Residual bias in the distribution of marine protected areas

Abstract

In recent years, marine conservation science and policy has reflected concerns that the global distribution of marine protected areas (MPAs) does not reflect the distribution of marine areas most at risk from human activity. Several research papers have raised the concern that there is a widespread pattern of residual bias in the distribution of MPAs. Residual bias occurs when the likelihood of an area being protected decreases as human pressures (such as fishing or pollution) on the marine environment increase. It is thought to occur due to political reluctance to remove user access to economically important areas. This research aimed to test for residual bias in MPAs in response to multiple different pressures and levels of protection. The research addressed this aim by investigating whether the type and intensity of pressures on the marine environment negatively affect the likelihood of an area being protected. These factors were addressed using spatial analysis methodologies to calculate the intensity of 17 different pressures from human activity within protected and unprotected areas. Binomial generalised linear models were then used to determine whether increasing intensity of 17 different pressures on the marine environment would decrease the likelihood of that area being protected. The area of study is described as 'global', and encompasses national waters (exclusive economic zones) of coastal states with marine protected areas in place.

This analysis indicated that residual bias was not a blanket phenomenon that applied to every pressure assessed. Rather, it is a highly variable pattern which appears to occur in response to some pressures, such as commercial pelagic fisheries, whereas others were found to be positively associated with protection, including human population and demersal commercial fisheries. Changing the level of protection (ranging from strict no-take reserves to sustainable resource use) did not change the direction of the relationship between protection and individual pressures, with all levels of protection being either positively or negatively associated with the different pressures.