No abstract

No abstract

Eutrophication of water bodies is an important environmental issue related to aquaculture. Strate ies for minimisin the impact of aquaculture on the environment include manipulation of diet b rmulations andgselection of raw materials, husbandry practices related to the feeding of fish, %uent water treatment, recovery of uneaten feed and dead fish, and farm site selection. Concerns about the impact of aquaculture on the environment have led to the introduction of legislation in a number of countries, and such le islation is like1 to become increasingly important in regulating the aquaculture such an approach must consider the complexities of fish giolog and nutritional requirements, and the many limnological, hydrogra hic and environmental factors wlich ultimately determine the degree of eutrophication. This paper &cusses some aspects of fish nutrition and husbandry ractices which determine dietary nutrient losses, and considers some aspects and implications of legisPation related to diet composition and feed usage.industry. Whilst legisBation on fish B iet composition re resents one possible regulatory mechanism,

No abstract

Abstract. The effect of betaine (+ amino acid) supplementation on the seawater adaptation of salmon, Salmo salar L., smolts was studied in two separate trials. The fish were fed with feed containing various levels (0‐5‐1‐5%) of FinnStim, a commercial product with betaine as the main component, for a 6–8 week period before seawater transfer and during the 3‐week period in sea water. Growth and mortality were followed during the course of the studies, and the ionic and osmotic balance of fish estimated prior to seawater transfer, and one day and one week after the transfer. Smolts fed with FinnStim had less weight loss after seawater transfer in both trials, and significantly lower mortality in the second trial, than the control smolts. Smolts fed with 1% FinnStim tended to have faster recovery in appetite after seawater transfer. While the main plasma electrolytes showed no clear response to FinnStim treatment, the intramuscular potassium load in sea water was less pronounced in FinnStim fish.