How “ghost” fishing gear affects species at risk and fishing outcomes
Southwestern Nova Scotia is one of Canada’s most productive lobster fishing areas, spanning over 21,000 square kilometers and contributing a significant portion of the country’s lobster supply.
With a busy fishery, however, came the growing challenge of Abandoned, Lost and Discarded Fishing Gear (ALDFG) – a collection of traps, ropes, hooks, cables and other fishing-related gear that drift away. in the water column or litter the ocean. ground. It is a global problem, but one that has not been widely quantified.
Researchers at Dalhousie University wanted to know how much gear might be in the Southwest Nova Scotia Fishing Area (SWNS) and how that might affect the existing fishery. Their recently published baseline study provides the first preliminary assessment of the environmental and economic impacts of ALDFG on the commercial lobster industry in the region.
Tony Walker, associate professor at Dal’s School for Resource and Environmental Studies, is co-author of the article, which suggests that ALDFG’s business losses could exceed $ 175,000 (CAN) per year.
“This study is important because although we are aware of the problem of ALDFG or ghost craft and know where the hot spots are in the region, this is the first time that a systematic project has focused and target on the recovery of the device, while simultaneously quantifying the environmental and economic impacts, âexplains Dr. Walker.
“This tells us that there are not only obvious environmental impacts of leaving this equipment in place, but it also highlights the potential economic losses that can be incurred without mitigation or policies.”
The fishermen made 60 recovery trips during the summer and fall of 2020, excavated approximately 1,523 square kilometers of the seabed and removed 7,064 kilograms of ALDFG. The captains towed grapples behind their commercial fishing boats from a hydraulic transporter and a steel cable winch or dredger and an A-frame winch, at a speed of 0.5 at 3 knots.
Lobster traps accounted for the majority of the gear recovered, while 1,500 kilograms of dredge line accounted for 22% of the gear recovered. Lost traps continued to capture 15 target and non-target species, including 239 lobsters and seven groundfish. Five of these were species at risk and included Atlantic Wolffish, Sculpin, Atlantic Cod, and Cusk.
Tires, party balloons, a fan belt and buoys with American markings were also recovered.
Dangers and Concerns
About 35 percent of the traps recovered were less than three years old, and based on the amount of cables recovered, the authors suggest that cables are discarded by commercial trawlers or trawlers when no longer in use. In Atlantic Canada’s trap fisheries, it is estimated that up to two percent of the total number of authorized traps are lost each year.
“This can create operational risks for other commercial vessels (lobster or groundfish) as it can compromise active gear, create marine debris and disrupt sensitive benthic habitats,” says the study, which was also written by Alexa Goodman, Ariel Smith and Jessie McIntyre of Coastal Action, and Craig Brown and Leah Fulton of Dal’s Department of Oceanography.
It also sets off an endless cycle of destruction, as cod, tusk, wolffish and sculpin are known predators of lobster and are frequently caught as bycatch in working lobster gear. Traps recovered with these bycatch also contained lobster, indicating the self-baiting cycle of ghost gear. Self-bait occurs when animals are trapped in ALDFG and die, attracting new scavengers which are also trapped, according to the report.
The oldest trap found was from 1987, when most of the recovered gear was not significantly degraded, losing less than 25 percent of its original integrity.
A global problem
Abandoned, lost and discarded fishing gear is estimated to account for a significant majority of the 20 percent of the world’s marine debris. For example, discarded fishing nets make up over 46 percent of the debris in the Great Pacific Garbage Patch.
âALDFG is unfortunately a pervasive global problem. Many people may not be aware that much of the global plastic pollution found in our oceans is made up of ALDFG,â says Dr Walker.
“Although this study focused on SWNS, the results are comparable to those from similar fisheries in the United States, Europe and South America.”
Other jurisdictions are also grappling with the problem. In the US Chesapeake Bay blue crab fishery, approximately 18 crabs have been killed per abandoned trap each year. The Florida Keys lobster fishery recorded lower losses from abandoned traps, but studies suggest that estimates of lobster bycatch rates could be two to four times lower than actual ghost fishing levels.
How to remove abandoned, lost and discarded “ghost” fishing gear from the ocean
Provided by Dalhousie University
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