Behavioural Response of the Lobster <i>Homarus americanus</i> to Traps

Abstract

A 180-m 2 tank was set up as a semi-natural benthic habitat in order to obtain quantitative visual observations on the behavioural response of lobsters to traps. The wood-lath parlour traps commonly used in the lobster fishery were very inefficient; only 2% of approaches to the traps led to capture. Large (&gt; 80-mm carapace length) lobsters (Homarus americanus) left before entering the traps in 92% of 428 observed approaches, and were able to escape back out the entrance in 76% of the cases where they actually fed at the bait. Traps baited with thawed mackeral (Scomber scombrus) elicited more approaches and captures than did traps containing salted mackeral. Unbaited traps were virtually ignored, indicating they were not attractive as shelter. Lobsters were apparently drawn out of their shelters by the scent of bait, since individuals which lived immediately downstream from the rotating trap positions approached much more frequently than others. However, overall rates of approach and capture varied greatly between lobsters, suggesting that individuals have different motivational levels. These differences could not be explained on the basis of sex or size. Forty percent of the large lobsters were never caught, despite being offered baited traps in 20 separate trials. Longer-term studies are needed to determine whether such individuals will enter traps at different times of year or whether they remain permanently untrapable.