Stomach Content and Stable Isotope Analyses of Sportfish in Lower Cook Inlet, Alaska

Presenter

Seraina Rioult-Pedotti

Campus

UMass Amherst

Sponsor

Meghan Graham MacLean, Department of Environmental Conservation, UMass Amherst

Schedule

Session 1, 10:30 AM - 11:15 AM [Schedule by Time][Poster Grid for Time/Location]

Location

Poster Board A26, Campus Center Auditorium, Row 2 (A21-A40) [Poster Location Map]

Abstract

Pacific halibut (Hippoglossus stenolepis) and black rockfish (Sebastes melanops) are two of the largest sport fisheries in lower Cook Inlet. As local halibut regulations have over the past decade, rockfish harvest has increased, stressing the population. Co-developed with the Alaska Department of Fish and Game (ADFG), this pilot study aimed to identify how stable isotope analysis (SIA) and stomach content analysis (SCA) can bolster existing knowledge on the influence of halibut and rockfish on their ecosystems. Local fishermen donated muscle tissue and stomach content samples of 35 halibut and 25 rockfish. Sex, length, and harvest location were obtained via the ADFG Port Sampling Program. Epibenthic crabs were found exclusively in halibut stomachs; whereas shrimp and snails associated with kelp were only found in rockfish stomachs. There was considerable overlap in forage fishes which were predominantly Pacific sand lance (Ammodytes personatus). Preliminary SIA from paired tissue and stomach contents contextualized SCA findings with long-term information on trophic position and sources of primary production. To manage populations, fisheries managers must understand how harvesting impacts interactions among managed and unmanaged species and how they relate to their habitats. Adding SCA and SIA to existing sampling programs could expand research efforts to further inform management.

Keywords

fisheries ecology, stable isotopes, trophic niche

Research Area

Environmental Science and Sustainability

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