Reproductive Ecology and Size- Dependent Fecundity in the Petrale

291 National Marine Fisheries Service Fishery Bulletin First U.S. Commissioner established in 1881 of Fisheries and founder NOAA of Fishery Bulletin Abstract—The petrale sole (Eopsetta Reproductive ecology and size- dependent jordani) is a commercially and ecologi- cally important flatfish found through- fecundity in the petrale sole (Eopsetta jordani) out the continental shelf from California through British Columbia, Canada. in waters of California, Oregon, and Washington Although stock assessments are rou- tinely conducted along the West Coast Lyndsey S. Lefebvre (contact author)1,2 of the United States for this population, Cherisa L. Friedlander2 these assessments have depended on 2 limited data for estimating reproductive John C. Field output. In this analysis, the reproductive strategy for this species was revisited, Email address for contact author: [email protected] fecundity estimates were updated, and size- dependent fecundity relationships 1 Institute of Marine Sciences were established from fish collected off University of California Santa Cruz California and the Pacific Northwest. 1156 High Street Results of histological analysis indicate Santa Cruz, California 95064 that petrale sole exhibit a determinate Present address for contact author: Integrated Statistics Inc. batch spawning strategy, with potential Population and Ecosystems Monitoring and Analysis Division annual fecundity (PAF) set prior to the Northeast Fisheries Science Center release of eggs over the course of sev- National Marine Fisheries Service, NOAA eral spawning events. Both PAF and 166 Water Street relative PAF (weight- specific fecundity) Woods Hole, Massachusetts 02543 increased significantly with maternal 2 length and weight. Regional differences Fisheries Ecology Division in the strength of the relationship Southwest Fisheries Science Center between relative PAF and size indicate National Marine Fisheries Service, NOAA that the maternal effect is stronger in 110 McAllister Way the Pacific Northwest; however, more Santa Cruz, California 95060 data are necessary to confirm regional patterns. Because reproductive output was not proportionate with female size, fisheries managers should consider using relative PAF in determining the The petrale sole (Eopsetta jordani) through October, and deeper spawning reproductive potential of this stock. is a commercially important flatfish grounds (with depths of 290–440 m), in the family Pleuronectidae (right- where they form discrete aggregations eyed flounders). Although their range along the outer shelf during late fall and extends from Baja California, Mexico, to winter (November–February) (Ketchen the western Gulf of Alaska, their great- and Forrester, 1966; CDFW, 2013; est abundance and commercial signifi- Stawitz et al., 2016). Tagging data indi- cance is generally from Santa Barbara, cate that individuals are capable of dis- California, through British Columbia, persing several hundred miles, although Canada (Alverson and Chatwin, 1957; most individuals have high fidelity to CDFW, 2013). Female petrale sole grow winter spawning habitats (Ketchen and considerably larger than males and can Forrester, 1966; Pedersen, 1975). reach a maximum total length (TL) of The petrale sole fishery off the U.S. 70 cm (although fish larger than 60 cm Pacific coast has a long history, having are rarely encountered) and live up to started in the late 1800s off California Manuscript submitted 15 November 2018. 31 years (Haltuch et al., 2013; Stawitz and Oregon (CDFW, 2013). The first Manuscript accepted 10 September 2019. et al., 2016). Hannah et al. (2002) esti- stock assessments in U.S. waters eval- Fish. Bull. 117:291–302 (2019). Online publication date: 30 September 2019. mated the length at 50% maturity at uated only populations north of Cape doi: 10.7755/FB.117.4.2 33 cm (corresponding to an age of 5 Blanco, Oregon, because of data con- years) for fish collected off Oregon. straints (Turnock et al., 1993; Samp- The views and opinions expressed or Petrale sole migrate seasonally between son and Lee, 1999), but recent stock implied in this article are those of the shallow feeding grounds (with depths assessments have assumed a single author (or authors) and do not necessarily reflect the position of the National of 70–200 m), where they disperse coast- wide stock (Haltuch and Hicks, Marine Fisheries Service, NOAA. across the continental shelf from March 2009; Haltuch et al., 2013). The petrale 292 Fishery Bulletin 117(4) sole is currently treated as a single stock in waters of waters of the Pacific Northwest (Oregon and Washington) Canada for management purposes (Starr and Fargo, were examined. The majority of samples collected for this 2004), although it is believed that there are 2 