the time-period covered. Two events during the

study period, a drought in 1976-77 and two extremely wet

years in 1974 and 1980 (Table 1), made it possible to examine the effects of large fluctuations in freshwater inflow

on the salinity and biota of the area. The intensive nature

ofthis study allowed reasonably accurate estimates of relative

abundances of major species during these events.

2

Materials and methods _

Sampling

During the study period, Marine Ecological Institute (MEl)

conducted educational cruises in south San Francisco Bay.

Each cruise took four hours, and occasionally two cruises

were made in a single day. On a typical cruise, two trawls,

two water samples, and a sediment grab sample were made,

each at one offive sampling stations (Fig. 1). The time, location, depth, and distance of each trawl were recorded.

The five sampling stations were loosely defined. Each

station was bounded on one side by the deepwater channel

and on the opposite side by shallows, with roughly defined

endpoints. The stations were in depths of 1.5 to 14 meters.

Sediment samples were collected with a Petersen grab

sampler having a 2-liter capacity or occasionally using a

Phleger core sampler with a 1-meter-long shaft. The sediments were qualitatively examined for texture and contents;

no attempt was made at quantification. Water samples were

collected with a Kemmerer bottle from 1 meter below the

surface. The temperature was determined using an electronic

meter or occasionally with a thermometer, both with an

accuracy of ±0.5°C. Salinity was determined by hydrometer
Table 1

Mean monthly delta outflow values (mean m3/s) at Chipps Island monitoring station, south San Francisco Bay. Source: Calif. State Water

Resour. Board, Sacramento, CA (unpubl. data, Nov. 1988).

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1973 2869 2891 2158 631 331 204 130 169 316 398 1696 2153

1974 3925 1688 2172 3091 723 480 250 362 594 524 679 793

1975 494 1592 1855 977 815 637 315 270 380 478 509 568

1976 265 212 222 250 115 111 123 128 101 103 103 119

1977 124 139 87 87 113 71 91 70 79 59 112 240

1978 1873 1589 2402 1715 1137 257 113 168 334 273 309 249

1979 862 1312 1069 410 380 151 152 98 143 221 345 539

1980 3345 3433 2807 812 592 421 317 118 280 209 189 353

1981 625 618 750 330 254 129 150 90 133 144 1017 2352

1982 2766 2510 2266 3967 1638 807 477 380 734 651 1108 2507

1983 2497 4904 7705 3341 2773 2031 1218 691 887 914 2098 4399

1984 2855 1175 988 417 317 226 289 233 384 337 734 879

1985 428 441 295 196 208 147 139 65 90 267 195 267

Mean 1764 1732 1913 1250 725 436 291 219 343 352 699 1186

SD 1342 1392 1971 1347 759 528 301 176 257 240 629 1287

with an accuracy of ±0.5 ppt. The otter trawl had a 4.9-

meter headline, 3.8-cm mesh, with O.64-cm mesh (stretched)

in the codend. The net was secured to the ship with 23-meter

warps. After the net was fully deployed, a timer was set for

10 minutes at which time the net was recovered manually.

The catch was placed in holding tanks on deck where the

fish were counted and identified.

Analysis

Since these data were collected as part of an education program, analysis methods had to take into account several

unusual characteristics of the data set. The two most important problems were unequal sampling effort between months

and the sometimes imprecise species identifications.

Initially about 3,500 trawls were made. Data were discarded from 939 trawls because of hung-up nets or illegible

or misplaced data sheets. A total of 2,561 trawls remained

for analysis. To correct for differences in the number of

trawls per month (Appendix A), the results were reported

as mean catch-per-trawl per month. Statistical techniques

capable of handling unequal sample sizes were used as required. All analyses were done on this basis except the

species list (Table 2). Data from months with less than five

trawls were not used in this study due to the possibility of

clustered distributions which might reduce the reliability of

abundance estimates.

Based on direct observation and discussion with the ship's

crew, some species identifications were considered questionable. In addition, many species had been recorded only

to family level. Captured taxa were organized using a simple classification system described below:

Primary species

1 Readily identifiable to species, and

2 common (at least 1% of total catch);

3

Primary family

1 Readily identifiable to family, and

2 common (as a family composing at least 1% of catch);

Secondary species

1 Readily identifiable to species, and

2 uncommon «1 % of catch);

Secondary family

1 Readily identifiable to family, and

2 uncommon «1 % of total catch);

Tertiary species

I Identification questionable and/or

2 uncommon or rare in the catch;

Tertiary family

1 Identification questionable and/or

2 uncommon or rare in the catch.

Data on the primary species/families were considered

sufficiently reliable to yield valid seasonal and yearly trends

and to allow statistical testing of distribution and the effects

of trawl variables. The secondary species/family data were

deemed inadequate for statistical analysis, and only yearly

and seasonal trends were used. Data on the tertiary species/

families were considered unreliable, and no analysis was

performed.

Seasonal trends were determined from the unweighted

mean monthly catch-per-trawl. To determine yearly trends,

relative values for the month of peak abundance were compared for each ofthe primary species/families showing pronounced seasonal trends. Otherwise, the mean monthly catch

values were compared over the entire year.

Prior to examining temporal and spatial distribution

patterns of the primary species/families, it was necessary to

test the effects of tide, time, depth, and location on catches.

This was necessary because MEl made no attempt to sample equally at all depths, tide states, times, or sampling

stations. In order to combine all ofthe trawls from an entire
Table 2

Species list for south San Francisco Bay from Marine Ecological Institute's trawl study, 1973-82.

(M = marine, F = fresh, E = estuarine, A = anadromous).

507 Secondary species

461 Secondary species

423 Secondary species

388 Secondary species

382 Secondary species

380 Secondary species

357 Secondary family

333 Secondary species

333 Secondary species

310 Secondary species

265 Secondary species

262 Secondary species

252 Secondary species

123 Tertiary species

96 Tertiary species

65 Tertiary species

58 Tertiary species

40 Tertiary species

30 Tertiary species

22 Tertiary species

14 Tertiary family

9 Tertiary family

2 Tertiary species

2 Tertiary species

I Tertiary species

1 Tertiary species

1 Tertiary species

1 Tertiary species

1 Tertiary species

1 Tertiary species

1 Tertiary species

1 Tertiary species

1 Tertiary species

Species

Northern anchovy, Engraulis mordax

English sole, Parophrys vetulus

Shiner surfperch, Cymatogaster aggregata

Gobys, Family Gobiidae

Yellowfin goby, Acanthogobius flavimanus

Chameleon goby, Tridentiger trigonocephalus

Bay goby, Lepidogobius lepidus

Cheekspot goby, Ilypnus gilberti

Pacific herring, Clupea harengus

Sanddabs, Family Bothiidae

Pacific sanddab, Citharichthys sordidus

Speckled sanddab, Citharichthys stigmaeus

Staghorn sculpin, Leptocottus armatus

Dwarf surfperch, Micrometrus minimus

Barred surfperch, Amphistichus argenteus

White surfperch, Phanerodon furcatus

Brown rockfish, Sebastes auriculatus

Pile surfperch, Damalichthys vacca

Smelt, Family Osmeridae and Atherinidae

Longfin smelt, Spirinchus thaleichthys

Surf smelt, Hypomesus pretiosus

Night smelt, Spirinchus starksi

Topsmelt, Atherinops affinis

Jacksmelt, Atherinopsis californiensis

California tonguefish, Symphurus atricauda

Brown smoothhound, Mustelus henlei

Leopard shark, Triakis semifasciata

Walleye surfperch, Hyperprosopon argenteum

Bay pipefish, Syngnathus leptorhynchus

White croaker, Genyonemus lineatus

Shad, Family Clupeidae

Threadfin shad, Dorosoma petenense

American shad, Alosa sapidissima

Diamond turbot, Hypsopsetta guttulata

Bat ray, Myliobatus californica

Plainfin midshipman, Porichthys notatus

Bonyhead sculpin, Artedius notospilotus

Starry flounder, Platichthys stellatus

California halibut, Paralichthys californicus

Black surfperch, Embiotoca jacksoni

Spiny dogfish, Squalus acanthias

Lingcod, Ophiodon elongatus

Pacific tomcod, Microgadus proximus

Pacific sardine, Sardinops sagax caeruleus

Striped bass, Morones saxatilis

Sand sole, Psettichthys melanostictus

Skates, Family Rajidae

Big skate, Raja binoculata

California skate, Raja inornata

Sturgeon, Family Acipenseridae

Green sturgeon, Acipenser medirostris

White sturgeon, Acipenser transmontanus

Rubberlip surfperch, Rhacochilus toxotes

Rainbow surfperch, Hypsurus caryi

Opaleye, Girella nigricans

Cabezon, Scorpaenichthys marmoratus

Rex sole, Glyptocephalus zachirus

C-O sole, Pleuronichthys coenosus

Calico rockfish, Sebastes dallii

Longjaw mudsucker, Gillichthys mirabilis

Spotfin croaker, Roncador stearnsii

Saddleback gunnel, Pholis ornata

Sevengill shark, Notorynchus maculatus

Type

M

M

M

E

M

M

M

M

M

M

E

M

M

M

M

M

E

M

M

M

M

M

M

M

M

M

M

F

A

M

M

M

M

E

M

M

M

M

M

M

A

M

M

M

A

A

M

M

M

M

M

M

M

M

M

E

M

4

N

199,389

49,469

37,469

7,017

6,534

6,052

3,344

2,446

1,107

919

884

744

510

Category

Primary species

Primary species

Primary species

Primary family

Primary species

Primary family

Primary species

Primary species

Secondary species

Secondary species

Secondary species

Secondary species

Secondary family
J F M A M J J A SON D

MONTH

35

30

/t/ -+--'

0...

