An Iterated Multiyear Simulation Model to Assess Impacts of Halibut Bycatch Limits

• Main Author: Hartley, Marcus
• Format: Conference Object
• Language: English; unknown
• Published: North American Association of Fisheries Economists
• Subjects: Fisheries > Economic aspects > Congresses; Sustainable fisheries > Congresses; Bering Sea; Pacific; Aleutian Islands
• Online Access: https://ir.library.oregonstate.edu/concern/conference_proceedings_or_journals/d791sh42j

Bering Sea/Aleutian Islands (BSAI) groundfish fisheries are hugely productive with 2008 – 2014 harvests averaging 1.6 million tons and generating $1.95 billion annually. The BSAI also hosts a commercial halibut fishery with 2013 landings of 3,500 tons and revenues of $41.5 million. Downward trends in halibut biomass combined with continued bycatch mortality in the groundfish fishery pushed the commercial harvests down to 2,000 tons in 2014, with lower harvest limits expected in 2015. Halibut bycatch mortality in the groundfish fisheries have exceeded commercial halibut harvests since 2012, and barring significant changes, bycatch will continue to exceed commercial harvests. An Iterated Multi-year Simulation (IMS) model was developed to assess future impacts to both the groundfish and commercial halibut fisheries of proposed reductions of up to 35 percent from current NMFS limits on bycatch mortality, established in the groundfish management plan. The IMS-model randomly selects from the basis years (2008 – 2013) to generate a simulated future from 2014 – 2023, in which the exploitable halibut biomass is held at 2014 estimates. Each randomly drawn year brings with it the halibut bycatch from that year, along with the groundfish harvests and revenue generated. Allowable future halibut harvests are estimated using the International Pacific Halibut Commission’s harvest policy algorithm, which nets out predicted bycatch mortality from exploitable biomass levels. After 10,000 iterations, the IMS-model yields distributions of expected bycatch and harvest levels, along with estimates of changes in the net present value of revenue over the 10-year future period for both the halibut and groundfish fisheries.