Predicting cetacean habitat in the Colombian Pacific EEZ: challenges and recommendations

Abstract

The study of cetaceans in the Colombian Pacific Exclusive Economic Zone has been limited to their distribution and abundance, and little is known about their habitat preferences and the ecological processes determining their range. The present study establishes a baseline habitat model for cetaceans in this area, identifying differences in habitat preferences and areas of predicted high occurrence. Four species were studied including: humpback whales (Megaptera novaeangliae); bottlenose dolphins (Tursiops truncatus); pantropical spotted dolphins (Stenella attenuata, coastal and offshore forms); and the sperm whale (Physeter microcephalus). Presence-only data was used to model habitat suitability with MaxEnt using static and dynamic environmental variables. Models for all species except for sperm whales had AUC > 0.7 indicating acceptable model performance. Models with static variables indicate that for humpback whales, depth was the main variable that contributed to the modeled distribution, and distance to shore was a more important contributor for the small cetaceans. Models including dynamic variables increased predictive power and fit, with AUC values higher than models employing only static variables. In the case of humpback whales, SST was a major variable contributing to the model and therefore, habitat suitability changed across months with higher predicted occurrence for the colder months. For pantropical spotted dolphins, SST had a similar effect for the offshore form but not major effects for the coastal form. Data limitations and a lack of dedicated cetacean surveys using appropriate methodologies prevented the use of more robust modeling approaches, and therefore, make it difficult to precisely identify areas of high priority for conservation and management. Nevertheless, this study provides an initial step to analyze the best available data in the country, but it is necessary to improve methods of data collection to increase the understanding of cetacean ecology and improve management practices.