万物简史英文版_比尔·布莱森- 第73节

even　at　a　depth　of　three　miles；　they　found　some　3；700　creatures　representing　almost　200species　of　organism。　but　the　dredge　could　only　capture　things　that　were　too　slow　or　stupid　toget　out　of　the　way。　in　the　late　1960s　a　marine　biologist　named　john　isaacs　got　the　idea　tolower　a　camera　with　bait　attached　to　it；　and　found　still　more；　in　particular　dense　swarms　ofwrithing　hagfish；　a　primitive　eel…like　creature；　as　well　as　darting　shoals　of　grenadier　fish。

where　a　good　food　source　is　suddenly　available鈥攆or　instance；　when　a　whale　dies　and　sinks　tothe　bottom鈥攁s　many　as　390　species　of　marine　creature　have　been　found　dining　off　it。

interestingly；　many　of　these　creatures　were　found　to　have　e　from　vents　up　to　a　thousandmiles　distant。　these　included　such　types　as　mussels　and　clams；　which　are　hardly　known　asgreat　travelers。　it　is　now　thought　that　the　larvae　of　certain　organisms　may　drift　through　thewater　until；　by　some　unknown　chemical　means；　they　detect　that　they　have　arrived　at　a　foodopportunity　and　fall　onto　it。

so　why；　if　the　seas　are　so　vast；　do　we　so　easily　overtax　them？　well；　to　begin　with；　theworld鈥檚　seas　are　not　uniformly　bounteous。　altogether　less　than　a　tenth　of　the　ocean　isconsidered　naturally　productive。　most　aquatic　species　like　to　be　in　shallow　waters　where　thereis　warmth　and　light　and　an　abundance　of　organic　matter　to　prime　the　food　chain。　coral　reefs；for　instance；　constitute　well　under　1　percent　of　the　ocean鈥檚　space　but　are　home　to　about　25percent　of　its　fish。

elsewhere；　the　oceans　aren鈥檛　nearly　so　rich。　take　australia。　with　over　20；000　miles　ofcoastline　and　almost　nine　million　square　miles　of　territorial　waters；　it　has　more　sea　lapping　itsshores　than　any　other　country；　yet；　as　tim　flannery　notes；　it　doesn鈥檛　even　make　it　into　the　topfifty　among　fishing　nations。　indeed；　australia　is　a　large　net　importer　of　seafood。　this　isbecause　much　of　australia鈥檚　waters　are；　like　much　of　australia　itself；　essentially　desert。　（anotable　exception　is　the　great　barrier　reef　off　queensland；　which　is　sumptuously　fecund。）because　the　soil　is　poor；　it　produces　little　in　the　way　of　nutrient…rich　runoff。

even　where　life　thrives；　it　is　often　extremely　sensitive　to　disturbance。　in　the　1970s；　fishermenfrom　australia　and；　to　a　lesser　extent；　new　zealand　discovered　shoals　of　a　little…known　fishliving　at　a　depth　of　about　half　a　mile　on　their　continental　shelves。　they　were　known　as　orange1the　indigestible　parts　of　giant　squid；　in　particular　their　beaks；　accumulate　in　sperm　whales　stomachs　into　thesubstance　known　as　ambergris；　which　is　used　as　a　fixative　in　perfumes。　the　next　time　you　spray　on　chanel　no。　5（assuming　you　do）；　you　may　wish　to　reflect　that　you　are　dousing　yourself　in　distillate　of　unseen　sea　monster。

roughy；　they　were　delicious；　and　they　existed　in　huge　numbers。　in　no　time　at　all；　fishing　fleetswere　hauling　in　forty　thousand　metric　tons　of　roughy　a　year。　then　marine　biologists　madesome　alarming　discoveries。　roughy　are　extremely　long　lived　and　slow　maturing。　some　maybe　150　years　old；　any　roughy　you　have　eaten　may　well　have　been　born　when　victoria　wasqueen。　roughy　have　adopted　this　exceedingly　unhurried　lifestyle　because　the　waters　they　livein　are　so　resource…poor。　in　such　waters；　some　fish　spawn　just　once　in　a　lifetime。　clearly　theseare　populations　that　cannot　stand　a　great　deal　of　disturbance。　unfortunately；　by　the　time　thiswas　realized　the　stocks　had　been　severely　depleted。　even　with　careful　management　it　will　bedecades　before　the　populations　recover；　if　they　ever　do。

elsewhere；　however；　the　misuse　of　the　oceans　has　been　more　wanton　than　inadvertent。

many　fishermen　鈥渇in鈥潯�sharks鈥攖hat　is；　slice　their　fins　off；　then　dump　them　back　into　the　waterto　die。　in　1998；　shark　fins　sold　in　the　far　east　for　over　250　a　pound。　a　bowl　of　shark　finsoup　retailed　in　tokyo　for　100。　the　world　wildlife　fund　estimated　in　1994　that　the　numberof　sharks　killed　each　year　was　between　40　million　and　70　million。

as　of　1995；　some　37；000　industrial…sized　fishing　ships；　plus　about　a　million　smaller　boats；were　between　them　taking　twice　as　many　fish　from　the　sea　as　they　had　just　twenty…five　yearsearlier。　trawlers　are　sometimes　now　as　big　as　cruise　ships　and　haul　behind　them　nets　bigenough　to　hold　a　dozen　jumbo　jets。　some　even　use　spotter　planes　to　locate　shoals　of　fish　fromthe　air。

