STANDARDIZED BIGEYE TUNA CPUE INDEX OF THE BAITBOAT FISHERY IN DAKAR (2005-2017)

Abstract

The tuna baitboat fishery in Dakar (Senegal) has been operating permanently in the area off Senegal since the beginning of the 1950s. Details of the activity of this fleet can be found in Fonteneau & Diouf (1994), Hallier & Delgado de la Molina (2000) and, more recently, in several ICCAT documents (e.g., Pascual-Alayón et al., 2017, 2018). The number of vessels peaked at the end of the 1950s with 85-90 baitboats. Vessel productivity increased in the 1980s when a new technique was developed, the associated-school fishing method, whereas the baitboat maintains a permanent association with the tunas it fish. This method was described for the first time by Fonteneau & Diouf (1994). The Dakar-based fleet currently consists of 14 vessels: six Senegalese-flagged, seven Spanish-flagged, and one French-flagged. Annual catches of skipjack, yellowfin and bigeye are around 15,000 mt. In this document we have analysed the data corresponding to the seven Spanish flagged baitboat vessels. The activity of this fleet has traditionally taken place in the coastal areas between 14ºN and 21ºN (Figure 1). Their catch is composed mainly by skipjack and, to a lesser extent, by yellowfin and bigeye. In the last 5 years they represented 84%, 10% and 6% of the total catches, respectively. Over the period analysed in this document (2005-2017) the proportion of bigeye has oscillated without tendency between a maximum of 16% in 2006 and a minimum of 3% in 2013; the proportion of bigeye in the last year of this analysis, 2017, was 10%. The annual average catch of bigeye during this period has been 741.8 MT with a standard deviation of 313.8 MT (Figure 2). The average weight of the three tropical tuna species in the catches of this fleet is around 2-3 kg, 4-10 kg and 6-12 for skipjack, yellowfin and bigeye respectively. They have oscillated around these values without tendency during the last 25 years (Figure 17 of Delgado de Molina, A., et al. 2014). The Tropical Tuna Workplan adopted by the SCRS in 2017 included the update of standardized bigeye CPUE indices until 2017 for the European baitboat fleet operating in Dakar. In this working document we present the analyses carried out with detailed VMS and logbook data from this fleet for the most recent period for which both sources of information were available.