Sometimes simple solutions are better. It all depends on the nature of the problem. For humpback whales, the problem is the rope connecting a crab trap on the seafloor to the buoy on the surface. And for fishermen, it’s fishery closures caused by whale entanglements.
Managing this issue is currently a major item on California’s agenda, and it appears less fishing gear may be the optimal solution. So says a team of researchers led by Christopher Free, at UC Santa Barbara, after modeling the benefits and impacts that several management strategies would have on whales and fishermen. Their results, published in the journal Biological Conservation, find that simply reducing the amount of gear in the water is more effective than dynamic approaches involving real-time monitoring of whale populations. There may even be solutions on the horizon that provide these benefits with fewer drawbacks.
“We were trying to figure out what types of management strategies would work best at reducing whale entanglements in the Dungeness crab fishery while also minimizing impacts to fishing,” said first author Free, a researcher at the university’s Marine Science Institute. “And what we found is that some of the simpler strategies, such as just reducing the amount of gear allocated to the fishermen, outperformed a lot of the more complex management strategies.”
Management falls into two basic categories. Static strategies remain the same regardless of conditions. These include gear reductions, season delays and early closures. Meanwhile, dynamic strategies adapt based on incoming information. These come in proactive and reactive flavors, depending on whether the change is based on surveys determining where whales are abundant or observed entanglements indicating where risk might be high.
Free and his colleagues created a computer model to investigate different management actions based on crab abundance, fisherman behavior and whale behavior. The model predicts how a given approach will affect total catch as well as the frequency with which whales encounter traps. Strategies included gear reductions and closures triggered by surveys, entanglements or time of year. The authors judged each action based on how well it reduced entanglement risk, while minimizing disruptions to the fishing season and total landings.
2023-09-30 17:24:03
Source from phys.org