292 
Fishery Bulletin 117(4) 
sole is currently treated as a single stock in waters of 
Canada for management purposes (Starr and Fargo, 
2004), although it is believed that there are 2 distinct 
stocks in British Columbia (Ketchen and Forrester, 1966; 
Starr and Fargo, 2004). Stock depletion was evident as 
early as the 1950s and 1960s in waters of both the United 
States (Haltuch et al., 2013) and Canada (Ketchen and 
Forrester, 1966), following increasing landings and tar¬ 
geting of petrale sole on their winter spawning grounds. 
Recent stock assessments indicate that the population 
in the United States was below target levels (25% of 
the unfished spawning output) from 1962 through 2014 
and below the overfished level (12.5% of the estimated 
unfished spawning output) from 1979 through 2011 
(Haltuch et al., 2013; Stawitz et al., 2016), although the 
stock was not declared overfished until 2009. Following 
subsequent reductions in allowable catch, and due in 
part to strong recruitment events, the stock abundance 
increased sharply from 2009 through 2015, and the stock 
was declared rebuilt in 2014 (Stawitz et al., 2016). 
High priority research recommendations in recent 
petrale sole stock assessments engendered new studies 
on the reproductive biology of the stock and on spatial 
variability in growth and recruitment (Haltuch et al., 
2011, 2013; Stawitz et al., 2016). The only published 
estimates of fecundity for petrale sole come from col¬ 
lections in the 1950s off California (Porter, 1964), and 
the reproductive strategy of this species was established 
solely on the basis of visual (macroscopic) evaluation of 
the ovaries. Annual fecundity estimates in that study 
ranged from 150,000 to 1.49 million eggs, and females 
were presumed to exhibit a determinate total spawning 
strategy (Murua and Saborido-Rey, 2003), releasing all 
eggs in a single spawning event annually. Relationships 
between maternal size and relative fecundity (the num¬ 
ber of eggs per gram of maternal somatic weight) were 
not examined. Subsequently, stock assessments for this 
species have assumed that fecundity is proportional to 
maternal length. 
In response to research recommendations in recent 
stock assessments and in cooperation with The Nature 
Conservancy and commercial fishermen, mature female 
petrale sole were collected from spawning grounds off 
Central California (Morro Bay) in the 2014-2015, 2015- 
2016, and 2016-2017 reproductive seasons (August- 
February) to estimate annual fecundity. Collections were 
expanded in the 2015-2016 and 2016-2017 reproductive 
seasons to include samples caught off Oregon and Wash¬ 
ington with cooperation from the West Coast Groundfish 
Bottom Trawl Survey of the Northwest Fisheries Sci¬ 
ence Center (NWFSC), National Marine Fisheries Ser¬ 
vice (NMFS) (Keller et al., 2012), and from Washington 
Department of Fish and Wildlife (WDFW) commercial 
port samplers. Histological analysis of ovarian tissue was 
used to determine the reproductive strategy of petrale sole 
and to identify suitable samples for inclusion in fecundity 
analyses. The relationships between fecundity and mater¬ 
nal size were established or updated, and regional differ¬ 
ences between fish collected off California and those from 
waters of the Pacific Northwest (Oregon and Washington) 
were examined. The majority of samples collected for this 
study came from commercial fishermen who targeted fish 
on their spawning grounds. Because maturity estimates 
from fish collected on spawning grounds can be biased 
(Murua and Saborido-Rey, 2003), we did not attempt to 
update maturity ogives in this study. 
Materials and methods 
Sample collection 
A total of 401 female petrale sole were collected from 
commercial and survey bottom-trawl operations off Cal¬ 
ifornia (number of samples [/z] =291), Oregon (n=l), and 
Washington (n=109) between August and February of 
the 2014-2015, 2015-2016, and 2016-2017 reproduc¬ 
tive seasons (Table 1, Fig. 1). The majority (n- 250) were 
collected off Morro Bay by commercial fishermen in all 
3 sampling years. Sixty females were collected by WDFW 
port samplers in Puget Sound, Washington, from com¬ 
mercial and tribal bottom trawlers, 40 in August 2015, 
10 in December 2016, and 10 in January 2017. The 
remaining fish (/z=91) were collected by the NWFSC West 
Coast Groundfish Bottom Trawl Survey off the coasts of 
Washington and Oregon and off part of California (from 
Bodega Bay south to Point Conception) from August 
through October in the 2015-2016 and 2016-2017 repro¬ 
ductive seasons. 
Fish collected by commercial fishermen in Morro Bay 
were stored on ice and landed 1-5 days after capture. On 
average, 40 fish per landing were selected to represent the 
entirety of the size range of the catch. Fish were trans¬ 
ported to the Fisheries Ecology Division of the Southwest 
Fisheries Science Center (SWFSC) and processed within 
24 h of landing. Total weight (TW, in grams) and TL (in 
millimeters) were recorded, and sagittal otoliths were 
removed for age analysis. Ovaries were excised, weighed 
(in grams), and assigned a macroscopic development stage 
(Table 2). Initially, the blind- and eyed-side ovarian lobes 
were weighed and recorded separately. A paired t-test con¬ 
ducted on 136 stage-2 and -3 ovaries demonstrated that 
weights did not significantly vary between blind- and 
eyed-side ovarian lobes (P=0.35, df=145). 
Fish collected by WDFW were processed at an unknown 
time after capture, and those collected by the NWFSC 
were processed immediately after capture. For both col¬ 
lections, sagittal otoliths were removed; TL (in centime¬ 
ters) and TW (in grams) were recorded; and one or both 
ovarian lobes (depending on their size and ability to fit 
in storage containers) were excised, placed individu¬ 
ally into muslin bags, and fixed in 10% neutral buffered 
formalin. Ovaries were processed at the SWFSC within 
1-6 months from the date of collection. Ovaries were 
removed from the formalin, assigned a macroscopic stage, 
blotted dry, and weighed (in grams). When only one ovar¬ 
ian lobe was present, the weight was doubled to estimate 
total gonad weight; a macroscopic stage-based correction 
