Banning fishery discards and using RAMP

European Union fishery ministers have agreed to phase out the practice of discarding unwanted or regulated animals (bycatch) from landed catches.  The practice of discarding bycatch can be tremendously wasteful of fishery resources including fish, elasmobranchs, invertebrates, birds, amphibians, reptiles, and mammals.

Discarding, Richard

Banning discarding from fisheries requires total retention of animals caught, which must be landed and processed.  As many of these discarded species are of low economic value, efforts are made to design fishing gears that avoid catching bycatch species in the first place.

Suuronen 2005

A key assumption in the ethical design of fishing gears that do not catch bycatch and discarded species is that animals survive gear encounters. Escaping animals must have significant survival rates after gear encounters if they are to continue contributing to recruitment and ecosystem function. If animals escape from fishing gears and do not survive, they are the same problem as discards in fisheries, except that they are hidden.

Suuronen 2005

Measurement of mortality rates for discards and for animals that escape from fishing gears is vital to the management of fisheries, as they represent a significant form of fishing mortality. Discard and escapee mortality rates have been difficult to measure and new, effective methods are needed.

Viability estimates for Pacific halibut bycatch, based on vitality codes (1-4) for injury and activity have been incorporated into fisheries management for several years.  Recent research results by Benoît et al. 2012 on discard mortality have suggested methods based on fishery-scale sampling with semi-quantitative vitality codes (excellent-1, good-2, poor-3, and moribund-4) and conditional reasoning.

Benoît et al. 2012. Post-capture survival probability over time (h) for five southern Gulf of St. Lawrence marine fish taxa (panels), as a function of their pre-holding vitality class score (colours). The shaded areas represent the 95% confidence band for the Kaplan–Meier empirical survival curve for each vitality class, plotted up to the time at which the last observation was made for a given taxon and vitality level. The lines represent the fits of the selected model for each species and vitality class. For cod and plaice, the fits for models M3 and M4 are presented using solid lines and dashed lines respectively (note that these lines largely overlap). The location of the circles along the line and the size of the circles indicate respectively the times at which observations were censored and the proportion of censored observations for the taxon and vitality level at that time.

Reflex impairment measured by RAMP is a quantitative measure of vitality that gives increased resolution and accuracy to the determination of health and survival of discards and animals encountering and escaping fishing gears. Future research on this subject can benefit from the incorporation of fishery-scale sampling of RAMP for discards and for animals escaping from fishing gears.

The banning of discarding will make the evaluation of mortality rates for animals escaping from fishing gears especially important. "Out of sight and out of mind" will not be a viable strategy with regards to evaluating fishing mortality for gears engineered to enhance escape of bycatch species.