In Tomales Bay, 4-, 5-, and 6-yr-old herring, Clupea harengus pallasi, composed 85% by number of the 1986-87 season's catch. In San Francisco Bay, 2-, 3-, and 4-yr-old herring composed 88% of the roundhaul catch, and 4-, 5-, and 6-yr-old herring composed 86% by number of the gill net catch.

The age composition of both the Tomales Bay and San Francisco Bay gill net catch has shifted to primarily 4-, 5-, and 6-yr-old herring.

Recruitment of 2-yr-old herring into the San Francisco Bay roundhaul fishery was good, with the 1985 yr class composing 37% of the catch.

The mean length of herring in the San Francisco Bay roundhaul catch decreased to 174 mm BL, and the mean length of the gill net catch decreased to 194 mm BL. The mean length of the Tomales Bay catch also decreased to

197 mm BL.

Average weight at age of Tomales Bay herring is below average for the fourth consecutive year. In San Francisco Bay the average weight at age is above average, even though length at age declined slightly.  (20pp.

Spratt, Jerome D.

English

Aquatic Commons


BIOLOGICAL CHARACTERISTICS OF THE CATCH 
FROM THE 1986-87 PACIFIC HERRING, 
CLUPEA HARENGUS PALLASI, ROE FISHERY IN CALIFORNI&/ 
by 
2/ Jerome D. Spratt 
ABSTRACT 
In Tomales Bay, 4-, 5-, and 6-yr-old herring, Clupea harengus pallasi, 
composed 85% by number of the 1986-87 season's catch. In San Francisco Bay, 
2-, 3-, and 4-yr-old herring composed 88% of the roundhaul catch, and 4-, 
5-, and 6-yr-old herring composed 86% by number of the gill net catch. 
The age composition of both the Tomales Bay and San Francisco Bay gill net 
catch has shifted to primarily 4-, 5-, and 6-yr-old herring. 
Recruitment of 2-yr-old herring into the San Francisco Bay roundhaul fishery 
was good, with the 1985 yr class composing 37% of the catch. 
The mean length of herring in the San Francisco Bay roundhaul catch 
decreased to 174 mm BL, and the mean length of the gill net catch decreased 
to 194 mm BL. The mean length of the Tomales Bay catch also decreased to 
197 mm BL. 
Average weight at age of Tomales Bay herring is below average for the fourth 
consecutive year. In San Francisco Bay the average weight at age is above 
average, even though length at age declined slightly. 
Marine Resources Administrative Report No. 87-13 
21 Marine Resources Division, Marine Resources Laboratory, 2201 Garden Road, 
Monterey, California 93940. 
ACKNOWLEDGMENTS 
I wish to thank Margaret Graham, Nicolas Paszty, John Sager, and Kate 
Symonds for collecting and processing herring during the season. 
INTRODUCTION 
The Department began monitoring the age, size, and sex composition of 
the Pacific herring, Clupea harengus pallasi, roe fishery catch in Tomales 
. 
and San Francisco Bays in 1973. Spratt (1981, 1982, 1983, 1984, 1985 and 
1986a) reported on data collected by sampling the herring roe fishery from 
1973 until 1986. This report complements previous data to provide a 
continuous seasonal series from 1973 through the 1986-87 season. 
METHODS 
Sampling 
In the Tomales Bay area, herring were collected at Marshall. In San 
Francisco Bay, herring were collected at Sausalito and San Francisco. Up to 
four samples were taken per day in each bay, when herring were available. A 
sample consisted of 2.3 kg (5 lb) collected after vessels unloaded. 
All samples were processed in a fresh condition and laboratory 
procedures have remained unchanged since the fishery began in 1973 (Spratt 
1981). A 1-kg (2.2-lb) sub-sample was randomly selected for processing. 
Every fish in the sub-sample was weighed to the nearest 0.1 g, measured in 
millimeters body length (nun BL), and sex and maturity were determined. Body 
length was used as the unit of measurement because the fleshy caudal 
peduncle of herring makes the hypural plate difficult to locate. Body 
length was measured from the tip of the snout to the end of the silvery part 
