Journal of Fishery Sciences of China (中国水产科学) 2013/20:6 PP.1274-1283
As the key species in the Antarctic ecosystem, Antarctic krill (Euphausia superba)is one of the most important linkage in the food web. In this study, we made detailed quantitative analysis from the view of time sequence of oscillation characteristics of Antarctic krill resources. The biological and physical process is also combined to explain the reason that the oscillation of krill resources. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) area 48 in the Atlantic Sector of Antarctic Ocean also is the main fishing ground of Chinese Antarctic krill fishery. Using the Empirical Mode Decomposition (EMD) estimation, the present study analyzes the monthly catch rate of Antarctic krill fishery from 1982 to 2011 to explain the multi-time scale oscillation mode characteristics of Antarctic krill fishery and its response relationship to the environmental oscillation. The result show that the oscillation represent 0.5 a, 1 a, 1.5 a, 2.5 a, 7 a and nearly 11 a periodicities, in which high-frequency oscillation has a significant impact on the Antarctic krill abundance fluctuation. The catch rates of three subareas in CCAMLR area 48 all show seasonal oscillations, low oscillation in summer and high oscillation in winter can be found. The CPUE peak points appear in May, June and September in subareas 48.1(50°–70°W, 60°–65°S), 48.2 (30°–50°W, 57°–64°S) and 48.3 (30°–50°W, 50°–¬¬57°S), respectively. The CPUE is generally the lowest in January. The primary oscillation periodicity (the explanation rate of variance is 46.7%) is 1 a, and the annual recruitment size of Antarctic krill is the most important contribution of the catch rate. The secondary seasonal oscillation periodicity (the explanation rate of variance is 35.6%) is 0.5 a. The 1.5 a oscillation period can be considered as a synthesis result of two main high-frequency. The 2.5 a oscillation of catch rate is related to the 3.0 a oscillation of seaice coverage and the longer oscillation periodicity (7 a and nearly 11a oscillation period) of catch rate has a linkage to the oscillation periodicity of climate-current system. The CPUEs have increasing trend in the CCAMLR subarea 48.1, 48.2 and 48.3, although the overall abundance has a remarkably decreasing trend in the Atlantic Sector of Antarctic Ocean, particularly subareas 48.2 and 48.3. A significant positive correlation can be found between seaice coverage and catch rate (coefficient of correlation is 0.44, and P < 0.01), the phase gap is 10 months with CPUE behind seaice coverage. The oscillation of seaice coverage anomaly can put a remarkably positive impact on the catch rate and catch rate anomaly of Antarctic krill fishery with a gap of 8 to 11 months (the coefficient of correlation respectively is 0.18 and 0.21, and P < 0.01). The oscillation of Antarctic krill fishery is a response of combined influence of environmental oscillation and life history cycle of Antarctic krill.