DiscardLess project - Discard Mitigation Strategies Toolbox

French demersal fishery in the Eastern English Channel

In the Eastern English Channel case study, the participatory approach implemented within DiscardLess allowed engaging in dialogue with fishers regarding the impact of the Landing Obligation (LO), the strategies for mitigating discards and the data and models used by scientists to evaluate management strategies. In the Eastern English Channel (EEC) (ICES Division VIId), a diversity of fleets targets a large variety of species with various gears. While netters seasonally rely on sole and dredgers on scallops, cod, plaice, whiting and cephalopods occupy the rest of the year. Trawlers are more diverse in their catch along the year and also target red mullet. Together the netters, dredges and trawl fleets averaged 448 vessels over the period 2008-2014. The application of the LO is complicated for these fleets by the mixed nature of the fisheries and a regulatory system (cod plan, technical measures, licenses and quotas) that limits fleet adaptability. These aspects were explicitly taken into account in the simulations presented in this section, using the spatialized simulation framework ISIS-Fish.

Model used

ISIS-Fish is a deterministic fisheries dynamic simulation model designed to investigate the consequences of alternative policies on the dynamics of resources and fleets for fisheries with mixed-species harvests (Mahevas and Pelletier, 2004; Pelletier et al., 2009). It allows quantitative policy screening of combined management options, such as total allowable catch (TAC), effort control, licenses, gear restrictions, Marine Protected Areas (MPAs), etc. Fishing mortality is the result of the interaction between the spatial distribution of population abundance resulting from the population sub-model and the spatial distribution of fishing effort provided by the exploitation and management sub-models at a monthly time-step (Figure 2.3.1). Fishing effort is standardized per métier and fleet according to gear selectivity and efficiency, ability to specifically target a species and technical efficiency. The effect of management measures can therefore be explicitly modelled either through modifications of the standardization parameters for technical measures (e.g. change in the selectivity curve) or through modification of the level and spatio-temporal distribution of fishing time for seasonal closures or effort control for instance.

Conclusion :

The participatory approach allowed drawing conclusions on the likely impact of the LO on the demersal fishery in the EEC. It confirmed expectations that quotas may not be limiting given the current stock conditions and if the uplifts correspond to the discard rates. The choke on sole was somehow unexpected as the discards are estimated to be quite low (9%) by the ICES working group. However, discards estimates used in the model based on available data were much higher. This mismatch likely explains the early choke predicted by the model and further analyses are ongoing to understand its source. The evaluations at fleet scale and in the short time evidenced the difficulties that some fleet may still meet in the first years of implementation. The impact of de minimis was particularly encouraging as it provided higher revenues for equivalent fish biomasses. However, it is recognized that such exemptions will likely make control more complex and the exact way they will be implemented is not clear yet. Finally, a fine analysis of the performance of the alternative modelled behaviours (more or less opportunistic) and avoidance strategies should provide fishers with leads to adapt to the regulation and limit these impacts.