Nurse shark uses escape hatch being tested in lobster trap study. (Photo by Dr. Rob Nowicki/Mote Marine Lab)
Scientists from the Mote Marine Laboratory in Sarasota and the Dutch Elasmobranch Society recently completed a six-month investigation into nurse sharks getting stuck in spiny lobster traps in the Saba bank shark sanctuary in the Dutch Caribbean.
Hundreds of nurse sharks were getting ensnared in the traps each year, increasing trap handling time and negatively impacting the lobster fishery.
“From both an economic and conservation perspective, it’s valuable for us to find a way to reduce nurse shark bycatch,” said Mote Postdoctoral Research Fellow Dr. Rob Nowicki. “More generally, by doing the experiment the way we are – recording behavior instead of capture/no capture events – we can understand exactly how the lobsters, sharks, and traps interact with one another. This gives us an additional level of insight that has already proven valuable in pursing trap modifications to reduce bycatch. We hope that these insights might be able to inform other Caribbean fisheries where nurse shark bycatch is an issue in the future.”
Scientists observed nearly 200 interactions documenting the sharks’ behavior with lobster traps and found that the sharks were more concerned with escaping the traps rather than eating the caged crustaceans. The team hopes that their findings may lead to improved trap design that limits the bycatch.
“Our original thoughts were that sharks enter traps and essentially treat them as lobster vending machines, but our work suggests that sharks first try and get out, and sometime after they give up the lobsters start to look tasty,” Nowicki said. “This has caused us to pivot objectives and explore how to design a trap that excels not at keeping sharks out, but at letting them escape quickly.
“Our preliminary results on this are looking very promising!”