The spawning biomass of Pacific herring in San Francisco Bay and Tomales Bay was estimated to be 99,495 tons and 7,149 tons, respectively during the 1981-82 season. This is the highest estimate to date for San Francisco Bay and continues a rising trend in abundance. The Tomales Bay population increased to the highest level in 4 years.  (22pp.

Spratt, Jerome D.

English

Aquatic Commons

S t a t e  of  C a l i f o r n i a  
The R e s o u r c e s  Agency 
DEPARTMENT OF FISH AND GAME 
BIOMASS ESTIMATES OF PACIFIC HERRING, 
CLUPEA HARENGUS PALLASI, I N  CALIF ORNLA 
FROM THE 1981-82 SPAWNING GROUND SURVEYS 
by 
J e r o m e  D .  S p r a t t  
MARINE RESOURCES 
A d m i n i s t r a t i v e  R e p o r t  No. 82-6 
AUGUST 1982 
BIOMASS ESTIMATES OF PACIFIC HERRING, 
CWPEA IIARENGUS PALLASI, I N  CALIFORNIA 
FROM THE 1981-82 SPAWNING GROUND SURVEYS - 
by 
21 Jerome D. S p r a t t  - 
ABSTRACT 
The spawning biomass of Pac i f i c  herr ing i n  San 
Francisco Bay and Tomales Bay was estimated t o  be 
99,495 tons and 7,149 tons, respect ively  during the  
1981-82 season. This is the  h ighes t  es t imate  t o  
d a t e  f o r  San Francisco Bay and continues a r i s i n g  
trend i n  abundance. The Tomales Bay populat ion 
increased t o  the  h ighes t  l e v e l  i n  4 years.  
11 Marine Resources Region, Administrat ive Report No. 82-6. 
- 
21 Marine Resources Region, Marine Resources Laboratory, 2201 Garden Road, 
- 
Monterey, Cal i fornia  93940. 
ACKNOWLEDGEMENT 
I wish to thank Walter Earl, Margaret Graham, Gary Stern, and Jeri  
Zemon who braved the elements t o  co l l e c t  samples of herring eggs. Depart- 
ment divers Larry Espinosa,.James E. Hardwick, Frank Henry, and James Houk 
collected subtidal vegetation samples i n  San Francisco Bay. 
BIOMASS ESTIMATES 0F.PACIFIC HERRING, 
CLUPEA HARENGUS PALLASI, I N  CALIFORNIA 
FROM THE 1981-82 SPAWNING GROUND SURVEYS 
I n  1973, The California Department of Fish and Game began estimating 
t h e  annual spawning biomass of Pac i f ic  herring,  Chpea harengus p a l h s i ,  i n  
Tomales and San Francisco Bays (Spratt ,  1981). B i o m a s s  is  derived from 
estimates of eggs deposited during each season. Both bays a r e  r e l a t i ve ly  
small i n  area and a r e  w e l l  sui ted f o r  in tensive spawning ground surveys. 
Tomales Bay biomass estimates have fluctuated around a mean of 6,000 tons. 
The San Francisco Bay estimates began t o  increase i n  1978 a s  sampling tech- 
niques were improved. In  1980-81 the spawning biomass was estimated to be 
wer 65,000 tons (Spratt ,  1982). 
This repor t  includes spawning biomass est imates f o r  Tomales Bay and 
San Francisco ~a~ during the  1981-82 spawning season and i t  provides con- 
tinuous s e r i e s  of annual herring spawning biomass est imates from 1973-74 
onward. These data  a r e  the bas i s  of the  herring roe  f i shery  management plan. 
DESCRIPTION OF STUDY AREA 
Tanales Bay 
Tomales Bay l i e s  in  Marin County, a shor t  d is tance north of San Fran- 
cisco. It is 20 km (12.4 m i l e s )  long and averages more than 1.5 km (0.9 
miles) wide. Hardwick (1973) mapped the d i s t r i bu t ion  and abundance of marine 
