提取牡蛎(Raising Oysters)

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

thelarvaedrifteduntiltheyattachedthemselvestothecleanshellsonthebottom.theretheyremainedandintimegrewintobabyoysterscalledseedorspat.thespatgrewlargerbydrawinginseawaterfromwhichtheyderivedmicroscopicparticlesoffood.beforelong,farmersgatheredthebabyoysters,transplantedthemoncemoreintoanotherbodyofwatertofattenthemup.untilrecentlythesupplyofwildoystersandthosecrudelyfarmedweremorethanenoughtosatisfypeoplesneeds.buttodaythedelectableseafoodisnolongeravailableinabundance.theproblemhasbecomesoseriousthatsomeoysterbedshavevanishedentirely.fortunately,asfarbackastheearly1900smarinebiologistsrealizedthatifnewmeasureswerenottaken,oysterswouldbecomeextinctoratbestaluxuryfood.sotheysetupwell-equippedhatcheriesandwenttowork.buttheydidnothavetheproperequipmentortheskilltohandletheeggs.

theydidnotknowwhen,what,andhowtofeedthelarvae.andtheyknewlittleaboutthepredatorsthatattackandeatbabyoystersbythemillions.theyfailed,buttheydoggedlykeptatit.finally,inthe1940sasignificantbreakthroughwasmade.themarinebiologistsdiscoveredthatbyraisingthetemperatureofthewater,theycouldinduceoysterstospawnnotonlyinthesummerbutalsointhefall,winter,andspring.latertheydevelopedatechniqueforfeedingthelarvaeandrearingthemtospat.goingstillfurther,theysucceededinbreedingnewstrainsthatwereresistanttodiseases,grewfasterandlarger,andflourishedinwaterofdifferentsalinitiesandtemperatures.inaddition,thecultivatedoysterstastedbetter!