of the body. Otoliths were removed for age determination and stored in 
gelatin capsules. Ages were assigned by the author using previously 
determined criteria (Spratt 1981), and otolith8 were read at least twice 
before final age determinations were made. 
- 2 -  
RESULTS 
Tomales Bay 
A total of 43 samples was collected this season and 381 individual fish 
. 
were processed. 
Age Composition 
The Tomales Bay fishery was restricted to gill nets in 1977. From the 
1977-78 season through the 1984-85 season, the catch was dominated by 5-, 
6-, and 7-yr-old herring. 
In the 1985-86 season, the age composition changed to predominantly 4-, 
5-, and 6-yr-old herring (Spratt 1986a). This pattern continued this 
season, with 4-, 5-, and 6-yr-old herring composing 85% of the catch (Figure 
1). The percent of 3-yr olds declined from 14% in the 1985-86 season to 4% 
this season. This is not consistent with the overall shift in the age 
composition of the catch to younger herring, and may be the first indication 
of a weak 1984 yr class. 
The number of older herring (age 7 through 9) in the catch has been 
decreasing. From 1979-80 to 1984-85, age 7 through 9 herring averaged 30% 
by number of the Tomales Bay gill net catch, but in 1985-86 and 1986-87, 
these three age groups averaged only 8% of the catch by number. 
Length Composition 
The average length of herring in the Tomales Bay catch during the 
1986-87 season declined slightly to 197 mm BL (Table I), the smallest 
average length since 1977. The combined average length of 5-, 6-, and 
7-yr-old herring (Table 2) actually decreased 4 mm BL from the 1985-86 
season (Spratt 1986a). However, the reduced number of smaller 3- and 
4-yr-old herring in the 86-87 catch compared with the 1985-86 season 
resulted in only a 1 mm BL decline in the overall mean length. 
- 
- The timing of the fishery in relation to spawning may have influenced 
the age composition this season. No herring were caught from the largest 
spawning run of the season near the end of February (Spratt 1987). Late 
season spawning runs are composed of a higher percentage of younger herring. 
Weight Com~osit ion 
The mean weight at age of Tomales Bay herring declined in the 1985-86 
season, after the dramatic increase following El Nino (Spratt 1985); This 
season the mean weight at age decreased again, and 3 out of the lest 4 yr 
the average weight of the dominant age classes has been below the long-term 
mean (Table 3). 
Sex Ratio 
The female to male number and biomass (weight) ratios of the 1986-87 
Tomales Bay catch were nearly equal (Table 4). The percent of females in 
the catch was 46% by number and 47% by weight. This is the first time that 
more males than females have been taken in the Tomales Bay gill net fishery. 
San Francisco Bay 
A total of 67 samples was collected this season and 710 individual 
herring were processed. In San Francisco Bay both the roundhaul and gill 
net catches are sampled, but sample data are analyzed separately. 
Age Composition 
The percent of 2-yr-old herring in the roundhaul catch is normally a 
good indicator of year class strength. This season recruitment of the 1985 
yr class (2-yr olds) was above average, with 2-yr-old herring comprising 37% 
by number of the catch. The relative strength of 3-yr olds (33%) in the 
catch indicates that the 1984 yr class could be stronger than the 1985-86 
sample data indicated. The 1985 yr class is the fourth consecutive strong 
year class to be recruited into the San Francisco Bay fishery. 
- 4 -  
The roundhaul fishery in San Francisco Bay was again confined to the 
latter half of the spawning season, when older herring are less available to 
the fishery. The first substantial roundhaul catches were made on January 
19, after about 50% of the season's herring had already spawned. As a 
result there was only one 8-yr-old and no 9-yr-old herring in the samples, 
