Lefebvre et ah Reproductive ecology and size-dependent fecundity in Eopsetta jordani 
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Figure 4 
Photomicrographs from histological slides of ovarian tissue from petrale sole (Eopsetta jordani ) collected in 2014- 
2017 off California, Oregon, and Washington, showing all phases of development: (A) immature, characterized by 
thin ovarian wall (OW), no stroma, and primary growth oocytes (PGs); (B) developing, characterized by oocytes at the 
mid-vitellogenic stage without evidence of spawning; (C) spawning capable, characterized by late vitellogenic oocytes 
without evidence of spawning; (D) actively spawning, characterized by hydrated oocytes (HOs) and postovulatory 
follicles (POFs); (E) regressing, characterized by POFs and only PGs; and (F) regenerating, characterized by a thick 
OW, only PGs, and thick stroma (S). Vl=primary vitellogenic oocytes; V2=secondary vitellogenic oocyte; V3=tertiary 
vitellogenic oocyte; and HO(r)=residual HO. The bars indicate a scale of 250 pm. 
Hannah et al., 2002). The reproductive season of petrale 
sole observed off California in this study, with a peak in 
December, overlapped with that observed previously for 
petrale sole in Oregon by Harry (1959), with a peak in 
December-January, and for those in Oregon and Washing¬ 
ton by Porter (1964), with spawning occurring sometime 
between December and March; however, the season ended 
earlier in California, with most spawning activity conclud¬ 
ing by January. With our limited collections from the 
waters of the Pacific Northwest, the onset of spawning 
appears to occur later in more northerly waters, with data 
from other sources indicating a 1-month lag compared 
with the timing of spawning observed for petrale sole in 
California (Haltuch 2 ). Seasonal differences in the onset 
and intensity of upwelling are well known between Cali¬ 
fornia waters and those of the Pacific Northwest (e.g., Par¬ 
rish et al., 1981), and such differences have been linked to 
shifts in the timing and the duration of spawning for other 
species of flatfish, such as the English sole (Parophrys 
vetulus) (Kruse and Tyler, 1983). Latitudinal variation in 
biological traits, such as growth and maturity, are common 
in many other commercially important fish species 
2 Haltuch, M. 2018. Personal commun. Northwest Fish. Sci. Cent., 
Natl. Mar. Fish. Serv., NOAA, 2725 Montlake Blvd. East, Bldg. 
South, Seattle, WA 98112-2097. 
(Sampson and Al-Jufaily, 1999; McBride et al., 2013), and 
both temporal and spatial differences in growth for many 
species of groundfish on the West Coast of the United 
States, including the petrale sole, have been previously 
characterized (Stawitz et al., 2015; Gertseva et al., 2017). 
In addition to providing more accurate estimates of PAF, 
maternal size was shown to significantly affect estimates 
of relative PAF in petrale sole, such that larger females 
contributed disproportionately more in terms of egg pro¬ 
duction compared with smaller females, as is common 
across fish taxa (e.g., Hixon et al., 2014; Barneche et al., 
2018). Furthermore, regional variation in fecundity rela¬ 
tionships were observed in this study. In California, the 
slope of the maternal size-fecundity relationship was less 
steep (and not statistically different from zero), compared 
with fish from the Pacific Northwest (Table 4, Fig. 5). This 
finding may be a reflection of differences in spawning 
season, such that fish off California have a longer spawn¬ 
ing season and, therefore, can extend their reproductive 
efforts over a wider temporal range. However, the entirety 
of the spawning season was not studied sufficiently in the 
Pacific Northwest to verify that durations of the spawning 
seasons differ regionally. The observed differences in the 
slopes of the fecundity relationships appear to be driven 
by the data from small females, with larger females hav¬ 
ing similar fecundity estimates in both regions. Although 
