Pacific halibut on the move: a renewed understanding of adult migration from a coastwide tagging study

2013 ◽  
Vol 70 (4) ◽  
pp. 642-653 ◽  
Author(s):  
Raymond A. Webster ◽  
William G. Clark ◽  
Bruce M. Leaman ◽  
Joan E. Forsberg
Keyword(s):  
Bering Sea ◽  
Stock Assessment ◽  
Fish Length ◽  
Commercial Fishing ◽  
Ontogenetic Migration ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis ◽  
Migration Probability ◽  
The Bering Sea ◽  
Passive Integrated Transponder Tags

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.

scholarly journals Discard mortality rates in the Bering Sea snow crab, Chionoecetes opilio, fishery

2015 ◽  
Vol 72 (5) ◽  
pp. 1525-1529 ◽  
Author(s):  
J. Daniel Urban
Keyword(s):  
Mortality Rate ◽  
Bering Sea ◽  
Fishery Management ◽  
Stock Assessment ◽  
Mortality Rates ◽  
Snow Crab ◽  
Commercial Fishing ◽  
Chionoecetes Opilio ◽  
Discard Mortality ◽  
The Bering Sea

Abstract Fish and invertebrates that are unintentionally captured during commercial fishing operations and then released back into the ocean suffer mortality at unknown rates, introducing uncertainty into the fishery management process. Attempts have been made to quantify discard mortality rates using reflex action mortality predictors or RAMP which use the presence or absence of a suite of reflexes to predict discard mortality. This method was applied to snow crab, Chionoecetes opilio, during the 2010–2012 fisheries in the Bering Sea. Discard mortality in the fishery is currently assumed to be 50% in stock assessment models, but that rate is not based on empirical data and is widely recognized to be in need of refinement. Over 19 000 crab were evaluated using the RAMP method. The estimated discard mortality rate was 4.5% (s.d. = 0.812), significantly below the rate used in stock assessment models. Predicted discard mortality rates from the 2010 to 2012 study were strongly correlated with the air temperature at the St Paul Island airport in the Pribilof Islands. Using this relationship, the discard mortality rate from 1991 to 2011 was estimated at 4.8% (s.d. = 1.08).

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 ◽  
...  
Keyword(s):  
Bering Sea ◽  
Life Stage ◽  
Gulf Of Alaska ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis ◽  
The Bering Sea

Biochemical Population Genetics of Pacific Halibut (Hippoglossus stenolepis) and Comparison with Atlantic Halibut (H. hippoglossus)

1984 ◽  
Vol 41 (7) ◽  
pp. 1083-1088 ◽  
Author(s):  
W. Stewart Grant ◽  
David J. Teel ◽  
Tokimasa Kobayashi ◽  
Cyreis Schmitt
Keyword(s):  
Genetic Distance ◽  
Bering Sea ◽  
Gene Diversity ◽  
Gulf Of Alaska ◽  
Atlantic Halibut ◽  
Protein Coding ◽  
Pacific Halibut ◽  
Three Samples ◽  
Hippoglossus Stenolepis ◽  
The Bering Sea

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.

Interannual stability from ensemble modelling

2018 ◽  
Vol 75 (12) ◽  
pp. 2109-2113 ◽  
Author(s):  
Ian J. Stewart ◽  
Allan C. Hicks
Keyword(s):  
Stock Assessment ◽  
Base Case ◽  
Single Model ◽  
Sensitivity Testing ◽  
Ensemble Modelling ◽  
Temporal Correlations ◽  
Pacific Halibut ◽  
Simple Simulation ◽  
The Pacific ◽  
Hippoglossus Stenolepis

Ensemble modelling for fisheries analyses is increasing and may improve on single-model approaches through better representation of uncertainty, reduced potential for bias, and greater stability in results. Stability, defined here as deviations from model estimates as each year of data are added, may be due to the use of multiple models (rather than periodic changes to a single base-case model) and from the buffering effect of characterizing the central tendency with a set of models. However, stability against the addition of new data, although logically appealing, has not been explored for fisheries stock assessment. We use the Pacific halibut (Hippoglossus stenolepis) ensemble as an example and provide a simple simulation to explore the general behavior of results from an ensemble of models. Counterintuitively, we found the models in the halibut example showed high temporal correlations among deviations. However, we found that a small number of models with low among-model deviation correlations could show a stability benefit. Among-model deviation correlations may be a useful diagnostic for analysts developing ensembles or for those performing sensitivity testing of single-model assessments.