distinct study came from commercial fishermen who targeted fish stocks in British Columbia (Ketchen and Forrester, 1966; on their spawning grounds. Because maturity estimates Starr and Fargo, 2004). Stock depletion was evident as from fish collected on spawning grounds can be biased early as the 1950s and 1960s in waters of both the United (Murua and Saborido-Rey, 2003), we did not attempt to States (Haltuch et al., 2013) and Canada (Ketchen and update maturity ogives in this study. Forrester, 1966), following increasing landings and tar- geting of petrale sole on their winter spawning grounds. Recent stock assessments indicate that the population Materials and methods in the United States was below target levels (25% of the unfished spawning output) from 1962 through 2014 Sample collection and below the overfished level (12.5% of the estimated unfished spawning output) from 1979 through 2011 A total of 401 female petrale sole were collected from (Haltuch et al., 2013; Stawitz et al., 2016), although the commercial and survey bottom-tra wl operations off Cal- stock was not declared overfished until 2009. Following ifornia (number of samples [n]=291), Oregon (n=1), and subsequent reductions in allowable catch, and due in Washington (n=109) between August and February of part to strong recruitment events, the stock abundance the 2014–2015, 2015–2016, and 2016–2017 reproduc- increased sharply from 2009 through 2015, and the stock tive seasons (Table 1, Fig. 1). The majority (n=250) were was declared rebuilt in 2014 (Stawitz et al., 2016). collected off Morro Bay by commercial fishermen in all High priority research recommendations in recent 3 sampling years. Sixty females were collected by WDFW petrale sole stock assessments engendered new studies port samplers in Puget Sound, Washington, from com- on the reproductive biology of the stock and on spatial mercial and tribal bottom trawlers, 40 in August 2015, variability in growth and recruitment (Haltuch et al., 10 in December 2016, and 10 in January 2017. The 2011, 2013; Stawitz et al., 2016). The only published remaining fish (n=91) were collected by the NWFSC West estimates of fecundity for petrale sole come from col- Coast Groundfish Bottom Trawl Survey off the coasts of lections in the 1950s off California (Porter, 1964), and Washington and Oregon and off part of California (from the reproductive strategy of this species was established Bodega Bay south to Point Conception) from August solely on the basis of visual (macroscopic) evaluation of through October in the 2015–2016 and 2016–2017 repro- the ovaries. Annual fecundity estimates in that study ductive seasons. ranged from 150,000 to 1.49 million eggs, and females Fish collected by commercial fishermen in Morro Bay were presumed to exhibit a determinate total spawning were stored on ice and landed 1–5 days after capture. On strategy (Murua and Saborido-Rey, 2003), releasing all average, 40 fish per landing were selected to represent the eggs in a single spawning event annually. Relationships entirety of the size range of the catch. Fish were trans- between maternal size and relative fecundity (the num- ported to the Fisheries Ecology Division of the Southwest ber of eggs per gram of maternal somatic weight) were Fisheries Science Center (SWFSC) and processed within not examined. Subsequently, stock assessments for this 24 h of landing. Total weight (TW, in grams) and TL (in species have assumed that fecundity is proportional to millimeters) were recorded, and sagittal otoliths were maternal length. removed for age analysis. Ovaries were excised, weighed In response to research recommendations in recent (in grams), and assigned a macroscopic development stage stock assessments and in cooperation with The Nature (Table 2). Initially, the blind- and eyed-side ovarian lobes Conservancy and commercial fishermen, mature female were weighed and recorded separately. A paired t- test con- petrale sole were collected from spawning grounds off ducted on 136 stage-2 and -3 ovaries demonstrated that Central California (Morro Bay) in the 2014–2015, 2015– weights did not significantly vary between blind- and 2016, and 2016–2017 reproductive seasons (August– eyed- side ovarian lobes (P=0.35, df=145). February) to estimate annual fecundity. Collections were Fish collected by WDFW were processed at an unknown expanded in the 2015–2016 and 2016–2017 reproductive time after capture, and those collected by the NWFSC seasons to include samples caught off Oregon and Wash- were processed immediately after capture. For both col- ington with cooperation from the West Coast Groundfish lections, sagittal otoliths were removed; TL (in centime- Bottom Trawl Survey of the Northwest Fisheries Sci- ters) and TW (in grams) were recorded; and one

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