A medical guide to handling interactions with marine creatures
By Joseph Becker, M.D. and Paul Auerbach, M.D., M.S.
No matter how careful they are, sooner or later most divers are stung, bitten, punctured or poisoned by a marine animal. While a healthy respect for marine life and the environment is a good safety measure, accidents happen and serious afflictions may result.
Sharks are commonly thought of as the animal most likely to cause injury, but in truth, there are many other marine animals that are more likely to injure divers. Creatures such as barracuda, seals, otters and eels – while not normally aggressive – may sometimes react defensively and bite humans.
Shark avoidance and injury prevention
It’s relatively common for divers to seek out and swim with sharks, but there may be circumstances in which it is preferable to avoid Hazardous Marine Life contact altogether. As with so many other scuba situations, prevention is the best solution to most problems. However, there are exceptions, and it’s important to know how to handle the challenge if there’s no option but to interact.
Avoidance: There are a few things you can consider before you enter the water. Certain geographic areas may be known to have significant shark populations or a history of documented shark attacks. Sanitation waste outlets, breeding inlets, deep channels, drop-offs and areas with dark or turbid water may be areas frequented by larger sharks. No matter the surroundings, divers should remain in groups as isolated humans are at a higher risk. It’s also wise to avoid wearing anything shiny in the water; you don’t want your favourite jewellery mistaken for a fishing lure. This is particularly important to avoid barracuda bites.
When you’re in the water, be aware of the presence of natural sources of shark food, such as seals or sea lions. Pinnipeds playing or swimming in the water does not necessarily mean an absence of sharks. Don’t stay in areas where there is blood. If you are injured, exit the
water immediately; if you are fishing, killed fish should be removed from the water, or at least isolated from divers in the water, as soon as possible. Don’t try to feed a shark; if done at all, it should be only by a trained expert.
Defence: It is always unwise to tease a potentially aggressive marine animal. If you are in the water with sharks, show them the healthy respect they deserve; most of the time they are content to share the water column with no fuss whatsoever.
However, if you do find yourself in a dangerous situation, continually face the shark and calmly leave the area with controlled movements. Don’t panic and avoid splashing behaviours. Don’t bolt for the surface, either; remain submerged, and seek cover with posterior protection, such as a crevice in a coral reef. This allows you a position of defence without worrying about an ambush from behind. Most sharks are stealth predators and being able to keep them in your line of sight is helpful.
If a shark does become aggressive, it can be repelled by blunt blows to the head, nose or eyes; these are sensitive areas with a high density of sensory nerve fibres. Use of weapons such as knives or bang sticks is not recommended, especially by those untrained in their use.
Inappropriate use of a weapon can cause unnecessary injury to both you and the animal that threatens you. There are a variety of products on the market that claim shark repellent qualities; they may have varying degrees of effectiveness, but practical application and evaluation have thus far been limited and, in some cases, inconclusive.
Care of the victim
If the unavoidable (or totally unexpected) occurs, traumatic injuries caused by marine life can present challenges both to immediate and longer-term medical management. Shark-related injuries in particular can result in significant trauma and substantial blood loss. Initial focus should be on providing basic life support as necessary, followed by stabilising the patient for transport to definitive emergency care.
Begin by assisting the victim out of the water. Apply direct pressure to any bleeding sites as quickly as possible. A barrier such as a cloth or gauze pads may be helpful, and gloves should absolutely be worn whenever possible to protect against blood borne disease. Do not release pressure to check on the wound for at least 10 minutes, and if a bandage soaks through with blood, place another directly on top of it and continue to hold pressure.
If the injured area is on an extremity, elevate the body part above the level of the heart. It is important not to apply bandages in a fashion that will restrict circulation beyond the dressing. The victim’s fingers and toes should be pink at the tips, not pale or purple. Almost all bleeding will stop with sustained direct pressure and immobilisation; however, some wounds, particularly those involving amputation or damage to large blood vessels, may bleed uncontrollably. In these cases, a tourniquet should be considered. It is highly recommended that you have training in applying tourniquets before attempting to do so, as tourniquets are potentially hazardous interventions that risk loss of limb.
Nearly anything may be used as a tourniquet: a length of rope, cord or webbing, but it must be well padded to reduce the risk of severe local tissue injury. Apply the tourniquet between the heart and the injury as close to the bleeding site as possible. Tighten it only until bleeding is controlled. Loosen tourniquets for a moment every 10 to 15 minutes to assess whether they are still necessary for bleeding control.
If the bleeding is brisk, retighten the device. If bleeding has ceased to the degree it can be readily controlled by direct pressure, remove the tourniquet and apply direct pressure, though keep the tourniquet handy in case it needs to be reapplied.
If internal organs or tissues are protruding through an injury, do not attempt to push them back inside the body unless it is absolutely necessary for transport. All wounds to the chest should be covered with a dressing. Wounds that appear to be bubbling or “sucking” should be covered with a dressing, taped and sealed on three sides. The fourth, un-taped side serves as a flutter valve that allows air to escape from the chest. Without this flutter valve, air pressure may develop in the space surrounding the lung, preventing lung expansion.
A splint may be used to immobilise an injured extremity to reduce pain, limit blood loss and protect a fractured limb. Aside from ready-made splints, a variety of objects may be used to improvise. Be careful that splints and dressings are not applied too tightly and that circulation to the extremity is not compromised. If the wound is minor, you may care for it by gently cleansing it with antiseptic solution, dressing and prophylactic antibiotics, per your physician’s instructions; however, any significant shark bite will likely require expert emergency medical care.
Many divers relish the opportunity to swim and interact with potentially aggressive marine animals. These interactions are almost uniformly uneventful; careful attention to both personal behaviour and the behaviour of the animals, as well as respect for the animals, will generally prevent the vast majority of attacks. However, an awareness of avoidance techniques and injury treatment principles will serve divers well in the rare but potentially deadly instances when injuries do occur.
Feature image (c) Steven Frink
DAN AP provides a full range of courses including First Aid, CPR and First Aid for Hazardous Marine Life Injuries. Visit “DAN Training” at www.danap.org