The contribution of diet to the dramatic reduction of the 2013 year class of Gulf of Alaska walleye pollock ( Gadus chalcogrammus )

2021 ◽  
Author(s):  
Jesse F. Lamb ◽  
David G. Kimmel
Keyword(s):  
Gulf Of Alaska ◽  
Walleye Pollock ◽  
Dramatic Reduction

Phenological and geographical patterns of walleye pollock (Theragra chalcogramma) spawning in the western Gulf of Alaska

2007 ◽  
Vol 64 (4) ◽  
pp. 713-722 ◽  
Author(s):  
Lorenzo Ciannelli ◽  
Kevin M Bailey ◽  
Kung-Sik Chan ◽  
Nils Chr. Stenseth
Keyword(s):  
Time Series ◽  
Additive Model ◽  
Gulf Of Alaska ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Geographical Patterns ◽  
Spawning Aggregations ◽  
Egg Distribution ◽  
Walleye Pollock Theragra Chalcogramma ◽  
Egg Density

Over 20 years of egg sampling data were used to reconstruct the geographical and phenological patterns of walleye pollock (Theragra chalcogramma) spawning aggregations in the Gulf of Alaska (GOA). The analyzed time series (1972, 1978–1979, 1981–2000) included a documented event of climate change (i.e., 1988–1989) and the rise and fall of the GOA pollock population abundance and harvests. We compared results from two generalized additive model (GAM) formulations: one assuming no change of egg distribution and phenology over the examined time series (stationary) and the other admitting such changes (nonstationary) across an epoch determined from the data. Results from both model formulations corroborate the existence of a high egg concentration in Shelikof Strait, historically the primary spawning area of pollock in the GOA. However, model results also highlight the presence of other secondary, and possibly transitory, centers of egg distribution at various locations along the shelf and slope regions of the GOA. In addition, results from the nonstationary (and statistically superior) formulation indicate that the abundance of the non-Shelikof aggregations has increased over time, along with a tendency for earlier occurrence and displacement toward shallower areas of the high egg density regions.

scholarly journals Growth, mortality, and recruitment signals in age-0 gadids settling in coastal Gulf of Alaska

2016 ◽  
Vol 73 (9) ◽  
pp. 2227-2237 ◽  
Author(s):  
Benjamin J. Laurel ◽  
Brian A. Knoth ◽  
Clifford H. Ryer
Keyword(s):  
Early Life History ◽  
Gulf Of Alaska ◽  
Walleye Pollock ◽  
First Year ◽  
Pacific Cod ◽  
Temperature Dependent ◽  
Gadus Macrocephalus ◽  
Class Strength ◽  
Saffron Cod ◽  
Recruitment Signals

Abstract Age-0 juveniles may be the earliest, reliable indicators of recruitment into commercial marine fisheries, but independent fisheries assessments are usually conducted on older life stages in adult habitats. We used an 8 year juvenile gadid survey along the coast of Kodiak, Alaska to examine annual abundance, growth and mortality in age-0 Pacific cod (Gadus macrocephalus), with comparisons to saffron cod (Eleginus gracilis) and walleye pollock (Gadus chalcogrammus) where possible. Annual abundance of age-0 fish was positively correlated among all three species, suggesting Pacific gadids respond similarly to processes controlling pre-settlement survival and/or delivery to coastal nurseries. In Pacific cod, June temperature was positively correlated with size-at-settlement but post-settlement growth was density- rather than temperature-dependent. Age-0 abundance indices for Pacific and saffron cod predicted the number of age-1 fish the following year (i.e. positive “recruitment signals”), but only in the larger nursery (Anton Larsen Bay) where age-1 gadids were more likely to remain resident after their first year. Recruitment signals for Pacific cod improved with later estimates of age-0 abundance, likely because of high mortality following settlement in July. In contrast, very few age-0 and age-1 walleye pollock were caught across the entire time-series of the survey. Collectively, these data suggest that nearshore surveys may be a tractable means of examining early life history processes and assessing year-class strength in juvenile Pacific and saffron cod, but have relatively low value in understanding the population dynamics of walleye pollock.

scholarly journals Modeling connectivity of walleye pollock in the Gulf of Alaska: Are there any linkages to the Bering Sea and Aleutian Islands?

