The risk of whale entanglements (worldwide) would be greatly reduced if trap fisheries (commonly used for catching crab, lobster and octopus) used ropeless fishing techniques which remove the need for floating ropes between the water surface and ocean floor.
In South African waters, Bryde’s whales are particularly vulnerable to entanglement in trap fishing ropes as they dive deep and fast to catch their food. Other species at risk include southern right and humpback whales due to their natural tendencies to investigate floating objects like rope and kelp.
Current technique is to drop the pot (and buoy) with a rope that is constantly at the surface. Allowing for theft, prop fouling, and whale deaths.
The ropeless fishing technique utilizes a device that allows for the trap to be deployed in waters without a surface buoy indicating its position. Instead, the buoy is only released when the time comes for harvesting, thus avoiding the risk of ropes floating in the water for long periods of time. The technique for triggering the buoys release, is from a sonar signal given once located via GPS.
By keeping the buoy and rope with the pot during its time on the ocean floor, it increases catch by keeping the pot “quiet” during its time on the bottom, it eliminates crab-pot thefts, accidental prop fouling, and most importantly… prevents whale deaths from entanglement with the trailing buoy rope. Once the pot has “soaked” for a given number of days, the device is triggered to release the buoy by a unique sonar signal. This allows crab-pots to be retrieved “at will”.
This device is innovative over the current state of the art of crab pot fishing by eliminating a rope in constant contact with the waters’ surface. It is cost effective by only increasing costs by 5% over current technology. It is made with many off the shelf components.
The devices have been in service for several years with no loss of pots. Many whales are still alive due to its implementation.
An all-inclusive ropeless fishing system for pot trap fishing. Comprised of three components:
- an acoustic release mechanism
- a deck box for acoustic sonar
- bottom stowed rope & hard float buoys.