Dietary and aqueous exposure of finfish to organochlorine compounds: A case study

The level of organochlorine compounds was determined in whole capelin, Mallotus villosus, and compared to concentrations determined in tissues of yellowtail flounder, Pseudopleuronectes ferruginea, that fed on capelin for 2 years while maintained in tanks. Capelin represent part of the diet of offshore yellowtail flounder, however, they come to the beaches to spawn and were collected inshore for the feeding experiment. Therefore, inshore-offshore capelin concentrations were compared to investigate differences, while variables such as fish weight and lipid content were examined to give a better view of the range of contaminants concentrations in capelin. During two years, weekly exposure of flounder was to 148 L of water, as opposed to a dietary intake of 1 g of capelin. Although the level of contaminants was only measured in capelin, it can be estimated for the water, using results obtained on the level of contaminants in sediments obtained in a different study. According to our calculations, levels of contaminants were three to 20 times higher from the aqueous compared to the dietary uptake of inshore flounder, increasing with lower hydrophobicity. Exposure was from less than 10 to up to 100 times lower in expected and/or published results for offshore food and water, respectively. This comparison suggests a major influence of inshore waters on the bioaccumulation of contaminants in some inshore marine species, although the effect of altering the diet of captive finfish can not be disregarded.