298 
Fishery Bulletin 117(4) 
A 10 
100% 
51 
c 
o 
Tn 
o 
CL 
E 
o 
O 
80% 
60% 
40% 
20% 
0% 
B 
100 % -| 
80% - 
60% - 
40% 
20% 
56 
0% - 1 
Aug. Sept. Oct. 
Dec. 
10 
Jan. 
Feb. 
□ Immature ci Developing s Gravid □ Spent ■ Resting 
Figure 3 
Composition of the macroscopic stages of ovarian development, by 
month, in petrale sole (Eopsetta jordani) collected off (A) California 
and (B) the Pacific Northwest (Oregon and Washington) in 2014- 
2017. The numerals above bars indicate number of samples. 
fish in the data from the Pacific Northwest region rela¬ 
tive to those from California. When all data are pooled, 
a 56-cm-TL fish produces 1.60 times as many eggs per 
gram as a 40-cm-TL fish. 
Discussion 
Accurate reproductive data are necessary for stock assess¬ 
ments. Even when the biology of a species is well under¬ 
stood, parameters such as fecundity exhibit spatiotemporal 
variation as a response to environmental conditions and 
body condition (McElroy et al., 2013; Beyer et al., 2015), 
and population shifts in egg production may occur over 
time as the demographics of a stock change (for example, 
when the number of small females increases) (Rideout and 
Morgan, 2007). Therefore, it is important to periodically 
revisit and review these types of data. 
Maximum estimates of PAF (>3 million eggs) for petrale 
sole along the West Coast of the United States were found 
to be more than double previous estimates (1.45 million 
eggs; Porter, 1964). Through histological examination of 
ovarian tissue and analysis of oocyte size-frequency dis¬ 
tributions, it was determined that petrale sole employed a 
determinate batch spawning strategy, as opposed 
to the determinate total spawning strategy sug¬ 
gested by Porter (1964). This updated under¬ 
standing of the petrale sole’s reproductive biology 
renders Porter’s fecundity estimates obsolete 
because those data likely include samples from 
females that had already initiated spawning 
for the season. Porter (1964) observed hydrated 
oocytes (“ripe eggs”) scattered throughout ovaries 
but assumed the fish spawned all eggs in a single 
event annually in part because of the homogene¬ 
ity in size of the remaining oocytes. The homoge¬ 
neity that Porter (1964) observed is explained by 
our observation of all oocytes contributing to PAF 
developing to the late stages of vitellogenesis 
prior to the first spawning event (evidenced his¬ 
tologically by all secondary growth oocytes being 
in late stages of vitellogenesis without evidence of 
spawning activity [no POFs present]), with indi¬ 
vidual batches advancing sequentially (evidenced 
histologically by the presence of POFs, hydrat¬ 
ing oocytes, and late-stage vitellogenic oocytes). 
Furthermore, Porter (1964) noted that, although 
most oocytes appeared to develop synchronously, 
there were some samples in which multiple sizes 
of oocytes were visible. He assumed that they 
would be resorbed and, therefore, did not include 
them in his fecundity estimates. However, on 
the basis of our observations, it is possible that 
oocyte recruitment was ongoing in those cases 
and, therefore, PAF would have been underes¬ 
timated from those individuals. Interestingly, 
Porter (1964) did also observe regional differ¬ 
ences in fecundity: fish from Eureka (Northern 
California) had a slightly greater number of eggs 
at length than those from Oregon, a finding consistent 
with what we observed in differences in relative PAF 
between small fish from Morro Bay (Central California) 
and those from Oregon and Washington. 
Histological analysis in which hematoxylin and Eosin 
Y staining was used also demonstrated the lack of a dis¬ 
tinct cortical alveolar stage oocyte in petrale sole. Primary 
growth (perinuclear stage) oocytes move into secondary 
growth with the appearance of cortical alveoli, a change 
that is triggered by the hormone gonadotropin (Wallace 
and Selman, 1981). In most fish, this oocyte stage is a 
distinct one that occurs prior to the appearance of vitello¬ 
genin; however, in petrale sole in our study, cortical alveoli 
appeared at the same time as the vitellogenin. Although 
rarely documented, the lack of a cortical alveolar stage has 
been observed in pollock (Pollachius virens ) (Skjaeraasen 
et al., 2016). This observation has little relevance in the 
context of our study; however, it is important to note that, 
although many aspects of oogenesis and reproductive biol¬ 
ogy can be generalized across teleosts, a great variety of 
reproductive patterns exist. 
Previous reproductive studies of petrale sole were 
focused on fish collected primarily off Oregon and to a 
lesser extent Washington (Harry, 1959; Porter, 1964; 