f l o r a  i n  Tomales Bay and found tha t  e e l  grass ,  Zostera tnarina, comprised 75 
percent by weight of a l l  vegetation i n  the  bay. The d i s t r i bu t ion  of e e l  
g rass  in  Tamales Bay has changed s l i g h t l y  each year ( ~ p r a t t ,  1981). The 
present d i s t r ibu t ion  (Figure 1) w a s  determined during March of 1982. Other 
species of marine f l o r a  a r e  u t i l i z ed  a s  spawning subs t ra te  i n  Tomales Bay, 
but e e l  grass  is the only spawning subs t ra te  included i n  my surveys. 
San Francisco 
The regular  survey area i n  San Francisco Bay includes a l l  shoreline and 
shallow subt ida l  a reas  t o  a depth of 4.6 m (15 f t )  bounded by the Golden 
Gate Bridge, Richmond Bridge and the San Francisco-Oakland Bridge (Figure 2).  
The f i r s t  major spawn outside the regular survey area occurred t h i s  season 
in south San Francisco Bay between Coyote Point and China Basin (Figure 6). 
This area  will b e  incorporated i n t o  fu ture  spawn surveys. While most spawns 
are subridal  i n  San Francisco Bay, there is a l s o  considerable i n t e r t i d a l  
spawning ac t iv i ty .  I n t e r t i d a l  spawns i n  San Francisco Bay l i t e r a l l y  cover 
a l l  avai lable  subs t ra te  i n  the area including bare rocks, sand, pier  pi l ings  
and marine f lo ra .  The two major subt idal  spawning a reas  a r e  Richardson Bay 
and the east bay between Richmond and Oakland. They cons is t s  of sparse beds 
of G m & t a r i a  spp, interspersed with Uzva sp. and some e e l  grass.  The only 
shallow areas  consis tent ly  not u t i l i zed  fo r  spawning a r e  broad mud f l a t s  
with no vegetation. 
METHODS 
Tamales Bay Sampling Techniques 
This season's spawning ground surveys were conducted from December 1, 
1981 t o  March 19, 1982. Spawn sampling techniques have remained r e l a t i ve ly  
unchanged s ince  1973 (Spratt ,  1981). Every e e l  g rass  bed (Figure 1) was 
sampled da i ly  from a 4.6- (15-ft) boat by tawing a vegetation sampler 
through the  bed. 
The d i s t r i bu t ion  of eel grass  changes yearly; new beds a r e  discovered, 
old ones disappear, and the a reas  of some beds change s ign i f ican t ly .  
Every year i n  March, after spawning has nearly stopped, the areas of 
a l l  eel grass  beds a r e  remeasured and these new da ta  a r e  used t o  calculate  
a l l  of the  season's spawns. Previous estimates of e e l  g rass  densi ty  ranging 
I 
2 from 0.5-4.0 kg/m (Sprat t ,  1981) were applied t h i s  season t o  each bed by . I I 
subjective,  on-site inspections. 
San Francisco Bay Sampling Techniques 
This season ' s spawning ground surveys were conducted from November 17, 
1981 u n t i l  March 12, 1982. Techniques used i n  San Francisco Bay t o  estimate 
spawning biomass have evolved over the years (Sprat t ,  1981) and current ly  
t he  major sampling e f f o r t  is  on sub t ida l  spawns, although i n t e r t i d a l  (shore- 
line) spawns still account f o r  a s ign i f ican t  pa r t  of each season's spawning 
ac t i v i t y .  In  order t o  compute biomass from subt idal  spawns, i t  is necessary 
2 t o  determine the weight (kg/m ) of vegetation present i n  the  spawning area.  