0...

'-.../ 25

>-

fZ

- 20

«

(J)

15

,---.... 25

U

(f)

Q)

Q)

'-- 20

U'

Q)

V

f) "--/

W 15

D:::

::::J

r

f-

«

D:::

Y

10 W

0.-

::2

w

f- 5

J F M A M J J A S 0 N D

MONTH

Figure 2

Seasonal temperature trends (mean and standard deviation) in the south

San Francisco Bay study area, 1973-82.

Figure 3

Seasonal salinity trends (mean and standard deviation) in the south

San Francisco Bay study area, 1973-82.

month into a single abundance value, it was important to

eliminate as many variables as possible. The analysis was

also useful for describing the distribution of different species.

The 15 months showing highest abundances of the primary

species were selected from the data set. A Friedman's test

(nonparametric, randomized block design) was employed,

with each month used as a block. Those months were omitted

in which total catch of a species was less than 5 fish.

To test for the effect of location on catch, the samples were

sorted by station, then mean catch-per-trawl was calculated,

and the stations were ranked within the block. To test for

tidal effects on catch, the trawls from each month were

divided into flood- and ebb-tide groups, and mean catch-pertrawl was calculated. To test for the effect of time of day,

the samples were sorted into two groups: trawls made before

10:00 a.m., and trawls made after 12:00 p.m. To test for

the effect of depth on catch, the samples from each month

were divided into two groups: samples from less than 3-meter

depths and those taken in depths greater than 4 meters.

To examine distribution patterns, the variance-to-mean

ratios for each month were plotted on histograms for each

species. The histograms were then inspected for evidence

of clustering which would show as skewing ofthe histogram

at some ratio greater than 1.0.

Results _

Physical characteristics

Temperature

Water temperatures in the sample area underwent distinct

seasonal changes during the study period (Fig. 2). From a

mean monthly low in January of 11.0°C, the temperature

climbed to a mean monthly high of 22.5°C in September.

The highest monthly average was recorded in September of

1979 at 24.5°C, and the lowest mean montWy temperature

was in January 1982 at 8.5°C (Appendix B). Standard deviations were less than 1.7°C, indicating little variation from

year to year.

Salinity

Salinity also showed a distinct seasonal pattern (Fig. 3), but

standard deviations of monthly means between years were

high. The mean monthly low of 20.5 ppt (SD = 5.70 ppt)

occurred in April. The mean monthly high of 30.0 ppt (SD

= 1.7 ppt) occurred in November. The highest monthly

salinity was 33.5 ppt in December 1977, and the lowest

monthly value was 12.5 ppt in April 1982 (Appendix C).

During the 1977 drought, the lowest montWy salinity was

30.5 ppt. Salinity can drop rapidly in the area, as evidenced

by a decrease from 30.5 ppt in December 1979 to a mean

value of 19.5 ppt in January 1980.

Substrate

Although no quantitative analysis was performed, sediment

samples appeared to be similar between stations. The northwest station had a small region of exposed oystershell bed

with some live oysters. Otherwise, the substrate consisted

of a fine silty clay with variable amounts of crushed shell

material. Color of the substrate varied from light brown to

dark blackish-brown. Some samples had a strong odor of

hydrogen sulfide. Living organisms typically included

amphipods, polychete worms, cockles, clams, and mussels.

In samples with oyster shells, several other types of inver5
tebrates were observed. Some of the core samples revealed

a layer of oyster shells buried at variable depths beneath the

top layer ofsediment. It was not possible to examine yearly

or monthly variations of the substrate samples.

Icthyological characteristics

General

A total of 59 species were observed during the study (Table

2). The species were sorted according to the classification

scheme described earlier into six primary species, two

primary families, 16 secondary species, two secondary

families, 18 tertiary species, and two tertiary families. Of

the 59 species, one was a freshwater type, five were anadromous, seven were classified as estuarine, and the rest were

marine (Table 2). All of the primary species/families were

marine.

Time of day showed no significant effect on the catch of

any ofthe primary species/families (Table 3). Gobies (Family

Gobiidae) were significantly more abundant during flood

tides than during ebb tides, indicating a movement into the

sample areas. English sole (Parophrys vetulus) were significantly more abundant in shallower areas. Shiner surfperch

(Cymatogaster aggregata) abundances were significantly different between stations, with station 4 (Fig. 1) having the

smallest catches. These findings made it necessary to assure

that each ofthe significant variables were equally represented

in each month. For months when this was not the case,

catches ofthe affected species were sorted, mean catch-pertrawl was calculated for each sort group ofthe variable, and

an unweighted mean catch-per-trawl was computed. These

values were then used in subsequent examinations.

The distribution analysis revealed that all of the primary

species/families exhibited clustered distributions. Figure 4

shows the histograms of the variance-to-mean ratios for all

months in the study. Since all of the histograms show the

variance-to-mean ratio is usually much greater than 1.0, there

is clear evidence of clustering. Since most species showed

no significant differences between stations, the aggregations

were considered to be smaller than catches at sampling

stations, with the possible exception of shiner surfperch. Of

the primary species/families, northern anchovy (Engraulis

mordax) and English sole exhibited the strongest degree of

clustering, and Pacific herring (Clupea harengus) and staghom sculpin (Leptocottus armatus) showed the lowest degree.

The clustering is probably spatial in nature since there was

no difference in catch based on time or tide. The only exception to this was the goby family which are probably both

spatially and temporally clustered, with groups offish moving

into the study areas during flood tides.

Seasonal changes

All of the primary species/families except dwarf surfperch

show clear seasonal trends (Fig. 5). Although the data are

less reliable, the majority of secondary species/families also

appear to show pronounced seasonal trends. In nearly all

6

Table 3

Results of nonparametric randomized block analyses (Friedman's

Test) on trawling variables in south San Francisco Bay, 1973-82,

from Marine Ecological Institute study. Critical value for depth,

tide, and time (0=0.05, 1 dO = 3.841. Critical value for location

(0=0.05, 3 dO = 7.815. Asterisks indicate significant effects.

Species Depth Tide Time Location

Northern anchovy 0.042 0.657 0.566 1.325

English sole 6.194* 1.887 1.633 3.402

Shiner surfperch 1.887 0.657 0.033 14.960*

Pacific herring 0.657 1.887 3.232 2.805

Goby family 0.657 6.194* 1.633 1.667

Sanddab family 1.887 3.733 1.633 LUI

Staghorn sculpin 3.733 0.042 1.633 0.902

Dwarf surfperch 0.042 0.657 0.566 4.541

species, peak abundance occurs from March through July

with progressively lower abundance through October and

November (Appendix D). Some species such as northern

anchovy and shiner surfperch were abundant year-round.

Others were nearly absent during many months, including

English sole which were virtually absent from August

through December.

Numeric diversity exhibited a seasonal change, with peak

diversity of 5.3 species per trawl occurring in April (Fig.

6). Lowest diversity typically occurred in October, with 2.2

species per trawl. Timing of maximum and minimum diversities varied substantially between years (Appendix E).

Species composition varied substantially among seasons

(Fig. 7). While at least six of the eight primary species/

families were always among the ten most abundant species,

their relative abundances varied substantially through the

year. In January the total number offish was low but relative

abundance of the species was fairly uniform. In October the

total number of fish was high but relative abundance of the

species was decidedly skewed, with two species (northern

anchovy and shiner surfperch) making up 95 %ofthe catch.

Annual changes

Many species exhibited large changes in abundance from year

to year (Table 4). Northern anchovy was four times as abundant in 1973 as in any other year. English sole was very abundant in 1974 and nearly absent in 1977. White croaker

(Genyonemus lineatus) and California tonguefish (Symphurus

atricauda) were nearly absent in all years except 1977. For

those species with identifiable yearly differences, 49% were

most abundant in 1974 and 50% were least abundant in 1977.

Based on delta outflows (Table 1), 1974 was the wettest year

and 1977 was the driest.

Although diversity varied between years, there were no

detectable trends in the variation. In a comparison of wet

and dry years, both magnitude and timing of high/low diversity appeared to vary randomly (Appendix E). Comparison

ofthe warmest year (1979) with the coldest year (1982) also

failed to show any trends.
50 50

Northern Anchovy English Sole

40 40

30 30

20 20

10 10

0 0

<.5 <.9 < 1. 1 < 1.5 <5 <25 < 100 100+ <.5 <.9 < 1. 1 < 1.5 <5 <25 < 100 100+

50 50

Shiner Surfperch Goby Family

40 40

30 30

r-.....

