Whales are majestic creatures that play a vital role in the ocean's ecosystem. Unfortunately, they are also at risk of getting entangled in fishing gear, especially the rope connecting a crab trap on the seafloor to the buoy on the surface.
This can cause serious injuries and even death for the whales, as well as economic losses and fishery closures for the fishermen.
How can this problem be solved in a way that benefits both whales and fishermen?
A team of researchers led by Christopher Free, at UC Santa Barbara, has proposed some possible solutions based on computer modeling.
Gear reductions are more effective than dynamic closures
They evaluated each strategy based on how well it reduced entanglement risk while minimizing disruptions to the fishing season and total landings.
The strategies included gear reductions, season delays, early closures, and dynamic closures triggered by surveys or entanglements.
The results showed that some of the simplest strategies, such as just reducing the amount of gear allocated to the fishermen, outperformed a lot of the more complex management strategies.
A 30% reduction emerged as the optimal course of action, as it reduced entanglement risk by 63%, while only reducing landings by 7%.
Dynamic closures, on the other hand, merely moved the lines around and did not significantly reduce entanglement risk.
Moreover, they increased uncertainty and variability for the fishermen, making it harder for them to plan their operations.
While gear reductions seem to be a promising solution, they may not be enough to prevent all entanglements.
Some whales may still encounter the remaining lines in the water, especially during periods of high whale abundance or migration.
Therefore, other measures may be needed to complement gear reductions, such as developing new technology that reduces or eliminates vertical lines.
One example of such technology is ropeless fishing gear, which uses acoustic signals or GPS to locate and retrieve traps from the seafloor without any rope attached.
This would eliminate the risk of whales getting entangled in vertical lines, while also reducing ghost fishing and gear loss.
However, ropeless fishing gear is still in its early stages of development and testing and may face some challenges in terms of cost, regulation, and enforcement.
Another example of new technology is weak rope or breakaway devices, which are designed to break or release under a certain amount of tension or pressure.
However, weak rope or breakaway devices may also have some drawbacks, such as increasing gear loss or compromising trap retrieval.
Whale entanglements are a serious threat to both whale conservation and crab fishing in California.
Reducing fishing gear could save whales with low impacts on California's crab fishermen, according to a recent study by UC Santa Barbara researchers.
However, other measures may also be needed to further protect whales and support fishermen, such as developing new technology that reduces or eliminates vertical lines.
By finding a balance between whale protection and fishery sustainability, both humans and whales can benefit from a healthy ocean.
