Sea Turtle LED
The Problem
Studies have shown that small-scale coastal gillnet fisheries have especially high levels of sea turtle bycatch, and it has been suggested that this source of mortality has contributed to population declines of several sea turtle species, as well as to obstructing sea turtle population recovery. The primary threat comes from fishing net entanglement resulting in injury or drowning, with 20% to 40% of entanglement incidents resulting in mortality. The identification of differences in sensory capabilities between sea turtles and the target fish species led researchers to develop visual deterrents to exploit the role of visual cues in sea turtle foraging behavior, and therefore in interactions with the fishing gear. Illuminating the nets with LEDs significantly reduced mean sea turtle catch rates with no significant impacts on the target catch. However, the cost of these LED devices put them far out of reach of most fishermen. In addition, current devices on the market suffer from saltwater intrusion leading to corrosion and failure of the device, entanglement in the net, and high maintenance and time costs associated with manually attaching the devices prior to casting the net every time.
Our Proposal
Based on prior research and interviewing, a series of design requirements was generated that would allow for a new LED to act as a sufficient sea turtle deterrent in global markets. The goals include: 1) Minimum of 3000 millicandles per LED unit 2) Green light (520 – 565 nm wavelength) 3) Unit cost under $9, if not less 4) More permanent and durable attachment to fishing nets that can be rolled in and stored with the nets, thus increasing convenience and saving time 5) Rechargeable batteries to decrease cost and reduce waste 6) Automatic salt-water activation switch to increase ease of use and save time 7) Use of corrosion-resistant and sun-resistant materials to increase lifespan 8) Multi-year lifespan 9) Ease of manufacture In order to address these goals, we designed a new LED device vastly different from those already on the market. Our device is sealed in marine epoxy, allowing for a completely water-proof seal that will not degrade over time. Unlike the O-ring seal, there is virtually no chance of salt water intrusion, which is catastrophic to the housed electronic components. The marine epoxy also supports an extremely strong and durable device, suitable for conditions on board of sea vessels and in storage areas. In addition, the marine epoxy protects the device from corrosion or prolonged and potentially hazardous UV sun radiation. Inductive charging coils allow the device to be easily recharged even when the electronic components are completely sealed.
We Assume that...
Small-scale fisheries have enough initial capital to purchase enough LED devices to span their nets.
Fisheries will realize the return on investment by preventing sea turtle entanglement, and be willing and able to make that initial investment.
The saltwater switch current draw will be insignificant compared to the capacity of the battery.
Constraints to Overcome
Currently, the largest barrier to implementation of LEDs is cost, followed by convenience and practicality of installation. Our LEDs address this by decreasing the initial cost of production of these marine LEDs while increasing the usable lifetime, thus drastically reducing the cost over the device's life. In addition, our devices our much more easily attached and can stay on the net, and recharge-ability eliminates the need to replace hundreds of batteries each year.