The science of sustainable seafood, explained

Keep it Simple: a case for traditional fishery management solutions

Earlier this year, Free et al. published, “Static management presents a simple solution to a dynamic fishery and conservation challenge.” They modeled and compared the overall effectiveness of various management solutions designed to reduce whale entanglements in trap fisheries. The authors specifically looked at the California Dungeness crab fishery and concluded that sometimes, the simplest solution is still the most effective. Free et al. recommended reducing the overall number of pots in the water, above any other management strategy.

We covered whale entanglements in trap fisheries numerous times over the past few years. American lobster and North Atlantic right whales have been the primary focus, with our most recent post about rope-less “on-demand” gear technologies. But we also wrote about Dungeness fishery closures and interviewed crabbers about early seasonal closures triggered by migrating humpback whales. The threat of fishing gear entanglement for critically endangered species impacts many fisheries worldwide, some of which are incredibly valuable to local economies and iconic to seafood menus. Free et al.’s study acknowledged the significance of these pot fisheries and modeled their results with economic output as a key consideration.

In particular, they explored the relative value of dynamic ocean management (DOM) to more traditional, static approaches like trap reduction. DOM strategies promise minimal bycatch without compromising catch and revenue. However, ideal DOM outcomes require truly dynamic management tools. These often are expensive (constant surveys, synchronized real-time data transfer, etc) or simply impossible in the jurisdictional structure (a panel of experts may require too much time to analyze the data and come up with a management consensus). For humpback whale entanglements, DOM proved too tedious and slow:

Reactive management failed to efficiently reduce entanglement risk because entanglements were rarely observed immediately (0–5 week delay) and management actions in response to an observed entanglement were implemented after a 2-week logistical delay; thus, by the time actions were taken (2–7 weeks after the original entanglement), more entanglements had often already occurred and the risk landscape had already shifted.

In addition to this “reactive management” example, Free et al. also evaluated “proactive dynamic management” in the form of whale abundance surveys and their ability to inform area closures. Unfortunately, these surveys were not, “geographically equitable” and would unfairly cluster closures, impacting some fishers far more than others.

Free et al. did not completely dismiss DOM as totally ineffective for practical use in Dungeness crab or other pot fisheries. Like rope-less fishing gear, DOM strategies could theoretically reduce most or all whale entanglements if everything worked perfectly. But at this time, too many imperfections still exist for DOM to be completely effective in pot fisheries that require time and money – mostly at the expense of fishers – to execute whale-dodging actions.

In the meantime, Free et al. argue the best solution is still one of the simplest – reduce the total number of pots allowed in the fishery.

Studies have shown that fishing gear reductions consistently reduce whale bycatch across many different geographies and jurisdictions. Reikkola et al. (2023) found mandatory gear reductions in Washington’s Dungeness crab fishery to reduce blue whale entanglements, Myers and Moore (2020) estimated similar results would occur for right whales if Maine reduced its trap limit for American lobster, and How et al. (2021) estimated gear modifications to reduce the amount of rope required in the Western Australia rock lobster fishery would achieve a similar effect.

But the most important overlaying factor for practical application is maintaining catch and overall revenue. For these factors, Free et al. still found pot reductions to be optimal. Their models projected that a 50% gear reduction would reduce entanglements by 50-60%, but still yield over 80% of the expected catch for a fishery with no gear reductions at all. If crab pots were reduced to just 10% of current numbers, their model suggested 85% of entanglements would be avoided, but over 50% of the normal catch would still be achieved; see below.

Figure from Free et al. 2023 showing relationship between potential whale entanglements and the potential maximum catch of Dungeness crab with various levels of crab pot reduction.
Performance dynamics of the gear reduction scenarios. Each point represents simulated tradeoffs between catch and entanglement risk in a season. Results show that gear reduction percentages result in similar percentages of reduced whale entanglements, but still maintain high percentage of overall catch across the fishery. From Free et al. 2023.

Referencing official catch data from 2018, a similar dynamic was apparent when comparing Canadian and Maine lobster landings. Canadian lobster fishers used only about 10% of the traps as their Maine counterparts, but still brought in over 25% of Maine’s catch.

However, there are some downsides to a gear reduction management strategy in the California Dungeness crab fishery. Smaller vessels could be unfairly impacted compared to larger vessels, or rather permit holders with fewer traps than those with a greater amount. Would a gear reduction be a percentage of each permit holder’s pots, or a fixed number for each permit holder regardless of vessel size or total pots? A longer fishing season would be required to produce more catch with fewer pots, as Free et al.’s model projected. That would be more overhead such as fuel costs, and lost time targeting other species. Many California Dungeness crab permit holders rely on crab landings as their top revenue. But shoulder seasons between crab and king salmon offer valuable time to prosecute open-access permits for groundfish like rockfish and halibut. Recent years have also seen more bluefin tuna in California waters. A longer crab season would complicate the gear-switching necessary to target these other species and limit the variety of species in local seafood markets. A longer season may not even be utilized by all fishers, who may want a break from fishing between crab and salmon season to make repairs, modify gear, and spend time with family.

But in exchange for these possible downsides, a reduction of pots would reduce the dreaded opening delay for California Dungeness crab. The 2023 season is already delayed again, for the sixth year in a row. The holidays are incredibly important for optimal pricing and demand, and most Dungeness crab permit holders would sacrifice open-access fishing time for assured Thanksgiving, Christmas, and New Year’s Dungeness crab sales.

Free et al. have provided a useful opportunity to stop and reflect on the rapidly evolving management discourse about minimizing interactions with critically engaged species in pot fisheries. Excellent work is being done in the Northwest Atlantic and worldwide to solve these unique and urgent fishery management problems. But right now, there is no silver-bullet solution. Until there is, we should not overlook the practical effectiveness of traditional management strategies like gear reductions.

Picture of Jack Cheney

Jack Cheney

Jack has sourced, sold, cooked, and sustainably certified seafood over the past 10 years. In addition to his contributions to Sustainable Fisheries UW, he is working to increase traceability into supply chains and educate consumers, chefs and retailers on the value of environmentally sustainable seafood. He earned a Master's in Marine Affairs from the University of Washington in 2015.

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