(J)

...c 20 20

-+--'

C

0 10 10

:2

'-..-/ 0 0

<.5 <.9 < 1.1 < 1.5 <5 <25 < 100 100+ <.5 <.9 < 1. 1 < 1.5 <5 <25 < 100 100+

50 50

U Pacific Herring Sanddab Family c

Q) 40 40

:::J

0-

Q) 30 30

L

LL

20 20

10 10

0 0

<.5 <.9 < 1.1 < 1.5 <5 <25 < 100 100+ <.5 <.9 <1.1 <1.5 <5 <25 < 100 100+

50 50

Stag horn Sculpin Dwarf Surfperch

40 40

30 30

20 20

10 10

0 0

<.5 <.9 < 1. 1 < 1.5 <5 <25 < 100 100+ <.5 <.9 < 1. 1 < 1.5 <5 <25 < 100 100+

Variance/Mean Ratio

Figure 4

Variance-to-mean ratios of monthly catches of the most abundant fish species collected in otter trawls, south San Francisco Bay, 1973-82.

Note the clustered distribution of species in the study area.

7
OL..L--'-----'----'-'--'--'-----'---'---'------'------'---'

o JFMAMJJASOND J F M A M J J A SON 0

NORTHERN ANCHOVY ENGLISH SOLE 200 50

150 40

30

100

20

50 10

0 0 -.J J F M A M J J A SON 0 J F M A M J J A S o N 0

5 SHINER SURFPERCH GOBY FAMILY «

ex:::

50 5

f- 40 4

I 30 3

(f)

- 20 2

LL

10

LL

0 0 J F M A M J J A S 0 N 0 0 J F M A M J J A S 0 N 0

ex::: PACIFIC HERRING SANDDAB FAMILY

W 10 5

OJ

2 4

=:=> 3

Z 5

2

Z

«

W 0 0

2 J F M A M J J A SON 0 J F M A M J J A SON 0

STAGHORN SCULPIN DWARF SURFPERCH

5 5

4 4

3 3

2 2

MONTH

Figure 5

Seasonal abundance trends of the most common fISh species caught in otter trawls, south San Francisco Bay, 1973-82.

8
Figure 6

Seasonal trends in numeric diversity offish species caught in otter trawls,

south San Francisco Bay, 1973-82, showing standard deviation range.

J F M A M J J A SON D

0"----'---'----'-----'----'---'------'--'---------'---'------'

62.1

1.5

18.2

3.5

0.6

I.I

I.I

1.0

0.2

0.2

0.1

0.1

0.0

0.0

0.2

0.2

0.2

0.0

0.1

0.2

0.0

Abundance

Lowest

Year

1980

1977

1977

1978

1977

1976

1977

1977

1975

1977

1976

1977

?

?

1979

1977

1977

?

1982

1978

1982

936.8

101.2

85.0

10.2

13.9

14.0

7.4

10.8

3.1

4.5

5.1

4.0

4.0

4.7

2.8

2.3

1.8

7.5

1.3

1.3

O.S

Abundance

Highest

Year

1973

1974

1974

1976

1974

1974

1974

1974

1979

1974

1974

1974

1977

1977

1973

1980

1979

1977

1978

1976

1974

Common name

Northern anchovy

English sole

Shiner surfperch

Goby family

Pacific herring

Sanddab family

Staghorn sculpin

Dwarf surfperch

Barred surfperch

White surfperch

Brown rockfish

Pile surfperch

Smelt family

California tonguefish

Brown smoothhound shark

Leopard shark

Bay pipefish

White croaker

Diamond turbot

Bat ray

Starry flounder

Table 4

Highest and lowest abundances of common fish species captured in

otter trawls, south San Francisco Bay, 1973-82. Abundances given

as mean number of fish per trawl during the month of highest/lowest

abundance.

2

MONTH

3

6

5

4

7,------------------------,

-.-l

S

<C

0:::

f-

(J)

w

U

W

0-

(J)

LL

o

*

10 20 30 40 50 0 10 20 30 40 50 0 10 20 30 40 50

JANUARY

NORTHERN ANCHOVY

ENGLISH SOlE

SHINER SURFPERCH

GOBY FAMILY

PACIFIC HERRING

SANDDAB FAMILY

STAGHORN SCULPIN • DWARF SURFPERCH

BARRED SURFPERCH

WHITE SURFPERCH

BROWN ROCKFISH

PILE SURFPERCH

SMELT FAMILY

LEOPARD SHARK

BAY PIPEFISH

SHAD FAMILY

I I I I

0 10 20 30 40 50 0

APRIL JULY

*

OCTOBER

**

•

I I I I

MEAN # O~ FISH PER TRAWL

Figure 7

Seasonal comparison of the most abundant species caught in otter trawls, south San Francisco Bay, 1973-82. Abundance values are unweighted.

Actual values for northern anchovy exceed the vertical axis (*80 fish per trawl, **129 fish per trawl). .

9
DRY YEAR (1977) MEAN YEAR WET YEAR (1974)

NORTHERN ANCHOVY

ENGLISH SOLE

SHINER SURFPERCH

GOBY FAMILY

PACIFIC HERRING

SANDDAB FAMILY

STAGHORN SCULPIN

DWARF SURFPERCH

BARRED SURFPERCH

BROWN ROCKFISH

SMELT FAMILY

CALIFORNIA TONGUEFISH

BROWN SMOOTHHOUND

PLAINFIN MIDSHIPMAN

o 10 20 30 40 50 0 10 20 30 40 50 0 10 20 30 40 50

MEAN # OF FISH PER TRAWL

Figure 8

Comparison ofspecies composition in otter trawls, south San Francisco Bay, in April during a wet year (1974), a dry year (1977), and the unweighted

mean value for 1973-82. Actual values for northern anchovy and english sole exceed the vertical axis (*61 northern anchovy per trawl,

**191 English sole per trawl).

Annual change in species composition was also large (Fig.

8). During the drought year 1977, English sole were effectively absent, many species were present in reduced numbers,

and some species were more common. The wettest year,

1974, saw increased abundances of most species but little

change in relative abundances of the most common species.

This may indicate that excess flows over a certain level may

alter only total abundance of species but not species composition, although this is only conjecture.

Discussion _

Life history

All of the primary species/families use the estuary as a

nursery area, although the estuary may not be the exclusive

nursery area for many species (Table 5). Northern anchovy

spawn both in the ocean and the estuary and all of its lifecycle stages are found within the estuary. Anchovy were

highly abundant throughout their months ofspawning (April

and September). Although English sole do not spawn in the

estuary, juveniles use the estuary for the first year of their

life. It is not known how important the estuary is to the sur10

vival of juvenile English sole, but one study in Oregon indicates that it may be quite important (Olson and Pratt 1973).

Peak abundances ofjuvenile sole occurred approximately 2-3

months after their peak spawning time in January, which is

consistent with the 7-10 week larval stage reported for this

species. Shiner surfperch are common both in the estuary

and in nearshore coastal waters. In this study shiners were

present year-round, although they were most abundant during the spring, when spawning occurs. The gobies (Family

Gobiidae) were most abundant during the spring when most

species spawn. Pacific herring (Clupea harrengus) use the

estuary as a spawning ground, laying their eggs on eelgrass

beds and hard substrates. Herring support a lucrative fishery

within the estuary, although commercial fishing is rare in

the sample area. Peak abundance of herring in March coincides with hatching of the eggs in early spring. Sanddabs

spawn in the ocean but, like English sole, are found as

juveniles within the estuary. Peak abundance ofsanddabs in

spring does not appear to coincide with any stage in their

life cycle. Staghorn sculpin spawn both in the ocean and the

estuary during the spring and winter. This may coincide with

their late-spring/early-summer peak abundances. Dwarfsurfperch spawn both in the estuary and the ocean during late

spring and early summer. No clear seasonal trends were
Table 5

Life history stages of selected species coUected in south San Francisco Bay as part ofMarine Ecological institute trawl study, 1973-82.

Spawning locations: 0 = ocean, E = estuary, D == delta (or

freshwater). Estuarine stages: A = adult, J =juvenile, L =larvae.

Lower-case letters imply lesser importance. Source: Wang 1981.

Spawning

Species Location Months Stages

Northern anchovy OlE IV,IX A,J,L

English sole a XI-II J,I

Shiner surfperch E III-VIII A,J

Yeliowfin goby OlE IV-VIII A,J,L

Bay goby OlE XI-VI A,J,L

Cheekspot goby OlE ? A,J,L

Chameleon goby E V-VIII A,J,L

Pacific herring E XI-IV A,J,L

Speckled sanddab a III-IX J,I

Staghorn sculpin OlE IX-IV A,J,L

Dwarf surfperch OlE IV-VIII A,J

Barred surfperch OlE ? A

White surfperch OlE ? A

Brown rockfish a XI-III J,I

Pile surfperch OlE ? A,J

California tonguefish E VI-IX A?,J

Brown smoothhound OlE A,J

Leopard shark OlE IV-VI A,J

Walleye surfperch OlE III-VIII A,J

Bay pipefish E V-VIII A,J

White croaker OlE XI-V A,J

Threadfin shad D IV-VIII A

American shad D IV-VII A;J

Diamond turbot a III-VII A,J,I

Bat ray OlE A,J

Plainfin midshipman OlE V-VIII A,J,L

Bonyhead sculpin OlE ? A,J

Starry flounder OlE XI-II A,J,L

California halibut a II-VII A,J,L

observed for this species, and therefore it is not possible to

determine whether a peak exists which would coincide with

a stage in their life cycle. Many of the secondary species/

families share similar life histories.

