Recording the Behaviour of Northern Stone Crab Lithodes maja Using HD Deep-Water Video Camera

The feasibility of exploiting a new marine species in a fishery depends on the gear to be used in that fishery. Assessing gears using underwater cameras and direct observation provides a great deal of insight that would be otherwise unavailable by looking at catch data alone. In this study, we employ underwater cameras to study pots designed to catch northern stone crab (Lithodes maja). Using these videos, we obtained precise estimates of the rate at which crabs approached, entered, and exited pots, as well as interactions with other species at depth.

We found that the rate at which stone crabs approached pots was low. Less than half of crabs that attempted entries successfully made it into the pot. However, once caught, crabs rarely exited pots, and the final catch rate was comparable to other studies. In addition, we found that white hake were caught at high rates in these pots. Also, we have found that current direction is strongly associated with approaches and entry attempts, with the vast majority occurring in a direction against the current.

This study has demonstrated that potting gear could be a viable technique for a multispecies fishery targeting both hake and crab.