The abundance of bottlenose dolphin (Tursiops truncatus) in Cardigan Bay, Wales, in relation to shellfish factory discards

Jodie Denton BSc (Hons) Marine Biology, Swansea University

The aim of the project was to investigate what impact whelk shell discards from the Quay Fresh and Frozen Foods Ltd factory, had on the abundance of bottlenose dolphins (Tursiops truncatus) in New Quay, Wales. The hypothesis was that there was a positive relationship between bottlenose dolphin abundance and the whelk shell discards from the factory. Whelk shell discards would attract prey species to the area, which in turn would attract bottlenose dolphins. This was tested by conducting two land-based surveys: one from the New Quay harbour wall for 5 months, and one from the shellfish factory for 5 weeks. A positive relationship was found between bottlenose dolphin numbers and the discards from the factory. A higher abundance of bottlenose dolphins was also found when the factory had been open for a prolonged period of time. This supported the initial hypothesis of the project as more bottlenose dolphins were found on days when the factory was open compared to days when the factory was closed. However more abundance data is needed from the shellfish factory to more accurately assess the relationship between bottlenose dolphin numbers and whelk shell discards. There also needs to be more abundance data when the factory has been closed for longer periods of time so a more accurate comparison can be made between the abundance of bottlenose dolphins seen when the factory is open and closed. This would show if the factory truly does cause an increase in bottlenose dolphin abundance in New Quay.

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