Effect of Temperature, Season, and Fish Size on Acute Lethality of Suspended Sediments to Coho Salmon (<i>Oncorhynchus kisutch</i>)

Abstract

Tolerance of underyearling coho salmon (Oncorhynchus kisutch) to Fraser River suspended sediments (SS) at 7 °C was independent of season of the year. However, coho of 0.52 g (4.0 cm) possessed only 35% of the tolerance of larger specimens. Tolerance to SS was temperature dependent, with 96-h LC50 at 1 and 18 °C being 47 and 33%, respectively, of the value at 7 °C. Tolerance was further reduced among underyearling coho which were later found to have a viral kidney infection. Cough reflex, oxygen transfer, oxygen saturation levels, metabolic rates, and capacity to do work all probably affect the relationship between SS tolerance and temperature.