Are MPAs protecting sharks & rays?

Marine protected areas (MPAs) are a popular conservation tool implemented around the world to manage marine biodiversity and protect sensitive habitats, but how do we make sure they’re achieving the conservation goals we set for them? This question interests Mark Bond, a postdoctoral researcher at Florida International University, whose PhD findings led him to conduct a global review of the effects of MPAs on elasmobranchs. As he notes, ensuring that MPAs adequately protect species is important to make their designation defensible and to maintain the trust of the people involved in their implementation and enforcement. ‘If we propose MPAs as a solution, we need to have empirical, long-term evidence that they work. If we can’t show this, we risk losing the trust of the stakeholders.’

Researchers typically investigate changes in the biomass (total mass), density (number of individuals in a given area), diversity and abundance of species inside and outside MPAs to assess their efficacy. ‘All the evidence that we have using these measures is limited to bony fishes and species like rock lobsters and conch,’ says Bond. To make more informed decisions about the conservation management of sharks and rays, scientists must take into account their different life history strategies, the fact that they are highly mobile and may move in and out of MPAs, and their conservation status. ‘We want to be confident that when we say MPAs work, they work for the species that we are talking about, and that we don’t need to rather employ another measure, like controlling trade,’ explains Bond. It’s about ensuring that we match the conservation strategy best suited to a species based on its individual life history and behaviour.

To explore how well we’re currently protecting elasmobranchs using MPAs, Bond trawled through the published scientific literature and reached out to scientists working around the world. An interesting preliminary note, he says, is that studies on elasmobranchs in MPAs are restricted to tropical coral reefs. ‘We’re very limited in terms of where we’re seeing this evidence, and also only from a very small set of species within that ecoregion. So we really need to broaden that to include temperate seas, and look to deeper waters.’ As his work is starting to show, identifying current gaps in the available data for sharks and rays can guide future research and collaborative efforts to help build a strong evidence base for decision-making.