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Fisheries Behavioral Ecology - Abstracts

Løkkeborg, S., B.L. Olla, W.H. Pearson, and M.W. Davis. 1995. Behavioural responses of sablefish, Anoplopoma fimbria, to bait odour. Journal of Fish Biology 46:142-155.


A behavioural bioassay was used to determine the response threshold to squid extract of sablefish, Anoplopoma fimbria, held at three different feeding regimens. Sablefish responded to the odour of bait by changing swimming activity and turning behaviour. The response threshold to bait odour was influenced by both the amount of food eaten and the duration of food deprivation. The total concentration of amino acids in the bait extract was assumed to determine the response threshold as chemical fractionation studies have shown that this class of compounds is essential for the stimulatory capacities of food extracts. When fed to satiation (9.4% wet body weight) and tested after one day of food deprivation, the mean response threshold to total dissolved free amino acids was 4.4 × 10-8m (range=7.6 × 10-8 to 3.6 × 10-8m). When fed at 1.6-2.3% wet body weight, the threshold sensitivity had increased to a mean value of 1.8 × 10-10m (range=8.4 × 10-10 to 7.0 × 10-11m) after one day of food deprivation; after four days of deprivation, the sensitivity had increased even further to a mean value of 1.4 × 10-11m (range=1.6 × 10-10 to 1.4 × 10-12m). It was also apparent that the intensity of behavioural responses to the bait odour increased with both stimulus concentration and duration of food deprivation. These results suggest that sablefish intensify their search for prey under increased feeding motivation. The active space of a bait source was estimated from the threshold values obtained. Depending on state of food deprivation, rate of chemical release from the bait and the current velocity, maximum lengths of active space within which sablefish would exhibit food searching responses vary from 10 m to several km. Stock assessment based on catch data from baited gear will need techniques that take into account those factors influencing active space for food searching.


Last updated 30 March, 2009

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