A15 - year studyof blue whale bowel movement off the coast of California reveal how busy shipping lanes cut powerful through their favorite alimentation grounds . go or halting the shipping traffic during season when whales are the most abundant could importantly decrease their risk of infection of ship strikes , according to thefindingspublished inPLoS Onethis week .
Blue whales ( Balaenoptera muscle ) living in the eastern North Pacific can move from the Gulf of Alaska all the mode to the Costa Rica Dome near the equator . The population has been depleted by commercial-grade whaling , and even though the International Whaling Commission commence protecting them in 1966 , there ’s been no evidence of substantial population growth . Something ’s still impeding their retrieval .
About 2,500 of the world ’s 10,000 disconsolate hulk spend time in waters off the west coast of the U.S. To determine which areas are the most important and when , a team led byLadd Irvine from Oregon State Universityattached transmitters to 171 blue whales off California and tracked their movements via orbiter from 1993 to 2008 . Scientists in inflatable sauceboat attach the tatter near the dorsal fin using a modified crossbow or a gun shooting compressed air .
During the summer and fall , Santa Barbara and San Francisco were the most heavily used expanse , leave the whales in the path of watercraft traveling to and from the Los Angeles and San Francisco ports . Once , five blue whales were hit within a seven - week period .
“ The principal expanse that appeal blue whales are extremely fertile , strong upwelling zona that produce large amounts of krill – which is fairly much all that they eat up , ” Irvine tell in anews release . They ’re the biggest beast that have ever lived , yet their diet is primarily these 5 - centimeter ( 2 - inch ) runt - similar critters . The whales maximise their nutrient intake during the summer and lessen before migrate south for the winter .
“ It ’s an infelicitous coincidence,“Irvine tells the Los Angeles Times . " The down hulk want to find the dense food provision . There ’s a circumscribed turn of those thick place , and it seems as though two of the chief unconstipated spot are cross by the shipping lanes . ”
investigator do n’t make out how many are being shoot by ships , Science reports , and they ca n’t say if these strikes are what ’s by all odds keeping the universe phone number downhearted . “ At a minimum , it ’s not helping,”Irvine total .
Blue whale may not be as acoustically cognizant as specie who apply echolocation to find quarry , and the rearward placement of engines creates an acoustical tail that make it punishing for whales to get a line oncoming ship .
Speed restriction could help , and moving the shipping lanes off LA and SF to slightly different areas – at least during summertime and fall down when grim whales are the most abundant – could lower their threat of injury and fatality rate , the investigator say . A similar shipping lane relocation in the Bay of Fundy off easterly Canada lowered the likeliness of vessels striking right whales by 80 percent . Here ’s a drear whale spouting !
figure : Craig Hayslip , Oregon State University Marine Mammal Institute ( top),Oregon State University ( middle),Flip Nickin , Minden Pictures ( bottom )
