Pygmy sperm whale (Kogia breviceps, De Blaineville 1838) strandings along the Atlantic coast of the southeastern United States: Analysis of association with environmental factors
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Marine mammal strandings have been reported for thousands of years and numerous hypotheses have been formulated in attempts to explain such events. Nonetheless, the causes of marine mammal strandings still are not well understood. The pygmy sperm whale (Kogia breviceps) is the second most commonly stranded cetacean on the southeastern coast of the United States, yet its biology is largely unknown. The present study examines stranding records along the Atlantic coast of the southern United States (from Cape Hatteras, NC to Miami, FL) from 1992 to 2006 in association with environmental factors. Strandings were mapped in a Geographical Information System (GIS) in connection with bathymetry and sea surface temperatures (SST) from satellite images. The images were processed to identify frontal zones as well as the position of the Gulf Stream. Monthly Multivariate El-Ni√±o Southern Oscillation Index (MEI), North Atlantic Oscillation Index (NAO), and records from NOAA‚Äôs National Data Buoy Center (wind speed and direction, wave height, average wave period, and barometric pressure) were also included in the analyses. The number of strandings per month was related to the environmental data using Generalized Linear Models (GLZ). The best GLZ models identified significant correlations with MEI, SST, wind speed, wave height, average wave period and barometric pressure. Although more work is needed to understand the distribution of pygmy sperm whales at sea and the factors influencing the occurrence of stranding events, this study is a step toward developing a model to predict pygmy sperm whale strandings.