Environmental Factors Influencing Bottlenose Dolphin Presence in the Coastal Waters of Connemara, Co. Galway

• Main Author: Lockyer, Antony
• Format: Thesis
• Language: English
• Published: 2013
• Subjects: Crump Island; Atlantic salmon
• Online Access: http://hdl.handle.net/10026.2/2396

Environmental conditions have an important influence on the habitats and movements of marine species. This study researches the effect of environmental factors on the presence of bottlenose dolphins in Connemara, Co. Galway, Ireland. The purpose of this research was to identify how tide, time of day and season affect bottlenose dolphin presence. Previous research indicates that all three variables can influence dolphin movements. However, it has been suggested that these are often indirect relationships due to prey availability. Passive acoustic monitoring was used at three locations; Inishbarna, Ballynakill Harbour and Crump Island. T-PODs were deployed from July until October, 2003. A total of 451 dolphin detections were made during this period over all three sites. Inishbarna was by far the most occupied site, accounting for approximately 73% of all detections. The number of detections increased throughout the months of July, August and September, with a sharp decline in October. The rate of detections was greatest over night, with a decrease in the rate of detections with increasing daylight hours. The data was evenly spread throughout all states of the tide. A General Linear Model was conducted to analyse which of the environmental factors were the most significant in determining dolphin presence. Season was found to be the most significant at a level of significance of 0.05. Time of day was also a significant factor in determining dolphin presence. State of the tide was the least significant. It was suggested that this was the result of prey availability due to the migration of Atlantic Salmon upstream to the Erriff River.