Deon Kotze, Santosh Bachoo, Darrell Anders, Mike Meyer, Herman Oosthuizen, Ronel Nel, Steven McCue, Linda R. Harris
Harnessing the economic potential of the oceans is key to combating poverty, enhancing food security, and strengthening economies. But the concomitant risk of intensified resource extraction to migratory species is worrying given that these species contribute to important ecological processes, often underpin alternatively livelihoods, and many are already threatened. We thus sought to quantify the potential conflict between key economic activities (five fisheries and hydrocarbon exploitation) and sea turtle migration corridors in a region with rapid economic development: Southern and East Africa. From 20 loggerhead and 14 leatherback tracks, we used movement-based kernel density estimation to identify three migration corridors for each of the two species. We overlaid these corridors on maps of the distribution and intensity of economic activities, quantified the extent of overlap and threat posed by each activity on each species, and compared the effects. These results were compared to annual bycatch rates in the respective fisheries. Both species’ corridors overlap most with longlining, but the effect is worse for leatherbacks: bycatch rates are substantial (ca. 1500 per annum) relative to the regional population size (<100 females nesting per annum), likely slowing the population growth rate. Artisanal fisheries are of greater concern for loggerheads, but the population appears to be withstanding the high bycatch rates because it is increasing exponentially. The hydrocarbon industry currently has a moderately low impact, but exploitation in key areas (e.g., Southern Mozambique) has the potential to undermine more than 50 years of conservation efforts, affecting >80% of the loggerhead population, 33% of the (critically endangered) leatherback population, and their nesting beaches. We support establishing blue economies, but oceans need to be carefully zoned and responsibly managed in both space and time to achieve economic (resource extraction), ecological (conservation, maintain processes) and social (maintain alternative livelihood opportunities, combat poverty) objectives.
This article is protected by copyright. All rights reserved