Including mark–recapture data into a spatial age-structured model: walleye pollock (Theragra chalcogramma) in the eastern Bering Sea

2011 ◽  
Vol 68 (9) ◽  
pp. 1625-1634 ◽  
Author(s):  
Peter-John F. Hulson ◽  
Sara E. Miller ◽  
James N. Ianelli ◽  
Terrance J. Quinn
Keyword(s):  
Bering Sea ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Test Accuracy ◽  
Total Biomass ◽  
Eastern Bering Sea ◽  
Walleye Pollock Theragra Chalcogramma ◽  
Age Structured ◽  
Management Advice ◽  
Movement Parameters

Integrated assessment models used to evaluate fish stocks are becoming increasingly complex, with some capable of incorporating spatial considerations. Such a model has been developed to estimate movement of walleye pollock (Theragra chalcogramma) between the northwestern and southeastern eastern Bering Sea. In this study, we investigate the feasibility of estimating movement using spatially disaggregated data supplemented by tagging data. Monte Carlo simulation was used to test accuracy and variability of parameter estimation in model scenarios with and without tagging information. Total biomass estimates for models with and without tagging data were unbiased, but uncertainty was smaller when tagging data were available. Uncertainty was also reduced in regional biomass and movement parameters when including tagging data. Our findings indicate that tagging information would be important to provide reliable spatially explicit fisheries management advice for eastern Bering Sea pollock.

scholarly journals Evaluating management strategies for eastern Bering Sea walleye pollock (Theragra chalcogramma) in a changing environment

2011 ◽  
Vol 68 (6) ◽  
pp. 1297-1304 ◽  
Author(s):  
James N. Ianelli ◽  
Anne B. Hollowed ◽  
Alan C. Haynie ◽  
Franz J. Mueter ◽  
Nicholas A. Bond
Keyword(s):  
Climate Change ◽  
Bering Sea ◽  
Management Strategies ◽  
Walleye Pollock ◽  
Status Quo ◽  
Theragra Chalcogramma ◽  
Recruitment Pattern ◽  
Control Rules ◽  
Eastern Bering Sea ◽  
Walleye Pollock Theragra Chalcogramma

Abstract Ianelli, J. N., Hollowed, A. B., Haynie, A. C., Mueter, F. J., and Bond, N. A. 2011. Evaluating management strategies for eastern Bering Sea walleye pollock (Theragra chalcogramma) in a changing environment. – ICES Journal of Marine Science, 68: 1297–1304. The impacts of climate change on fish and fisheries is expected to increase the demand for more accurate stock projections and harvest strategies that are robust to shifting production regimes. To address these concerns, we evaluate the performance of fishery management control rules for eastern Bering Sea walleye pollock stock under climate change. We compared the status quo policy with six alternative management strategies under two types of recruitment pattern simulations: one that follows temperature-induced trends and the other that follows a stationary recruitment pattern similar to historical observations. A subset of 82 Intergovernmental Panel on Climate Change climate models provided temperature inputs from which an additional 100 stochastic simulated recruitments were generated to obtain the same overall recruitment variability as observed for the stationary recruitment simulations. Results indicate that status quo management with static reference points and current ecosystem considerations will result in much lower average catches and an increased likelihood of fishery closures, should reduced recruitment because of warming conditions hold. Alternative reference point calculations and control rules have similar performance under stationary recruitment relative to status quo, but may offer significant gains under the changing environmental conditions.

scholarly journals Expected declines in recruitment of walleye pollock (Theragra chalcogramma) in the eastern Bering Sea under future climate change

2011 ◽  
Vol 68 (6) ◽  
pp. 1284-1296 ◽  
Author(s):  
Franz J. Mueter ◽  
Nicholas A. Bond ◽  
James N. Ianelli ◽  
Anne B. Hollowed
Keyword(s):  
Climate Change ◽  
Bering Sea ◽  
Late Summer ◽  
Walleye Pollock ◽  
Future Climate ◽  
Future Climate Change ◽  
Theragra Chalcogramma ◽  
Climate Projections ◽  
Eastern Bering Sea ◽  
Walleye Pollock Theragra Chalcogramma

