Abstract

Cetaceans are difficult to observe in the wild, and demand complex logistics for dedicated collection of
biological data. As such, the distribution of most cetacean species is still poorly understood. Ecological
niche models are useful in studying species distributions and their ecological determinants, and platforms
of opportunity (e.g. commercial nautical operators) can provide an alternative source for that data
in cetaceans. In this study, we modelled common dolphin (Delphinus delphis) habitat preferences using
ecological niche modelling and presence data obtained from distinct platforms of opportunity in two
different areas in the Portuguese coast (west and south mainland Portugal) for the period 2005e2007.
Models from southern Portugal were projected to western Portugal and vice-versa, to check for
robustness in predicting the species ecological niche. Our results show that data from platforms of
opportunity can result in robust ecological models and provide extremely useful information on cetacean
ecology. We found that common dolphins exhibit a patchy distribution pattern over the Portuguese
coastline, and identified key habitats for their occurrence. The most important variable associated with
this species’ distribution was chlorophyll concentration which, given the results from previous research,
we hypothesise reflects an ecological specialisation on pelagic schooling fish. Given that the most
abundant schooling fish species in Portugal is increasingly overexploited and in constant decline, more
attention should be given to the conservation of common dolphin in Portuguese waters.