Abundance and Operating Area by Benthic Trawl of Atlantic Horse Mackerel Trachurus trachurus in the Northern and Eastern Area of Tunisia

Trachurus trachurus (Linné, 1758) is widely represented in Tunisian catches. These quantities landed varied according to the areas and seasons. Taking into account the quantitative importance and economic contributions for the fishing sector, it is useful to assess the biomass and locate areas of concentration. Exploration and experimental trawling operations are carried out aboard the oceanographic vessel O/V “Hannibal” in all Tunisian waters. This study focuses on the results obtained in the North and East areas of Tunisia. In the East area, the depth prospected vary from 40 to 227 m with 49 hauls and that of the North area oscillate between 30 and 512 m and 53 hauls. Three important areas of Trachurus trachurus concentration were reported in the Eastern waters, particularly in the Gulf of Hammamet, above the Curba banks, Mamur and Hallouf. The overall biomass index varies, depending on the area, from 100 to 455 kg/km2. In the Northern waters, 4 specific areas of concentration of this species were noted, including a particularly important toward the North East of the Gulf of Tunis, above the El Hawaria bank at depths of 100 m. The 3 other areas were, respectively, the north of Bizerte, above the Cani Islands bank; above Stafette and Fratelli benches and toward the extreme northwest of Tunisia, south of Galite. The biomass index estimated ranges from 118 to 532 kg/km2.