Quantitative observations on marine mammals and reptiles of Kuwait's Boubyan Island

Quantitative observations were recorded on air breathing marine vertebrates in the immediate vicinity of Boubyan Island from 17 February 2004 through 1 March 2005. In 398 hours of observation time during daylight, we made 159 sightings of Indo-Pacific Humpback Dolphins (Sousa chinensis) for a combined total of 524 individuals. We also recorded 38 individual sea-snake (Hydrophis spp.) sightings. No marine turtles were observed during the study period. Pod size of the dolphins ranged from one to at least 30. Of the 159 sightings, 40% was comprised of a single individual, and 26% consisted of pairs. Pods of 10 or more members were observed on 13 occasions. Overall, we saw an average of 1.35 Sousa for each hour of observation time. Seasonal counts peaked in the spring with nearly 2 Sousa/h, and reached 3.3/h in April. Observation rates in the winter dipped to less than 0.7 Sousa/h. Khor Abdullah had the highest overall observation rate with 2.6 Sousa/h, and in the fall, this rate jumped to 4.3/h. In comparison, Hydrophis sea snakes were few with an overall observation rate of 0.1/h. This low number reflects the fact that sea snakes are present mostly in the summer, and are far less noticeable. Seasonal observation rates peaked in the summer with nearly 0.3/h and dipped to zero during the winter months. Sea snakes initially showed up in April when water temperature was just over 21 degrees C, and were no longer observed in November when water temperatures dropped from >20 degrees C in October to about 15 degrees C by December. Both Sousa and Hydrophis are relatively long-lived, apex species and could serve as environmental indicators for Boubyan Island's planned development. Monitoring population abundances and tissues for contaminants is recommended.