March 4, 2024

Quantification of Interactions Between Common Bottlenose Dolphins (Tursiops truncatus) and a Commercial Shrimp Trawler near Savannah, Georgia


Carolyn Kovacs and Tara Cox


Abstract: The common bottlenose dolphin (Tursiops truncatus) has been known to forage in association with shrimp trawlers by feeding on fish caught in or disturbed by nets and on discarded bycatch. In addition, common bottlenose dolphins in the estuarine waterways near Savannah, Georgia display a high rate of begging behavior, and it is hypothesized that interactions between bottlenose dolphins and the shrimp trawl fishery may be a contributing factor. The purpose of this study was to determine which activities of the shrimp trawl fishery resulted in associations between trawlers and bottlenose dolphins, and which activities resulted in bottlenose dolphins begging from the trawler. The presence of common bottlenose dolphins around a commercial shrimp trawler and the activity of the trawler were recorded for 129 h over 20 d from August to November 2010 and June to October 2011. Bottlenose dolphins associated with the shrimp trawler (i.e., within 150 m of the trawler) for 68 ± 33% of the day; and they associated with the vessel for the majority of the time spent in the net positions of haulback (90 ± 20%) and trawling (89 ± 17%). However, bottlenose dolphins approached the vessel (i.e., within 10 m) most often while the fishermen were manipulating and cleaning the nets (60 ± 23%) and least often during trawling (2 ± 5%). Begging was observed on 90% of days and occurred most often when the fishermen were cleaning the nets and bringing the trawl doors onboard the vessel (79% of days). Whether or not a bottlenose dolphin interacted with a trawler was dependent on several factors, including trawler activity, net position, and fisherman behavior. Furthermore, bottlenose dolphins that forage behind active trawlers may later engage in begging behavior as a result of direct interactions with fishermen, perpetuating the begging problem near Savannah.
Key Words: shrimp trawler, fisheries interactions, begging, bottlenose dolphins, Tursiops truncates
Document Type: Research article
DOI: 10.1578/AM.40.1.2014.81
Page Numbers: 81-94

Info SKU: Vol__40__Iss__1__Kovacs Category: