Nephrops bycatch reduction in North Sea (2016)

The recent EU Landing obligation means that fishers must land all quota species and cannot discard them overboard. This has resulted in heightened pressure on fishers to increase their catch selectivity. Insufficient quotas for landing bycatch exist for species such as Flatfish and Whiting. Landing these ‘choke’ species may therefore result in the inhibition of fishing and the unfulfillment of target species quotas. Additionally, catching juvenile species can deplete future reproductive stocks. Subsequently, the minimum landing size for Nephrops is 25mm in carapace length. As high discard rates can occur when fishing for Nephrops, Youngs Seafood LTD were seeking a way of reducing juvenile catch and bycatch, whilst maintaining target capture of Nephrops, an important commercial species.

BRDs can be implemented on fishing gear to increase catch selectivity. One such device is artificial light, where light can elicit differential behavioural responses in fish by

• a) causing attraction or repulsion to fishing nets and
• b) illuminating escape routes for non-target species on modified fishing gear.

Using the latter knowledge, this scientific study used 4-6 LED lights attached to an escape-inducing square mesh panel (SMP) on a Bottom Trawler, to determine whether juvenile catch and bycatch could be reduced. Lights were programmed to emit constant white light and fishing took place at 47-97m depth.

The addition of light to the SMP reduced juvenile catch of target species and bycatch species by illuminating escape routes. Nephrops above 30mm in carapace length were not affected by light; therefore, target capture was maintained. Light could allow fishing vessels to effectively comply with the landing obligation and to also maintain potential reproductive stocks by avoiding juvenile catch.