Abstract

In September 2000 and January 2001 several experiments were conducted to determine the pursing depth and sinking speed in purse seines employed in the small pelagic fishery in the northern of Chile. During this period, 10 fishing trips were performed on two of the most common type of vessels, with a total of 21 purse seine sets. Similar dimensions and characteristic design nets were employed for both fishing vessels in this research. Nevertheless, both nets showed different constructions with two kinds of netting central bodies; knots and knotless. The maximum pursing depth and the required time to reach them were compared by means of bathykymograph measures, and the average sinking speed for each set was determinate as well. Furthermore, the pursing depths were analyzed through a protracted series of observations each 30 s apart during the fishing sets. The maximum average pursing depth of the knot's netting was higher than the knotless one, such that the knot netting purse seine reached 93,8 m in depth and the knotless netting purse seine reached only 71,3 m. The same statistical behaviour was observed in the sinking speed of the central body, were the knot netting was higher than the knotless one. However, no differences were noticed in the bunt net speeds.