Each f a l l ,  Department d ivers  co l l ec t  quant i t a t ive  samples of vegetation from 
Richardson Bay, Belvedere Cove, Tiburon, K i e l  Cove and the e a s t  bay between 
Richmond and Oakland. The boundaries of known vegetation beds were determined I 
by dragging a vegetation sampler through them. Permanent sampling s t a t  ions 
w e r e  selected randomly by placing a gr id  over the  beds, the  numbering points 
where gr id  l i n e s  intersected.  In  the  ea s t  bay 27 s t a t i ons  were selected,  and . 
in the Richardson Bay a rea  24 s t a t i ons  were selected.  Divers removed a l l  
2 
vegetation from three  0.25-m quadrats a t  each s t a t i on ,  The vegetation 
was damp dr ied and weighed t o  the  neares t  gram immediately a f t e r  col lect ion.  
When a subt idal  spawn occurred, the  vegetation sampler was used t o  
2 
co l l ec t  samples and determine spawning area  (m,). The number of eggslkm of 
vegetation was determined using techniques developed i n  the  1979-80 season . 
(Spratt ,  1981). The estimate of egg deposition i s  the product of number of 
2 tggs/hn vegetation, kg vegetation/m2, and spawn area  (m ) . 
Biomass Computation 
The techniques used t o  estimate t o t a l  number of eggs deposited during 
a season d i f f e r  between Tomales and San Francisco Bays. However, conversion 
from numbers of eggs spawned t o  tons of adu l t s  is iden t i ca l  f o r  both bays. 
Hardwick's (1973) estimate of fecundity was used to  convert numbers of 
eggs t o  tons of herring,  Hardwick estimated fecundity a t  114 eggs/gram of 
herring (both sexes combined) f o r  Tamales Bay herring,  and t h a t  103.5 mil l ion 
, eggs would be produced by one ton of adu l t  herring.  
The t o t a l  eggs deposited during the season is the sum of the est imates 
of each individual spawn. The number of eggs spawned is converted t o  shor t  
. tons  of spawners by multiplying by ,966 x the  reciprocal  of fecundity 
per ton of adul t  herring. 
RESULTS 
' Tomales Bay 
Another eel grass' bed w a s  discovered t h i s  season: bed 28A near the 
south end of the  bay. This bed was found ;hen la rge  numbers of g u l l s  were 
observed c i rc l ing  i n  the  area  a s  herr ing were spawning. This bed may not 
have been newly formed but  I believe it was the  f i r s t  time it was u t i l i z ed  
f o r  spawning s ince our survey began. There is  now a t o t a l  of 32 known e e l  
grass beds i n  Tomales Bay (Figure 1). Bed measurements i n  March, 1982 re- 
vealed that the, t o t a l  amount of eel grass  ava i lab le  f o r  spawning declined 
2 
s l i g h t l y  t o  3.9 mill ion m (Table 1). 
The f i r s t  spawn located t h i s  season occurred on November 30, 1981, and 
a t o t a l  of nine spawning runs occurred u t i l i z i n g  23 individual  spawning ' 
sites (Table 2). 
I estimate a minimum spawning escapement of 6,298 tons. The commercial 
herring roe  f ishery takes herring j u s t  p r io r  t o  spawning; therefore ,  the  
spawning biomass est imate f o r  the  season should include the  catch. The catch 
of pre-spawners increases the biomass estimate f o r  the  1981-82 season t o  
7,149 tons of herring. 
San Francisco Bay 
. . 