2016 ◽  
Vol 132 ◽  
pp. 227-239 ◽  
Author(s):  
Carolina Parada ◽  
Sarah Hinckley ◽  
John Horne ◽  
Michael Mazur ◽  
Albert Hermann ◽  
...  
Keyword(s):  
Bering Sea ◽  
Gulf Of Alaska ◽  
Walleye Pollock ◽  
Aleutian Islands ◽  
The Bering Sea

Transport, Distribution, and Abundance of Larval and Juvenile Walleye Pollock (Theragra chalcogramma) in the Western Gulf of Alaska

1991 ◽  
Vol 48 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Sarah Hinckley ◽  
Kevin M. Bailey ◽  
Susan J. Picquelle ◽  
James D. Schumacher ◽  
Phyllis J. Stabeno
Keyword(s):  
Early Life ◽  
Gulf Of Alaska ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Life Stages ◽  
Early Life Stages ◽  
Early Juvenile ◽  
Walleye Pollock Theragra Chalcogramma ◽  
Eggs And Larvae ◽  
Egg Abundance

The spawning distribution of walleye pollock (Theragra chalcogramma) and subsequent southwesterly drift of eggs, larvae, and juveniles were investigated in Shelikof Strait, March–September 1987. In mid-March, a hydroacoustics survey found that spawning adults were concentrated in the deeper parts of Shelikof Strait, as were eggs collected in this area during an ichthyoplankton survey about 1 mo later. In May, a concentration of young larvae was found 100–150 km to the southwest of the spawning area. In late June and early July, the center of distribution of late larval and early juvenile walleye pollock was further to the southwest, between the Shumagin and Semidi Islands. By August and September, juveniles were mostly distributed downstream of the Shumagin Islands. The rate of drift of eggs and larvae through June was estimated at 4–6 cm/s. The trajectories of satellite-tracked buoys deployed in the region of greatest egg abundance revealed similar patterns to those of the early life stages of walleye pollock. These observations demonstrate that transport is an important factor determining the distribution of pollock larvae in downstream coastal nursery areas.

scholarly journals The evaluation of two management strategies for the Gulf of Alaska walleye pollock fishery under climate change

2009 ◽  
Vol 66 (7) ◽  
pp. 1614-1632 ◽  
Author(s):  
Z. Teresa A’mar ◽  
André E. Punt ◽  
Martin W. Dorn
Keyword(s):  
Climate Change ◽  
Management Strategy ◽  
Management Strategies ◽  
Gulf Of Alaska ◽  
Walleye Pollock ◽  
Reference Level ◽  
Climate Indices ◽  
Management Performance ◽  
Intergovernmental Panel ◽  
Alternative Management

Abstract A’mar, Z. T., Punt, A. E., and Dorn, M. W. 2009. The evaluation of two management strategies for the Gulf of Alaska walleye pollock fishery under climate change. – ICES Journal of Marine Science, 66: 1614–1632. Management strategy evaluation (MSE) is the process of using simulation testing with feedback to examine the robustness of candidate management strategies to error and uncertainty. The structure of the management strategy can be selected to attempt to satisfy desired (but conflicting) management objectives. MSE was used to assess the performance of the current management strategy and an alternative management strategy (the “dynamic B0” strategy) for the fishery for walleye pollock (Theragra chalcogramma) in the Gulf of Alaska (GOA), when age-1 recruitment was driven by climate. The relationships between age-1 abundance and climate indices (and the uncertainties associated with these relationships) were characterized within an age-structured operating model that was fitted to the data for GOA walleye pollock. Projections into the future were based on the fitted relationships and predictions of those indices from the Intergovernmental Panel on Climate Change (IPCC) models, using the current or the alternative management strategy to determine catch limits. Management performance (the ability to leave the stock close to the management reference level and achieve high and stable catches) deteriorated when age-1 recruitment was forced by climate, although stocks were kept near the reference level on average. In addition, the ability to estimate management-related quantities, such as spawning biomass, deteriorated markedly when recruitment was forced by climate. Performance was sensitive to the choice of IPCC dataset and, in particular, estimation and management performance was poorest (outcomes most variable) for the IPCC datasets that led to the greatest variation in recruitment to the fishery. Although basing management on a “dynamic B0” management strategy led to improved management and estimation performance, the magnitude of the improvement was slight.

Sign in / Sign up

Export Citation Format

Share Document