Preliminary Study On Fishery Biology And Otolith Morphology Of Pacific Saury In The Southwest Of Pacific Ocean

In this paper, based on the sampling data coming from the survey on thenorthwest pacific ocean in the period of May to July in2009and April in July of2010by stick-held dip net fishing-boat “TIANSHUN”, biological characters have beenstudied in preliminary stage. Further more, on the basis of the123pacific sauryotoliths sampled from the northwest Pacific Ocean in the period of May to July in2009, shapes of otoliths and growth mode have been analyzed. The main results inthis paper are as following:(1) Among the654fishes investigated in the period of May to July in2009, therange of fork length from161-333mm, the average fork length is282.80mm; amongthe654fishes investigated in the period of April to July in2010, the range of forklength from108-344mm, the average fork length is278.82mm. There are significantdifferences between the distribution of fork length in the year of2009and2010usingANOVA（F=6.76，P﹤0.05）.(2) Among the year of2009, there are326female fishes and247male fishes,significant differences are showed between female and male fork length distributionusing ANOVA（F=13.62，P﹤0.05）; Among the year of2010, there are354femalefishes and301male fishes, significant differences are showed between female andmale fork length distribution using ANOVA（F=29.97，P﹤0.05）.(3) StagesⅡand Ⅲ of gonad maturity in the year of2009take the biggestproportion, the percentages are23.82%and40.80%respectively. StagesⅡand Ⅲ ofgonad maturity in the year of2010also take the biggest proportion, the percentagesare40.98%and29.51%respectively.(4) Feeding grade distribution in the year of2009and2010haven`t showsignificant differences. In which the proportion of grade one\two\three are the highestin both2009and2010.(5) The weight range of2009is21g to257g. The average weight is140.45g. Theweight range of2009is9g to220g. The average weight is119.44g. the difference ofweight distribution are significant by ANOVA（F=102.91，P﹤0.05）.(6) The relational expressions between fork length and body weight of654fishesinvestigated in the year of2009using Power function return are as following: The all: W=8.3212×10-7L3.3479（R~2=0.8974，n=654）Female fishes: W=2.6576×10-6L3.1484（R~2=0.8098，n=252）Male fishes: W=2.6576×10-6L3.1484（R~2=0.8098，n=252）The relational expressions between fork length and body weight of654fishesinvestigated in the year of2009using Power function return are as following:The all: W=1.4213×10-6L3.2345（R~2=0.9131，n=701）Female fishes: W=2.0499×10-6L3.1721（R~2=0.7070，n=354）Male fishes: W=2.6903×10-7L3.5281（R~2=0.7151，n=301）(7) Observed by the microscope, the otolith of Pacific Saury could be dividedinto four parts: Anterior, Posterior, Dorsal and Ventral. The satolith rostrum is obvious.All rostrums are longer than antirostrums. In principal component analysis, fiveprincipal components (PC) were identified. The percentages of variations inherent inthe original data that could be explained by these five PCs were62.93%、8.18%、6.97%、5.72%and4.38%respectively. Overall these four PCs explained86.284%ofthe total variations inherent in the original variables. We use gray constellationclustering to calculate the comprehensive index value, and we may find that there wasthe only one population in this sampling fish. The noficeabilify tests of averagedifference result were all below3, it showed that no significant different being foundin the shape characters of pacific saury otoliths.(8) We analysis the shape of them, discuss the difference and the grow pattern. Weuse the data progress method of principal component analysis, figure that TSL、DED、DVR、TRL could as token of otolith shape. In the whole process of the growth, eachpart of the otolith is growth at the different speed, the trend of transformation is: totalsagitta length(TSL) and Total sagitta height(TSH) grow at different speed, theantirostrum and rostrum becoming distinctness slowly, the growing of antirostrum ismuch more quick than rostrum. The connection of TSL and length of the fish is TSL=0.70274×BL1.3867（R~2=0.7685,n=123),and the connection between the two isdistinctness （P<0.05）,the connection between DED and BL isDED=6.8296*BL0.849877(R~2=0.7833， n=123),the DVR with BL isDVR=0.835819*BL1.254(R~2=0.7937,n=123).But at the same time, the connectingbetween TSH and BL is not evidence(P>0.05). Along with the growth of the pacificsaury, the change of TRL is very small, and the range is0~180um.