California Dungeness Crab Fishery (United States)
Dungeness crab (Metacarcinus magister) support California’s most lucrative commercial fishery and play a central role in the portfolio of species targeted by fishers. Recently, the fishery has experienced extensive closures and unpredictability resulting from heatwave-induced harmful algal blooms, which produce biotoxins that accumulate in crabs and present a public health risk if consumed, and increased entanglements of humpback whales and other protected species in Dungeness crab fishing gear, which presents a conservation risk. The massive economic importance of the fishery has catalyzed extensive government and stakeholder actions to increase the resilience of the fishery to these climate-induced stressors. The resilience of the fishery has depended on participatory management for guiding management of entanglement risks, expansions in the resolution of biotoxin management zones and the options for managing biotoxin risk in the fishery, and use of the federal fisheries disaster program to provide relief to impacted fishers, processors, and dealers. The fishery is insulated by the high productivity and economic importance of the resource. The resilience of the fishery to climate change could be further enhanced by reforming the federal fisheries disaster program to be more accurate, timely, and equitable, increasing the spatial-temporal resolution of biotoxin monitoring to enable more surgical management, and using quantitative tools to guide decisions around entanglement risk management.
Dungeness crab (Metacarcinus magister) range from Point Conception, California through the Alaskan Aleutian Islands (CDFW, 2011) and support one of the most economically important fisheries on the U.S. West Coast (NMFS, 2020). In California, Oregon, and Washington, the commercial Dungeness crab fishery has generated ~$200 million in gross revenues every year since 2010, and annually supports over 1,000 participants (CDFW, 2020). As a result, the Dungeness crab fishery is central in fishing networks from Central California to Washington, which makes both fishers and adjacent fisheries sensitive to perturbations to this critical fishery (Fisher et al., 2021; Fuller et al., 2017). Landings (and likely the population size) of Dungeness crab have fluctuated through time as a result of environmental factors (Armstrong et al., 2011; Rasmuson, 2013). However, until recently, simple “3S” management — which only allows harvest of male crabs (sex) larger than 6.25 inches (size) from midwinter through summer (season) — has been sufficient to maintain a sustainable and profitable fishery (Richerson et al., 2020).
A recent marine heatwave nicknamed “the blob” (Bond et al., 2015) dramatically disrupted this traditionally sustainable, profitable, and relatively easily managed fishery through two indirect pathways. First, during the 2015-16 season, the marine heatwave caused a harmful algal bloom (HAB) of unprecedented size and duration (McCabe et al., 2016; McKibben et al., 2017), leading to extended coastwide closures of Dungeness crab and other critical fisheries (especially in California) as a result of dangerous levels of biotoxin contamination (Free et al., 2022). Then, in California, the opening of the delayed season in mid-April resulted in the inadvertently intensified overlap in fishing effort and humpback whale abundance, exacerbated by the heatwave-driven compression of humpback whale foraging grounds (Santora et al., 2020). This perfect storm of heatwave-sparked shifts resulted in a dramatic spike in the number of humpback whale entanglements, the majority of which were attributed to Dungeness crab fishing gear (Saez et al., 2020). This precipitated a lawsuit by the Center for Biological Diversity alleging that California’s management of the Dungeness crab fishery threatened endangered species and was non-compliant with the Endangered Species Act (CA DOJ, 2017).
The economic impacts of HAB and whale entanglement closures have been significant. In California, revenues were 58% lower during the 2015-16 season than during the previous five years (PSMFC, 2021, p. 20). This led the Governor of California to request federal fisheries disaster assistance stating that the delay had cost an estimated $48.3 million in direct economic impacts (Brown, 2016). However, this pronouncement was made before the fishery even opened. A re-analysis that more accurately considered population size and participation in non-crab fisheries estimated that losses were closer to $26.1 million, with losses coming from the Dungeness crab fishery and other non-crab fisheries in nearly equal proportions (Holland & Leonard, 2020). Although this estimate is closer to the $25 million of disaster aid ultimately appropriated by Congress (Thom, 2018), the aid was not distributed to affected harvesters, processors, and dealers until more than three years after the disaster (C. Bonham, personal communication, July 19, 2018). Furthermore, smaller vessels — potentially limited by their mobility — were disproportionately impacted by the delay (Jardine et al., 2020) yet received less disaster relief than larger vessels (C. Bonham, personal communication, July 19, 2018). Furthermore, early closures of the fishery during the 2019-20 and 2020-21 fishing seasons to reduce whale entanglement risk cost the fishery an estimated $9.7 million and $14.4 million in revenues, respectively (Seary et al., 2022).
The resilience of the commercial Dungeness crab fishing fleet to these stressors has depended on a combination of fisher behavior, federal disaster relief, improvements to biotoxin monitoring and management, and the development of a particory adaptive management program for mitigating whale entanglement risk. During the 2015-16 season delays, the ability of fishers to move and target different species reduced the economic impact on the livelihoods of some fishers (Fisher et al., 2021). Furthermore, Congress declared the 2015-16 season a federal fisheries disaster and distributed $25 million in disaster aid to affected harvesters, processors, and dealers (Thom, 2018), easing revenue losses during the heatwave. The state also improved its biotoxin management program by establishing clear biotoxin management zones that are closed and opened based on the monitoring conducted within them (Free et al., 2022). This action increased transparency, consistency, and predictability for fishers and enabled more efficient management (i.e., management that eliminates public health risk through the lowest impacts to fishing communities). Finally, and perhaps most importantly, a multi-stakeholder working group was convened to inform an extensive and ongoing overhaul of California’s marine life entanglement risk management plan (CDCFGWG, 2018). This working group includes representatives from the fishing industry and ensure that fishing industry interests, knowledge, and experience are represented in management decisions. Although the overwhelming economic importance of the fishery has made the fishery a high priority and enabled these resilience actions, it may inhibit long-term resilience if fishers are unable to escape the “gilded trap” of being so dependent on a lucrative but potentially volatile fishery.
Although these attributes have generally promoted the resilience of the California Dungeness crab fishery to extreme climate events, there are still several challenges to overcome. First, vessels that specialize in Dungeness crab were more likely to stop fishing during the 2015-16 season and smaller boats were less able to relocate to new fishing grounds (Fisher et al., 2021). This will require management flexibility to allow fishers to diversify their portfolios, especially during challenging times. Second, federal fisheries disaster relief was not distributed to affected harvesters, processors, and dealers until more than three years after the disaster and smaller vessels received smaller payouts despite being disproportionately impacted (Bellquist et al., 2021). Ensuring more accurate, timely, and equitable disaster assistance will be necessary for this program to become an efficient instrument for enhancing climate resilience. Third, California lags behind the other West Coast states in the spatial-temporal frequency of its biotoxin monitoring, which could impede the efficiency of biotoxin management in the fishery (Free et al., 2022). Finally, recent research suggests that the management options considered by the whale entanglement working group would reduce entanglement risk but at considerable cost to the fishery (Free et al., in prep; Samhouri et al., 2021). Investment in new quantitative approaches for evaluating the performance of alternative strategies for preventing whale entanglements is necessary to guide informed management decisions.
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Photo: Fishing for Dungeness crab in California. Credit: California Department of Fish and Wildlife