Tracking bottlenose dolphin movement and behavior in the Corpus Christi ship channel

Port Corpus Christi and Port Aransas, Texas, have undergone considerable infrastructure and oil exportation growth over the past 40 years. As humans continue to transform and exploit these coastal marine habitats, understanding dolphin and vessel interactions in the area is vital to improve conservation and management practices. As dolphins increased diving intervals and avoidance behavior in the presence of vessels, protecting marine mammals in areas of high vessel activity is urgent. To test the hypothesis that the movement patterns and behaviors of free-swimming bottlenose dolphins (Tursiops truncatus) are altered by vessel presence and size near Port Aransas, a shore-based digital theodolite is being used. Dolphin behavioral state and movement are analyzed in response to vessel activity. Distance between dolphin positions and habitat features are being calculated in ArcGIS Pro. Large vessels may elicit social and travel behavioral states as dolphins rode on the bows of most large tankers and cargo carriers. Dolphins mill and forage along channel banks and near the ferry crossing, suggesting that physical structures of concrete seawalls and mixing currents from vessel activity are utilized by dolphins to capture prey. In the morning and afternoon, dolphins oriented along the channel perimeter against the current flow with no positional changes in movement, indicating that tides may influence this population’s movement and behavior patterns. Understanding behavioral associations with diverse microhabitats in the Port Aransas area is crucial to conserve critical environments utilized by dolphins.