A mixed-species yield model for eastern Bering Sea shelf flatfish fisheries

2002 ◽  
Vol 59 (2) ◽  
pp. 291-302 ◽  
Author(s):  
Paul D Spencer ◽  
Thomas K Wilderbuer ◽  
Chang Ik Zhang
Keyword(s):  
Bering Sea ◽  
Optimal Solution ◽  
Single Species ◽  
Mixed Species ◽  
Yield Model ◽  
Pacific Halibut ◽  
Eastern Bering Sea ◽  
Hippoglossus Stenolepis ◽  
Hippoglossoides Elassodon ◽  
Trawl Fisheries

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.

Survival outcome patterns revealed by deploying advanced tags in quantity: Pacific halibut (Hippoglossus stenolepis) survivals after release from trawl catches through expedited sorting

2019 ◽  
Vol 76 (12) ◽  
pp. 2215-2224 ◽  
Author(s):  
Craig S. Rose ◽  
Julie K. Nielsen ◽  
John R. Gauvin ◽  
Timothy Loher ◽  
Suresh A. Sethi ◽  
...  
Keyword(s):  
Survival Rates ◽  
Estimation Methods ◽  
Fish Length ◽  
Air Exposure ◽  
Pacific Halibut ◽  
Archival Tags ◽  
Hippoglossus Stenolepis ◽  
Survival Estimation ◽  
Survival Differences ◽  
Trawl Fisheries

Bycatch of Pacific halibut (Hippoglossus stenolepis) limits many trawl fisheries in Alaska and greatly concerns stakeholders from local communities and fisheries that rely on Pacific halibut. To reduce Pacific halibut mortality, trawlers in the Bering Sea that target flatfish have been developing expedited release procedures to sort Pacific halibut from catches earlier than current regulations allow, while continuing accurate bycatch accounting. We studied survival rates of released Pacific halibut from three trawlers by deploying accelerometer-equipped pop-up satellite archival tags (PSATs) on 160 fish handled under expedited procedures. PSATs recorded and transmitted two metrics indicating swimming activity every 2 h while attached to the fish (for up to 60 days). Analysis of the resulting survival outcomes largely validated current survival-estimation methods, based on structured viability assessments, and found that longer fish length, shorter duration of air exposure, and shorter duration of trawl tow improved predicted Pacific halibut survival. Differences in these results were detected among vessel trips and species targeted by trawling. PSATs provided detailed data from nearly all tagged fish, while exposing fish to conditions experienced by normal releases.

scholarly journals Analysis of match–mismatch between commercial fishing periods and spawning ecology of Pacific halibut (Hippoglossus stenolepis), based on winter surveys and behavioural data from electronic archival tags

2011 ◽  
Vol 68 (10) ◽  
pp. 2240-2251 ◽  
Author(s):  
Timothy Loher
Keyword(s):  
Environmental Variability ◽  
Temporal Distribution ◽  
Seasonal Migration ◽  
Boreal Winter ◽  
Commercial Fishing ◽  
Pacific Halibut ◽  
Archival Tags ◽  
Hippoglossus Stenolepis ◽  
The Face ◽  
Opening And Closing

Abstract Loher, T. 2011. Analysis of match–mismatch between commercial fishing periods and spawning ecology of Pacific halibut (Hippoglossus stenolepis), based on winter surveys and behavioural data from electronic archival tags. – ICES Journal of Marine Science, 68: 2240–2251. The fishery for halibut (Hippoglossus stenolepis) in the eastern Pacific is closed during the boreal winter, roughly corresponding to the seasonal spawning of the species. Opening and closing dates for each season are stipulated annually based on economics and biology. Historical surveys and data from electronic tags are analysed to assess the extent to which recent closures have encompassed the annual spawning cycle of the species, as defined by migration to offshore spawning sites, active spawning, and return to feeding areas. These were assessed by calculating mean maximum daily depth profiles for fish exhibiting seasonal migration, calculating the date-specific proportions of the tagged population either migrating to or resident on their feeding or spawning grounds, and examining the temporal distribution of spent and running fish in historical surveys along with evidence of spawning contained in high-resolution tag data. The data indicate that fishery closures over the past 20 years have been consistently too short to protect the entirety of a migration period that begins as early as September and is not substantially completed until May. Additionally, some recent season openings have encroached on the active spawning season. Failure to fully protect spawning migrations may allow seasonal interception fisheries, and the selective removal of early and late spawners could cause changes in stock demographics, restrict effective spawning, and influence long-term stock productivity, especially in the face of environmental variability.

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