Genetic evidence shows larvae from reserves are reseeding fisheries
Researchers have proven, using DNA analysis, that larvae from adult fish inside a network of no-take marine reserves in Hawai'i are spilling into fished areas and helping to reseed fisheries. Studying more than 1000 juvenile and adult yellow tang - a fish species popular in the aquarium trade - scientists determined that many healthy juvenile fish had spawned from parents long distances away, as far as 184 km, including from MPAs. The research team claims its study is the first direct evidence of large-scale population connectivity within an existing and effective network of MPAs.The network of nine reserves under study was designated in 1999 on the west coast of the island of Hawai'i. Called fish replenishment areas (FRAs), the closures were intended primarily to address a long-standing user conflict between dive tour operators and aquarium fish collectors (MPA News 11:1, "Updates on MPA Networks in Progress..."). The study "Larval Connectivity in an Effective Network of Marine Protected Areas" appears in the journal PLoS ONE at www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0015715.
MPAs generally improve fish catch per unit effort for most, but not all
A review of the scientific literature on marine protected areas has determined that, following MPA designation, catch per unit effort (CPUE) for local fishing groups generally remains stable or increases in cases of older and smaller MPAs. The study, published in Conservation Biology, suggests both biological and social factors are at play in this. Older MPAs tend to build up fish biomass over time, and smaller MPAs may experience higher rates of fish spillover to adjacent waters. Meanwhile MPAs may also reduce competition for fish resources by reallocating fishing rights.
However, CPUE did not increase across the board: a minority of fishing subgroups, about 15%, experienced declines in CPUE following MPA designation. "This suggests that MPAs may represent a viable strategy for enhancing food security and empowering local communities, but current MPA practices negatively affect at least a minority of fishers," write the authors. The abstract for the study "Impacts of Marine Protected Areas on Fishing Communities" is available at http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2010.01523.x/abstract. For the full article, e-mail lead author Michael Mascia at michael.mascia [at] wwfus.org.