What we are currently working on…
The team here at Fishtek Marine are currently working on a prototype device to prevent shark bycatch in longline fisheries, here’s our story so far …
Currently, one quarter of chondrichthyans (shark, ray and chimaeras species) are threatened according to the Red List criteria of the International Union for the Conservation of Nature. The main threat they face is over exploitation through capture in fisheries, either as a target species, but more often a by-product (incidentally caught but retained) or a bycatch (incidentally caught but unwanted and discarded) species. Pelagic longlining for high value tuna and bill fish can have particularly high shark and ray capture rates, with as much as a quarter of the total catch consisting of sharks. Many shark species are not able to sustain such high levels of exploitation and as a result shark populations are declining dramatically.
Despite the prevalence of shark bycatch in pelagic longline fisheries and the global recognition to develop and implement mitigation measures to reduce the incidental catch of sharks, progress in research and implementation of such measures has generally lagged behind measures for other bycatch species such as seabirds. A number of measures including chemical additives in bait, hook shape, depth of setting and electro positive rare earth metals have been trialled without any significant result.
Fishtek’s proposed solution
SharkGuard is the product our team are MOST EXCITED about. The Fishtek team realised that the central issue with mitigating shark bycatch, is that sharks behave in a very similar way to the target tuna and bill fish species; they both feed on similar prey and generally occupy the same marine zones. However, there is one striking difference, sharks have an acute sensitivity to electrical fields, possessing Ampullae of Lorenzi and will exhibit a very active avoidance response to electrical currents of 10V/m (Megan and Lowe, 2006). This was the key to developing a shark bycatch mitigation device.
Fishtek engineers set about designing and prototyping the SharkGuard, a device that delivered the appropriate field strength to the baited hook, was very small, powered by a single AA battery and capable of mass production, offering a robust and operationally affordable device costing only a few cents per hook set.
Some extremely encouraging initial trials
The prototype SharkGuard was intensively tank tested to ensure the current strength was optimised before producing units for sea trialling. Phase I sea trials were completed in January 2016 and reported in August 2016. Initial results are very encouraging with >90% reduction in sharks hooked on baits protected by the SharkGuard compared to a baited control line.
Fishtek engineers are now working on a more advanced prototype for full commercial sea trials. This next stage is critical to prove the efficacy of SharkGuard on a wider range of shark species in a commercial fishing operation. If the results of the phase I sea trials are replicated, the SharkGuard has the potential to dramatically reduce shark bycatch in the global pelagic longline fleet. Watch this space, follow Fishtek Marine’s updates on twitter.