Effectiveness of Large-Scale Marine Protected Areas in the Atlantic Ocean for Reducing Fishing Activities

Rafael Almeida Magris

doi:10.3389/fmars.2021.711011

Abstract

The implementation of large-scale marine protected areas (MPAs) depends upon scarce conservation resources, while their effects on biodiversity conservation are rarely assessed to date. Quantitative evaluations are necessary to assess the effectiveness of large-scale MPAs in enhancing ecosystem resilience, protecting biodiversity, and mitigating expanding threats. In this study, the effectiveness of large-scale MPAs, which are remotely managed and in offshore areas of the southwestern Atlantic Ocean (Brazil), was assessed concerning the occurrence of fishing activities within their boundaries before and after their implementation. Two sets of MPAs surrounding the São Pedro and São Paulo archipelago (SPSP) and the Trindade-Martin Vaz Islands (TMV) were established in early 2018, each comprising one no-take (i.e., fully-protected) and one multiple-use (i.e., partially-protected) area. For this assessment, I used satellite detections of Vessel Monitoring System transmission to quantify the fishing pressure (i.e., “likely fishing days”) from commercial fisheries spanning 5 years (2015–2019). I then derived three metrics – fishing area, intensity, and density – to compare fishing activity within each MPA and year. The results showed that the effectiveness of the multiple-use MPAs was variable and contrasting, with SPSP experiencing a reduction in the fishing intensity and area and TMV experiencing an increase in both measures. An inverted pattern was evident for the no-take MPAs: while the one in the SPSP region experienced an increase in the fishing density after its establishment following a squeeze factor, the no-take MPA in the TMV region observed a decrease in the fishing density when comparing years before and after MPA implementation. These outputs can support managers in planning the implementation of further conservation strategies, such as monitoring and enforcement plans, and the analyses here also contribute to enhancing our understanding on the implications and challenges of adopting large-scale MPAs in the offshore environment as a high-profile strategy of ocean conservation.

Highlights

Fishing is a leading cause of disturbances in the marine realm with consequences such as trophic cascade (Mumby et al, 2006; Shears et al, 2008) and loss of habitats (Kaiser et al, 2002; Lundquist et al, 2018)
Following White et al (2020), I sought to partially control for changes in fishing pressure not related to the modification of the protection status of the study regions. For this last set of analyses, I compared each measure of fishing pressure calculated as above against the same metrics associated with cells randomly selected across Brazil’s EEZ, and limited to the corresponding total size of one set of large-scale marine protected areas (MPAs) (i.e., 455,000 km2)
For the São Pedro and São Paulo archipelago (SPSP) region (Figure 1), I recorded a hotspot of likely fishing days on the northwestern portion of the multiple-use MPA, between the years 2015 and 2016, and on the southern portion of this MPA for the year 2017

Summary

INTRODUCTION

Fishing is a leading cause of disturbances in the marine realm with consequences such as trophic cascade (Mumby et al, 2006; Shears et al, 2008) and loss of habitats (Kaiser et al, 2002; Lundquist et al, 2018). Recent years have seen an increase in the development of large-scale MPAs (i.e., larger than 100,000 km2) over offshore and deep areas (Boonzaier and Pauly, 2016), following an ad hoc, opportunistic process (O’Leary et al, 2018) For these conservation efforts to drive outcomes for biodiversity, they must translate into significant mitigation of human impacts, derived from fishing activity. The system is not tamper-proof (Appleby et al, 2018), it might be the only tool available to assess patterns of fishing activity and provides historical valuable information such as the vessel’s identity, position, and associated fishing gear These data can provide a unique baseline for determining whether MPAs are effective at reducing threats in the absence of other monitoring tools. I used a longterm, large dataset tracking the movements of commercial fishing vessels before and after the two of the largest MPAs in the southern Atlantic Ocean (within Brazil’s exclusive economic zone) were established – i.e., between the years 2015 and 2019 – to provide evidence of their effectiveness at reducing fishing pressure

METHODS

RESULTS

DISCUSSION

DATA AVAILABILITY STATEMENT