The Relationship Between The Distribution Of Saury Fishing Ground And Its Environmental Factors

Saury fishery is an important fishery in the North Pacific. And the Pacific saury(Cololabis saira) is widely distributed in the sub-arctic and sub-tropical North PacificOcean and is one of the most important commercial fish species in China. As forthe short life cycle saury fish are extremely sensitive to environmental change, thecatch has a very dramatic change in years, and the location of fishing grounds changewith the environmental conditions.Based on of the catch data collected by Chinese Pacific Saury fishing vessels, suchas the vessel main parameters, the year, the month, the latitude, the longitude, the daycatch, the net number, the nominal CPUE, combined with the remote sensing data (SST,SSS, Chl-a and SSH) in North Pacific, this paper used efficiency ratio to standardize theCPUE of saury in Northern Pacific firstly, then used the GLM model to analyse therelationship between the catch and CPUE of Pacific Saury and all of the factors, andanalyzed the distribution of fishing ground of Pacific Saury and their relationship withthe environment factors by using Marine Explorer4.0on a grid of1°×1°scale.Theresults are as follows:(1)Based on of the catch data collected by Chinese Pacific Saury fishing vesselsand the remote sensing data, selected the year, the month, the latitude, the longitude, theSST, the SSS, the Chl-a and the SSH, used to analyse the relationship between the eightfactors and CPUE, and the relationship between the interaction of factors and CPUE.Meanwhile, in order to distinguish the influence of CPUE from different factors, andto avoid the interaction among the factors, we used the gradually adding the factoranalysis method to the model in the use of GLM model. Based of the AIC, we can getthe best GLM model. Analysis results show that, the SST is the most significantinfluence to the CPUE in the environment factors, then the SSS is the second, the Chl-ais the third, but results show that the SSH have no impact to the CPUE; the latitude isthe most significant influence to the CPUE in the other factors, the year is the second,and then is the month and longitude. (2)Based on the catch data collected in the full time series by Chinese PacificSaury fishing vessels, the spatial-temporal distribution of fishing grounds of PacificSaury were analyzed. The results show that, the fishing grounds of Pacific Saury inthe Northern Pacific high sea mainly distributed outside the200miles exclusiveeconomic zone of Russia in the waters near36°00’~48°00’ N,151°00’~163°00’ E. The catch of Pacific Saury increased as time goes on. The low catch of PacificSaury appeared during the month of5-7. And the highest catch appeared during themonth of10-11.Analysed the trend of the catch of Pacific and CPUE in the full time series by2009and2010, we can see: the movement of the barycenters of catch had a tendency fromsouth to north firstly and then moved in the opposite direction on the latitude. PacificSaury will get to the northernmost at8month, and then get to the south. On thelongitude it moved from east to west. The movement of geometric center of CPUE hada tendency from south to north firstly and then moved in the opposite direction on thelatitude, and this is the same as the barycenters of catch. But on the longitude it had atendency from east to west firstly and then moved in the opposite direction, and this isdifferent from the barycenters of catch.(3)Based on the catch of Pacific Saury by Chinese Pacific Saury fishing vesselsand the SST, analyse the relationship between the fishing grounds and the SST by usingthe Marine Explorer4.0on a grid of1°×1°scale. The results shows that the fishinggrounds mainly distributed in SST of9~20℃. There are significant differences of theoptimum SST among every month. During2009, the optimum SST is13~13.5℃inJune,11~11.5℃in July,14~14.5℃in August,13.5~14℃in September,12.5~13℃in October,17~17.5℃in November; During2010, the optimum SST is16~16.5℃inMay,13.5~14℃in June,13~13.5℃in July,12~12.5℃in August,13.5~14℃inSeptember,10.5~11℃in October. Meanwhile, SST decreased firstly and thenincreased as time goes on.Krnska1-Wallis test showed that there were no significant differences in CPUErelated to temperatures during investigative period. So the SST of fishing ground issuitable, and it can be the standard of looking for fishing grounds.(4) Based on the catch of Pacific Saury by Chinese Pacific Saury fishing vesselsand the SSS, analyse the relationship between the fishing grounds and the SSS by usingthe Marine Explorer4.0on a grid of1°×1°scale. The result indicated that the SSS is closely related to the catch and CPUE of Pacific Saury. And there is rarely difference toSSS of every month. During2009, the catch of Pacific Saury mainly distributed in theSSS of33-33.1and34-34.1. The most CPUE mainly distributed in the SSS of34-34.1.During2010, the catch of Pacific Saury mainly distributed in the SSS of32.8-33.1, andthe most CPUE mainly distributed in the SSS of32.8-32.9.(5) Based on the catch of Pacific Saury by Chinese Pacific Saury fishing vesselsand the Chlorophyll-a, analyse the relationship between the fishing grounds and theChlorophyll-a by using GIS visualization and statistical methods. The results indicatedthat the Chlorophyll–a is closely related to the catch and CPUE of Pacific Saury. Therewere significant differences in catch related to Chlorophyll–a in2009, and the catch ofPacific Saury distributed in the Chlorophyll–a of0.25~0.75mg/m3. The most CPUEmainly distributed in the Chlorophyll–a of0.4~0.5mg/m3. There is difference of thedistribution of Chlorophyll–a between2009and2010. And the catch of Pacific Saurydistributed in the Chlorophyll–a of0.2-1.2mg/m3, the most CPUE distributed scatted.