Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4659
Title: The Impact of Temperature Stress and Pesticide Exposure on Mortality and Disease Susceptibility of Endangered Pacific Salmon
Author: J. P. Dietrich, A. L. Van Gaest, S. A. Strickland, M. R. Arkoosh
Publication Year: 2014
Journal: Chemosphere
Keywords: Pacific salmon,pesticides,Malathion,Disease susceptibility,Temperature stress,Multiple stressors

Anthropogenic stressors, including chemical contamination and temperature stress, may contribute to increased disease susceptibility in aquatic animals. Specifically, the organophosphate pesticide malathion has been detected in surface waters inhabited by threatened and endangered salmon. In the presence of increasing water temperatures, malathion may increase susceptibility to disease and ultimately threaten salmon survival. This work examines the effect of acute and sublethal exposures to malathion on ocean-type subyearling Chinook salmon held under two temperature regimes. Chinook salmon were exposed to malathion at optimal (11 °C) or elevated (19 and 20 °C) temperatures. The influence of temperature on the acute toxicity of malathion was determined by generating 96-h lethal concentration (LC) curves. A disease challenge assay was also used to assess the effects of sublethal malathion exposure. The malathion concentration that resulted in 50% mortality (LC50; 274.1 μg L−1) of the Chinook salmon at 19 °C was significantly less than the LC50 at 11 °C (364.2 μg L−1). Mortality increased 11.2% in Chinook salmon exposed to malathion at the elevated temperature and challenged with Aeromonas salmonicida

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The Northwest Fisheries Science Center (NWFSC) supports the conservation and management of living marine resources and their habitats in the Northeast Pacific Ocean.

Our research assists resource managers in making sound decisions that build sustainable fisheries, recover endangered and threatened species, sustain healthy ecosystems, and reduce risks to human health.