Changes in illegal fishing dynamics in a large-scale MPA during COVID-19.

Global socio-ecological shocks, such as the COVID-19 pandemic, can threaten progress in protecting vulnerable marine environments by altering behaviour of resource users1. When government priorities shift from environmental protection towards safeguarding human populations, control of illegal activity in protected areas can alter. Resulting increases in illegal fishing in large-scale marine protected areas (MPAs) are of particular concern as they contain a large proportion of marine protected area globally2. Here, we report on average 19 times as many suspected illegal fishing vessels per month in 2022 (n = 19) compared with 2010 to 2020 (n = 1) in an Indian Ocean MPA. Although illegal fishing has been a pervasive problem, the current spike in Indian vessels targeting a broad trophic diversity of reef-associated species is of particular concern and we suggest such changes in illegal activity in MPAs globally may persist over long timescales unless management is broad and adaptive to individual context. When considering potential solutions, widespread adoption of technology, such as remote surveillance of vessels, can mitigate illegal activities but remains unfeasible for many MPAs globally due to financial and political barriers. Instead, we suggest broader approaches, including a renewed focus on regional approaches to combating illegal fishing, formal bilateral agreements between competent authorities in relevant countries and an increase in community-based work.

A comparison of methods to determine chimpanzee home-range size in a forest-farm mosaic at Madina in Cantanhez National Park, Guinea-Bissau.

Human activities impact the distribution of numerous species. Anthropogenic habitats are often fragmented, and wildlife must navigate through human-influenced and 'natural' parts of the landscape to access resources. Different methods to determine the home-range areas of nonhuman primates have not considered the additional complexities of ranging in anthropogenic areas. Here, using 6 months of spatial data on the distribution of chimpanzee presence (feces, feeding traces, nests, opportunistic encounters; n = 833) collected across the wet and dry seasons, we examine different analytical techniques to calculate the home-range size of an unhabituated chimpanzee (Pan troglodytes verus) community inhabiting a forest-farm mosaic at Madina, Cantanhez National Park in Guinea-Bissau. The minimum convex polygon method and the grid cell (500 m × 500 m cell size) method estimated the chimpanzees home-range size at 19.02 and 15.50 km2, respectively with kernel analysis calculating a lower value of 8.52 km2. For the grid cell method, home-range estimates varied with cell size, with larger cells producing larger estimates. We compare our home-range estimates with other chimpanzee research sites across Africa. We recommend the use of kernel analysis for determining primate home ranges, especially for those groups exploiting fragmented habitats including forest-farm mosaics, as this method takes account of inaccessible or infrequently used anthropogenic areas across the complete home range of the primate group. However, care must be taken when using this method, since it is sensitive to small sample sizes that can occur when studying unhabituated communities, resulting in underestimated home ranges.