Multiple life‐stage connectivity of Pacific halibut ( Hippoglossus stenolepis ) across the Bering Sea and Gulf of Alaska

2020 ◽  
Author(s):  
Lauri L. Sadorus ◽  
Esther D. Goldstein ◽  
Raymond A. Webster ◽  
William T. Stockhausen ◽  
Josep V. Planas ◽  
...  
1984 ◽  
Vol 41 (7) ◽  
pp. 1083-1088 ◽  
Author(s):  
W. Stewart Grant ◽  
David J. Teel ◽  
Tokimasa Kobayashi ◽  
Cyreis Schmitt

The gene products of 35 protein-coding loci were examined for Mendelian variation in three samples of Pacific halibut (Hippoglossus stenolepis) and one sample of Atlantic halibut (H. hippoglossus). Contingency table analyses of allelic frequencies for five polymorphic loci revealed no significant frequency differences between the Bering Sea and the Gulf of Alaska but detected significant Ada-2 frequency differences between these regions and Japan. Average genetic distance between the samples of Pacific halibut was 0.0002 ± 0.0007, and gene diversity analyses showed that 98.7% of the total genetic variation was contained within populations, 0.4% was due to differences between the Bering Sea and the Gulf of Alaska, and 0.9% was due to differences between these regions and Japan. These results are consistent with a larval drift, juvenile migration model of population genetic structure where not all juveniles home to their natal areas. Nei's genetic distance between Pacific and Atlantic halibut was 0.162 ± 0.073, and the molecular clock hypothesis suggests that these species became reproductively isolated from one another in the Pliocene between 1.7 and 4.5 million years ago.


2013 ◽  
Vol 70 (4) ◽  
pp. 642-653 ◽  
Author(s):  
Raymond A. Webster ◽  
William G. Clark ◽  
Bruce M. Leaman ◽  
Joan E. Forsberg

Results of a coastwide tagging study show that ontogenetic migration of Pacific halibut (Hippoglossus stenolepis) continues for larger fish, whereas in recent years the assumption had been that only smaller, younger fish migrated. In 2003–2004, a total of 67 000 Pacific halibut tagged with passive integrated transponder tags were released by the International Pacific Halibut Commission (IPHC) from Oregon to the Bering Sea. Portside scanning recovered over 3000 of these tags. Models were fitted that allowed commercial fishing mortality to be a function of fish length, year, and IPHC regulatory area, while migration probability was a function of area and length. Estimates from the models support the view that exploitation rates were much higher in eastern than western areas prior to the reduction of quotas following new results from a coastwide stock assessment in 2007. We explore possible explanations for differences between tagging and IPHC stock assessment results and note that this research provides confirmation of historical inferences regarding patterns of halibut migration based on conventional tagging.


2020 ◽  
Vol 71 (10) ◽  
pp. 1355
Author(s):  
Craig Kastelle ◽  
Thomas Helser ◽  
Todd TenBrink ◽  
Charles Hutchinson ◽  
Betty Goetz ◽  
...  

In rockfish (Family Scorpaenidae), age determination is difficult and the annual nature of otolith growth zones must be validated independently. We applied routine age determination to four species of Gulf of Alaska rockfish: two shallower-water species, namely harlequin rockfish (Sebastes variegatus) and redstripe rockfish (Sebastes proriger), and two deep-water species, namely shortspine thornyhead (Sebastolobus alascanus) and shortraker rockfish (Sebastes borealis). The estimated ages (counts of presumed annual growth zones in the otoliths) were then evaluated with bomb-produced radiocarbon (14C) and Bayesian modelling with Markov chain Monte Carlo simulations. This study successfully demonstrated the level of accuracy in estimated ages of redstripe rockfish (a 35% probability of underageing, and ~5% probability of overageing) and harlequin rockfish (a 100% probability that they were underaged by ~3 or 4 years). Measured Δ14C in shortspine thornyhead and shortraker rockfish otoliths was lower and increased later than expected. Hence, incorrect age determination could not be evaluated. This is likely caused by dissimilar environmental and biological availability of 14C between these two species and the Pacific halibut (Hippoglossus stenolepis) reference chronology, or underageing of these two species.


