A new study published in the journal Mammal Review has found that in South America, pinnipeds such as seals, sea lions, and fur seals are currently at significant risk from interactions with local fisheries and aquaculture. These animals often become entangled in nets or cages and, as a result, many of them drown.
By analyzing studies conducted over the past 25 years on operational and biological interactions between these marine mammals and South American fisheries and aquaculture activities, the researchers discovered that two species – the South American sea lion (Otaria flavescens) and the South American fur seal (Arctocephalus australis) – are involved frequently in such interactions. However, since the economic losses to fisheries and aquaculture related to sea lion depredation are rather low, no major actions to solve this problem have been undertaken. Moreover, while incidental capture and mortality of seals has been reported widely, the precise magnitude of this issue remains largely unknown.
According to the scientists, not much progress has been made to incorporate protective measures to mitigate such interactions, due to a variety of factors, including a poor understanding of ecosystem complexity, the costs of modifying fishing gear, and the scarcity of official fishing controls.
“Limited progress and inconsistency exist among the different countries of South America regarding conservation priorities and actions to reduce marine mammal bycatch and to manage pinniped-related damage and predation,” the authors wrote.
“The causes of the limited progress in the adoption of mitigation measures in South America are multiple, including ecological aspects that are unknown or that cannot be overcome with current technology; the high costs of modifying nests or incorporating acoustic deterrent devices; and the scarcity of fishing controls, particularly in the large artisanal fleets.”
In order to solve this problem and help with the conservation of these species, long-term education programs should be established among the fishing communities, teaching them about the critical roles these marine mammals play in their ecosystems and the negative impacts of their removal.
“This study provides a deep analysis on the interactions between pinnipeds and fisheries and aquaculture in South American waters, highlighting the need to improve policy and management relating to marine mammal interactions,” concluded corresponding author Maritza Sepúlveda, an expert in Ecology and Evolutionary Biology at the University of Valparaíso in Chile.
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