and the relative age composition of the roundhaul catch continues to be 
heavily weighted toward herring that are under 6 yrs old (Figure 1); 
On February 10, 1987, a 1-yr-old herring (110 mm BL) was collected 
while sampling the roundhaul catch in San Francisco Bay. This is the first 
1-yr-old herring that I have sampled from the roundhaul catch, although 
lyr-old herring have been taken in the bay (Reilly and Moore 1985). 
The 1984-85 season is the first full season in which 2 118-in. minimum 
mesh was allowed in the San Francisco Bay gill net fishery. Since then, the 
age composition of the gill net catch has shifted to include more 4-yr-old 
herring and now the dominant age groups are 4-, 5-, and 6-yr olds. In the 
1986-87 season 4- and 5-yr olds alone accounted for 70% of the catch by 
number and 69% by weight (Figure 1). The 1981 yr class (6-yr olds) is one 
of the weaker year classes in the fishery, but together 4-, 5-, and 6-yr-old 
herring comprise 86% and 87% of the gill net catch by number and weight, 
respectively. 
Length Composition 
The mean length of the San Francisco Bay roundhaul catch has ranged 
between 176 and 183 mm BL in 12 out of 14 seasons. The exceptions are the 
El Nino year of 1983-84 and the current season, when catch averaged 174 mm 
BL (Table 1). The mean length of 2-, 3-, and 4-yr-old herring decreased 
from 1 to 6 nun BL from the 1985-86 eeason (~pratt 1986a) (Table 5). These 
- 3 - 
- at-e strong year classes and density-dependent factors may be affecting 
growth. In addition 6- through 9-yr-old herring comprised only 6% of the 
catch. Both of these factors contribute to the drop in overall average 
length of the catch. 
The mean length of the gill net catch in San Francisco Bay is below 200 
mm BL for the third time in three seasons (Table 1). The overall average 
length of the gill net catch has changed since the minimum mesh size was 
lowered from 2 1/4- to 2/18-in. mesh during 1984. This caused an increase 
in the number of 3- and 4-yr-old herring in the catch, However, this season 
the mean length of 4- and 5-yr-old herring decreased 6 and 3 mm BL, 
respectively. The low numbers of the weak 1981 yr class (6-yr-old) herring 
in the catch is also contributing to the lower mean length of the gill net 
catch. 
Weight Composition 
The overall weight composition of the San Francisco Bay roundhaul and 
gill net catches (Figure 1) parallels that of the age composition. The 
roundhaul catch was dominated by 2- and 3-yr-old herring, while the gi'll net 
catch was composed mainly of 4- and 5-yr-old herring. 
Samples from the roundhaul catch in the 1986-87 season indicate that 
the overall gain in weight of ages 2 through 6 was above average for the 
second consecutive year. However, only the older age groups were 
significantly above average (Table 7). Growth rates are density dependent; 
even so, the collective weight at age of the four strong entering year 
classes remains above average. 
Sex Ratio 
The sex and biomass (weight) ratios of the San Francisco Bay gill net 
and roundhaul fisheries were again similar this season. Females composed 
60% of the gill net catch and 56% of the roundhaul catch by number 
(Table 4). This season the percentage of females in the gill net catch 
. -- 
increased to a near normal level, somewhat surprising considering the 
smaller mesh size now in use in the fishery. The high percentage of females 
in the roundhaul catch probably reflects the selectivity caused when boats 
release catches with low roe content or high percent of unripe fish. 
DISCUSSION 
Tomales Bay 
Since 1977, the three dominant age groups in the Tomales Bay gill net 
catch have been 5-, 6-, and 7-yr-old herring comprising between 72% and 82% 
of the catch. In the 1985-86 season, the percentage of 5-, 6-, and 7-yr-old 
herring in the catch dropped to 55%. This was due to initial recruitment of 
