Haul data analysis from the Polish krill fishery in 1997–1999

The analysis of fishing data obtained from the ship’s log of the Polish commercial vessel M/T Pollux facilitated the characterization of catches and concentrations of krill between February and June from 1997 to 1999 in statistical area 48. Records from each haul were used for analysis and since the vessel carried out catches along with other Polish vessels, the results describe Polish catches in this period and area. Each fishing season was different. In 1997 the catches were carried out in sub-area 48.1 and 48.3, in 1998 they were exclusively carried out in sub-area 48.1 and in 1999 in sub-areas 48.1 and 48.2. On average, the vessel made from 7 to 9.5 hauls daily which lasted an average of 60-70 minutes. Differences in catch rates in various areas and years were observed. The highest catch rates (4-5 t/h) occurred near Elephant Island and King George Island, as well as near the South Orkneys and King George Island in 1998 and 1999, respectively. During the day, commercial krill concentrations occurred deeper, at depths of 10-140 m, while at night the concentrations were closer to the surface, at depths of 10-100 m. The day catch rates were several times higher than at night (4.35-9.33 during the day and 0.8-3.33 at night). In general, the night concentrations were shallower than the day-time ones in the area of King George, however, in 1997 and 1998 the situation was the opposite.