南极大西洋扇区南极磷虾渔获率序列的振荡模态分析

Oscillation mode analysis on the time series of Antarctic krill(Euphausia superba) catch rate in the Atlantic Sector of Antarctic Ocean

为了解释南极大西洋扇区的48区南极磷虾（Euphausia superba）资源的多尺度振荡模态特征及其与环境振荡之间的响应关系，采用经验模态分解方法，对1982—2011年问的南极磷虾月均渔获率进行了分析。结果表明，其振荡表现出了0．5a、1a、1．5a、2．5a、7a和11a等多个周期，其中高频振荡对南极磷虾资源变动影响较大，低频振荡影响较小：3个亚区渔获率都为冬高夏低季节性振荡，48．1～48．3亚区最高值依次出现在5月、6月和9月，渔获率的最低值出现在1月；所有振荡周期中以1a为最主要振荡周期（方差解释率为46．7％），南极磷虾年补充规模对其渔获率最为重要；其2．5a振荡和海冰面积3．0a；振荡有关；渔获率低频振荡周期与气候．海流系统振荡周期有关。海冰面积和渔获率有较好的正相关关系（相关系数为O．44，位相差10个月）。海冰面积异常振荡会在8～l1个月之后对渔获率和渔获率异常产生的正相关影响。磷虾资源的振荡是环境振荡和磷虾生物周期综合作用的反映。

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 1 la 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.