Distribution pattern

The majority of species in the study area exhibit spatial

clustering on a small scale. Clustering in fish is caused by

both behavioral and environmental factors. In the study area

there are few distinct habitats: no rocky areas, eelgrass beds,

or wharf pilings. The substrate is believed to be relatively

uniform. While schooling behavior accounts for the spatial

clustering in anchovy, herring, and perch, the explanation

for clustering in the flatfish is less clear. It is possible that

the benthic environment is less uniform than previously

thought. This is supported by the strong contagious distribution of English sole and sanddabs (Fig. 4). Such a distribution could be explained by a variable habitat. Jones (1961)

found that benthic invertebrates in the estuary exhibited a

11

Table 6

Comparison of the ten most abundant species in the south San Francisco Bay, February-July, combined for aU years, as reported in this

study and in the Aplin study (1967). Species organized according

to form used by Marine Ecological Institute.

MEl Aplin

Species % Species %

Northern anchovy 61.60 Northern anchovy 95.08

English sole 15.70 Smelt family 2.26

Shiner surfperch 13.70 Shiner surfperch 1.25

Goby family 2.30 Pacific herring 0.77

Pacific herring 1.90 English sole 0.22

Sanddab family 1.80 Shad family 0.19

Staghorn sculpin 1.20 Staghorn sculpin 0.09

Dwarf surfperch 0.90 Goby family 0,07

Barred surfperch 0.40 Striped Bass 0.04

White surfperch 0.30 Leopard shark 0.04

clustered distribution. Recent studies by the U.S. Geological

Survey (USGS) have found a series of north-south furrows

in the south San Francisco Bay (John Chin, USGS, Menlo

Park, CA 94025, pers. commun. Oct. 1988). The furrows

are hundreds of meters in length, several meters wide, and

up to a meter deep. The substrate in the bottom ofthe furrows

may be somewhat coarser than on the sides. The furrows

are thought to be hydrological in origin and may account for

some ofthe clustering of benthic fish species. For example,

ifthe bottom ofthe furrows are found to have substrates more

favorable for food, this could cause fish to congregate. This

is only speculation, however, and requires further investigation.

Species composition

The most abundant species were found to be northern anchovy, English sole, and shiner surfperch. Aplin (1967) listed

northern anchovy, smelts, and shiner surfperch as the most

abundant species in the MEl study area. Direct comparison

between Aplin's study and ours is not possible, due to Aplin's

manner of presentation. However, by computing percent

composition for all years during the interval of FebruaryJuly for each study, it is possible to arrive at a rough comparison of species composition between the two studies

(Table 6).

Aplin found large concentrations of northern anchovy,

which made up 95 % of his catch compared with only 62%

ofthe catch in this study. Smelt (all species combined) made

up 2.3% ofAplin's catch but less than 1% of ours. English

sole comprised less than 1%of Aplin's catch compared with

16% of ours. Dwarf surfperch were never taken by Aplin,

but they were the eighth most abundant species in this study.

Aplin collected large numbers of striped bass (Morone saxatilis), which were fairly rare in this study. Aplin caught

8 showy snailfish (Liparis pulchellus), 2 king salmon (Oncorhynchus tshawytscha), and 2 steelhead (Salmo gairdnerii),
all of which were never caught in our study. During Aplin's

4-year study he recorded 29 species compared with 59 in

our 9.5-year study. Explaining these differences provides important insights into the design of a sampling program for

the estuary.

The near absence of smelt from this study was in distinct

contrast to the high levels in Aplin's study. The DFG study

(1987) also indicates large numbers ofsmelt in the area. The

explanation for this difference lies in the fact that the majority ofsmelt were caught by midwater trawl. The otter trawl

is unable to sample the upper water column, and consequently

the smelt present in the sample area were not caught in our

study. Aplin collected 8 showy snailfish, and the DFG study

indicates this species is caught by otter trawl only in the deep

channel (Pat Coulston, Calif. Dep. Fish Game, Stockton,

CA 95211, pers. commun. Sept. 1988). Since few of the

trawls in this study were made in the deep channel, Showy

snailfish were missed by MEL The differences in relative

abundance of northern anchovy between the Aplin study and

ours can be explained by two factors: use of the midwater

trawl, and the patchy distribution of this species. Because

Aplin combined the midwater trawls with otter-trawl data,

because both otter and midwater trawls can ca!ch large

numbers of anchovy, and because there is an overlap in the

portion of the water c~lurnn swept.by th~ t;vo type~ o~ net,

it is concluded that theIr abundance m Aplm s study is hIgher

relative to the benthic species than in actuality. The higher

abundance ofstriped bass and the presence of steelhead and

salmon are due either to historical changes in abundance or

gear effectiveness. In this study, 59 species were collected

compared with 29 in the Aplin study. In a study of otter.trawls

in Santa Monica bay, Fay et al. (1978) concluded that it took

more than 100 trawls to catch 95% ofthe catchable species.

Therefore the difference in number of species may be attributed i~ part to the small number of trawls used in the

Aplin study.

This study examined the effect of location on catch of the

primary species/families. Although a significant difference

in catch of shiner surfperch was observed between the five

stations the overall effect on the abundance estimates was

small· therefore, it can be concluded that a single station can

be us~d to represent a fairly large geographic area. Thi~ is

an important consideration when designing a samphng

program. . .

Given the clustered distributions found m thIS study, and

the finding by Fay et al. (1978) that multiple tows ~ere required to assess species composition in Santa.Momca Bay,

it seems apparent that multiple trawls are important for

assessing species abundance in a given area. Equally apparent

is the necessity for midwater trawls and perhaps other

methods (beach seines, gillnets, traps) in analyzing species

composition of the estuary.

12

Wet vs. dry years

Although the primary objective of this study was to examine

the ecological nature of the study area, it was also possible

to examine the differences between wet and dry years.

Although 1982 actually showed higher freshwater inflows

than 1980, 1982 was excluded from this comparison because

the trawl data were incomplete. Results of this study indicate

that the majority of common species were most abundant

during wet years and least abundant during dry years (Table

4). The specific objective of the ongoing DFG study is to

determine the effect of delta outflows on species abundance

within the estuary. A direct comparison between the DFG

study and this one is not possible, but an indirect comparison

can be made.

DFG has ranked species on a five-step scale based on

response to outflow: positive, slightly positive, mixed, slightly negative, and negative. To do this they classified each of

the 6 years in their study as either wet or dry and then

classified the response of the species. Their study, conducted

from 1980 to 1985, included both midwater and otter trawls

and was estuary-wide. In order to compare our results with

theirs, a similar ranking system was established.

Based on delta outflows (Table 1) 1974 and 1980 were

defined as wet years, and 1976 and 1977 as dry years. A

species which was most abundant in a wet year and least

abundant in a dry year was classified as a positive-response

species. If a species was either most abundant in a wet year

or least abundant in a dry year, it was classified as a slightly

positive-response species. A species with neither highest nor

lowest abundance in a wet or dry year, or with both in the

same type year, was classified as a mixed-response species.

A species with highest abundance in a dry year or lowest

abundance in a wet year was classified as a slightly negativeresponse species. A species most abundant in a dry year .and

least abundant in a wet year was classified as a negativeresponse species.

Table 7 compares the observed responses to outflow

between our study and the DFG study (1987). Ofthe species

observed in my study, 48 % showed a positive response and

10% showed no response compared with 24% and 52%,

respectively, in the DFG study. California tonguefish were

nearly absent from our study in all years except 1977, when

they were very common; thus they were classified as a

negative-response species. On the other hand, the DFG study

classified them as a positive-response species. English sole,

the second most abundant species in this study, were nearly

absent during the 1977 drought and were classified as a

positive-response species, whereas DFG classified th.em. as

a mixed-response species. Pearson (1985) found a sigmficant correlation between delta outflows and English sole

abundance in the south San Francisco Bay. The present study

indicates that 62 % of the species show at least a slightly

positive response to wet years. The DFG study indicates 33 %

of the species showed a slightly positive response or better

to wet years.
Table 7

Species abundance responses to increased delta outflows into south

San Francisco Bay, as determined by this study and the California

Department of Fish and Game study (DFG 1987).

Some ofthe differences in interpretation between ours and

the DFG study may be due to the effect ofthe different timeperiods sampled. In DFG's study, 1981 was classified as dry,

but delta outlfows that year were more than twice as great

as either year classified as dry (1976 and 1977) (Table 1)

in this study. On the other hand, the wettest year in the MEl

sampling program (1974) had only about half the volume

of delta outflows as the wettest year in the DFG study (1983).

Although both studies had extreme ranges of outflows, the

effect of the differences hetween the two studies could be

relevant in the interpretation of wet-versus-dry response. In

addition, 5 years of the MEl study were not classified as

either wet or dry. This conservative approach allows for the

possibility of average flows and avoids the forced explanation of species abundance as the effect of either high or low

flows. Consequently, it was surprising to find more species

showing a strong response (either positive or negative) to

outflow in the MEl study than in the DFG study. This is particularly true given that all of the years in the DFG study

were classified as either wet or dry.

