Human-wildlife conflicts with crocodilians, cetaceans and otters in the tropics and subtropics.

Patrick Cook,Carlos A Peres,João Vitor Campos-Silva,Joseph E Hawes

doi:10.7717/peerj.12688

Abstract

Conservation of freshwater biodiversity and management of human-wildlife conflicts are major conservation challenges globally. Human-wildlife conflict occurs due to attacks on people, depredation of fisheries, damage to fishing equipment and entanglement in nets. Here we review the current literature on conflicts with tropical and subtropical crocodilians, cetaceans and otters in freshwater and brackish habitats. We also present a new multispecies case study of conflicts with four freshwater predators in the Western Amazon: black caiman (Melanosuchus niger), giant otter (Pteronura brasiliensis), boto (Inia geoffrensis) and tucuxi (Sotalia fluviatilis). Documented conflicts occur with 34 crocodilian, cetacean and otter species. Of the species reviewed in this study, 37.5% had conflicts frequently documented in the literature, with the saltwater crocodile (Crocodylus porosus) the most studied species. We found conflict severity had a positive relationship with species body mass, and a negative relationship with IUCN Red List status. In the Amazonian case study, we found that the black caiman was ranked as the greatest ‘problem’ followed by the boto, giant otter and tucuxi. There was a significant difference between the responses of local fishers when each of the four species were found entangled in nets. We make recommendations for future research, based on the findings of the review and Amazon case study, including the need to standardise data collection.

Highlights

Conflict between humans and wildlife poses a major challenge for biological conservation (Dickman, 2010)
Our focal study reserves represent an important site for globally significant communitybased conservation arrangements (Campos-Silva & Peres, 2016; Campos-Silva et al, 2018) that benefit a wide range of large-bodied freshwater piscivores, including the black caiman (Melanosuchus niger), the giant otter (Pteronura brasiliensis), and two cetaceans: the Amazon river dolphin or boto (Inia geoffrensis) and the tucuxi (Sotalia fluviatilis) (Fig. 2)
Amazonian case study Interview responses showed a significant difference between the perception of black caiman, giant otters, botos and tucuxis as problem species (Chi-squared: χ2 = 204.69, df = 3, p < 0.001, n = 49)

Summary

Introduction

Conflict between humans and wildlife poses a major challenge for biological conservation (Dickman, 2010). Piscivores can impose significant impacts on human livelihoods in freshwater and brackish environments, including attacks on people and damage to fishing gear, in addition to co-depletion of fish stocks (Rosas-Ribeiro, Rosas & Zuanon, 2012; Sideleau & Britton, 2013). Managing such conflicts to ensure long-term persistence of wildlife populations is vital to maintaining ecosystem integrity (Rio et al, 2001). This is challenging in tropical and subtropical regions where freshwater fisheries more often represent a critical component of the subsistence diets and commercial revenues of local people (Michalski et al, 2012)

Methods

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Discussion

Conclusion