it　is　estimated　that　about　a　quarter　of　every　fishing　net　hauled　up　contains　鈥渂y…catch鈥濃�攆ishthat　can鈥檛　be　landed　because　they　are　too　small　or　of　the　wrong　type　or　caught　in　the　wrongseason。　as　one　observer　told　the　economist：　鈥渨e鈥檙e　still　in　the　dark　ages。　we　just　drop　a　netdown　and　see　what　es　up。鈥潯�perhaps　as　much　as　twenty…two　million　metric　tons　of　suchunwanted　fish　are　dumped　back　in　the　sea　each　year；　mostly　in　the　form　of　corpses。　for　everypound　of　shrimp　harvested；　about　four　pounds　of　fish　and　other　marine　creatures　aredestroyed。

large　areas　of　the　north　sea　floor　are　dragged　clean　by　beam　trawlers　as　many　as　seventimes　a　year；　a　degree　of　disturbance　that　no　ecosystem　can　withstand。　at　least　two…thirds　ofspecies　in　the　north　sea；　by　many　estimates；　are　being　overfished。　across　the　atlantic　thingsare　no　better。　halibut　once　abounded　in　such　numbers　off　new　england　that　individual　boatscould　land　twenty　thousand　pounds　of　it　in　a　day。　now　halibut　is　all　but　extinct　off　thenortheast　coast　of　north　america。

nothing；　however；　pares　with　the　fate　of　cod。　in　the　late　fifteenth　century；　the　explorerjohn　cabot　found　cod　in　incredible　numbers　on　the　eastern　banks　of　north　america鈥攕hallowareas　of　water　popular　with　bottom…feeding　fish　like　cod。　some　of　these　banks　were　vast。

georges　banks　off　massachusetts　is　bigger　than　the　state　it　abuts。　the　grand　banks　offnewfoundland　is　bigger　still　and　for　centuries　was　always　dense　with　cod。　they　were　thoughtto　be　inexhaustible。　of　course　they　were　anything　but。

by　1960；　the　number　of　spawning　cod　in　the　north　atlantic　had　fallen　to　an　estimated　1。6million　metric　tons。　by　1990　this　had　sunk　to　22；000　metric　tons。　in　mercial　terms；　thecod　were　extinct。　鈥渇ishermen；鈥潯�wrote　mark　kurlansky　in　his　fascinating　history；　cod；　鈥渉adcaught　them　all。鈥潯�the　cod　may　have　lost　the　western　atlantic　forever。　in　1992；　cod　fishingwas　stopped　altogether　on　the　grand　banks；　but　as　of　last　autumn；　according　to　a　report　innature；　stocks　had　not　staged　a　eback。　kurlansky　notes　that　the　fish　of　fish　fillets　and　fishsticks　was　originally　cod；　but　then　was　replaced　by　haddock；　then　by　redfish；　and　lately　bypacific　pollock。　these　days；　he　notes　drily；　鈥渇ish鈥潯�is　鈥渨hatever　is　left。鈥�

much　the　same　can　be　said　of　many　other　seafoods。　in　the　new　england　fisheries　offrhode　island；　it　was　once　routine　to　haul　in　lobsters　weighing　twenty　pounds。　sometimes　theyreached　thirty　pounds。　left　unmolested；　lobsters　can　live　for　decades鈥攁s　much　as　seventyyears；　it　is　thought鈥攁nd　they　never　stop　growing。　nowadays　few　lobsters　weigh　more　thantwo　pounds　on　capture。　鈥渂iologists；鈥潯�according　to　the　new　york　times；　鈥渆stimate　that　90percent　of　lobsters　are　caught　within　a　year　after　they　reach　the　legal　minimum　size　at　aboutage　six。鈥潯�despite　declining　catches；　new　england　fishermen　continue　to　receive　state　andfederal　tax　incentives　that　encourage　them鈥攊n　some　cases　all　but　pel　them鈥攖o　acquirebigger　boats　and　to　harvest　the　seas　more　intensively。　today　fishermen　of　massachusetts　arereduced　to　fishing　the　hideous　hagfish；　for　which　there　is　a　slight　market　in　the　far　east；　buteven　their　numbers　are　now　falling。

we　are　remarkably　ignorant　of　the　dynamics　that　rule　life　in　the　sea。　while　marine　life　ispoorer　than　it　ought　to　be　in　areas　that　have　been　overfished；　in　some　naturally　impoverishedwaters　there　is　far　more　life　than　there　ought　to　be。　the　southern　oceans　around　antarcticaproduce　only　about　3　percent　of　the　world鈥檚　phytoplankton鈥攆ar　too　little；　it　would　seem；　tosupport　a　plex　ecosystem；　and　yet　it　does。　crab…eater　seals　are　not　a　species　of　animal　thatmost　of　us　have　heard　of；　but　they　may　actually　be　the　second　most　numerous　large　species　ofanimal　on　earth；　after　humans。　as　many　as　fifteen　million　of　them　may　live　on　the　pack　icearound　antarctica。　there　are　also　perhaps　two　million　weddel　sea