SEAwise Report on the impacts of fisheries on stocks and landings under existing management plans
The SEAwise project works to deliver a fully operational tool that will allow fishers, managers, and policy makers to easily apply Ecosystem Based Fisheries Management (EBFM). This SEAwise report investigates the impact of existing management plans on the stocks and landings. The analyses are based on the simulations carried out for deliverables 6.4 and 6.7 in Task 6.3 and Task 6.4, respectively. A wide range of models has been applied to various case study areas across the Northeast Atlantic and Mediterranean.
The work provides important information on likely impact of different management scenarios on the stocks and the landings at different time horizons. The scenarios investigated include management related to attaining Maximum Sustainable Yield (MSY) in both a strict MSY approach and a Pretty Good Yield (PGY) approach (allowing sustainable deviations from single species FMSY point estimates). Additionally, two additional scenarios were run to evaluate the impact of a management regime based on MSY and the landing obligation. In one of the scenarios the effort level was maintained at current level and in the second a more realistic fleet dynamic constrained by catch quotas and not constrained by a landing obligation was implemented.
The current fisheries management, based on MSY target with implementation of landing obligation, led to an increase in SSB, a fishing mortality level well below the target in most of the cases, and an increase in landings in the long term. The increase in landings was large in the case studies that had stocks at very low level at the beginning of the simulation, but limited in other cases. The change in average age of the stock was case study dependent and any increase was not related to the status of the stocks.
The PGY scenario where the fishing mortality ranges were used to introduce flexibility in the TAC and quota system did not solve the problem of choke species in the mixed fisheries. Each case study used a different approach to use the ranges but none of them resulted in significant decrease in the loss of fishing opportunities. A management scenarios that seemed to significantly improve the fisheries status is the one explored in the Mediterranean case study where a substantially lower loss in fishing opportunities (difference between fishing mortality and fishing mortality target) was attained. This may be linked to the use of effort management, which is, at least in simulations, very effective.
The illustrations in this report provide readily usable input for the web interface summarising the impacts under different management scenarios.
Read more about the project at www.seawiseproject.org
