Modelling spillover effects of a marine protected area in the Western Indian Ocean

Abstract

This study estimated the abundance gradient of fishes in the waters surrounding a marine protected area (MPA) and used this information as evidence of spillover from the MPA. Fish landing data were collected from trap fishermen over a 12-month period from the Blue Bay Marine Park on the west coast of Mauritius in the Western Indian Ocean. Two indicators of abundance were used: catch per trap, and number of fish per trap. A Generalised Linear Model was used to standardise the catch data by removing the effects of individual fishermen’s productivity from the abundance measurements while the negative-binomial distribution was used for the number of fish. The study found a slight declining gradient of catch beyond the MPA up to a distance of 4 km. The study also established that the individuals belonging to key species caught near the MPA were larger than those of the same species caught more than 4 km away. The negative gradient reinforces the evidence of spillover occurring from the MPA.