Data from: Shark movement strategies influence poaching risk and can guide enforcement decisions in a large, remote Marine Protected Area

Large, remote marine protected areas (MPAs) containing both reef and
pelagic habitats, have been shown to offer considerable refuge to
populations of reef-associated sharks. Many large MPAs are, however,
impacted by illegal fishing activity conducted by unlicensed vessels.
While enforcement of these reserves is often expensive, it would likely
benefit from the integration of ecological data on the mobile animals they
are designed to protect. Consequently, shark populations in some protected
areas continue to decline, as they remain a prime target for illegal
fishers. To understand shark movements and their vulnerability to illegal
fishing, three years of acoustic tracking data, from 101 reef-associated
sharks, were analysed as movement networks to explore the predictability
of movement patterns and identify key movement corridors within the
British Indian Ocean Territory (BIOT) MPA. We examined how space use and
connectivity overlap with spatially-explicit risk of illegal fishing,
through data obtained from the management consultancy enforcing the MPA.
Using individual-based models, the movement networks of two sympatric
shark species were efficiently predicted with distance-decay functions
(>95% movements accurately predicted). Model outliers were used to
highlight the locations with unexpectedly high movement rates where MPA
enforcement patrols might most efficiently mitigate predator removal.
Activity space estimates and network metrics illustrate that silvertip
sharks were more dynamic, less resident and link larger components of the
MPA than grey reef sharks. However, we show that this behaviour
potentially enhances their exposure to illegal fishing activity. Synthesis
and applications. Marine protected area (MPA) enforcement strategies are
often limited by resources. The British Indian Ocean Territory MPA, one of
the world’s largest ‘no take’ MPAs, has a single patrol vessel to enforce
640,000 km2 of open ocean, atoll and reef ecosystems. We argue that to
optimise the patrol vessel search strategy and thus enhance their
protective capacity, ecological data on the space use and movements of
desirable species, such as large-bodied reef predators, must be
incorporated into management plans. Here, we use electronic tracking data
to evaluate how shark movement dynamics influence species mortality
trajectories in exploited reef ecosystems. In doing so we discuss how
network analyses of such data might be applied for protected area
enforcement.