The known subt ida l  spawning a reas  of the  bay were surveyed by Depart- 
ment d ivers  in  November of 1981 t o  estimate the densi ty  of vegetation. 
2 Vegetation dens i t i es  were highest  i n  Richardson Bay (.480 kg/m ) 
and 
bay 
the 
K i e l  Cove f.579 
revealed a much 
s t a t i ons  barren 
kg/m2) (Figure 3). The vegetation survey of the  east 
2 lower mean densi ty  of .009 kg/m with 78 percent of 
. 
(Figure 4). 
The f i r s t  spawn of t h e  season was located on November 5 ,  1981 near  
Tiburon. There were a t  least 11 spawning runs during the  season (Table 3) ,  
and spawn was deposited a t  s i x  loca t ions  i n  the  Bay (Figures 5, 6 and 7) in- 
cluding t h e  f i r s t  major spawn t o  occur i n  south San Francisco Bay. Subt ida l  
spawns accounted f o r  77 percent  of the  estimate. 
Richardson Bay, Kie l  Cove, and associa ted  shore l ine  accounted f o r  90 
percent  of the  season's  spawning a c t i v i t y .  The e a s t  bay w a s  less s u i t a b l e  
t o  he r r ing  because of the  low vegeta t ion  d e n s i t i e s .  
I estimated spawning escapement a t  89,080 tons of herr ing .  The commer- 
c i a l  he r r ing  r o e  f i she ry  ca tch  of pre-spawners was 10,415 tons. Including 
the  ca tch ,  t h e  spawning biomass f o r  the  1981-82 season was 99,495 tons ,  the  
h ighes t  es t imate  t o  da te .  Two spawns near  Tiburon on March 13 and Apr i l  11 
occurred a f t e r  our  surveys terminated and were no t  included i n  est imates.  
DISCUSSION 
Tanales Bay 
Spawning ground surveys i n  Tomales Bay a r e  begun on December f i r s t  each 
season. Since 1973, January and February have combined f o r  88 percent  of 
a l l  spawning a c t i v i t y .  Within t h i s  time frame, t h e r e  has been a s h i f t  i n  the  
t i m e  of peak spawning. I n  the  p a s t  3 years ,  92 percent  of the  spawning has 
occurred i n  January. 
The Tomales Bay biomass es t imate  has  ranged between 4,728 tons i n  1975 
and 22,163 tons  i n  1978 (Table 4) .  Excluding the  anomalous 1978 season, the  
Tomales Bay estima'te has averaged near ly  6,000 tons per  year .  The spawning 
population i n  the  bay cur ren t ly  appears s t a b l e  and f l u c t u a t e s  normally from 
year t o  year.  
San Francisco Bay 
The months of peak spawning a c t i v i t y  i n  San Francisco Bay a r e  December, 
January and February. However, from the  '1977-78 t o  1980-81 seasons over 90 
percent  of spawning a c t i v i t y  w a s  completed by t h e  end of January (Spra t t ,  
1982). I n  the  1981-82 season the re  were more l a r g e  spawnings ?nd more l a t e  
season spawnings reflecting t h e  season's l a rger  spawning biomass. February 
and March accounted for 40 percent of the  season's spawning a c t i v i t y .  
The es t imate  of herr ing spawning biomass i n  San Francisco Bay has in- 
creased since the 1976-77 season (Table 5). Unt i l  t h i s  season, increases 
i n  the est imate of spawning biomass have been a t t r i bu t ed  t o  the  following 
changes i n  methodology: ( i )  extensive subt idal  spawning a reas  were included 
i n  surveys b e g i ~ i n g  with the  1979-80 season, and ( i i )  the  month of November 
