August 19, 2015
New Study Suggests Fishing Gear Changes May Reduce Large Whale Entanglements
BY: Alison Shapiro
One of the ocean’s most iconic species worldwide is, quite literally, facing a whale of a problem these days. Fishing gear continues to claim the lives of hundreds of whales each year, entangling them in dangerous nets and ropes.
However, a new study indicates the number of whales found entangled in fishing gear could be reduced by almost three quarters if the fishing industry made one simple adjustment — use slightly weaker ropes.
New recommendations published in the journal Conservation Biology suggest that reducing the breaking strength of ropes used in fishing gear from the current average of 2,616 pounds for the ropes tested in the study to 1,700 pounds or less could shrink large whale entanglements by 72 percent.
According to the report, weaker ropes would still be strong enough for routine fishing operations and would help “achieve nearly all of the mitigation legally required for US stocks of North Atlantic right and humpback whales.”
For their research, the authors scrutinized fishing gear that had been removed from entangled whales along the U.S. East Coast and the Canadian Maritimes. For 16 years, the team observed rope polymer type, breaking strength and diameter in relation to the species, age and injury severity for each entangled whale.
What they found was that tangled North Atlantic right and humpback whales were often found in ropes that had significantly stronger breaking strengths at manufacture than minke whales, another large whale species. For example, right whales were found entangled in fishing gear ropes with a breaking strength of 4,338 pounds, whereas minke whales became entangled in ropes with a breaking point of 2,353 pounds. This indicates there are physical strength differences between whale species. No adult right whales were discovered entangled in fishing gear ropes under 4,500 pounds, whereas all the entangled minke whales in the study died when they were caught in heavier gear.
Additionally, adult right whales were found in stronger ropes than humpback whales of all age classes, and the injuries sustained to right whales have become more severe over the past 30 years. This may be due to changes in rope manufacturing starting in the mid 1990’s that resulted in stronger ropes, the authors wrote.
The North Atlantic right whale is one of the most endangered species in the U.S., and one of the rarest of the world’s large whales.
As the journal’s authors point out, “entanglement in fixed fishing gear is a conservation concern for whales worldwide, including in the U.S. where deaths of North Atlantic right and humpback whales have exceeded management limits for decades.”
It is estimated that 308,000 whales and dolphins die annually across all the world’s oceans due to entanglement in fishing gear, according to the International Whaling Commission. And unfortunately, destructive fishing gear and practices take the lives of all kinds of other ocean creatures as well. Bycatch, or the unintended capture of ocean wildlife, is responsible for the death of thousands of marine animals each year that become trapped in fishing nets and lines that stretch for miles in the water.
The journal’s authors are proposing that reducing the breaking strength of ropes is one possible solution that should be developed and tested immediately for feasibility in fixed gear fisheries, such as those that use traps and pots. Doing so could save a record amount of endangered whales from unnecessary death from entanglement in fishing gear.