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Ecology & Evolutionary Biology

TEST 2: BIODIVERSITY: the variability among living organisms from all sources including among others, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part. Conservation of any species is highly complicated and includes factors such as its ABUNDANCE, RATE OF REPRODUC- TION, EXTINCTION RATE, NATURAL DISASTERS, MANKINDS INFLUENCE, etc. ex. global warming -> melting arctic ice recedes away from land -> polar bears swim further to hunt -> unable to properly feed cubs. ---- estimated that polar bears will become extinct within next 100 years or sooner. Reasons why numerous species of marine mammals have become threatened or near extinction: a) SLOW REPRODUCTION RATE: at most only one offspring per year --> difficult to increase pop. size b) SLOW POPULATION GROWTH: maturing rate of killer whale is 12 years old c) RETURNING TO SAME GEOGRAPHIC REGION to feed or breed --> easy to capture and exploit d) LOW POPULATIONS or DISTRIBUTIONS:susceptible to any outside stress such as commercial exploitation COSEWIC: Committee on the Status of Endangered Wildlife in Canada EXTINCT: species no longer exists EXTIRPATED: species no longer exists in the wild in Canada but occurs elsewhere in the world ENDANGERED: species faces imminent extirpation THREATENED: species likely to become endangered if limiting factors are not reversed SPECIAL CONCERN: species is of special concern because of characteristics that make them particularly sensitive to human activities or natural events As of 2007, marine mammals make up of 45% of all ENDANGERED species, 50% of all THREATENED species, and 56% of all SPECIAL CONCERN species. Total number of mammalian species (land&marine) in brackets Number of species involved are indicated by X followed by the number. ex. 2 species of beluga whales are endangered out of a total of 20 mammalian species that are endangered Extinct(2) Extirpated(3) Endangered(20) Threatened(17) Special Concern(27) Mink, Sea Whale, Grey x 1 Whale, Beluga x 2 Seal, Northern Fur x 1 Narwhal x 1 Whale, Blue x 2 Whale, Beluga x 2 Otter, Sea x 1 Whale, Killer x 1 Whale, Bowhead x 2 Bear, Polar x 1 Whale, North Atlantic Right Whale x 1 Whale, Fin x 1 Porpoise, Harbor x 2 Whale, North Atlantic Pacific Right x 1 Whale, Humpback x 1 Sea lion, Stellar x 1 Whale, Northern Bottlenose x 1 Whale, Killer x 2 Seal, Lacs des Loup (Harbor) x 1 Whale, Sei x 1 Walrus, Atlantic x 1 Whale, Beluga x 2 Whale, Bowhead x 1 Whale, Fin x 1 Whale, Grey x 1 Whale, Killer x 1 Extinct(2) Extirpated(3) Endangered(20) Threatened(17) Special Concern(27) Whale, Sowerbys Beaked x 1 Marine mammals make up: 45% all endangered species, 50% all threatened, 56% all special concern Examples: EXTINCT: Sea Mink (Neovision Macrodon) became extinct in 1894 before it could be scientifically described cousin of American mink, longer bulkier version with longer and coarser reddish pelt thought to be nocturnal, solitary animal hunted to extinction by European fur market DIST.--> along coast of NA ranging from Nova Scotia to New England states. EXTIRPATED: Atlantic Grey Whale (Eschrischtius robustus) Department of fisheries and oceans: Recovery Strategy for the grey whale, Atlantic Population in Canada 2007): re- covery of the Atlantic grey whale is not feasible at this time ---> species is considered to be extirpated all other sources of reference consider the grey atlantic species to be extinct extirpated from western North Atlantic waters since before end of 1800s medium large baleen whale would have required northern regions filled with rich food sources, warm and protected lagoons for birth and migratory pathway (based on pacific grey whales) unclear why it went extinct, generally accepted that whaling was sole reason responsible DIST. --> North American seaboard from Florida up into NFL and possibly into Hudson Bay ENDANGERED: Beluga Whale (delphinapterus leucas) smaller populations are in danger of being wiped out (the ones on COSEWIC list) endangered due to commercial hunting carried on in past and have not yet recovered despite ban on whaling DIST. --> arctic sea. sunpopulations ranging from 40,000 in the Beaufort Sea and 18,000 in eastern Bering sea --> a highly endangered pop (150-300) in St Lawrence river from comm. hunting and diseases due to toxins THREATENED: Northern Fur Seal (Callorhinus ursinus) one of only 2 fur seals in Northern Hemisphere distinctive feature: small head, short snout, long hind flippers with long digits, hair abruptly stops at wrist male: dark brown or black. females: dark brown to light grey with light gray/cream stripe on throat/lower chest male: 2.1 m and females up to 1.5 m hunted commercially for fur major threats today: sudden drop in pup survival, competition for food from overfishing, trapped in fish nets DIST. --> northern Pacific ocean bordered by Sea of Okhotsk (JP), Bering Sea (Russia, Alaska), eastern Pacific (Cali) --> few breeding sites of coast of russia, alaska, and cali --> approx. 1.2 million individuals scattered across this range SPECIAL CONCERN: Atlantic Walrus (Odobenus rosmarus rosmarus) single species of pinniped family Odobenidae which has upper canine teeth in both sexes adult males: 3.2m 1200-1500kg. females: 2.7m 600-850 kg skin 2-4 cm thick and tough. Skin of males thicker and covered in fibrous tubercles around neck as protection from at- tacks or are visual sexual characteristic DIST. --> central arctic CA down to NS but pop along atlantic coast of CA extirpated due to comm hunting --> 5-8 distinct geo subpops 10-15,000 individuals --> pop that once inhabited Martimes believed to have numbered in tens of thousands but not re-established despite banning of comm. hunting in CA since 1932 HUNTING/WHALING AND MARINE MAMMALS estimated 36% of marine mammals are at risk of extinction History of Huntingexploitation of marine mammals for OIL, MEAT, BALEEN AND BONES coastal natives hunted for pinnipeds and near shore cetaceans over 8500 years ago starting 11th century, commercial hunting seriously reduced population of #s of many species and caused extinction of sever- al species while others became threatened or endangered 1860s, modern whaling began in NORWAY using motorized boats and harpoon cannons firing grenades 1972, last whaling stations closed in CA and USA JAPAN and ICELAND (grr..) continue to hunt over 1000 whales or dolphins of various species per year Examples of extinct species or on their way to extinction: Stellars sea cow extinct by 1768 Atlantic grey whale extinct around early 1700s Caribbean monk seal rare by 1850s and extinct 1960s Atlantic Walrus exterminated from eastern Atlantic seaboard by 1800s Reduced populations: Sea Otter reduced from 300,000 to several thousand between 1741 to 1900 Fur seals hunted in massive scales resulting in US listing 5 pinniped species as endangered Cetaceans uncontrolled hunting resulting in US listing 11 as endangered Whales: over 2 MILLION killed in southern hemisphere during 20th century PINNIPEDS: - started with Stone Age people attacking with clubs. other tools: harpoons, gaffs, firearms, nets and traps - use of firearms increased proportion of sinking loss - hunted for their meat, fat and pelts - ivory tusk of walrus make them highly prized animals and at least 10,000 walrus are taken per year by natives in arctic - over 10,000 seals killed every year by natives - apprx. 100,000 to 200,000 harp seals killed per year by comm. hunters during spring seal hunt along east cost of CA SIRENIANS: - Stellars sea cow hunted to extinction after 25 years of
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