Development of the krill stock in the elephant island region during the 1996/97 season

During December 1996 the Elephant Island standard grid was surveyed for krill and salps. Krill and salps were present at almost all of the stations, other epipelagic zooplankton species were relatively scarce. Maximum krill density exceeded 7350 juvenile krill per 1000 m3. In general krill density was much higher than in previous years. The krill stock was dominated by length classes around 35 mm, representing age group 2+ and the year-class 1994/95 (proportional recruitment R2 = 0.85). The year-class 1995/96, the present juvenile age group 1 +, does not repeat the very successful recruitment of the preceeding year-class. In December 1996 adult krill was mostly (68 %) found to be in the prespawning stage, indicating an average year for krill reprodution in this area, which is not the optimum starting point for a good recruitment of this year-class. At the same time the salp abundance was above average, but still one order of magnitude lower than in the salp bloom years 1992/93 and 1993/94.