Percentage conservation targets are problematic for marine mammals

Abstract

Pompa et al. (1) carried out a systematic assessment of conservation requirements for marine protected areas (MPAs) to conserve all marine and freshwater mammal species globally. Although this is an impressive assessment, the conclusions of the study are problematic. The authors point out that the target areas in their analysis comprise 12% of the ocean's area. This number is eerily reminiscent of percent conservation targets in terrestrial conservation (2). We have outlined previously (3) why percentage targets for terrestrial conservation areas are problematic. However, percentage targets continue to be advocated for in marine conservation (4). Percentage targets, in both terrestrial and marine domains, are most commonly based on the concept of representativeness. Identifying areas that are representative of wider biodiversity patterns requires good data on the overall distribution of these elements. In the terrestrial realm, this is difficult enough; this is even more challenging in oceans, in which biodiversity patterns are even less well understood. Recent work suggests strategies for assessing the suitability of marine species survey data for understanding habitat representation, and that given the paucity of marine data, that opportunistic conservation planning may be as effective as systematic plans (5).