Geographical variations may also have been responsible

for the observed differences. The abundance estimates in the

DFG study are based on single monthly trawls in several

areas throughout the estuary, while this study used multiple

trawls in a small region. The south bay is a distinct and

separate part of the estuary. It is possible that when a given

species is examined on an estuary-wide basis, as in the DFG

study, it will show a different response than when examined

on an area-by-area basis. If both the DFG and MEl abundance estimates are accurate, then clearly one possible

Species

Northern anchovy

English sole

Shiner surfperch

Goby family

Pacific herring

Sanddab family

Sra.ghorn sculpin

Dwarf perch

Barred surfperch

White surfperch

Brown rockfish

Pile perch

California tonguefish

Brown smoothhound

Leopard shark

Walleye surfperch

Bay pipefish

White croaker

Diamond turbot

Bat ray

Starry flounder

MEl

Slightly negative

Positive

Positive

Slightly negative

Positive

Positive

Positive

Positive

Mixed response

Positive

Positive

Positive

Negative

Mixed response

Positive

Positive

Slightly positive

Negative

Slightly negative

Slightly negative

Slightly positive

DFG

Mixed response

Mixed response

Mixed response

Positive

Slightly positive

Positive

Slightly positive

Negative

Mixed response

Mixed response

Mixed response

Mixed response

Positive

Mixed response

Positive

Negative

Negative

Mixed response

Mixed response

Mixed response

Positive

13

interpretation is that many species show different responses

in different areas of the estuary. In designing a sampling

regime for the estuary, two factors are in competition: scope

of the study, and sample size. If the scope is limited, the

range of questions which can be answered are limited.

Typically sample size increases (and therefore reliability) as

scope decreases. This study emphasized sample size but was

limited in scope. Because of the large sample size used in

this study, the estimates of abundance for most species should

be reasonably accurate. It would be useful to look for regional

differences within species in response to outflows within the

estuary when the data become available. It is important,

however, to note that this study cannot be applied to the

estuary as a whole, but rather only to the southern portion.

Citations _

Aplin, J.A.

1967 Biological survey of San Francisco bay 1963-1966. Mar. Resour.

Operations Ref. 67-4, Calif. Dep. Fish Game, Stockton, CA 95205,

131 p.

Conomos, T.J.

1979 Properties and circulation of San Francisco bay waters. In

Conomos, T.J. (ed.), San Francisco Bay: The Urbanized Estuary,

p. 47-84. Pac. Div., Am. Assoc. Adv. Sci., San Francisco.

DGF (Calif. Dep. Fish Game)

1987 Delta outflow effects on the abundance and distribution of San

Francisco Bay fish and invertebrates, 1980-1985. DFG Exhibit 60

entered by the California Department of Fish and Game for the State

Water Resources Control Board. 1987 Water QUality/Water Rights

Proceeding on the San Francisco Bay/Sacramento-San Joaquin Delta.

Bay-Delta Project, Calif. Dep. Fish Game, Stockton, CA 95205,

345 p.

Fay, R.C., J.A. Vallee, and P. Brophy

1978 An analysis of fish catches obtained in an otter trawl in Santa

Monica Bay 1969-1973. Calif. Dep. Fish Game 64(2):104-120.

Jones, M.L.

1961 A quantitative evaluation ofthe benthic fauna off Pt. Richmond,

California. Univ. Calif. Pub!. Zoo!. 67(3):219-320.

McCulloch, D.S., D.H. Peterson, P.R. Carlson, and T.J. Conomos

1970 Some effects of freshwater inflow on the flushing of the South

San Francisco bay: A preliminary report. U.S. Geo!. Surv. Circ.

637-A, Menlo Park, CA 94025, 27 p.

Olson, R.E., and t. Pratt

1973 Parasites as indicators of English sole nursery grounds. Trans.

Am. Fish. Soc. 102(2):405-411.

Pearson, D.E.

1985 Environmental factors influencing English sole (Parophrys

vetulus) populations in San Francisco bay, California. Masters thesis,

Univ. Pacific, Stockton, CA 95211, 102 p.

Rozengurt, M.A., M.J. Herz, and S. Feld

1987 The role of water diversions in the decline of fisheries of the

delta-San Francisco bay and other estuaries. Tech. Rep. 87-8,

Romberg Tiburon Centers, Tiburon, CA 94920, 158 p.

Wang, J.C.S.

1981 Taxonomy of the early life stages of fishes: Fishes of the

Sacramento San Joaquin Estuary and Moss Landing Harbor-Elkhorn

Siouth, CA. Ecological Analysts, Inc., San Francisco, 168 p.
Appendix A

Trawl-effort distribution of Marine Ecological Institute study, south

San Francisco Bay, 1973-82.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1973 31 22 46 46 22 21 10 1* 35 14 20

1974 20 35 55 36 50 12 8 11

1975 3* 14 29 41 5 6 25 23 17

1976 42 56 40 22 55 34 18 7 19 29

1977 34 14 55 47 58 27 12 2* 24 24 7

1978 16 6 22 60 44 36 8 11 24 32

1979 3* 5 29 37 55 27 19 9 9 22 6 8

1980 8 13 35 31 41 34 13 11 6 4 17 25

1981 20 31 44 60 52 19 12 8 10 19 20 6

1982 6 33 56 58 66 29

Dashes indicate no trawls: asterisks indicate less than 5 trawls (not used

in study).

Appendix B

Mean monthly water temperatures (DC) for south San Francisco Bay, 1973-82.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1973 13.5 13.0 16.0 19.0 20.0 20.5 21.0 18.0 15.0 11.5

1974 10.0 11.5 13.5 16.0 16.5 18.0 12.5

1975 13.5 14.0 17.0 21.0 18.5 14.0 11.5

1976 10.5 12.0 15.5 14.5 18.0 17.0 21.0 19.5 18.5

1977 11.0 14.0 13.0 16.5 16.0 18.5 21.0 18.5 16.0 12.5

1978 13.0 14.0 16.0 17.0 19.0 19.5 21.0 21.0 18.5 16.0

1979 11.0 14.0 16.0 20.0 22.0 23.5 23.0 24.5 20.0 15.5 14.5

1980 13.5 14.0 15.5 18.0 17.5 18.0 22.5 23.0 23.5 19.5 16.5 13.5

1981 12.0 12.5 15.0 17.0 18.5 21.0 21.5 22.0 20.5 17.0 15.5 13.5

1982 8.5 12.5 13.5 16.5 18.0 19.0

Mean 11.2 12.8 14.3 16.2 18.0 19.6 21.7 22.0 22.4 18.7 15.9 12.8

SD 1.8 1.2 1.1 1.2 1.2 1.6 1.1 1.0 1.9 0.9 1.5 1.1

Appendix C

Mean monthly salinities (ppt) for south San Francisco Bay, 1973-82.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1973 17.0 18.5 19.0 21.5 23.0 26.0 28.0 29.0 26.0 21.0

1974 19.5 16.5 19.5 15.5 18.5 28.0 27.0

1975 20.0 18.5 18.0 21.5 23.0 27.5 28.0 29.0

1976 28.5 28.0 27.5 28.0 29.0 30.0 30.0 30.5 30.5 32.0

1977 31.0 30.5 30.5 30.5 31.0 32.0 32.0 33.0 33.0 33.5

1978 24.5 21.0 20.5 18.5 20.0 21.5 25.0 26.5 28.0 30.5

1979 26.0 22.0 22.0 25.0 25.0 27.5 28.5 28.5 30.0 30.5 30.5

1980 19.5 18.0 13.5 18.0 22.5 24.5 25.5 25.5 27.0 28.0 30.0 28.5

1981 29.5 26.5 25.5 24.5 26.0 27.0 28.5 29.0 30.5 31.5 30.0 26.0

1982 16.5 17.5 16.5 12.5 13.5 18.5

Mean 24.1 22.3 21.4 20.7 22.5 24.8 27.1 27.5 29.1 29.5 30.0 27.9

SD 5.7 5.4 5.2 5.6 5.4 4.3 2.8 1.5 1.7 1.9 2.2 3.9

14
Appendix D

Mean catch-per-trawl of fISh species in south San Francisco Bay, 1973-82.

(tr indicates < 1, dash indicates no samples taken)

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Northern anchovy

1973 1 I 64 982 357 267 327 331 91 5

1974 3 17 27 61 228 62 15 10

1975 tr 40 58 77 145 61 83 tr

1976 2 Ir 3 10 35 155 112 24 13 17

1977 2 tr 3 28 50 124 72 26 3 tr

1978 2 2 3 205 200 185 73 226 44 37

1979 71 4 45 89 136 191 159 35 30 9 2

1980 I 7 2 10 62 39 26 31 12 56 5 1

1981 2 8 tr 63 230 88 139 14 100 95 20 14

1982 II I 3 4 46 34

Mean 3 11 5 47 193 133 128 151 43 80 31 5

SO 3 23 8 59 271 98 76 132 39 98 33 5

English sole

1973 tr I II 42 9 3 0 0 tr

1974 4 17 42 191 108 tr 0 tr

1975 14 48 101 24 9 tr tr 1

1976 2 12 9 15 29 17 0 0 0 0

1977 Ir tr tr tr I 3 0 0 0 0

1978 8 28 64 29 5 5 tr tr tr I

1979 6 23 30 45 8 0 0 0 tr tr tr

1980 tr 5 20 27 63 12 3 0 0 0 0 Ir

1981 4 24 47 22 II 4 0 0 0 0 0 1

1982 0 tr 4 22 32 45

Mean 2.4 9.9 22.4 40.1 43.7 13.8 1.9 0.2 0 tr 0.1 0.3

SO 2.8 10.4 21.8 54.6 37.3 13.6 3.2 0.3 0 0.1 0.1 0.4

Shiner surfperch

1973 4 6 20 40 81 37 13 7 5 2

1974 2 6 8 37 43 2 7 tr

1975 5 25 44 34 11 1 tr tr

1976 tr 2 4 9 34 14 11 3 1 tr

1977 1 0 5 8 12 20 12 2 3 2

1978 tr I 4 15 42 29 2 6 4 2

1979 0 10 7 26 74 6 14 8 2 2 9

1980 Ir tr 12 8 17 50 11 1 3 6 3 4

1981 2 2 4 18 22 29 15 3 7 10 9 0

1982 6 7 14 33 28 36

Mean 2 3 7 18 29 45 13 7 5 4 3 2

SO 2 4 4 II 15 28 10 6 3 3 3 3

Gobies (all species)