Abstract Mueter, F. J., Bond, N. A., Ianelli, J. N., and Hollowed, A. B. 2011. Expected declines in recruitment of walleye pollock (Theragra chalcogramma) in the eastern Bering Sea under future climate change. – ICES Journal of Marine Science, 68: 1284–1296. A statistical model is developed to link recruitment of eastern Bering Sea walleye pollock (Theragra chalcogramma) to variability in late summer sea surface temperatures and to the biomass of major predators. The model is based on recent advances in the understanding of pollock recruitment, which suggest that warm spring conditions enhance the survival of early larvae, but high temperatures in late summer and autumn are associated with poor feeding conditions for young-of-year pollock and reduced recruitment in the following year. A statistical downscaling approach is used to generate an ensemble of late summer temperature forecasts through 2050, based on a range of IPCC climate projections. These forecasts are used to simulate future recruitment within an age-structured stock projection model that accounts for density-dependent effects (stock–recruitment relationship), the estimated effects of temperature and predation, and associated uncertainties. On average, recruitment in 2040–2050 should expectedly decline by 32–58% relative to a random recruitment scenario, depending on assumptions about the temperature relationship, the magnitude of density-dependence, and future changes in predator biomass. The approach illustrated here can be used to evaluate the performance of different management strategies and provide long-term strategic advice to managers confronted with a rapidly changing climate.

A probabilistic cellular automata approach for predator–prey interactions of arrowtooth flounder (Atheresthes stomias) and walleye pollock (Theragra chalcogramma) in the eastern Bering Sea

2012 ◽  
Vol 69 (2) ◽  
pp. 259-272
Author(s):  
Kun Chen ◽  
Kung-Sik Chan ◽  
Kevin M. Bailey ◽  
Kerim Aydin ◽  
Lorenzo Ciannelli
Keyword(s):  
Cellular Automata ◽  
Bering Sea ◽  
Environmental Changes ◽  
Spatial Scales ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Predator Prey ◽  
Eastern Bering Sea ◽  
Walleye Pollock Theragra Chalcogramma ◽  
Arrowtooth Flounder

We developed a hybrid cellular automata (CA) modelling approach to explore the dynamics of a key predator–prey interaction in a marine system; our study is motivated by the quest for better understanding of the scale and heterogeneity-related effects on the arrowtooth flounder (Atheresthes stomias) and walleye pollock (Theragra chalcogramma) dynamics during the summer feeding season in the eastern Bering Sea (EBS), but can be readily extended to other systems. The spatially explicit and probabilistic CA model incorporates individual behaviours and strategies and local interactions among species, as well as spatial and temporal heterogeneity due to geographical and (or) environmental changes in the physical environment. The model is hybridized, with an individual-based model (IBM) approach for increasing its capacity and continuum and for balancing between computational efficiency and model validity, which makes it suitable for simulating predator–prey dynamics in a large, complex ecological environment. We focus on the functional and aggregative responses of predators to prey density at different spatial scales, the effects of individual behaviours, and the impacts of systematic heterogeneity. Simulations from the model with suitable parameter values share qualitatively similar features found in field observations, e.g., local aggregations around hydrographical features. Spatial heterogeneity is an important aspect of whether local-scale functional and aggregative responses reflect those operating over large, or global, scales.

Using acoustic data from fishing vessels to estimate walleye pollock (Theragra chalcogramma) abundance in the eastern Bering Sea

2011 ◽  
Vol 68 (7) ◽  
pp. 1231-1242 ◽  
Author(s):  
Taina Honkalehto ◽  
Patrick H. Ressler ◽  
Richard H. Towler ◽  
Christopher D. Wilson
Keyword(s):  
Bering Sea ◽  
Low Cost ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Accurate Information ◽  
Commercial Fishing ◽  
Acoustic Data ◽  
Eastern Bering Sea ◽  
Fishing Vessels ◽  
Walleye Pollock Theragra Chalcogramma

Eastern Bering Sea walleye pollock ( Theragra chalcogramma ) support one of the world’s largest fisheries. Because of walleye pollock’s high recruitment variability and relatively short life span, timely and accurate abundance indices are needed for fisheries management. Walleye pollock are surveyed biennially with an acoustic-trawl (AT) survey and annually with a bottom trawl (BT) survey. The latter tracks the demersal portion of the population using chartered fishing vessels, whereas the AT survey tracks the younger, midwater portion using research vessels and is critical for evaluating prerecruit abundances. Acoustic data collected from commercial fishing vessels conducting the BT survey were analyzed to provide information on midwater walleye pollock abundance at relatively low cost. A retrospective analysis of AT survey data identified a suitable index area to track midwater walleye pollock abundance. The BT survey acoustic data in that area tracked the AT survey abundance and captured its broad spatial patterns. This study is unique because commercial vessel acoustic data were used to estimate a new annual abundance index whose performance can be evaluated by a biennial research vessel survey. The new index will benefit managers by providing more accurate information on near-term abundance trends when dedicated research ship time is not available.

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