Towards effort quantification through VMS and observers' data: the case of shrimps trawlers in Mauritanian waters
2021
Quinzán, M. (Marta) | Czerwinski, I.A. (Ivone Alejandra) | García-Isarch, E. (Eva)
The Spanish shrimp trawlers is one of the most important fleets operating in Mauritania. They target 3 species:-Penaeus notialis (at 20-80 m depth)-Parapenaeus longirostris (at 100-350 m depth)-Aristeus varidens (at 400-800 m depth)in 3 types of fishing operations that can be carried out during the same day.A critical challenge is to define suitable metrics of effective fishing effort since logbooks only provide information of catches by day. Accurate CPUE obtained from these vessels could be considered good abundance indices of its target stocks, which is of paramount importance for assessment purposes. The objective of this analysis was to use Vessel Monitoring System (VMS) information to robustly infer fleet activity as well as estimate units of effort directed to each of the three target species of the Spanish trawlers operating within the EEZ of Mauritania. The estimates of trawling effort by target species obtained from VMS data show consistency in both values and temporal trends with those registered by observers on-board. The adoption of a consistent method for analysing VMS data will help to ensure that calculations of trawling effort are repeatable and comparable among studies.
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