Targeting Swordfish Deep During the Day to Reduce Bycatch

R/OPCCFRW-4

In this collaborative fisheries research project, scientists are tagging and tracking swordfish to learn more about the billfish’s movement patterns in relation to sea turtle habitat. The team is also collaborating with the fishing industry to test two innovative gear modifications for reducing bycatch in the commercial swordfish fishery off California. The key idea behind the gear modifications are to set hooks at depths that will efficiently target (catch) swordfish but not sea turtles and marine mammals closer to the sea’s surface. One experimental gear modifies a deepset buoy configuration currently used by small-boat swordfish fishermen off Florida. The other is a deep-set long-line for larger fishing vessels. Both were pilot tested successfully by the lead investigators in 2011. In 2012-2013, PIER scientists tagged 10 swordfish within the Pacific Leatherback Closure Area, established to protect the critical habitat of migrating leatherback sea turtles. The tracking data is being used to characterize swordfish habitat and tailor the trial deep-set operations. The NOAA Fisheries team meanwhile has been conducting field trials of the deep-set long-lines and in 2012 made 17 deployments in waters off Central and Southern California, with hooks set at an average depth of 235 meters. With this configuration, researchers caught a range of marketable species, including one swordfish, 37 opah and two albacore tuna. Bycatch was dominated by blue sharks. There were no sea turtle or marine mammal interactions. The coming year's fieldwork will focus on figuring out why so few swordfish were caught and whether different strategies might increase swordfish catches, while still minimizing sea turtle interactions.

Co-principal Investigators