Effect of Diets Containing Dogfish (Squalus acanthias) Meal on the Mercury Content and Growth of Pen-Reared Coho Salmon (Oncorhynchus kisutch)

Abstract

The use of dogfish (Squalus acanthias) meal as a complete replacement for herring or other low mercury (Hg) content fish meal in rations intended for rearing cultured salmon introduces the risk of producing fish that exceed the current U.S. FDA tolerance level of 0.5 ppm Hg. The amount of Hg that accumulates in the muscle is related not only to the total Hg content of the fish, but is probably also related to the form in which it is present in the diet and to other constituents that may react with the Hg in the diet. Our results indicate that dogfish meal may be used as a partial (< 50%) replacement for the fish meal portion of the diet without encountering Hg values (in the muscle) that exceed 0.5 ppm Hg. No evidence was found that naturally occurring chelating agents in dehydrated orange peel or polygalacturonic acid–cellulose complexes (PG) have the ability to chelate and prevent the deposition of Hg in either the muscle or the liver of the fish. It was observed that growth is decreased in coho salmon (Oncorhynchus kisutch) fed OMP-type diets in which 50% or more of herring meal was replaced with dogfish meal.