the 1982 and 1983 yr classes as 3- and 4-yr olds. This season these 2 yr 
classes, which are still not fully recruited, comprised 58% of the catch as 
4- and 5-yr olds. 
A spawner-recruit relationship has never been demonstrated for Pacific 
herring. However, the strength of the entering year classes in the Tomales 
Bay herring fishery may be below normal in the near future, because of very 
low spawning escapement in the 1983-84 season and unusual spawning behavior 
in the 1985-86 season that could effect survival (Spratt 1986b). The 
initial recruitment (3%) of the 1984 yr class in the 1986-87 catch as 
3-yr olds is poor compared to the 1983 yr class, which composed 13% of the 
1985-86 catch as 3-yr olds. The 1986 yr class will not be fully recruited 
until the 1990-91 season as 5-yr olds. 
Growth characteristics of Tomales Bay herring have also been below 
normal since 1983 (Table 3). The Tomales Bay herring population remains 
within the range of previous seasons' estimates (Spratt 1987), but 
- 
- 7 -  
recruitment patterns and growth characteristics indicate the status of the 
pofiul at ion is changing. 
San Francisco Bay 
The age and size composition of the San Francisco Bay roundhaul catch 
changed little over the first 11 herring seasons. Only 2 yr classes have 
been weak (1977.and 1981), and the catch was dominated by 2- and 3-yr-old 
herring with a good representation of older herring in the catch. 
The last three seasons there have been fewer herring over 5 yr old in 
the catch than at any other time. I believe this is a result of the 1982-83 
El Nino which caused a significant reduction in the size of the herring 
population in San Francisco Bay. During the El Nino, herring that are now 
6 through 9 yr old were 2 through 5 yr old. These 4 yr classes (1978, 1979, 
1980, and 1981) experienced unusually high natural mortality when the San 
Francisco Bay herring population declined from nearly 100,000 tons in 1982 
to 40,000 tons in 1984. 
Since the El Nino, the San Francisco Bay population has been increasing 
due to four consecutive relatively strong year classes (1982, 1983, 1984, 
and 1985) and the population is now composed of relatively few older 
herring. In addition, gillnetters are now using smaller mesh nets in order 
to keep catch production up, which has caused a shift to younger herring in 
the gill net catch. Three-, 4- and 5-yr-old herring composed 77% of the 
1986-87 gill net catch. 
The age and length composition of the San Francisco Bay herring catch 
(roundhaul and gill net) should improve next season as these 4 year classes 
move through the fishery. 
- 8 -  
CONCLUSION 
Three good year classes are maintaining the Tomales Bay herring 
fishery. However, there is reason to believe that the 1984 and 1986 yr 
classes could be weak. Therefore, with the prospect of poor recruitment 
coupled with below normal growth characteristics the past 3 yr, it is 
probable that t6e Tomales Bay population will remain below the long-term 
average level of 6,700 tons in the near future. 
In San Francisco Bay four consecutive years of good recruitment coupled 
with recent good growth characteristics indicate the population is in 
excellent condition and may continue to increase in the near future. 
Herring populations of Tomales and San Francisco Bays are exhibiting 
sustained opposite trends in abundance for the first time, with different 
growth and recruitment patterns. This is further evidence that the two bays 
may be genetically distinct. 
- 9 
REFERENCES 
Reilly, P.N. and T.O. Moore. 1985. Pacific herring, Clupea harengus 
pallasi, studies in San Francisco Bay and the Gulf of the Farallones, 
June 1984 to March 1985. Calif. Dept. Fish and Game, Mar. Res. Admin. 
Rept. 85-4:l-73. 
Spratt, J.D. 1981. Status of the Pacific herring Clupea harengus pallasi, 
in California to 1980. Calif. Fish and Game, Fish Bull. 171:l-104. 
. 1982. Biological characteristics of the catch from the 1980-81 and 