was included i n  surveys beginning with the 1980-81 season. 
The estimated herr ing spawning biomass i n  San Francisco Bay f o r  the  
1981-82 season is 99,495 tons, the  highest  est imate to  da te ,  and an increase 
of 50 percent over t h e  1980-81 est imate of 65,441 tons. There were no 
changes i n  methodology t h i s  season. The population increased due t o  excel lent  
survival  r a t e s  of the  1978, 1979 and 1980 year c lasses .  Herring a r e  noted f o r  
na tura l  cycles i n  abundance and the San Francisco Bay population may continue 
to  increase  o r  may s t a b i l i z e  a t  a high l eve l  f o r  several  years.  However, a t  
some point  i n  t he  f u t u r e  the  population i s  l i ke ly  t o  dec l ine  due to  unfavor- 
ab le  environmental condit ions.  
REFERENCES. 
Hardwick, James E. 1973. B i o m a s s  ebtimates of spawning herr ing,  CZupea 
harengus p a l h i ,  herr ing eggs, and associa ted  vegeta t ion i n  Tomales 
Bay. Ca l i f .  Fish and Game 59(1):36-61. 
Spra t t ,  J. D. 1981. Sta tus  of the  P a c i f i c  herr ing,  CZupea harengus 
p a Z h i i , i n  Cal i fornia  t o  1980. Ca l i f .  Fish and Game, Fish. Bull. ,  
(171) : 1-104. 
- . 1982. Biomass estimates of P a c i f i c  herr ing,  CZupea hurengus 
p a l h i ,  i n  Cal i fornia  from the  1980-81 spawning ground surveys. Ca l i f .  
,Dept. F ish  and Game, Mar. Resource Admin. Rept. 82-2:l-21. 
TABLE 1. Tomales Bay Eel Grass Beds as Measured in March 1 9 8 2  
Ar ea Area Bed Bed 
number (m2) number (m2 
3 2,100 1 6 ~  14,600 
4 100 17 2,200 
5 8,400 18 o 
6 9,400 19 116,600 
7 8,100 2 o 235,500 
8 11,OOO 2QA 55,900 
9 North 19,800 2 1  1,488,000 
g South 18,200 22 140,000 
10 4,100 23 1,209,000 
11 North 15,400 24 20,900 
U Middle 7 , 500 25 165,000 
- 11s0uth  2,600 26 160,000 
K 2,400 e7 52,000 
13 loo 28 21,000 
\ 
2 8 ~  . . 11,800 
TOTAL AREA 3,882,250 
TABLE 2. Herring Spawn Data f o r  Tomales Bay, 1981-82 Season. 
* 2 No. eggs per  Kg e e l  g r a s s  No. e?gs Mil l ions  
Date Location a rea  (m ) kg e e l  g r a s s  per  m per m 2 of eggs Tons 
30 k v  81 
15 Dec 81 
22 Dec 81 
22 Dec 81 
22 Dee 81 
22 k c  81 
22 k c  81 
6 Jan 82 
6 Jan 82 
6 JZUI 82 
6 JZUI 82 
6 Jan 82 
19 Jan 82 
24 Jan 82 
25 Jan 82 
25 Jan 82 
25 Jan 82 
7 Feb 82 
7 Feb 82 
17 Feb 82 
l 8  Feb 82 
28 Feb 82 
28 Feb 82 
Total 
10 Trace 
133,680 1,098 
7,543 73 . 
63,126 610 
284,400 2,747 
42 trace 
4,047 39 
1,132 11 
1,822 18 
6,072 59 
27,589 266 
652,045 6,298 
* See Figure 1. 
t 
No. eggs per Kg vegetalion No. eggs Millions 
Date Location Area (m2) kg vegetation per (m per (m2) of eggs Tons 
5-6 Nov81 Kielcove 67,000 233 000 580 13 5,000 9,045 90 
18-19 Nov 81 Richardson Bay 2,716,000 205,000 ,400 82,000 222,567 2,150 
28-29 Nov 81 Richardson Bay 3,971,000 140,000 .450 63,000 250,173 2,420 
2-3 Dec 81 Treasure Ialand 7,300 * .  * 771,000 5,628 50 
2-3 Dec 81 Treasure Island 41,000 3,688,000 .~OO 1,844,000 75,604 
* 
730 
8-9 Dec 81 Angel Island l27,OOO * 350,000 44,450 
* 
430 
9-10 Dec 81 Sausalito 38,000 * 913,000 34,694 340 
22-27 Dee 81 Richardson Bay 5,330,000 1,500,000 .260 390,000 2,078,700 20,080 
5-8 Jan 82 Sausalito 238,000 * st. 3,157,000 751,366. 7,260 
