Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis 88040-900, Brazil.
Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Radolfzell 78315, Germany.
Proc Natl Acad Sci U S A. 2023 Feb 7;120(6):e2207739120. doi: 10.1073/pnas.2207739120. Epub 2023 Jan 30.
Interactions between humans and nature have profound consequences, which rarely are mutually beneficial. Further, behavioral and environmental changes can turn human-wildlife cooperative interactions into conflicts, threatening their continued existence. By tracking fine-scale behavioral interactions between artisanal fishers and wild dolphins targeting migratory mullets, we reveal that foraging synchrony is key to benefiting both predators. Dolphins herd mullet schools toward the coast, increasing prey availability within the reach of the net-casting fishers, who gain higher foraging success-but only when matching the casting behavior with the dolphins' foraging cues. In turn, when dolphins approach the fishers' nets closely and cue fishers in, they dive for longer and modify their active foraging echolocation to match the time it takes for nets to sink and close over mullets-but only when fishers respond to their foraging cues appropriately. Using long-term demographic surveys, we show that cooperative foraging generates socioeconomic benefits for net-casting fishers and ca. 13% survival benefits for cooperative dolphins by minimizing spatial overlap with bycatch-prone fisheries. However, recent declines in mullet availability are threatening these short- and long-term benefits by reducing the foraging success of net-casting fishers and increasing the exposure of dolphins to bycatch in the alternative fisheries. Using a numerical model parametrized with our empirical data, we predict that environmental and behavioral changes are pushing this traditional human-dolphin cooperation toward extinction. We propose two possible conservation actions targeting fishers' behavior that could prevent the erosion of this century-old fishery, thereby safeguarding one of the last remaining cases of human-wildlife cooperation.
人类与自然的相互作用产生了深远的影响，这些影响很少是互利的。此外，行为和环境的变化可能会使人类与野生动物的合作关系转变为冲突，从而威胁到它们的持续存在。通过跟踪手工捕鱼者和以洄游性鲻鱼为目标的野生海豚之间的精细行为相互作用，我们揭示了觅食同步性是使双方都受益的关键。海豚会将鲻鱼群驱赶到海岸边，增加网捕渔民能够捕获的猎物数量，从而使渔民的觅食成功率更高——但前提是渔民的投网行为与海豚的觅食线索相匹配。反过来，当海豚靠近渔民的渔网并向渔民发出信号时，它们会潜得更深，并调整其主动觅食声纳，以适应渔网下沉和关闭的时间——但前提是渔民能够适当地回应它们的觅食线索。通过长期的人口统计调查，我们发现合作觅食为网捕渔民带来了社会经济效益，使合作海豚的存活率提高了约 13%，因为这种觅食方式减少了与易受捕捞影响的渔业的空间重叠。然而，由于鲻鱼数量的减少，合作捕鱼的短期和长期利益都受到了威胁，这降低了网捕渔民的觅食成功率，并增加了海豚在替代渔业中被误捕的风险。我们使用一个用我们的经验数据参数化的数值模型预测，环境和行为的变化正在使这种传统的人类与海豚的合作关系走向灭绝。我们提出了两种可能的保护措施，旨在针对渔民的行为，以防止这种百年渔业的侵蚀，从而保护这一尚存的人与野生动物合作的最后案例之一。
