Early Life History of Greenland (Reinhardtius hippoglossoides) in the Eastern Based on Recent Field Studies (2007-2009): #49 Spawning, Distribution, and Physical Processes Affecting Drift and Dispersal Deborah M. Blood, Janet T. Duffy-Anderson, Ann C. Matarese Dongwha Sohn Phyllis J. Stabeno Wei Cheng ([email protected]) ([email protected]) ([email protected]) ([email protected]) ([email protected]) ([email protected]) Resource Assessment and Engineering Conservation (RACE), Alaska Fisheries Science Center, NMFS, NOAA College of Oceanic and Atmospheric Sciences, Oregon State University Pacific Marine Environmental Laboratory (PMEL), Ocean and Atmospheric Research (OAR), NOAA Joint Institute for the Study of the Atmosphere and Ocean (JISAO) NOAA, University of Washington 7600 Sand Point Way NE, Seattle, WA 98115-6349, U.S.A. Corvallis, OR 97331-5503, U.S.A. 7600 Sand Point Way NE, Seattle, WA 98115-6349, U.S.A. 7600 Sand Point Way NE, Seattle, WA 98115-6349, U.S.A.

INTRODUCTION DISTRIBUTION OF EGGS AND LARVAE DRIFTERS

Greenland halibut (Reinhardtius hippoglossoides) is a circumpolar widely distributed in the Atlantic Eggs and Pacific Oceans. Spawning is reported during the colder winter months, and at depths generally greater than 2007 2008 2009 500 m. Their eggs and larvae are pelagic (Jensen 1935, Pertseva-Ostroumova 1961, Stene et al. 1999). Eggs from field studies in the are 3.9-4.7 mm in diameter; larvae hatch >6 mm SL and remain in the water column until reaching sizes near 60 mm SL. At one time, Greenland halibut (GH) supported a commercial fishery in the eastern Bering Sea (EBS) of up to 80,000 mt, but catches have declined significantly since the 1970s. Although many aspects of GH life history have been widely studied in the North Atlantic Ocean, little is known about their ecology and biology in the EBS, particularly for early life history (ELH) stages. Observed ELH patterns from previous studies suggest that Bering Sea GH are sensitive to fluctuations in flow and

hydrographic conditions that influence advection of eggs and larvae Adult Greenland halibut (Reinhardtius hippoglossoides) toward on-shelf settling grounds. We began collecting information on from Mecklenburg et al. 2002 Line drawing of GH egg spawning ecology, distribution of eggs and larvae, and egg density of GH in 2007. These data, along with (approx. 3.7 mm diameter, preserved) empirical data from subsurface moorings and satellite-tracked drifters, are being used in a 3-D hydrographic Depth of GH eggs 1MF08 (collected with MOCNESS) Trajectories of drifters released from Pribilof Canyon (2007, 2009) and Bering Canyon (2008). Trajectories are predominantly to the northwest. circulation model to evaluate dispersal and transport trajectory of the early life-history stages. Satellite-tracked drifters drouged at 40 m depth were released in Pribilof Canyon (2007, 2009) and Bering Canyon (2008) to track subsurface water movement. GH egg distribution 1MF08 Months of tracking revealed that several drifters were retained in the Bering Slope Current and transported northwards along the shelf edge. Selected drifters showed STUDY AREA evidence of entrainment in mesoscale eddies at the shelf break, and others were advected over the outer shelf. Results suggest that GH larvae in submarine canyons During 16-22 February 2008, 111 eggs (approximately 3.8-4.3 mm in diameter before preservation) were collected with bongo tows. GH eggs were found are dispersed northwards along the shelf break, or up onto the outer continental shelf. 175°W 170°W 165°W 160°W Historical information on GH adult and consistently in small numbers throughout Bering Canyon where gear depth was >250 m and bottom depths were 400-1000 m. To ascertain the vertical distribution of Aleutian North Slope Current 58°N Undefined Current GH eggs, MOCNESS tows were conducted at eight stations; positive catches occurred at depths as shallow as 50-100 m to depths of 300-400 m, but most eggs were early-life stages in the EBS during the last 60°N Bering Slope Current collected at 200-300 m. GH eggs ranged from early to late stage, but the majority of eggs were in the late stage of development. Stages of the eggs indicated that The Northeastern Pacific Regional Ocean Model System is being 30 years indicate that GH eggs and larvae Zhemchug Cross Shelf Flow Canyon used to simulate transport and drift of GH larvae from presumed occur in winter near Bogoslof Island, while spawning had been occurring for several weeks. spawning grounds in Bering, Pribilof, and Zhemchug Canyons to progressively larger larvae and pelagic Bering Sea In 26 February-5 March 2009, only six GH eggs were collected in bongo tows in Bering Canyon. Positive catches occurred at five stations at gear depths ≥400 m and hypothesized nursery areas over the outer and middle shelves. juveniles are found over the southeast outer 56°N 58°N eggs were middle to late stage. Low numbers of eggs collected and later stages of egg development, together with adult maturity information, supported the hypothesis Pribilof Islands Larvae are simulated as semi-passive particles, and are released shelf near the Pribilof Islands. These that spawning had ended several weeks earlier. Based on 2008-2009 fieldwork, spawning occurs January-early February. 50 m along horizontal transects (red dots) spanning the width of each patterns suggest that GH eggs and larvae 100 m canyon. Larvae are released at multiple depths under each drift along the shelf edges in the North Pribilof Egg density experiments using field collected eggs were conducted onboard during the 2008-2009 February cruises. The density of GH eggs at 2-4°C was Canyon horizontal location, and are individually tracked at depth from 1 Aleutian Slope Current and Bering Slope 1.0235-1.0278. No relationships were evident between egg size and density or between egg stage and density. 56°N April-1 September over 10 years (1995-2004). Current until they reach the shelf. A 54°N Initialization points for 3-D model 200m potential mechanism for transport onto the U nima k Bering Canyon Pa shelf is through deep-sea canyons (Bering, s In February 2008, 34 larvae (8.8-16.0 mm SL, mean - 10.2 mm Bogoslof Island s Larvae Pribilof, and Zhemchug). SL) were collected in the bongo tows. Larvae were collected at Gulf of Alaska 54°N 52°N stations where the maximum tow depth was 275-600 m (bottom 170°W 165°W 160°W Bering Sea Study Area depth 300-1000 m). A small number of larvae (10) were collected in MOCNESS tows and all were caught between 200 and 450 m. Few larvae were collected during the late February 2009 cruise, all ADULT SPAWNING ECOLOGY of which were yolk-sac stage. GH yolk-sac larva A total of nine bottom trawls were conducted 26 February-2 (14.3 mm SL) During May 2007-2009, a total of 65 larvae were collected in the March 2009 along the continental slope in Bering Canyon, bongo tows from the slope of Bering Canyon (>500 m), the outer Pribilof Canyon, and one point between these two locations at shelf, and the Bering Sea Basin (>1000 m) regions. Larval size depths of 521-820 m. Most GH were collected at depths of ranged from 15.8 mm to 26.0 mm SL with a mean length of 21 mm 750-800 m. Of 88 GH collected, there were 53 males and 24 SL. The smallest larva (15.8 mm) still had some unabsorbed yolk. females. Females were all past spawning condition in the early Although few GH larvae were collected in MOCNESS tows stages of atresia; about 60% of the males were spent. 2007-2008, historical records show that almost all GH have been Post-spawning condition of adults indicated that spawning collected in April over Bering Canyon and the Bering Sea Basin activity had probably ended 2-4 weeks earlier. where bottom depths are >500 m; most have been collected where depths are >1000 m. Although larvae are found throughout the 3-D visualization of particle trajectories GH larval distribution 1MF08 water column from a depth range of 401-530 m to a range of 0-45

