提取牡蛎(Raising Oysters)

intheoysterswereraisedinmuchthesamewayasdirtfarmersraisedtomatoes-bytransplantingthem.first,farmersselectedtheoysterbed,clearedthebottomofoldshellsandotherdebris,thenscatteredcleanshellsabout.next,they"planted"fertilizedoystereggs,whichwithintwoorthreeweekshatchedintolarvae.

thelarvaedrifteduntiltheyattachedthemselvestothecleanshellsonthebottom.theretheyremainedandintimegrewintobabyoysterscalledseedorspat.thespatgrewlargerbydrawinginseawaterfromwhichtheyderivedmicroscopicparticlesoffood.beforelong,farmersgatheredthebabyoysters,transplantedthemoncemoreintoanotherbodyofwatertofattenthemup.

untilrecentlythesupplyofwildoystersandthosecrudelyfarmedweremorethanenoughtosatisfypeople＇sneeds.buttodaythedelectableseafoodisnolongeravailableinabundance.theproblemhasbecomesoseriousthatsomeoysterbedshavevanishedentirely.

fortunately,asfarbackastheearly1900＇smarinebiologistsrealizedthatifnewmeasureswerenottaken,oysterswouldbecomeextinctoratbestaluxuryfood.sotheysetupwell-equippedhatcheriesandwenttowork.buttheydidnothavetheproperequipmentortheskilltohandletheeggs.theydidnotknowwhen,what,andhowtofeedthelarvae.

andtheyknewlittleaboutthepredatorsthatattackandeatbabyoystersbythemillions.theyfailed,buttheydoggedlykeptatit.finally,inthe1940＇sasignificantbreakthroughwasmade.

themarinebiologistsdiscoveredthatbyraisingthetemperatureofthewater,theycouldinduceoysterstospawnnotonlyinthesummerbutalsointhefall,winter,andspring.latertheydevelopedatechniqueforfeedingthelarvaeandrearingthemtospat.

goingstillfurther,theysucceededinbreedingnewstrainsthatwereresistanttodiseases,grewfasterandlarger,andflourishedinwaterofdifferentsalinitiesandtemperatures.inaddition,thecultivatedoysterstastedbetter!