17-22 Jan 82 Richardson Bay 4,284,000 695,000 .boo 278,000 1,190,952 11, 500 
21-22  an 82 Sausalito 67,000 * * 2,871,000 192,357 1,860 
25 Jan- 2 Feb South Bay 290,000 * * 2,641,000 765,890 7,400 
10-12 Feb 82 Richardson Bay 5,120,000 3,418,000 .I10 376,000 1,925,120 18,600 
16117 Feb 82 Tiburon l09,000 * * 1,044,000 113,796 1,100 
17 Feb 82 Kiel Cove 67,000 976,000 -580 566,000 37 , 922 370 
28 Feb 82 Richardson Bay 3,761,000 ' 44,000 .240 10,500 39,490 380 
5-6 Mar 82 Tiburon 129,OOO * sc 1,288,000 . 166,152 1,600 
5-6 Mar 82 Kiel Cove 67,000 4,353,000 -580 2,525,000 169,175 1,630 
7-8 Mar 82 Richardson Fhy 4,284,000 1,117,000 .240 268,000 1,148,112 11,090 
TOTAL 30,713,300 9,221, 193 899 080 
a 
* This is an intertidal spawn (shoreline) and vegetation parameters are not used. 
TABLE 4. Tomales Bay Pacific Herring Spawning Biomass Estimates 1973-74 
through 1981-82 Seasons 
Spawn estimate Catch Spawning b lomass 
Season (tons) (tons) (tons) 
TABLE 5. San Francisco Bay Pacific Herring Spawning Biomass Estimates 1973-74 
through 1981-82 Seasons. 
Spawn est imate Catch Spawning biomass 
Season (tons) (tons) ( tons) 
1973-74 4,241 1,938 6,179 
1974-75 26,820 514 27,334 
FIGURE 1. Tomales Bay with numbered eel grass beds. 
:.'* HAYWARD 
FIGURE 2. Herring spawning ground survey area in  San Francisco Bay. 
. . . . . V E G E T A T I O N  B O U N D A R Y  
S T A T I O N  
.077 D E N S I T Y  kg/m2 
MARIN PENlNSULA %, 
DENSITY 
1981 
FIGURE 3. Vegetation density kg/m2 in  thg Richardson Bay area i n  the f a l l  of 1981. 
\ 
VEGETATION DENSITY 
FALL 1981 
LEGEND 
. ... . VEGETATION BOUNDARY 
STATION WITH VEGETATION 
FIGURE 4 .  Vegetation density kg/m2 in  the eastern part of San Francisco Bay in  
the fall of 1981. - 
. . 
INTERTIDAL HERRING 
SPAWNS 
SEASON 
. . .. 
. . 
5-8 M A R  1982 
16-17 FEB 1982 
8 - 9  DEC 1981 
9 -10 DEC 1981 TREASURE 
21-22 JAN1982 ISLAND 
5-6 JAN 1982 
2-3 DEC 1981 
SAN FRANCISCO 
FIGURE 5. Intertidal  herring spawnings and dates of occurrence i n  
San Francisco Bay during the 1981-82 season. 
SPAWN 
LOCATION 
FIGURE 6 .  Location of intertidal spawning i n  south San Francisco Bay during 
the 1981-82 season. 
HERRING 
SPAWN 
2-3 DEC 
SUBTIDAL HERRING SPAVdi4S 
1981-82 SEASON 
SCALE 
I 
ONE' MILE 
I 
NOTE: THERE WERE 7 SPAWNINGS I N  RICHARDSON 
BAY, AND 3 I N  KIEL COVE. 
FIGURE 7.  Location of subtidal  spawning in San Francisco Bay during the 1981-82 season. 


Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1981-82 spawning ground surveys

The spawning biomass of Pacific herring, Clupea harengus

pallasi, in San Francisco Bay and Tomales Bay was estimated

to be 59,000 tons and 11,200 tons, respectively during the

1982-83 season. This represents a 40% decline in San

Francisco Bay and a 50% increase in Tomales Bay populations.

Unusually high ocean temperatures and record rainfall in

California are believed to have affected the distribution

and/or survival of herring and caused changes in spawning habits.  (26pp.

Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1982-83 spawning-ground surveys

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Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1981-82 spawning ground surveys

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