1973 0.6 0.5 0.4 1.5 5.8 7.5 2.5 0.1 0 0.5

1974 0.3 0.7 1.6 4.6 5.6 0.3 1.0 0.5

1975 2.4 7.8 7.9 0.4 3.3 0.3 0.2 0.1

1976 0.1 0.1 8.7 10.2 6.4 1.7 3.8 6.4 0.1 0.2

1977 0.1 0.5 1.1 2.2 4.4 4.2 3.0 0.3 1.0 0.3

1978 0.3 1.0 1.7 2.1 3.1 3.5 1.8 1.0 0.5 0.6

1979 0.4 1.1 3.2 5.2 1.2 0.5 0.7 0.6 0.1 0 1.0

1980 0 0.2 4.3 5.9 6.0 3.2 2.3 0.5 0.3 0.4 0.1 0.5

1981 1.0 1.5 1.9 4.6 2.6 3.1 1.3 3.0 0.8 0.4 1.2 0.2

1982 0.8 0.7 5.8 9.1 5.9 1.5

Mean 0.4 0.7 2.9 5.0 4.9 2.7 2.9 1.5 2.0 0.3 0.5 0.7

SO 0.4 0.4 2.6 3.2 1.9 1.7 2.1 1.2 2.9 0.2 0.5 0.7

15
Appendix D (continued)

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Oec

Pacific herring

1973 1.5 1.1 2.4 1.4 0.2 0.7 0 0.3 2.6 15.6

1974 1.3 2.5 8.1 13.9 3.5 0 1.9 2.4

1975 0 0.9 tr 0.1 0.3 tr 0.7 3.1

1976 1.1 1.3 1.6 9.6 1.5 0.2 0 0 0.2 0.1

1977 0.1 0.1 0.5 0.6 0.4 0.1 0 0.2 0.3 1.4

1978 0.1 0.3 0.8 4.5 5.3 0.9 10.3 0.6 0.2 0.8

1979 0.2 0.7 7.1 1.2 3.7 0.1 3.2 0.1 0.1 1.3 1.4

1980 0.6 3.5 1.8 9.7 0.5 0.1 0.9 0.2 1.0 1.4 2.2 1.7

1981 0.2 1.2 0.2 0.5 0.1 0.2 0 0.1 0.4 1.2 0.6 0.2

1982 0.3 0.1 1.0 34.1 1.0 0.1

Mean 0.5 1.2 1.6 8.3 1.5 1.8 1.5 0.8 0.4 0.4 1.2 3.7

SO 0.5 1.2 2.4 10.2 1.7 3.6 3.6 1.4 0.5 0.5 0.9 5.3

Sanddabs (all species)

1973 2.5 4.4 4.4 4.2 0.3 0.4 0.1 0 0.1 0.2

1974 1.8 4.2 4.2 14.0 12.1 0.1 0 0.2

1975 0.6 tr 1.4 0.8 0 0 tr 0.4

1976 0.4 0.5 0.4 0.8 0.4 1.1 0.1 0.6 0.1 tr

1977 0.8 0.7 2.3 2.6 3.2 6.6 1.6 0.5 1.4 1.1

1978 6.6 2.5 6.8 6.4 1.6 0.1 0 0 0.7 1.0

1979 2.6 5.5 5.4 4.5 0.2 0 0 0 0 0.7 1.9

1980 2.7 1.8 1.5 3.0 1.7 2.1 0.8 0 0 0 0.3 1.2

1981 1.9 3.6 1.8 1.8 1.4 0.6 0.1 0 0.9 0.5 2.5 0

1982 1.7 3.7 4.9 4.4 1.1 1.2

Mean 2.3 2.4 3.2 4.3 3.2 1.4 0.4 tr 0.4 0.2 0.7 0.7

SO 2.1 1.3 2.2 3.9 3.4 2.0 0.5 tr 0.5 0.3 0.9 0.7

Staghorn sculpin

1973 0.5 4.4 2.1 3.6 15.9 0.9 0.1 0 0.1 0.2

1974 0.1 0.8 1.7 7.4 6.8 0.1 0 0.1

1975 0.7 2.2 3.2 1.8 0.3 0.1 0.1 0.4

1976 0.2 tr 0.3 0.7 4.0 1.6 0.7 1.0 0.1 0.1

1977 0.2 0 0.4 0.4 0.4 1.1 1.0 0.3 2.3 0.3

1978 0.3 0.8 1.8 0.8 0.6 0.4 0 0 0 tr

1979 0 3.6 1.6 3.1 1.9 0.1 0 0 0 0 0

1980 0.1 0.1 1.1 1.7 3.5 1.0 0.3 0 0 0 0.4 0.4

1981 0.2 0.4 2.9 0.8 1.1 1.2 0 0 0.2 0.2 0.2 0

1982 0.3 0.5 0.4 0.8 1.4 0.6

Mean 0.2 0.3 1.7 1.8 2.8 2.8 0.4 tr 0.3 0.1 0.4 0.2

SO 0.1 0.3 1.4 2.0 2.0 4.9 0.3 tr 0.5 0.4 0.6 0.2

Dwarf surfperch

1973 1.5 0.8 1.8 2.3 1.4 10.8 10.0 0.4 0.4 0.6

1974 4.4 2.2 4.5 3.7 0.9 0.9 5.1 0.1

1975 0.9 0.1 0.2 0 1.3 0.1 0.1 0.2

1976 0 0.1 0.2 0.3 0.1 0.1 0.3 0.1 0 tr

1977 0.7 0.1 0.3 0.1 0.1 0.3 1.0 0.2 1.0 0.4

1978 0.1 0.2 1.4 0.3 0.2 0.3 0.4 1.0 0.9 0.3

1979 0 1.0 0.7 01 0.9 3.0 3.1 0.7 0.1 4.8 3.1

1980 0 0 0.5 0.1 0.2 tr 0.7 0.5 0.3 0.6 0.5 tr

1981 0.7 1.3 0.8 0.9 0.2 4.4 1.8 0.4 0.8 0.2 2.4 0.5

1982 0 4.6 1.6 0.5 0.1 0.3

Mean 0.8 1.1 1.2 0.9 0.5 0.9 2.4 3.0 0.5 0.4 1.6 0.7

SO 1.6 1.5 1.3 1.1 0.7 1.4 3.5 4.1 0.3 0.3 2.0 1.1

16
Appendix D (continued)

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Barred surfperch

1973 - 0.1 0.3 0.2 0.2 1.5 2.0 0.3 - 0.1 0.1 0.2

1974 0.1 0.2 1.7 1.3 0.1 - - - - 0 0.3 0.2

1975 - - 0 0.1 0 0.2 0 - - 0.9 1.0 1.2

1976 0.8 0.6 tr 0 0.1 0 1.0 - 0 0 0 -

1977 0 0.3 tr 0.6 1.3 0.1 2.3 - - 0 0.1 0.1

1978 0.8 0.8 2.1 0.3 0.3 0.5 0.3 0 - tr 0.2 - 1979 - 0.3 0.2 0.1 1.0 3.1 0.2 0 0 0 0 0.5

1980 0.7 1.2 0.1 0.1 0.1 tr 0.4 0 0.7 0.6 0.2 0.2

1981 0 0.8 0.3 0.6 0.2 0.3 0.1 0.8 0.3 0.6 0.1 2.7

1982 1.2 0.5 0.3 0.3 0.5 0.6 - - - - - -

Mean 0.5 0.5 0.5 0.4 0.4 0.7 0.8 0.2 0.2 0.2 0.2 0.7

SD 0.5 0.4 0.7 0.4 0.5 1.0 1.0 0.3 0.3 0.3 0.3 0.9

White surfperch

1973 - 0 0 tr 0.1 4.0 4.6 0 - 0.3 0.1 0.1

1974 1.0 0.3 4.5 0.1 0.3 - - - - 0 0 0

1975 - - 0.1 0.7 0 0.4 0 - - 0 0 0

1976 0.6 0 0 0 0 0 1.0 - 0 0 0 -

1977 0.2 0 0 0 0 0.2 0.1 - - 0.1 0.4 0

1978 0 0 0.1 0.1 2.8 1.0 0 0 - 0.1 0 - 1979 - 0 0.1 0 0.1 0 0 0.1 0 0 1.0 0

1980 0 0 0.1 0 0 0.3 0 0 0 0 0 4.3

1981 0 0.1 0.1 0 0.1 0.1 0 0 0.1 0.1 0 0.2

1982 0 0.1 0 0 0 0 - - - - - -

Mean 0.3 0.1 0.5 0.1 0.3 0.6 0.8 tr tr 0.1 0.2 0.7

SD 0.4 0.1 1.4 0.2 0.9 1.2 1.7 tr tr 0.1 0.3 1.6

Brown rockfish

1973 - 0 0 0.1 0.2 0.8 1.1 0.2 - tr 0 0.1

1974 0.5 0.7 1.4 5.1 1.2 - - - - 0 0.1 0

1975 - - 0 0.2 0.1 0 0 - - 0 0 0.1

1976 tr 0 0 0.1 tr 0 0.1 - 0.1 0 0 -

1977 0 0 0 0 0 0.8 1.2 - - 0.1 0.1 0

1978 0 0 0.3 tr 0.1 0.6 0 0.2 - 0.7 0.2 - 1979 - 0 1.4 0.3 0.3 0.1 0.1 0.2 0 0 0 0.8

