简介：Overthepastfewdecades,extremechangeshaveoccurredinthecharactersofexploitedfishpopulations.Themajorityofthesechangeshaveaffectedthegrowthtraitsoffishlifehistory,whichincludeasmallersize-at-age,anearlierage-at-maturationandamongothers.Currently,thecausesoftheselifehistorytraitschangesstillrequiresystematicanalysesandempiricalstudies.Theexplanationsthathavebeencitedaremerelyexpressedintermsoffishphenotypicadaptation.Ithasbeenclaimedthattheoriginaltraitsoffishcanberecoveredoncetheintensityofexploitationofthefishiscontrolled.Sustainedenvironmentalandfishingpressurewillchangethelifehistorytraitsofmostfishspecies,sothefishindividual’straitsarestillinsmallsize-at-ageandatearlierage-at-maturationinexploitedfishpopulations.Inthispaper,weexpressedourviewofpointsthatfishinggearhasimposedselectivityonfishpopulationsandindividualsasvariousotherenvironmentalfactorshavedoneandsuchchangesareunrecoverable.Accordingtotheexistingtendofexploitedfishindividual’slifehistorytraits,wesuggestedfurtherresearchesinthisfieldandprovidedbettermethodsoffisherymanagementandtherebyfisheryresourcesprotectionthanthoseavailableearly.

简介：TheDiverGasRecoverySystem(DGRS)isanimportantaccessoryequipmentofthe300mSaturationDiveSystem.Thesystemfacilitatestherecyclingofthebreathinggasesfordivers,therefore,ithasgreateconomicbenefits.InApril1995,a300munmannedtestanda100mmannedtestontheHY2031DGRSwerecarriedoutsuccessively.Tenmonthslater,anothermannedtestontheHY2032DGRS