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By Eleri Griffiths, Blue Parks Intern

Featured Image: The Channel Islands MPA network is located in the Southern California Bight off the coast of southern California. It covers over 3,800 km2 of coastal and ocean waters and includes seagrass beds, kelp forests and coral gardens. The islands’ sandy beaches and rock formations are home to many thousands of seals and sea lions, and also provide nesting habitats for a variety of seabirds. Photo courtesy of Channel Islands National Marine Sanctuary.

Off the coast of southern California, the marine protected area (MPA) network around the Northern Channel Islands aims to preserve biodiversity in a group of fully protected no-take areas, surrounded by a large highly protected area, where some fishing for certain species is permitted. Last year these MPAs, managed collaboratively among California’s Department of Fish and Wildlife, Channel Islands National Park, and Channel Islands National Marine Sanctuary, earned a Blue Park Award. On the Blue Park award’s anniversary, we are learning more about the successful reduction of fishing threats and the challenge from climate change that the park faces.

Long term studies of marine populations around the northern Channel Islands have helped MPA managers and researchers evaluate the effectiveness of their regulations and determine how management strategies can be improved. A recent study conducted by marine biologist Will White and his colleagues [1], compared fishing on four kelp forest fish species inside the MPA network with nearby non-MPA sites. All four species are popular targets for recreational and commercial fishers. The study showed that fishing inside the MPA was effectively zero, while fishing outside of the MPA was up to ten times greater than previous estimates. This suggests that the regulations and enforcement effectively redirected previous fishing activity within the MPA to legal fishing areas. This type of research is complicated because fish can move across MPA borders into areas where they can be legally captured, even if their home range is inside an MPA. However, the population data from within the Channel Islands MPA resembled unfished populations (e.g., the presence of older and larger individuals), rather than populations that have experienced spillover into fished areas. These results suggest that the Channel Islands MPA regulations and enforcement are effectively stopping illegal fishing inside the boundaries and conserving targeted species. [1]

A kelp forest off the coast of Santa Cruz Island. Kelp forests provide nursery habitats for many species of juvenile fish, and are important to the regional ecology of the Channel Islands. Photo: Robert Schwemmer.

However, other studies suggest fishing pressure is not the only relevant threat to Channel Islands’ ecosystems. A recent study published by Freedman et al. (2020) also analyzed the kelp forest fish data of the Channel Islands MPA network to examine fish community structure changes as a result of marine heatwaves. Marine heatwaves significantly increase water temperature and greatly impact marine ecosystems; they are predicted to increase in frequency and intensity as climate change worsens. The Channel Islands experienced a heatwave between October 2014 and June 2016. This study found that as a result of the marine heatwave, populations of warm water species of fish increased at similar rates inside and outside of the MPA, while cool water species declined inside and outside MPA boundaries. So, while MPA regulations effectively protect species from fishing impacts in the Channel Islands MPAs, they may not be as effective at mitigating the impacts of marine heatwaves on fish community structure. [2]

Of course, fish aren’t the only species impacted by warming ocean temperatures. The sunflower sea star (Pycnopodia helianthoides) was added to the IUCN Red List as Critically Endangered after an outbreak of sea star wasting syndrome (SSWS) from 2013-2017 that decimated populations throughout its range from Alaska to southern California. While it is uncertain if the warming climate triggered the outbreak of SSWS, it is clear that the disease was exacerbated by warming conditions, and unusually warm water temperature has been associated with the timing of region-specific outbreaks. For example, the Channel Islands population of Pycnopodia has been studied extensively over time. In deep-water trawl surveys in California between 2004 and 2014, population density of Pycnopodia averaged 2.78 kg/10 ha. However, none were found in 2015 and 2016, and in the Channel Islands they appeared to be locally extinct. Pycnopodia is not a targeted species, but still experienced extreme population declines (its global population was reduced by 91%. Pycnopodia’s decline indicates that even populations of a non-targeted species within a well-regulated MPA can be dramatically impacted by warming ocean temperatures. [3]

A sunflower sea star (Pycnopodia helianthoides) in the Channel Islands National Marine Sanctuary. Photo: Robert Schwemmer, NOAA.

These studies all point toward an important question: how can MPAs be managed to minimize the impact of a warming ocean on marine species and ecosystems? What additional or alternative management strategies and regulations need to be put in place? Freedman et al. (2020) acknowledge that increasing fishing regulations in MPAs or otherwise adjusting fishing pressures may not be enough to address the community-level effects of warming ocean temperatures. Because place-based protections cannot fully mitigate the global effects of climate change, strong policies are needed at all levels of government to stem greenhouse gas emissions and control additional climate change impacts that are being felt not only in the Channel Islands, but across the global ocean.

Impacts from warming, acidification, and hypoxia will increase as climate change accelerates, and more research is needed on the effectiveness of different management actions to navigate the threats posed by these changes. Different species will respond and adapt to warming temperatures and other climate impacts differently. Thus, the appropriate management actions to mitigate climate impacts may be different on a site-by-site basis; and these considerations need to be better understood and addressed.

Fortunately, work on mitigation strategies has already started in the Channel Islands National Marine Sanctuary, the Channel Islands National Park, and the California State MPAs to try to reduce impacts from climate change which threatens their conservation goals. Their respective management plans do identify strategies to mitigate these threats, and include actions such as continued monitoring and evaluations with various research partners and agencies, biodiversity conservation work, issuing lower numbers of visitor permits and educating visitors on “Leave No Trace” practices. Mitigation strategies to address climate change will need to evolve as we learn more about what works and what doesn’t. Currently, the Channel Islands National Marine Sanctuary is updating its management plan with a climate change action plan. This focus on conservation management in the face of climate change could provide a valuable guide for other MPA managers on the west coast and elsewhere. [4, 5, 6]  We certainly hope so.

[1] Wilson White, J. et al. (2020) Analysis of fish population size distributions confirms cessation of fishing in marine protected areas, Conservation Letters, pp. 1-9.

[2] Freedman, R.M. et al. (2020) Marine protected areas do not prevent marine heatwave-induced fish community structure changes in a temperate transition zone, Scientific Reports 10: 1-8.

[3] Gravem, S.A. et al. (2021) Pycnopodia helianthoides. The IUCN Red List of Threatened Species 2021. Retrieved December 2020 from

[4] U.S. Department of Commerce, NOAA, National Marine Sanctuary Program (2008) Channel Islands National Marine Sanctuary Management Plan/Final Environmental Impact Statement.

[5] U.S. Department of Interior, National Park Service (2015) Channel Islands National Park Final General Management Plan / Wilderness Study / Environmental Impact Statement.

[6] California Department of Fish and Wildlife (2016) 2016 Master Plan for Marine Protected Areas.