Possible Effects of Temporary Closure of Fishing Fleets on Resources Recovery: Case of Trawl Fleets in the Gulf of Cadiz (Southern Spain)

Important trawling fisheries are undertaken in the Gulf of Cadiz (Southwest Spain), affecting a large number of species of fishing interest (more than 50) and discarded species (more than 150). This fishery activity is... [ view full abstract ]

Important trawling fisheries are undertaken in the Gulf of Cadiz (Southwest Spain), affecting a large number of species of fishing interest (more than 50) and discarded species (more than 150). This fishery activity is regulated by several technical measures, such as the prohibition of fishing between the coastline and six miles off the coast, the use of 50 mm mesh size, in addition to establishing minimum sizes of some species and since 2005, the closure of the entire fleet between 15^th September and 30^th October. From the research and monitoring point of view, since 1997, demersal resource assessment surveys have been carried out on board oceanographic vessels in November and March. In the present study, we made a comparison (abundance; biodiversity; mean size ) variations based on data obtained in the campaigns between November (just when the closure ends) and March of the following year. Two periods were considered: 1997 to 2004, when there were no closures; and 2005 to 2017, when the biological closures took place. In addition, the results of these analyses were compared with the evolution of fishing yields obtained by the trawl fleets during those periods. 

The implementation of the biological rest has had a positive effect in relation to the different indices of diversity that we have studied. In relation to commercial activity, we observe a positive effect just after the cessation of fishing with highest yields of the year. We also observe a trend of growing yield since the implementation of the biological rest