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Status of Stocks & Multispecies Assessment Program

Studies to Evaluate the Impact of Incidental Salmon Catch in Groundfish Fisheries

Figure 4, see caption
Figure 4.  Example of relative probabilities of randomized input values used in the simulation model to evaluate bycatch impacts on salmon populations.

The regulations on incidental take of Pacific salmon by Alaska groundfish fisheries are an important part of the multispecies management system. These regulations are currently being revised due to new information collected over the past decade and due to changes in the magnitude and pattern of salmon catch. To evaluate these practices, methods that appropriately account for the impact incidental catches have on salmon populations are required.

Recently, REFM Division scientists have developed a simulation model that is proposed for analyses that will be undertaken by the North Pacific Fishery Management Council. The model is designed to account for the observed interannual variability of salmon run-sizes and allows for sources of variability including the salmon age-composition, ocean survival, and run-size estimation uncertainty (e.g., Fig. 4).

The model and results from an example case study was presented to the Councilís Salmon Bycatch Workgroup. Preliminary results show how variability propagates from these sources and that the identified sources of uncertainty make it possible to assess the impact of bycatch levels on salmon runs. This provides a tool that will allow managers to quantitatively assess alternatives and better understand the trade-offs in evaluating effective real-time management systems, in particular, caps that limit incidental salmon takes.

By James Ianelli

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