Reducing Shark Bycatch with Electropositive (E+) Metals

	Features
	Aquaculture Bycatch Partnerships and Communications Recreational Fisheries Trade and Commercial Services Grants International Interests LAPP Clearinghouse Permits Magnuson-Stevens 2007 Regulations Seafood & Health Strandings Legislation Sustainable Fisheries Leadership Awards
What is Bycatch? National Bycatch Strategy Recent Regulatory Actions Fisheries Recent Regulatory Actions Protected Resources International Activities Research and Monitoring Reports and Articles Regional Bycatch Summaries Related Laws Meetings Conservation Engineering Presentations Conservation Engineering Videos

Location:

NOAA Fisheries Pacific Island Fisheries Science Center, Honolulu, Hawaii

 Project Summary:

NOAA Fisheries conducted experiments to test the ability of electropositive metals to deter sharks from feeding on baitfish. Utilizing a shark viewing cage (Figure 1), we are able to film and observe choice experiments. Galapagos sharks (Carcharhinus galapagensis) and sandbar sharks ( Carcharhinus plumbeus) were the most commonly observed sharks in the area. Results indicate that bait associated with lead metal was eaten over bait associated with electropositive metal (Figure 2 and Video 1). In addition, sharks exhibited more aversion behaviors as they approached bait associated with the electropositive metal (Video 2). These results suggest that electropositive metals do influence feeding behavior in sharks.

Figure 1. Conducting paired bait trials with Galapagos sharks off the North Shore, Oahu. Click image to download Video 1.

Figure 2.  Results from choice experiments. Bait associated with E+ metals are chosen less. Click to download Video 2.

Innovation/Highlight:

In conducting these experiments, NOAA Fisheries developed an assay to examine potential shark deterrent strategies that could be potentially useful in reducing the incidental capture of sharks in a fisheries setting. Experiments with an alloy of electropositive metals (Pr and Nd) indicate that the metal deters feeding and may be useful in reducing shark interactions with longline gear.

Resource Challenge:

The incidental capture of sharks and rays is estimated at over 1,000,000 metric tons annually (approximately 40 million individual animals). In several fisheries, it is common to have rates of shark bycatch exceed the capture rates of targeted fish species. The problem of shark and ray incidental capture is a major concern, in particular, due to their importance as predators at the top of the marine food chain. Removal of these predators not only affects the population structure of shark and ray species, but also indirectly affects the larger marine communities.