Fluorine accumulation in Atlantic salmon ( Salmo salar), Atlantic cod ( Gadus morhua), rainbow trout ( Onchorhyncus mykiss) and Atlantic halibut ( Hippoglossus hippoglossus) fed diets with krill or amphipod meals and fish meal based diets with sodium fluoride (NaF) inclusion

Abstract

Meals produced from different marine invertebrate species have been suggested as good alternative protein sources in fish diets. The aim of this study was to evaluate the possible uptake of fluorine from krill ( Thysanoessa inermis and Euphausia superba) and the amphipod Themisto libelulla in fish fed diets where the fish protein was partly or fully substituted with proteins from krill meal or amphipod meal. Feeding trials with Atlantic salmon ( Salmo salar), Atlantic cod ( Gadus morhua), rainbow trout ( Onchorhyncus mykiss) and Atlantic halibut ( Hippoglossus hippoglossus) were carried out, and fluorine were analysed in different organs, including muscle, bone and faeces as well as experimental diets and meals. Amphipod meal had the highest fluorine level (4000 ±800 mg kg − 1 ), while meal from Thysanoessa inermis and Euphausia superba showed about one fourth of that level (780 ± 160 mg kg − 1 and 1160 ± 230 mg kg − 1 , respectively). The fluorine concentration increased in the diets with increasing substitution of fish meal with krill or amphipod meal. Fluorine also increased in faeces with increasing fluorine levels in the diets. None of the analysed organs showed any increase in fluorine concentration compared to the control fish which was fed a diet with only fish meal as protein source. All four species were also fed a fish meal based diet where sodium fluoride (NaF) was added (150 mg F kg − 1 dry wt.). Again no organs showed any increase in fluorine levels. Growth and health parameters were not negatively altered. This indicates that the four fish species, when kept in a marine environment, were not affected by relatively high dietary fluorine level.