175°W 170°W 165°W 160°W m, most are found at depths ≤45 m. Smaller larvae are found most 180°180° 175°W175°W 170°W170°W 165°W frequently at greater depths than larger larvae. Three-dimensional approaches are being used to visualize model output. Daily horizontal and vertical positions of GH larvae are mapped over geographic space for each 57°N 58°N58°N submarine canyon to visualize dispersal trajectories. Variations in trajectory paths will be reconciled with environmental forcing factors in each year to determine which factors contribute significantly to variations in dispersal and connectivity. These efforts will help us better understand spatial and temporal variability in dispersal of Greenland halibut collected 2009 60°N

Pribilof Islands slope-spawned fish larvae. Bering Sea GH flexionfl i larva l 57°N (17.4 mm SL) 56°N

! ! ! Bering Sea ! ! ! ! ! ! ! 58°N ! ! ! ! ! ! ! ! ! ! Pribilof Islands 54°N ! ! ! ! ! ! ! Literature cited ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Jensen, A. 1935. ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! The Greenland halibut (Reinhardtius hippoglossoides), its development and migration. K. Dan. Vidensk. Selsk. Skr. 9:1-32. ! ! ! ! ! ! ! ! ! 54°N ! ! ! ! ! ! ! ! ! ! ! Mecklenburg, C.W., T.A. Mecklenburg, and L.K. Thorsteinson. 2002. ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Fishes of Alaska. Am. Fish. Soc., Bethesda, MD. 1037 p. ! ! 56°N ! ! ! ! ! ! ! ! ! ! ! ! ! ! Pertseva-Ostroumova, T.A. 1961. ! ! 54°N ! ! ! ! ! ! ! ! ! ! ! ! The reproduction and development of far-eastern . Tr. Inst. Okeanol. Akad. Nauk SSSR, 484 p. [In Russian; Eng. transl. avail. Fish. Res. Bd. Can., Pac. Biol. Stn., Nanaimo, B.C., Canada V9R Greenland Halibut Larvae !

! Gulf of Alaska 2 ! ! MEAN-CATCH/10m ! 5K6, Transl. Ser. 856, 1967.] ! ! 0 ! ! Stene, A., A.G. Gunderson, O.T. Albert, K. J. Nedreaas, and P. Solemdal. 1999. 51°N 52°N 0.01 - 6.02 ! ! 0300150 ! Early development of Northeast Arctic Greenland halibut (Reinhardtius hippoglossoides). J. Northw. Atl. Fish. Sci., Vol. 25: 171-177. km 6.03 - 8.49 54°N 8.50 - 13.41 Gulf of Alaska 170°W 165°W 160°W 0 150 300 13.42 - 50.68 Acknowledgments Trawl locations 2009 km Vertical distribution of GH larvae by larval length 175°W 170°W 165°W 160°W We thank the North Pacific Research Board for support of this project. Lorenzo Ciannelli (OSU) and Kevin Bailey (AFSC), principal investigators for this study, offered assistance and helpful discussions. Tiffany Vance and Zachary Winters-Staszak provided invaluable (mean ± standard deviation) collected in April 1992-1994 mapping assistance. We thank the officers and crew of the NOAA Ships Miller Freeman and Oscar Dyson as well as our scientific colleagues who helped us accomplish the fieldwork. Morgan Busby took the photographs, Rachael Cartwright illustrated the egg and yolk-sac Depth of capture of adult GH GH larval distribution May 2007-2009 with MOCNESS. larva, and Ashlee Maust illustrated the flexion larva.

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