Adverse human interactions (HI) are an increasing problem for coastal marine mammals, including bottlenose dolphins in Sarasota Bay, whose ranges overlap frequently with human activities and human sources of food. Close encounters with boats or fishing gear have the potential to injure or kill dolphins. In addition, when animals are intentionally or accidentally fed by humans, this can contribute to adoption of unnatural foraging behaviors such as begging, scavenging, and feeding on bait or catch directly from active fishing gear, which put dolphins in harm’s way.
The SDRP works to study and mitigate human interactions with wild dolphins in several ways, including conducting research in the long-term “natural laboratory” of Sarasota Bay to monitor human interaction (HI) trends, providing rescue and post-release monitoring support for injured animals, and participating in outreach efforts intended to reach a wide audience, most recently via educational videos highlighting the impacts of HI through stories of real Sarasota Bay resident dolphins.
As a part of these efforts, we are wrapping up a pilot study funded by the Mississippi-Alabama Sea Grant Consortium which utilized long-term SDRP data archives in concert with new data on human interactions collected in Sarasota Bay to determine the primary factors contributing to HI in our study area. With the help of collaborators Lars Bejder, Fredrik Christiansen, David Lusseau, and masters student Eilidh Siegal, we have completed several major analyses exploring spatial, temporal, and social contributions to the persistence and spread of unnatural foraging behaviors within the Sarasota Bay community. This research is critical to improving the lives of dolphins in Sarasota Bay and elsewhere by informing future outreach and management efforts.
Long-term records indicate that HI rates in Sarasota Bay are generally increasing and that a disturbingly high proportion of resident animals (~35%) were observed engaging in behaviors of concern from 1993-2014. Over this same period more than 70 individuals were observed with HI-related injuries (e.g., boat strike, fishing gear entanglement or ingestion), with ~30 leading to death or requiring intervention by human rescuers.
Although HI observations in Sarasota Bay fortunately remain less frequent than in other major hotspots in the Southeast USA, we continue to identify new individuals incorporating unnatural behaviors into their repertoires and suffering from boat or fishing gear-related injuries each year. In late June 2015, F222 (a 17-yr-old male Sarasota Bay resident), was observed with deep, fresh boat strike wounds (see photo). Despite a rather severe injury, F222 fortunately survived and has been seen several times near a local fishing pier with his external wounds now healed. Unfortunately, he now appears to have separated from his long-time male partner and is spending more time alone and engaging in risky behaviors, such as patrolling around active fishing gear, so we will continue to monitor him throughout his recovery.
In addition, over the past year harassment of resident dolphins in our study area by recreational boaters and tour operators has continued to be a problem, and SDRP staff members have yet again been called upon to participate in disentanglement operations in other parts of Florida. These trends point to the need for continued focus on reducing potentially dangerous behaviors by both dolphins and humans, and the SDRP remains committed to these efforts in our research and outreach endeavors.
This article appeared on pages 6-7 in the December 2015 issue of Nicks n Notches.