Since 2019, the University of New Hampshire has led an investigation into the feasibility of using composite materials to replace rope in kelp aquaculture systems to mitigate the risk of marine mammal entanglement in such structures. The substantial bending stiffness of composite rods should help prevent entanglement of marine mammals.
Entanglement in rope-based fishing gear led to 27 of the 54 known deaths or serious injury events in North Atlantic Right Whales (NARWs) since 2017. NARWs are listed as critically endangered by the International Union for the Conservation of Nature. Entanglement risk reduction has been highlighted as a key priority by NOAA’s protected animal resource division.
Tests comparing the performance of various types of composite rod are underway as are lab-based experiments simulating the potential for the composite line to break when interacting with NARW morphologies. Analysis of the degradation of strength and modulus of elasticity of fiberglass as a function of outdoor exposure and use in kelp farm applications has also been completed.
These experiments use the morphology of various of NARW body parts in which the whale contact surface is represented by a circular arc oriented perpendicular to the composite lines.. The applied force, resultant deformed geometry and breaking limit was recorded. This testing will indicate whether the fiberglass rods will break as intended when interacting with different body parts of a NARW at pushing forces achievable by these animals. If successful such breaking behavior will release marine mammals who might otherwise get entangled, while retaining high tensile strength during normal operation.
This research has been conducted using fiberglass rebar from one manufacturer. To widen the scope of investigation, two specimens of fiberglass from two other manufacturers made with different resin-fiber ratios are currently undergoing ocean exposure experiments to evaluate their degradation characteristics in ocean water. If shown to be sufficiently durable, these materials will also be evaluated for their breaking limits using trials similar to those described previously.