1962 ◽  
Vol 19 (5) ◽  
pp. 815-838 ◽  
Author(s):  
Gordon C. Pike

Observations of gray whales from the coasts of British Columbia, Washington, and Alaska are compared with published accounts in order to re-assess knowledge of migration and feeding of the American herd. Source of material is mainly from lighthouses and lightships.The American herd of gray whales retains close contact with the shore during migration south of Alaska. Off Washington and British Columbia the northward migration begins in February, ends in May, and is at a peak during the first two weeks in April; the southward migration occurs in December and January, and is at a peak in late December. Northward migrants stop occasionally to rest or feed; southward migrants are travelling faster and appear not to stop to rest or feed during December and January. Gray whales seen off British Columbia, sometimes in inside protected waters, from June through October, probably remain in this area throughout the summer and fall months.Available evidence suggests that gray whales retain contact with the coast while circumscribing the Gulf of Alaska, enter the Bering Sea through eastern passages of the Aleutian chain, and approach St. Lawrence Island by way of the shallow eastern part of the Bering Sea. Arriving off the coast of St. Lawrence Island in May and June the herd splits with some parts dispersing along the Koryak coast and some parts continuing northward as the ice retreats through Bering Strait. Gray whales feed in the waters of the Chukchi Sea along the Siberian and Alaskan coasts in July, August and September. Advance of the ice through Bering Strait in October initiates the southern migration for most of the herd. In summering areas, in northern latitudes, gray whales feed in shallow waters on benthic and near-benthic organisms, mostly amphipods.There is no evidence to indicate that gray whales utilize ocean currents or follow the same routes as other baleen whales in their migrations. Visual contact with coastal landmarks appear to aid gray whales in successfully accomplishing the 5000-mile migration between summer feeding grounds in the Bering and Chukchi Seas and winter breeding grounds in Mexico.Reconstruction of the migration from all available data shows that most of the American herd breeds and calves in January and February, migrates northward in March, April and May, feeds from June through October, and migrates southward in November and December.


1982 ◽  
Vol 87 (C8) ◽  
pp. 5785 ◽  
Author(s):  
J. D. Schumacher ◽  
C. A. Pearson ◽  
J. E. Overland

2002 ◽  
Vol 59 (2) ◽  
pp. 291-302 ◽  
Author(s):  
Paul D Spencer ◽  
Thomas K Wilderbuer ◽  
Chang Ik Zhang

A variety of eastern Bering Sea (EBS) flatfish including yellowfin sole (Limanda aspera), rock sole (Lepidopsetta bilineata), flathead sole (Hippoglossoides elassodon), and Alaska plaice (Pleuronectes quadrituberculatus), co-occur in various degrees in EBS trawl fisheries, impeding attempts to obtain single-species management targets. A further complication is the bycatch of Pacific halibut (Hippoglossus stenolepis); halibut bycatch limits, rather than single-species catch quotas, have been the primary factor regulating EBS flatfish harvest in recent years. To examine bycatch interactions among the EBS flatfish listed above, an equilibrium mixed-species multifishery model was developed. Equilibrium yield curves, scaled by recent average recruitment, are flat topped or asymptotically increasing, reflecting low fishing selectivity during the first several years of life and low growth relative to natural mortality. A linear programming analysis indicated that relaxation of the halibut bycatch constraint at the optimal solution of catch by fishery would produce approximately 20 times more flatfish yield than a similar relaxation of any flatfish catch quota. A strategy for establishing halibut bycatch limits that considers the foregone revenue in the halibut and flatfish trawl fisheries reveals how the choice of halibut bycatch limit is affected by the management goal for the flatfish complex.


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