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Sea Lion Attacks a Scuba Diver

At 1:38 p.m. a land-based representative of a liveaboard company called me about a sea lion biting one of his passengers on the stomach.
The incident occurred at approximately 12:35 p.m. at Los Islotes (near the islands of Espiritu Santo and Isla Partida, Mexico). The patient was conscious and lucid the entire time. He stated that at the time of the attack he was scuba diving in less than 20 fsw at the sea lion colony with a group of 24 other divers under the supervision of at least one guide. After the attack fellow divers and the crew helped him back aboard the ship. His 3mm wetsuit was removed to assess and control the bleeding.

Upon arrival at the beach at approximately 2:47 p.m., the patient had been transported by the ship to a waiting panga boat to get him ashore. The patient was in overall good condition, and his wounds had been dressed and bandaged by the crew prior to my arrival. We determined that waiting for an ambulance may delay transport (unfortunately ambulances in this area cannot always provide timely responses). The decision was made to transport the diver and the dive trip's leader in a private vehicle.

During the transport vital signs were normal, and the diver did not show any signs of distress despite his obvious wounds. Due to the patient appearing stable and the bleeding being controlled, a closer local clinic was chosen. Area hospitals are usually quite busy with patients, and treatment for this diver may not have been prompt.

We arrived at the local clinic at 3:56 p.m., and the attending physician assumed the patient's care. As I assisted with removing the bandaging and dressing, I was able to more fully observe the wounds. The wounds were primarily two parallel lacerations approximately 2 inches long, 0.5 inch wide and 0.5 inch deep, with some smaller adjacent puncture wounds. 
The doctor and his staff thoroughly cleaned the wounds, injected a local anesthetic and sutured the wounds closed. Two internal sutures were used first in each wound as they required a multilayer closure. Before complete closure, a sterile "wick" was inserted for drainage. One of the small puncture wounds required a single suture to close.
A nurse at the doctor's direction prophylactically administered a tetanus booster. By 6:05 p.m. the patient was discharged by the physician and escorted by us to his hotel. DAN World/Traveler EMS were then contacted first via email and then later by phone. This incident is an excellent reminder for why professional dive operators need to have a preexisting emergency action plan and not hesitate to implement it. The incident is also a clear reminder that any action plan needs to incorporate emergent situations other than just those involving decompression illness. Training in first-aid skills for trauma are also a must.

The dive operator contacted local personnel who were familiar with local resources. With their input decisions were made based on the resources available. The decision to transport an injured patient without medical supervision should never be taken lightly. Keep in mind that an apparently stable patient can deteriorate during transport. In this case the transport and treatment facility choice produced a positive outcome.

With any injury in the marine environment that penetrates the skin, medical evaluation and treatment are essential. Documentation indicates that seal bites in particular have a very high probability of infection. Proper cleaning and disinfection cannot be overstated, even with apparently small wounds. Despite thorough and appropriate care, any wound needs to be monitored for at least 7 to 10 days for signs of infection. Those signs can include increased swelling at or around the wound, increased redness, foul smelling discharge from the wound, red streaks extending away from the wound site, fever and nausea.

The events and the diver's behavior prior to the bite are unknown. It is entirely possible that the attack was unprovoked or the diver may have inadvertently, unintentionally triggered an aggressive response from the sea lion, but we cannot speculate. Regardless of how playful or docile a marine animal may appear, we as visitors to their environment need to be diligent in our attentiveness to their behavior. Be sure to discuss with local experts how to observe and approach animals, and always follow the recommendations.

— Marty McCafferty, EMT-P, DMT, DAN Medical Information Specialist

Photos by Ed Stetson, used with permission


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