| Jumbo flying squid, Dosidicus gigas, is an very important economic squid and has a widespread distribution throughout the Eastern Pacific between California (37°N-40°N) and Chile (45°S-47°S), meanwhile it’s very important component in this ecological system. The Squid off Peru has been developed by industrial vessels from Japan in1989and it was developed by Chinese industrial vessels in2001. The annual catch of Dosidicus gigas is attained787,000tons in the last five years. Like as other economic squids Dosidicus gigas is short-lived species so that environment variable would be influence the resources and distribution of Dosidicus gigas, meanwhile the Eastern Pacific is a region of complex surface oceanography in the world. Therefore, in order to execute the responsibility of resources conservation and sustainable utilization we should take more attentions on the relationships between distribution, resources and environment variable for further study.In this study, based on the fishing data, SST of spawning ground, temperature of deep water collected by Chinese squid fleets in the waters off Peru from2003to2010and the data of Nino to represents El Nino/La Nino, the methods of spatial distance and aggregative analysis were used to calculated the gravity of fishing ground and found out the reasons lead to position difference. Pick out the months influenced by El Nino or La Nino and draw the distribution of CPUE, SST and deep water temperature of fishing ground by Marine Explore and Sufer to analyze the variation of fishing ground in different oceanic climate. Calculated the proportion of favorable SST of fishing ground (PF) and spawning ground (Ps) by grey incidence system to compare the relationship between PF, Ps, CPUE and data of Nino to analyze the relationship between environmental change and Dosidicus gigas resources. The results were as follows: (1) There were some difference on the gravity between years. It was found that the position of longitude showed westward move with months, whereas its latitude showed northward shift from January to June and southward shift from July to December. The cluster analysis showed that four groups are divided, i.e.(2003,2006and2008),(2004,2007and2009)) respectively. The results indicated that the gravities of catch between2006and2009are different. The formers weight position of catch is82°23’W and12°53’ and the latter weight position of catch is81°47’W and14°27’S, which have1.5degrees of latitude difference. The results showed that the monthly difference in fishing ground may be caused by the migration of jumbo flying squid, and the annual difference in fishing ground may be related to the changes of marine environment.(2) Under the El Nino, the fishing ground was around79°—84°W and10°—17°S with the optimal range of19—22℃SST during Oct to Dec in2006and2009, while under La Nina during Oct to Dec in2007, the fishing ground was around81°—85°W and10°—14°S with the optimal range of17—20℃SST. The main fishing ground compared to that in El Nino years move to further northward for1—2°and its average SST decreased2℃. The distribution of water layers temperature indicated that T15and T50of2007was significantly higher than that in2006with maximum temperature difference of6—9℃, and but T100and T200of2007was a few higher than that in2006with maximum temperature difference of1℃. The vertical temperatures structure indicated that the upwelling is not formed in fishing ground from Oct to Dec in2006, and the fishing ground was distributed at the mixed region between oceanic water and coastal water. But the strong upwelling is formed in coastal waters from Oct. to Dec. in2007, and the fishing ground was distributed at the intensive isotherm around the upwelling area. In addition, changes in nutrients of water layer will lead to change the distribution of Dosidicus gigas because of strong upwelling is more useful for it to feeding. Therefore it is concluded that El Nino/La Nina events are closely related to the change of distribution of fishing ground of Dosidicus gigas.(3) The largest proportions of favorable SST in fishing ground are during September to November, and December and January of next year for the spawning ground. The grey correlation between the Ps and Nino1+2SSTA is higher than that between the PF and Nino1+2SSTA, which shows that the effect of Nino1+2SSTA on spawning ground is significant. Meanwhile, the correlation between Ps and CPUE is higher with the value of above0.4and exhibits continuity in time from November to February of the next year. The results indicated that the La Nina condition could increase the proportion of favorable SST in the fishing ground and form the wide upwelling, which is beneficial to D. gigas’’feeding and growth, and improve the recruitment of D. gigas. Otherwise, the adverse environmental condition will be not helpful to the recruitment of D. gigas. |
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