108 
Abstract— Annual and batch fecundi- 
ties of yellowfin sole, Limanda aspera, 
in the eastern Bering Sea were deter- 
mined. Most individuals had a determi- 
nate, group-synchronous mode of oocyte 
development as evidenced by a dis- 
tinctly separate distribution of fully 
yolked oocytes in more advanced ova- 
ries. The spawning of batches by an indi- 
vidual female occurs in uninterrupted 
succession, as indicated by the presence 
of oocytes with migratory-stage nuclei 
in nearly all females undergoing oocyte 
hydration. Total fecundity ranged from 
295,615 to 3,635,108 oocytes per female 
and is described by 3.3225 x TL 3 - 6312 , 
where T = total fish length (cm). The 
length-fecundity relationship was found 
to be the same in both southeast and 
northwest areas of the eastern Bering 
Sea, despite known growth differences 
between the two areas. Individual 
females spawn from 8 to 11 batches. 
The first batch spawned is generally 
smaller in number than succeeding 
batches. After spawning begins, fish 
remain in the nearshore spawning area 
(<30 m bottom depth) until spent. The 
presence of residual chorion tissue from 
unspawned ova in the ovary lumen 
of some maturing females indicates 
that at least some females are capable 
of spawning more than one series of 
batches within one reproductive season. 
The annual fecundity, therefore, for 
such individuals is consequently con- 
sidered indeterminate 
Manuscript accepted 10 August 2000. 
Fish. Bull. 99:108-122 (2001). 
Annual and batch fecundities of yellowfin sole, 
Limanda aspera, in the eastern Bering Sea 
Daniel G. Nichol 
Erika I. Acuna 
Resource Assessment and Conservation Engineering Division 
Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
7600 Sand Point Way NE, BIN C15700 
Seattle, Washington 98115-0070 
E-mail address (for D. G. Nichol): dan nichol@noaa gov 
Yellowfin sole, Limanda aspera, 1 have 
historically been among the more abun- 
dant fishes in the eastern Bering Sea, 
where biomass estimates have exceeded 
2 million metric tons (t) annually since 
1980 2 * 4 (Wilderbuer et ah, 1992; Nichol, 
1998). Yellowfin sole has been an impor- 
tant commercial trawl species with 
annual catches averaging 135,630 t 
froml991 to 1998. 2 Yellowfin sole spawn 
from May through August in nearshore 
waters of Bristol Bay northward to at 
least Nunivak Island (Fadeev, 1970; 
Nichol, 1995) at depths less than 30 m 
(Nichol, 1995). Yellowfin sole, like many 
other flatfishes, are batch spawners 
(Nichol, 1995). They spawn pelagic eggs 
that have been observed in the plank- 
ton with diameters of approximately 
0.76-0.85 mm (Waldron, 1981; Mata- 
rese et ah, 1989). Adult yellowfin sole 
generally undergo long migrations from 
wintering grounds near the shelf-slope 
break to spring-summer grounds at 
bottom depths less than 50 m (Wak- 
abayashi, 1989; Nichol, 1998). 
Annual fecundity has been used as 
a measure of reproductive output for 
many species; its use as a parameter 
in fishery population models makes it 
relevant to stock assessment. Annual 
fecundity is defined as the total num- 
ber of eggs spawned by a female in a 
single year. Batch fecundity, defined as 
the number of eggs released at one time, 
can be estimated for any female from 
counts of hydrated oocytes as long as 
the female is not ovulating or spawn- 
ing. Directly estimating annual fecundi- 
ty from counts of advance-stage oocytes 
is feasible only if the number of eggs to 
be spawned is determinate or fixed prior 
to spawning (Hunter et al., 1985, Hunt- 
er et ah, 1992). Females with a determi- 
nate fecundity, just prior to spawning, 
will have a fixed number of advanced- 
yolked oocytes that are separated from 
the other less developed oocytes by a 
distinct gap in size; these can either 
be spawned in batches or all at once. 
In contrast, species whose ovaries are 
characterized by continuous oocyte size 
distributions may be able to develop 
unyolked oocytes continually and add 
them to the stock of advanced-yolked oo- 
cytes even after spawning begins. These 
species will typically develop multiple 
groups of oocytes with size distribu- 
tions that overlap. The method to esti- 
mate annual fecundity in such species 
with the least error uses batch fecun- 
dity, spawning frequency, and spawn- 
ing season duration (Yamamoto, 1956; 
Hunter and Macewicz, 1985a). Prior to 
estimating annual fecundity, we exam- 
ined oocyte size distributions to deter- 
mine which mode of oocyte development 
yellowfin sole undergoes. 
Assuming that yellowfin sole females 
have a determinate fecundity, two po- 
tential problems associated with esti- 
mating annual fecundity must be ad- 
dressed. First, because yellowfin sole 
spawn eggs in batches, annual fecundi- 
ty may be underestimated if partially 
spawned fish are included in estimates. 
1 Scientific name follows Cooper and Chap- 
leau ( 1998). 
2 Wilderbuer, T. K., and D. Nichol. 1998. 
Yellowfin sole. Section 3 in Stock assess- 
ment and fishery evaluation report for the 
groundfish resources of the Bering Sea/ 
Aleutian Islands regions. North Pacific 
Fishery Management Council, 605 West 
4 th Ave, Suite 306, Anchorage, AK 99501. 
