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Date of Award
Department or Program Affiliation
Environmental Sciences, Marine and Estuarine Science Program
Master of Science (MS)
Sobocinski, Kathryn L.
Bodensteiner, Leo R., 1957-
Walleye pollock (Gadus chalcogrammus) and Chinook salmon (Oncorhynchus tshawytscha) are economic and cultural resources in Alaska. Chinook salmon bycatch is a large concern within the pollock fishery. Current strategies to reduce salmon bycatch include modifying trawl gear by implementing artificial light near or on escapement panels to increase salmon escapement. The visual characteristics of pollock and Chinook salmon were investigated to understand the perception of trawl gear. The visual pigments of each species were measured using microspectrophotometry (MSP). Pollock were dichromats with spectral sensitivity ranging from 449nm–518 nm and Chinook salmon were trichromats with sensitivity ranging from 436 nm–545 nm. The green opsins within Chinook salmon will activate when stimulated by wavelengths that are outside of the spectral sensitivity of pollock. Microspectrophotometry data defining pollock and Chinook salmon visual pigments, spectral irradiance data from the Bering Sea, and spectral reflectance of commonly used trawl components were input into two visual models, VPModel® and the R package pavo. Visual models predict how the organism’s visual system responds to visual stimuli. Modeling the spectral distribution and physiological visual characteristics predicts how fish interact and adapt to the changing light environment. Spectral irradiance availability decreased with depth and increasing chlorophyll a concentration. Target contrast against the background space light was dependent on the light environment characteristics including depth. Using the physiological data and theoretical model output provides spectral range and intensity limitations to behavior experiments aiming to increase the escapement potential of Chinook salmon in the pollock fishery
Alaska, Chinook salmon, walleye pollock, fishing, trawl, vision
Western Washington University
Subject – LCSH
Walleye pollock fisheries--Bycatches--Bering Sea; Chinook salmon--Alaska; Trawls and trawling--Bycatches--Bering Sea; Bycatches (Fisheries)--Bering Sea
Bering Sea; Alaska
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Haehn, Rebecca, "Visual characteristics of walleye pollock and Chinook salmon: Modeling theoretical visual space and target contrast of trawling materials in the Bering Sea" (2023). WWU Graduate School Collection. 1252.