1981-82 Pacific herring, Clupea harengus pallasi, roe fishery in 
California. Calif. Fish and Game, Mar. Res. Admin. Rept. 82-10:l-16. 
. 1983. Biological characteristics of the catch from the 1980-81 and 
1981-82 Pacific herring, Clupea harengus pallasi, roe fishery in 
California. Calif. Fish and Game, Mar. Res. Admin. Rept. 83-4:l-11. 
. 1984. Biolonical characteristics of the catch from the 1983-84 
Pacific herring, Clupea harengus pallasi , roe fishery in California. 
Calif. Fish and Game, Mar. Res. Admin. Rept. 84-4:l-18. 
. 1985. Biolonical characteristics of the catch from the 1984-85 
- 
Pacific herring, Clupea harengus pallasi, roe fishery in ~alifornia. 
Calif. Fish and Game. Mar. Res. Admin. Rept. 86-5:l-15. 
. 1986a. Biological characteristics of the catch from the 1985-86 
Pacific herring, Clupea harengus pallasi, roe fishery in California. 
Calif. Fish and Game, Mar. Res. Admin. Rept. 86-5:l-15. 
. 1986b. Biomass estimates of Pacific herring, Clupea harengus 
pallasi, in California from the 1985-86 spawning-ground surveys. 
Calif. Dept. Fish and Game, Mar. Res. Admin. Rept. 86-3:l-28. 
. 1987. Biomass estimates of Pacific herring, Clupea harengus 
pallasi, in California from the 1986-87 spawning-ground surveys. 
Calif. Dept. Fish and Game, Mar. Res. Admin. Rept. 87-12. 
TABLE 1 .  Kean Length of Pacific Herrrng from Tomales a n d  San 
Franc1  sco B a v  R 0 2  Fi sherz ec , 1972-73 through l?St -97 
Seasons. 
hean Mean Mcar: 
lenoth S i z e  l e n g t h  Size l e n o t h  S i z e  
Seaso- mm EL range mm BL range mm PL rang= 
----------------------------------------------------------------- 
165' 140-216 
217 194-248 
No Samples 
214 196-236 
Note. T o m a l e s  Eav has been r e s t r i c t e d  t 3  0 x 1 1  nets m l y  since 
1377. The 1984-e5 seascn w a s  the f i rct  + u l l  seascrri i n  
v h i c h  2 l/e-ir,mesh was allowed i n  the San Frar ,c i scc :  Ea;. 
gillpet *ishery .  
TABLE 2. Lencth Frequency of the T o m ~ l e s  Bay Gillnet C a t c h  i n  tnf 
IBSt-87 Season. 
TGBLE 3. M ~ a n  Weiqht (9) a t  Age of Herring i n  the Tomales Bav 
GI ? l net Cstch by Season. 
9 Caiculatec  fro^ ages 4 through 8 onlv: t h e y  comprise  over 95% of the  
sam? es. 
TABLE 4. Female to M a l e  Sex and B i o m a r s  (Wezqht )  k a t l c s  
of  t h e  Catch for  the 1986-87 Season bv Area. 
T o m a l e s  Bav 
S e x  ratio 
Biomass ratio 
San Francisco Bav Gillnet 
Sex Ratio 1:0.6 
biomass ratio 1:C).6 
San F r a n c i s c o  Bay Houndhaul 
S e x  ratio 1 : 0.3 
Biomass rati o 1:0.7 
TGELE 5. Length Frequencv o i  t h e  Saq Frar!=iscc Bak Gi l lnet C a t r h  
in the 1986-87 Season. 
Age 
St. d e v .  - 3.4 4.0 4.1 4 .3  4 .9  4.3 - 
TkEtE &. Length Freauencv of the San Francisco Bav F.'~uncb,a.ul 
Catch ~n the 1986-87 Season. 
Mean 161 173 185 197 202 207 210 - 
St. dev. 8.0 4.4 0.7  4 . 8  4.4 6 . 3  - - 

TOMCKES W Y  G I L L  NET 
~ 
I e6iE COMPOSITION UEIOHT COtlPOSITION 
SAN FRFUJCISCO BAY G I L L  NET 
.-....-.- ..-.......-........... 
C 
Z 
W 
U 
w 
W 
P 
.. ..............-. ............ 
fW3E COMPOSITION LJEIGHT COMPOSITION 
S~IN FRMCISCO BAY ROUNDMUL 
.....-.. ...-.............. .......... 
C 
z 
W 
U ......... ....-................. ............................................................. 
f5 
0- 
............................................ -.. .....-.......-.. 
rnq 
7 8 0 
W E  COMPOSITION UEIGHT COMPOSITION 
FIGURE 1. We and w e i g h t  c o m w s i t i o n  of the 1986-87 Pacific 
herring roe fishery landings by' area. 


Biological characteristics of the catch from the 1986-87 Pacific herring, Clupea harengus pallasi, roe fishery in California

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Biological characteristics of the catch from the 1986-87 Pacific herring, Clupea harengus pallasi, roe fishery in California

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