台湾海峡及其邻近海域四种底层及近底层鱼类生态学特征变化的-研究

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1、Abstract2006谢ththatof1970s，1980sand1990s，themaximumandmeailbodylengths，thedominantlengthsandweights，themaximumandmeanbodyweights，themeanages，theminimumsizesatfirstsexualmaturity,theasymptoticbodylengths∞0andtheasymptoticbodyweights(眠)ofthefourdemersalspecie

2、sdecreasedgraduallyinrecentdecades，indicatingthatthepopulationswereyoungerinage，smallerinsizeandearlierinsexualmaturity．Atthesametime，thegrowthcoefficients(pincreasedandagesattheinflexionpointofweight(∞wereyoungerthanbefore．Thetotalmortalitycoefficient(z)an

3、dthefishingmortality(Doffourdemersalspecieswereathighlevels，theexploitationratio(Dhadbeenreachedorexceeded0．5，whichindicatedthatthefourdemersalspeciespopulationhadbeenfullyexploitedoroverexploited．(2)Fishingandclimatechangeswerethemostimportantfactorsleadin

4、gtothefluctuationsofpopulationandecologicalparametersoffishes．Thefishingeffectsonthefisheryresourceswereasfollows：firstly,theamountofresourcesdecreased；secondly,inpopulationlevel，individualsweresmallerinsizeandyoungerinage，andpopulationstructurebecamesimpli

5、stic，reflectinginecologicalcharacteristics，individualsmanifestedasthegrowthrateincreased，ageattheinflexionpointofweightbeingyoungerandsexualmaturitybeingearlier,etc．；thirdly,inecosystemlevel，thelong．1ivedandhightrophiclevelfisheshadbeenreplacedbytheshort-li

6、vedandlowtrophiclevelinvertebratesandfishesgradually；finally,someirrationalfishingpracticessuchastrawlinggreatlychangedthemarinehabitats，andthenthreatenedthegrowthandreproductionofmarineorganisms，especiallydemersalfishes．Inaddition，overfishinghadmadethefish

7、populationstoafragilestatus；therebystrengthenedthethreatscausedbyclimatechanges，andmadetheecosystemunderhighexploitationpressuremoresensitivetoenvironmentalchanges．Climatechangescouldaffectfishpopulationandtheirecologicalcharacteristicsinbothdirectandindire

8、ctways．Theincreasingseasurfacetemperaturescausedbyclimatechangeswouldaffectfishgrowthandreproductionfromorganization，individual，populationandecosystemperspectives．ClimateextremeeventssuchasENSOhadleade