Although small protected marine zones are important for conservation, they do not protect fish as well as larger areas do.
Nicholas Graham at James Cook University in Townsville, Australia, and Tim McClanahan at the Wildlife Conservation Society in New York assessed biomass and composition of coral-reef fish in several marine protected areas in the Indian Ocean. The authors compared small no-take zones — areas less than 10 square kilometres that were protected from human disturbance — with much larger marine 'wildernesses'. At a depth of 9 metres, mean fish biomass in the 640,000-square-kilometre Chagos Archipelago weighed in at six times the amount per hectare than that of the most successful small no-take zone. Coral reef wildernesses in the Caribbean Sea and Pacific Ocean were similarly heavy with biomass.
Bioscience http://dx.doi.org/10.1525/bio.2013.63.5.13 (2013)