Modeling whale entanglement injuries: An experimental study of tissue compliance, line tension, and draw-length

Two test systems were developed to evaluate the influence of draw-length and tissue compliance on entanglement-induced epidermal abrasion in humpback (Megaptera novaeangliae) and right whale (Eubalaena glacialis) tissue samples. Under straight pull abrasion tests, an adult right whale fluke required 3.7 times the load and 15 times the draw-length of a right whale calf flipper to induce epidermal failure whereas a humpback fluke was intermediate between these extremes. A load applied tangentially to the leading edge of the fluke or flipper resulted in a substantial, but reversible, deflection of the leading edge in the direction of the applied load. The maximum possible deformation of the leading edge under shear load, prior to the line slipping relative to the skin, was defined as the tissue compliance limit. Oscillatory abrasion tests revealed that line draw-lengths exceeding the tissue compliance limit resulted in substantially increased tissue abrasion. In actual entanglements, line draw-length relative to the tissue compliance may determine if the line will cut into the body or simply press against the skin. Increasing the entangling line's ability to stretch in response to a load could potentially minimize sliding of the line relative to the skin and help mitigate entanglement injuries.