Marine protected areas benefit some fish... but not others

Titan Triggerfish (Balistoides viridescens) in Maldives. Credit, Jan Derk.A new study published in Ecological Applications demonstrates that the outcomes of fully protected, no-take areas in the ocean differ among fish species.

Many previous studies have shown that not all species increase in abundance in no-take areas, and this study indicates that the conservation benefits depend partly on the fish’s life history and ecological traits.

During the last 10 to 15 years, people with an interest in ocean conservation have pushed increasingly for establishment of marine reserves, which are areas of the ocean where all types of fishing and many other human activities are prohibited.

Currently, only a tiny fraction of the world’s ocean is protected in marine reserves. Marine scientists have conducted extensive research on marine reserves and found that the reserves typically produce ecological benefits that complement those of other resource management approaches.

In general, biodiversity is higher in marine reserves, and fish and invertebrates are bigger and more abundant within the protected areas.  

In the new study, Joachim Claudet along with 20 collaborators examined 40 fish datasets from 12 European marine reserves. The data covered a period of 33 years.

For each species, they quantified the difference in abundance between marine reserves and comparable unprotected areas outside, and they categorized the species based on life histories and ecological traits.

The study confirms the widely recognized fact that fish species do not respond uniformly to the establishment of marine reserves.

As expected based on intuition and previous studies, the scientists found that commercially targeted fish species tended to be more plentiful in the protected waters. Large-bodied species that do not usually swim in schools showed the biggest increase in marine reserves.

Interestingly, species that are commonly caught as bycatch in commercial fisheries did not show the same pattern of increase as the species targeted by commercial fisheries. Unexploited speces also rarely showed increases from protection.

Most notably, the research team found that wide-ranging fish with extensive home ranges were more abundant inside marine reserves, even though some people have postulated that marine reserves would offer little protection for these species.

To explain this finding, the authors suggest that wide-ranging species may preferentially stay in marine reserves, where they find healthier habitats and more plentiful prey.

This study provides further evidence that marine reserves should be viewed not as a panacea for protecting all species equally, but rather as a useful management tool that is likely to benefit some species more than others.

-- By Peter Taylor

Claudet, J., Osenberg, C., Domenici, P., Badalamenti, F., Milazzo, M., Falcón, J., Bertocci, I., Benedetti-Cecchi, L., García-Charton, J., Goñi, R., Borg, J., Forcada, A., de Lucia, G., Pérez-Ruzafa, A., Afonso, P., Brito, A., Guala, I., Diréach, L., Sanchez-Jerez, P., Somerfield, P., & Planes, S. (2010). Marine reserves: Fish life history and ecological traits matter Ecological Applications, 20 (3), 830-839 DOI: 10.1890/08-2131.1