1980 0 0 tr 0.3 tr tr 0.2 0 1.3 0.2 0.1 0.8

1981 0.1 0.2 0.4 0.3 0.2 1.5 0.8 0.4 0.8 0.3 1.2 0.3

1982 0.3 0.2 0.7 0.4 0.4 0.3 - - - - - -

Mean 0.1 0.1 0.4 0.7 0.3 0.5 0.4 0.2 0.6 0.2 0.2 0.3

SD 0.2 0.2 0.6 1.6 0.4 0.5 0.5 0.1 0.6 0.2 0.4 0.4

Pile surfperch

1973 - 0.7 0.1 0.3 0.5 0.4 2.4 4.0 - 1.5 0.6 1.1

1974 1.4 0.8 0.9 0.7 0.1 - - - - 1.5 1.4 0.6

1975 - - 0.1 0 0.3 3.6 0 - - 0 0.4 0

1976 0 0 0 0 0.1 0.4 0.2 - 0.3 0 0 -

1977 0.1 0.1 0.1 0 0 0.1 0 - - 0 0.5 0.1

1978 0.1 0 0.1 0.1 0.3 1.6 0 0.3 - 0 0.2 -

1979 - 0.2 0.3 0.6 0.1 0.3 0.3 0.4 0.1 0 0.3 0.6

1980 0 0 0 0.1 0 0.1 1.5 0 0.2 0 0 0

1981 0.1 0.1 0.1 0.1 0 1.2 1.5 0 0 0.1 0.1 0.2

1982 0 0.2 0.1 0 0 0.4 - - - - - -

Mean 0.2 0.2 0.2 0.2 0.1 0.9 0.7 0.9 0.2 0.3 0.8 0.4

SD 0.5 0.3 0.3 0.3 0.2 1.1 1.1 1.7 0.1 0.7 0.9 0.4

17
Appendix D (continued)

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Oec

Smelts (all species)

1973 0.3 0.1 0.2 0 0 0.1 0 0.1 0.3 0.2

1974 0.4 0.1 0.2 0.1 0.2 0 0 0

1975 0 0.3 0.6 0 0 0 0 0

1976 0.2 0.3 0 0.3 0 0 0.1 0 0.2 0

1977 4.0 3.0 0.7 0.9 0.1 0 0 0 0.1 0.4

1978 0.4 0 0.1 0.1 0 0 0 0 0 0

1979 0.8 0.2 0.1 0 0 0.1 0 0.1 0.1 0 0.1

1980 0.1 0.2 0.3 0,1 0 0 0.1 0 0 0 0 0.1

1981 0.2 0.1 0 0.1 0 0 0 0 0 0 0.2 0

1982 0 0.1 0.2 0,1 0.2 0

Mean 0.8 0.5 0.2 0.2 0.1 0 0.1 0 tr tr 0.1 0.1

SO 1.4 1.0 0.2 0.2 0.2 0 0.1 0 tr 0.1 0.1 0,1

California tonguefish

1973 0 0 0 0 0 0.1 0 0 0 0

1974 0 0 0 0 0 0 0 0

1975 0 0 0 0 0 0 0 0

1976 0 0 0 0 0 0 0 0 0 0

1977 0 0 0,2 0.8 3.4 4.7 2,8 0 0 0

1978 0 0 0 0 0.2 0.3 0 0,1 0 0

1979 0 0 0 0 0.1 0.1 0 0 0 0 0

1980 0 0 0 0.1 (1,3 0.3 0.3 0,2 0.2 0 0 0

1981 0 0 0 0 0 0 0.1 0 0 0 0 0

1982 0 0 0 0 0.1 0.1

Mean 0 0 tr 0,1 0.4 0.6 0.4 0,1 0.1 0 0 0

SO 0 0 tr 0.3 1.1 1.5 1.0 0,1 0.1 0 0 0

Brown smoothhound sharks

1973 tr 0 tr 0.6 2.8 0.3 0 0.1 0,1 0.1

1974 0 tr tr 0 0.3 0.1 tr 0.1

1975 0 0.1 0.6 0.2 0 0.1 tr 0.1

1976 0 0.1 0 0 0.4 0.7 0.1 0,1 0 tr

1977 0 0.1 0.1 0.4 0.7 0.9 0.2 0.3 0.4 0.6

1978 0.1 0 0 tr 02 0.2 0,1 0 tr 0.2

1979 0 0.1 0.1 02 tr 0 0.1 0.1 0,1 0 0.3

1980 0 0.1 0 0.1 0.4 0.9 0 0 0 0 0.3 0.1

1981 0.1 0 0 0.2 0.2 0.1 0.1 0,1 0,2 0.3 0 0

1982 0 0 0 tr 0 0

Mean tr tr tr 0.1 0.4 0.6 0,1 0.1 0.1 0,1 0.1 0.1

SO tr tr tr 0.1 0.2 0.9 0.1 0.1 0.1 0.1 0.2 0.2

.------"

Leopard sharks

1973 tr 0 0.3 0.8 2.3 0 0 tr 0 0

1974 0.1 0,2 0.1 0,2 0.2 0.2 0,5 0.1

1975 0 0.3 0.1 0 0 0 tr 0.2

1976 0.1 0.1 0,2 0,2 0.2 tr 0 0 0 0

1977 0 0.1 0.1 0.4 0.7 0.9 0 tr 0.1 0.1

1978 0.1 0.2 0.2 0,2 0.:5 0,1 0 0.1 0 tr

1979 0 1.0 0.1 tr 0 0.1 0 0.2 0 0 0.5

1980 0.3 0 0 0.8 0.2 0.4 0 0.2 0 0 0.2 tr

1981 0.2 0.1 tr 0.5 t, 0 0 0 0 0 tr 0

1982 0 0,1 0,3 0.1 0.:. 0

Mean 0.1 0.1 0,2 0.3 0.2 1.2 tr 0.1 0.1 tr 0.1 0.1

SO 0.1 0,1 0.3 0.2 0-' .4 2.7 tr 0.1 0.1 1.0 0.2 0.2

III
Appendix D (continued)

Year Ian Feb Mar Apr May Iun lui Aug Sep Oct Nov Dec

Walleye surfperch

1973 0 0 0 0.2 0.3 0.1 0 tr 0 0

1974 0 0.3 tr 0 tr 0 0 0

1975 0 0.1 0.1 0 0 0 0 0

1976 0 0 0 0 0 tr 0.2 0 0 0

1977 0 0 0 0 0.1 0.2 0.3 0 0 0

1978 0 0 0 0 0.1 2.8 0 l.l 0 0

1979 0 0.1 0 tr 0.4 0.2 0.9 0 0 0.3 0.8

1980 0 0 0.1 0 0.1 1.4 0 0 0 0 0 0.1

1981 0.3 tr 0.1 0.1 tr 0.7 0 0.1 0.1 0.1 0.2 0

1982 0.3 0 tr 0.1 0.3 2.3

Mean 0.1 tr tr tr 0.1 0.8 0.1 0.4 tr tr 0.1 0.1

SO 0.1 0.1 0.1 tr 0.1 0.9 0.1 0.5 0.1 tr 0.1 0.3

Bay pipefISh

1973 0.1 0 tr 0.1 0.1 2.6 0.3 tr 0.1 0

1974 0 0.1 0.2 0.5 0.6 0.1 0.1 0

1975 0.1 0 0.1 0 0 0.2 tr 0

1976 0 0 0.2 0.9 tr tr 0.1 0.4 0 0.1

1977 0 0.1 0 tr 0 0 0.2 0 tr 0

1978 0 0 0.1 0.1 0.7 0.1 0.1 0.2 0.2 0.1

1979 0 tr 0.1 0.2 0.2 0.4 0.7 1.8 0.4 0 0

1980 0 0.2 0.1 0.3 0.4 0.4 0 0.2 0.7 0.1 0.2 0.1

1981 0.1 0.1 0.1 tr tr 0.1 0.2 l.l 0 0.1 0 0

1982 0.2 0 tr 0 0 0

Mean tr 0.1 0.1 0.2 0.2 0.1 0.4 0.5 1.5 0.1 0.1 tr

SO 0.1 0.1 0.1 0.3 0.3 0.1 1.0 0.4 1.2 0.1 0.1 tr

White croaker

1973 0 0 0 0 0 0 0 0 0 0

1974 0.1 0 0 0 0 0 0 0

1975 0 0 0.1 0 0 0 0 0

1976 0 0 0 0 0.1 0 0 0 0 0

1977 0 0 0.1 0.3 1.5 7.5 0 0 0 0

1978 0 0 0.1 0 0 0 0 0 0 0

1979 0 0.1 0 0 0 0 0 0 0 0 0

1980 0 0 0 0 0 0.3 0 0 0 0 0 0

1981 0 0 0.1 0.2 0 0 0 0 0 0 0 0

1982 0.2 0 0.1 0.1 0.2 0

Mean tr 0 0.1 0.1 0.2 0.9 0 0 0 0 0 0

SO 0.1 0 0.1 0.1 0.5 2.5 0 0 0 0 0 0

Shad (all species)

