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The science of sustainable seafood, explained

A biodiversity framework for U.S. MPAs must include all threats and solutions

A recently proposed method to evaluate biodiversity protection in U.S. marine waters is severely flawed and will damage U.S. interests if adopted by NOAA.

Gignoux-Wolfsohn et al. 2024, published in One Earth, only considered U.S. waters sufficiently protected if they are no-take areas, despite strong evidence that other forms of protection may be equally or more effective. The net result of Gignoux-Wolfsohn et al. 2024 is a catalog of what biota are found in no-take marine protected areas (MPAs), not an effective framework for marine biodiversity protection.

Frameworks are important tools in conservation, science, and government as they provide a standardized series of guidelines for practitioners to follow. For example, National Standard 2 of the Magnuson-Stevens Act states that conservation and management measures shall be based on “the best scientific information available.” Best available science is a framework for decision-making and management.

Gignoux-Wolfsohn et al. 2024 propose a new framework for biodiversity protection. They (correctly) begin their framework by identifying elements of marine biodiversity of concern and what metrics are available. However, they fail to identify the specific threats to each type of biodiversity—a critical flaw. Actors and organizations cannot determine what level of protection is needed without identifying those threats. For example, Gignoux-Wolfsohn et al. 2024 state: “cold-water corals harbor rich biodiversity in the deep sea but cold-water coral habitat is poorly protected in most U.S. waters.”

Yet, every known deep-water coral bed in U.S. waters is protected from bottom trawling—the most significant threat to deep-water coral. But, because fishing is allowed hundreds of feet above the coral, they are not considered “protected” by Gignoux-Wolfsohn et al. 2024.

Gignoux-Wolfsohn et al. 2024 acknowledge that they are working from a perspective that no-take fishing protected areas (FPAs) “are most effective at increasing biomass, diversity, and body size of marine life,” so the protections in place for deep-water coral don’t count in their framework because hook and line fishing is allowed in the water column, even though hook and line fishing does not affect the deep-water coral. This is the major conceptual flaw in their framework—specific threats need specific actions, not broad fishing bans.

The framework did not consider the many forms of biodiversity protection that are not no-take areas, e.g. overfishing has largely been eliminated in the United States by regulating fishing effort and catch. Bycatch has been greatly reduced by gear technology improvements such as turtle excluder devices, streamer lines to prevent seabird bycatch in longlines, and a wide range of other technical measures, which are far more effective than closing areas to fishing and simply moving boats and fishing effort elsewhere.

All of these issues are highlighted in the contrast between the measured protection in Alaska compared to the U.S. Pacific Islands. Under the framework, the Pacific Islands scored high due to large no-take areas, while Alaska scored low due to few no-take areas.  Yet the large MPAs in the Pacific Islands have had little impact on biodiversity because fishing in the closed areas simply moved elsewhere. The many actions taken in Alaska including extensive bycatch reduction, strict regulation of catch, and closure of sensitive habitats to bottom contact gear have had far more benefits to biodiversity than the actions taken in the Pacific Islands.

Reality says Alaska fisheries management is among the very best in the entire world, a theoretical framework that says otherwise is operating on flawed principles.

The framework relies on MPA dogma

The orthodoxy reflected in Gignoux-Wolfsohn et al. 2024  is that no-take MPAs are the most effective form of biodiversity protection; yet it is widely accepted that there are many non-fishing threats to marine biodiversity like global warming, ocean acidification, sea level rise, exotic species, shipping, coastal development, and terrestrial runoff of sediments and pollutants. No-take MPAs have no impact on those threats.

The Australian State of New South Wales ranked the threats to their coastal marine ecosystems and found the top three threats were urban stormwater discharge, estuary entrance modification, and agricultural diffuse source runoff. Recreational fishing ranked as threat #13 and commercial fishing #17. Thus, MPAs failed to protect their coastal waters from the top 12 threats.

There are also fishing threats that no-take MPAs either don’t reduce or reduce very little, for example bycatch of non-target species. The primary impact of MPAs on fisheries is to cause the boats to fish elsewhere, with a net result that the bycatch may continue or even increase as fishing effort becomes concentrated in smaller areas. While fishing impacts are eliminated inside an MPA, the net result is no benefit to regional or global biodiversity. 

Recent reviews of the extensive MPA network in California have concluded there is no evidence for a regional increase in biodiversity or target fish abundance, nor is there evidence for the MPAs providing climate resilience. MPAs do not appear to increase the resilience of U.S. coral reefs because fishing threats are dwarfed by warming and terrestrial impacts. The effect of MPAs “protecting” biodiversity by reducing fishing is, at best, equivocal.

In summary, the framework proposed by Gignoux-Wolfsohn et al. 2024  provides no useful measure of biodiversity protection, and unless modified to specifically evaluate actions that reduce threats, is not a credible guide for progress in ocean protection.

Picture of Max Mossler

Max Mossler

Max is the managing editor at Sustainable Fisheries UW.

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