Scientists wanted to know more about the population of Spinner Dolphins and particularly they wanted to understand if human presence would have some kind of effect on the dolphins’ behavior at Maku’a Beach. Maku’a is a small bight located in the Waianae coast of O’ahu. O’ahu is the most populated island and the one that attracts the most visitors. Maku’a Beach is used by spinner dolphins to rest during the day after spending the night feeding in offshore waters. As the number of visitors increase in the area, their interaction with dolphins also increases. So, during 2005, researchers were interested in looking at how the dolphins behave with and without the presence of swimmers in the bay. They found that a group of dolphins of about 67 individuals used to arrive at Maku’a Beach very early in the morning, dolphins arrived almost every day between 5:45 am and 8:45 am. As the beach is shallow and accessible, people can approach the dolphins easily, probably without knowing that they can perturb dolphins’ resting hours. For many decades, Maku’a Beach has been a popular area for swimmers interested in encountering dolphins, mainly during weekends and mornings. The researchers found that dolphins started to rest later in the morning when the tourists were swimming near them, so they delayed and compressed their time and may be the quality of resting compared with other studies. Also they observed that when the number of swimmers increased at Maku’a Beach, the dolphins departed earlier from the study area. So, the researchers suggest that the presence of swimmers in the beach may be affecting negatively the resting of the dolphins; however, they said that more studies should be performed to be able to affirm this.
To know more information about this study read: Kerri Danil, Daniela Maldini, and Ken Marten, 2005. Patterns of Use of Maku’a Beach, O’ahu, Hawai’i, by Spinner Dolphins (Stenella longirostris) and Potential Effects of Swimmers on Their Behavior. Aquatic Mammals, 31(4), 403-412, DOI 10.1578/AM.31.4.2005.403
Photo Credit: Photo taken by the SAPPHIRE Project (Duke and Murdoch Universities) under permit from NOAA Fisheries.