1973 0.2 0 0.1 0 2.7 0.1 0 0 1.2 1.5

1974 1.2 0.5 0 0 0 0 0.4 l.l

1975 0.2 0.1 0 0 0 0 0.4 0.8

1976 0.6 0.9 0.3 0.1 0 0 0.2 0 0 0

1977 0 0 0 0 0 0 0 0 0.8 0.6

1978 0.4 0.2 0.1 0 0 0 0 0 0 0.1

1979 0.6" 0.2 0.1 0 0 0 0 0 0 0 0

1980 0 0.5 0 0 0 0 0 0 0 0 0 0.4

1981 0.1 0 0 0 0 0 0 0 0 0 0.1 0.3

1982 0 0 0 0 0 0

Mean 0.3 0.3 0.1 tr 0 0.3 tr 0 0 0 0.3 0.7

SO 0.4 0.3 0.1 tr 0 0.9 tr 0.1 0 0 0.4 0.5

19
Appendix D (continued)

Year Ian Feb Mar Apr May Iun lui Aug Sep Oct Nov Oec

Diamond turbot

1973 0.1 0.4 0.1 0.1 1.3 0.2 0 0 0 0.2

1974 0 0.2 0.2 0.2 0.1 0.1 0 0.2

1975 0 0.2 0.2 0 0 0 0 0.1

1976 0.2 tr 0.1 0.2 Ir 0 0 0.1 0 0

1977 0.1 0 0.1 0.2 0.1 0.2 2.5 tr 0.8 0.9

1978 0.5 1.3 0.3 0.2 0.2 0 0 0 0 0

1979 0 0.1 0.2 tr 0 0 0 0 0 0 0.1

1980 0 0 0.7 0.2 0.1 0.1 0 0.1 0 0 0 0

1981 0.1 0.1 0.1 0.1 tr 0 0 0 0.5 0 0.1 0

1982 0 Ir 0.1 0.1 0.1 0

Mean 0.1 0.2 0.2 0.2 0.1 0.2 0.3 Ir 0.2 tr 0.1 0.2

SO 0.2 0.4 0.2 0.1 0.1 0.4 0.8 tr 0.2 tr 0.3 0.3

Bat rays

1973 0 0 tr C.4 1.3 0.2 0.1 tr 0.1 0

1974 0 0 0.1 0.3 C.3 0.1 0.3 0

1975 0.1 0.1 0.2 0 0 0 tr 0

1976 0 tr 0.2 0.6 0.2 0.3 0.1 0 0 tr

1977 0 0.1 0.1 0.3 0.3 0.3 0.3 0.2 0.1 0

1978 0 0 0.1 tr 0.2 0.1 0 0 0 0.1 0

1979 0.2 tr 0.2 0.4 0 0.1 0.2 0.4 0 0 0

1980 0 0.1 tr Ir 0.3 0.4 0 0 0 0 0.2 0

1981 0 Ir 0.2 0.6 tr 0 0 0.1 0.3 0.3 0.2 0

1982 0 0 0 0 tr tr 0.3

Mean 0 0.1 0.1 0.2 0.2 0.3 0.1 0.1 0.2 0.1 0.1 0

SO 0 0.1 0.1 0.2 0.1 0.4 0.1 0.1 0.2 0.1 0.1 0

Plainfin midshipmen

1973 0 0 0.2 0 0.1 0.2 0.2 0 0 0

1974 0 0 0.1 0.6 0 0 0 0

1975 0 1.1 0.4 0.2 0 0 0 0

1976 0 0 0 0 0.1 0 0.4 0.7 0 0

1977 0 0 0 0.4 0.3 0.2 0 0 0 0

1978 0 0 0 0.1 0.1 0 0 0 0.1 0.3

1979 0 0.2 0.2 () 0 0.3 0.4 0 0 0 0

1980 0 0 0.1 0.2 0 0.2 0.2 0.2 0.2 0.2 0.1 0.2

1981 0 0 0 0.1 0 0 0 0 0 0 0.2 0

1982 0 0 0.1 0.5 0.3 0

Mean 0 0 0.2 0.3 0.1 0.1 0.1 0.2 0.2 0 0.1 0

SO 0 0 0.1 0.2 0.1 0.1 0.1 0.2 0.1 0.1 0.1 0.1

Bonyhead sculpin

1973 0 0 0 0 0 0 0 0 0 0

1974 0 0.1 0.2 1.0 0.1 0.1 0 0.3

1975 0.1 tr 0.1 0.2 0 0 0 0

1976 0 tr 0 0 tr 0 0 0 0 0

1977 0 0.2 0.2 0.2 0.2 tr 0 0 0.2 0

1978 0.1 1.3 0.1 0.1 0.2 0.2 0 0 0 tr

1979 0.2 tr 0.1 G Ir 0.1 0 0 0 0 0.3

1980 0 0.2 0.4 0.2 0.1 0.2 0.2 0 0 0 0.1 0

1981 0.4 0.2 0.5 0,1 0.1 0.1 0.3 0 0 0 0 0.2

1982 0.2 0.2 0.3 tr 0.1 0.1

Mean 0.1 0.3 0.2 0.2 0.1 0.1 0.1 0 0 Ir Ir 0.1

SO 0.1 0.4 0.2 0.3 0.1 0.1 0.1 0 0 Ir 0.1 0.1

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Appendix D (continued)

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Starry flounder

1973 0.5 0.5 0.2 0.2 0.1 0.1 0 0 0 0.2

1974 0.4 0.2 0.1 0.1 0.1 0.1 0.3 0.2

1975 3.7 0.6 0.1 0 0.3 0 0.1 0.2

1976 0.1 0.1 tr 0.1 tr tr 0 0 0 tr

1977 0 0 tr 0.1 tr tr 0 0 0.3 0.1

1978 0.3 0.2 0 tr 0.2 0 0 0 tr 0.1

1979 0 tr 0.1 0 0 0 0 0.1 0 0 0

1980 0 0.1 0.1 0.1 0.1 0.1 0.2 0.1 0.5 0.2 0.1 0.1

1981 0.3 0.1 0.3 tr tr 0 0.1 0 0 0 0 0

1982 0 0 tr 0 tr 0

Mean 0.1 0.1 0.5 0.1 0.1 tr 0.2 tr 0.2 tr 0.1 0.1

SD 0.2 0.1 l.l 0.2 0.1 tr 0.2 tr 0.2 0.1 0.1 0.1

California halibut

1973 0 0.3 0.1 tr 0 0 0.2 tr 0 0

1974 0 tr 0.1 0.1 0 0 0 0.9

1975 0.1 0.1 0 0 0.3 0 0 0.1

1976 0.1 0.5 0 0 0 0 0 0 0 0

1977 tr 0.2 tr tr tr 0 0.1 0 0.4 l.l

1978 0.9 1.8 0.6 0.1 0.1 0 0 0.2 0.7 0.5

1979 0.2 0.5 0.8 0.4 0.1 0 0 0 0 0 0

1980 0 0.2 tr 0 0 tr 0 0 0 0 0.1 tr

1981 0 0.1 0.1 tr tr 0 0 0.1 0.1 0.1 0.2 0

1982 0 0.2 0.1 0.1 0.1 tr

Mean 0.1 0.4 0.1 0.1 0.1 tr 0.1 0.1 tr 0.1 0.1 0.3

SD 0.3 0.6 0.2 0.2 0.1 tr 0.1 0.1 0.1 0.2 0.2 0.5

Appendix E

Mean number of species per otter trawl in south San Francisco Bay, 1973-82. Dash indicates no trawls.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1973 2.8 4.4 5.8 6.6 5.0 6.2 5.3 2.6 3.1 3.1

1974 4.4 4.8 5.8 8.3 6.2 3.1 3.5 3.1

1975 3.0 4.6 5.5 4.8 2.2 1.8 1.7 3.1

1976 2.4 1.8 2.8 4.7 4.5 4.0 2.9 3.7 1.5 1.3

1977 1.9 1.4 3.2 4.2 4.9 5.8 5.3 2.0 2.8 4.1 3.9

1978 3.8 5.3 5.3 4.1 5.2 4.9 2.5 3.5 3.2 2.8

1979 3.8 6.2 6.0 5.2 3.7 3.0 4.4 3.2 1.8 3.8 5.4

1980 2.4 3.8 3.9 4.7 4.8 5.4 4.3 2.5 3.7 2.4 3.2 2.6

1981 2.7 3.9 4.0 4.8 3.6 5.1 3.6 3.0 4.2 3.4 4.0 2.3

1982 4.0 4.0 5.2 5.3 5.3 5.0

Mean 3.1 3.5 4.4 5.3 5.2 4.5 3.8 3.7 3.4 2.2 3.0 3.4

SD 1.0 1.3 1.2 1.2 0.8 1.5 1.4 l.l 0.8 1.0 0.9 1.0

21