Review of thirty-two years of toothed whale strandings in Santa Catarina, southern Brazil (Cetacea: Odontoceti)

Thaís Dos S Vianna,Carolina Loch,Pedro V De Castilho,Morgana C Gaidzinski,Marta J Cremer,Paulo C Simões-Lopes

doi:10.1590/s1984-4689zool-20160089

Abstract

Marine mammal strandings provide valuable insights into local biodiversity. Strandings can be caused by both natural and anthropogenic factors. In the state of Santa Catarina, Southern Brazil, organized marine mammal collections started in the 1980s through opportunistic and non-systematic collection efforts, representing a record of over 30 years of marine biodiversity. This study aimed to perform a preliminary review of 32 years of stranding records within this region. The secondary aim was to elucidate the stranding dynamics of the three most commonly recorded species. A total of 460 records were obtained, representing 17 species of odontocetes. The species registered most frequently were the franciscana, Pontoporia blainvillei (Gervais & d' Orbigny, 1844) (n = 173), bottlenose dolphin, Tursiops truncatus (Montagu, 1821) (n = 100), and Guiana dolphin Sotalia guianensis (Van Beneden, 1864) (n = 97). Most of the stranding records were observed in the second half of the year during the austral winter and spring. The apparent causes of death could not be determined for most of the specimens due to carcass decomposition. For the specimens in which the apparent cause of death could be determined, 27% of the strandings were compatible with anthropogenic interactions. While the focus of this study was a preliminary assessment of stranding data obtained through opportunistic collection, it is evident that future systematic monitoring efforts and stable networks of collaborators will generate more reliable coastal biodiversity inventories and will allow the knowledge of population dynamics of marine mammal species. In particular, for threatened and vulnerable species, or species with poor natural history data, strandings are a fundamental tool for the understanding of marine biodiversity. Ideally, future more refined analyses of stranding data should be used to inform conservation and management policies and to elucidate the biology and ecology of marine and coastal ecosystems within this region.

Highlights

Marine mammal strandings provide valuable records of biodiversity in coastal areas worldwide (Macleod et al 2005, Leeney et al 2008, Pyenson 2010)
For areas with strong wind and wave dynamics, such as the cold fronts that occur in southern Brazil (Rodrigues et al 2004), carcass drift may play a large role in the stranding dynamics
Stranding data were obtained through database records from four scientific collections/ museums in the region: Universidade Federal de Santa Catarina (UFSC); Universidade da Região de Joinville (UNIVILLE); Universidade do Estado de Santa Catarina (UDESC); and Museu de Zoologia Professora Morgana Gaidzinski, Universidade do Extremo Sul Catarinense (UNESC)

Summary

Introduction

Marine mammal strandings provide valuable records of biodiversity in coastal areas worldwide (Macleod et al 2005, Leeney et al 2008, Pyenson 2010). Marine currents and coastal winds can interfere with carcass drift and stranding location (Peltier et al 2012). Coastal species are less influenced by marine currents and coastal winds, commonly stranding near their home ranges (Pyenson 2010, 2011, Prado et al 2013). The reliability and validity of stranding data is highly dependent on a dependable network of collaborators, long sampling periods and systematic and uniform collection efforts in a certain area. Santa Catarina is one of the tourist hotspots in Brazil, and it is often common that strandings of whales and dolphins will be reported in the media as they happen

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