Dispersal and behavior of Pacific halibut Hippoglossus stenolepis in the Bering Sea and Aleutian Islands region

Abstract

Currently, it is assumed that eastern Pacific halibut Hippoglossus stenolepis belong to a single, fully mixed population extending from California through the Bering Sea, in which adult halibut disperse randomly throughout their range during their lifetime. However, we hypothesize that hali but dispersal is more complex than currently assumed and is not spatially random. To test this hypo thesis, we studied the seasonal dispersal and behavior of Pacific halibut in the Bering Sea and Aleutian Islands (BSAI). Pop-up Archival Transmitting tags attached to halibut (82 to 154 cm fork length) during the summer provided no evidence that individuals moved out of the Bering Sea and Aleutian Islands region into the Gulf of Alaska during the mid-winter spawning season, supporting the concept that this region contains a separate spawning group of adult halibut. There was evidence for geographically localized groups of halibut along the Aleutian Island chain, as all of the individuals tagged there displayed residency, with their movements possibly impeded by tidal currents in the passes between islands. Mid-winter aggregation areas of halibut are assumed to be spawning grounds, of which 2 were previously unidentified and extend the species' presumed spawning range ∼1000 km west and ∼600 km north of the nearest documented spawning area. If there are indeed independent spawning groups of Pacific halibut in the BSAI, their dynamics may vary sufficiently from those of the Gulf of Alaska, so that specifically accounting for their relative segregation and unique dynamics within the larger population model will be necessary for correctly predicting how these components may respond to fishing pressure and changing environmental conditions. Aquat Biol 12: [225][226][227][228][229][230][231][232][233][234][235][236][237][238][239] 2011 Aleutian Islands. It is assumed that adult halibut feed in shallow, nearshore areas during the summer, undertake a spawning migration to deeper water during winter, and return to their summer grounds during spring (Dunlop et al. 1964, Best 1981. In the Southeast Bering Sea (SEBS), spawning appears to be concentrated in relatively discrete winter spawning grounds near the edge of the continental shelf in the Bering Canyon and the Pribilof Canyon ( Fig. 1) (St-Pierre 1984). After spawning, egg and larval stages drift pelagically in the Bering Sea gyre for approximately 6 mo (Skud 1977, St. Pierre 1989 and then settle in nearshore areas (Thompson & Van Cleve 1936). After settling, it is thought that juvenile halibut conduct contranatant migrations to the area in which they were spawned to maintain population stationarity (Skud 1977, Hilborn et al. 1995.From the 1930s through the 1950s, at least 3 stocks of halibut were recognized, 1 in the Bering Sea and 2 in the Gulf of Alaska (GOA) (Fukuda 1962, Skud 1977. After this period, research indicated extensive intermingling of halibut among areas, and it was assumed that there was only a single stock of halibut. This research was based, in part, on...

Continental shelf residency by adult Atlantic halibut electronic tagged in the Gulf of Maine

“…This fine scale stock structure may explain the disparity in abundance between U.S. and Canadian Atlantic halibut, and shed light on why the U.S. Atlantic halibut fishery has not recovered since its collapse (Shakell et al 2016). Similar examples of relatively isolated spawning components of adult fish have been proposed for Atlantic halibut in a Norwegian fjord (Seitz et al 2014) and Pacific halibut in the Aleutian Islands (Seitz et al 2011). Although this study was small in both sample size and geographic scope, it adds to the body of knowledge about Atlantic halibut and provides direction for future research.…”

Pop-up satellite archival tag (PSAT) temporal data resolution affects interpretations of spawning behaviour of a commercially important teleost

“…Many spawning locations are known for Pacific halibut [32,33] and have been elucidated based on PSAT data for both Pacific halibut [5,34] and Northeast Atlantic halibut [10] populations. However, such critical population information is currently acknowledged as lacking in the two Northwest Atlantic halibut stocks that support combined landed values in excess of $38 million CDN annually [9,31].…”

“…The increasing application of pop-up satellite archival tags (PSATs) to questions in marine research has expanded from a focus largely on large pelagic species [1][2][3] to include large flatfishes, including Pacific halibut (Hippoglossus stenolepis) [4][5][6][7], Greenland halibut (Reinhardtius hippoglossoides) [8], and Atlantic halibut (Hippoglossus hippoglossus) [9,10]. A recognized advantage of PSATs is their ability to collect data on temperature, depth, and light levels and then transmit those data directly through the Argos satellite system [11] following their programmed release and emergence at the water's surface.…”

Variance in age-specific sex composition of Pacific halibut catches, and comparison of statistical and genetic methods for reconstructing sex ratios

“…Changes in localized sex ratio have been observed in North Sea dab Limanda limanda, presumably due to sex-specific seasonal migration patterns (Saborowski and Bucholz, 1997). During summer, Pacific halibut are known to aggregate according to sex and size on small spatial scales (i.e., within tens to hundreds of meters ;Loher and Hobden, 2012), and are also known to be seasonally-migratory (St. Pierre, 1984), often moving among IPHC regulatory areas in the process (Leaman et al, 2002;Loher and Seitz, 2006;Loher and Blood, 2009;Seitz et al, 2011). Since the inception of individual quota fisheries in 1994, the IPHC has been engaged in considerable debate regarding the possibility of extending the open commercial fishing period (St. Pierre et al, 1994;Gilroy et al, 2000;Leaman et al, 2000;Leaman et al, 2002) into what has subsequently been shown to constitute the species' seasonal migratory and spawning period .…”