292 CouquiaudFigure 2.1g. Irrawaddy dolph<strong>in</strong>Figure 2.1k. Risso’s dolph<strong>in</strong>Figure 2.1h. Killer whaleFigure 2.1l. Rough-tooth dolph<strong>in</strong> (Photograph from C.Gaspard)Figure 2.1i. Pacific humpack dolph<strong>in</strong>Figure 2.1j. Pacific white-sided dolph<strong>in</strong>Figure 2.1m. Hybrid false killer whale x bottlenosedolph<strong>in</strong>
2. Whales, Dolph<strong>in</strong>s, and Porpoises: Presentation <strong>of</strong> the <strong>Cetaceans</strong> 293Ma<strong>in</strong>ta<strong>in</strong><strong>in</strong>g the water temperature <strong>in</strong> captivity atthe same level as the orig<strong>in</strong>al habitat is critical.Although mar<strong>in</strong>e mammals have efficient ways<strong>of</strong> regulat<strong>in</strong>g temperature, expos<strong>in</strong>g the animal toexcessive heat is as life threaten<strong>in</strong>g as excessivecold (Geraci, 1986b). They can tolerate and adaptto some variation, but they should not be exposedto drastic and sudden changes to ma<strong>in</strong>ta<strong>in</strong> a balancedenergy budget. It is important to keep ananimal wet, especially the flippers and flukes,dur<strong>in</strong>g transportation, to prevent overheat<strong>in</strong>g.Odontocetes have teeth, which they use tograsp prey or for social <strong>in</strong>teractions. In some species,the teeth are barely apparent, or their numberis greatly reduced, as <strong>in</strong> the narwhal or beakedwhales. Odontocetes do not chew their food, butsome dolph<strong>in</strong>s behead fish by smash<strong>in</strong>g or shak<strong>in</strong>g.Other cetaceans swallow their fish whole, headsfirst. They eat a wide variety <strong>of</strong> fish, squid, andcrustacean; and some larger whales, such as killerwhales <strong>in</strong> the wild feed on other mar<strong>in</strong>e mammalsand birds (see Chapter 7 for details). The smallestspecies <strong>of</strong> odontocete, the harbour porpoise,requires a daily portion <strong>of</strong> food estimated to be upto 13% <strong>of</strong> its body weight <strong>in</strong> w<strong>in</strong>ter (Evans, 1987),whereas the bottlenose dolph<strong>in</strong> may need between3 and 6.5% <strong>of</strong> body mass per day (Barros & Odell,1990), depend<strong>in</strong>g on the type <strong>of</strong> food, the watertemperature, season, activity, and if females arepregnant or nurs<strong>in</strong>g (Reddy et al., 1994; Kastele<strong>in</strong>et al., 2003). In contrast, the baleen whales haveplates <strong>of</strong> kerat<strong>in</strong>, hang<strong>in</strong>g from the palate, <strong>in</strong>stead<strong>of</strong> teeth. These plates filter zooplankton, fish, andsquid from the water <strong>in</strong>to the mouth (Evans, 1987).Because Baleen whales require such a specializeddiet and such large quantities <strong>of</strong> food, they rarelyhave been kept <strong>in</strong> captivity (Stewart, 2001).Pelagic mar<strong>in</strong>e species live <strong>in</strong> a salty environmentthat is four times more concentrated thanbody fluids. The anatomy and physiology <strong>of</strong> cetaceansare aimed at reduc<strong>in</strong>g water loss. This canbe observed <strong>in</strong> the small amounts <strong>of</strong> water lostdur<strong>in</strong>g respiration and <strong>in</strong> the production <strong>of</strong> concentratedmilk, faeces, and ur<strong>in</strong>e. Salt and waterbalance is achieved ma<strong>in</strong>ly through food, whichprovides water directly available or derived fromthe oxidation <strong>of</strong> fat. The fattier the fish eaten, themore water is available to the cetacean. As a result,a prolonged fast <strong>in</strong> a sick animal can quickly leadto dehydration (Geraci, 1986a).<strong>Cetaceans</strong> are voluntary breathers, mean<strong>in</strong>gthat their breath<strong>in</strong>g is under conscious control;the blowhole is normally closed. Thisis different from humans whose breath<strong>in</strong>g is<strong>in</strong>voluntary and a reflex. Dur<strong>in</strong>g sleep periods,dolph<strong>in</strong>s rest each hemisphere <strong>of</strong> their bra<strong>in</strong>separately while the other hemisphere is activelykeep<strong>in</strong>g the animal <strong>in</strong> motion and control<strong>in</strong>gbreath<strong>in</strong>g. All cetacean species studied have beenshown to exhibit unihemispheric slow-wave sleep(Mukhametov et al., 1977; Mukhametov, 1987,1988; Mukhametov & Lyam<strong>in</strong>, 1994; Lyam<strong>in</strong>et al., 2002; Ridgway, 2002) or signs <strong>of</strong> this sleepstate behaviourally (Lyam<strong>in</strong> et al., 1998, 2000;Sekiguchi & Koshima, 2003). Dur<strong>in</strong>g respiration,a cetacean exchanges about 80% <strong>of</strong> the airconta<strong>in</strong>ed <strong>in</strong> their lungs as opposed to 17% forhumans. Exhal<strong>in</strong>g and <strong>in</strong>hal<strong>in</strong>g usually takes lessthan one second.Some cetaceans can hold their breath fromseveral m<strong>in</strong>utes to more than an hour. Bottlenosewhales have been recorded under water for aslong as 80 m<strong>in</strong>, and sperm whales at depth <strong>of</strong>3,195 m (Leatherwood & Reeves, 1983; Evans,1987; Kl<strong>in</strong>owska, 1991; Hooker & Baird, 1999).Many <strong>of</strong> the smaller whales and dolph<strong>in</strong>s can diveto several hundred meters for up to 10 m<strong>in</strong>. Thenecessity to dive at great depths and to hold theirbreath for long periods <strong>of</strong> time has brought aboutanatomical and physiological adaptations. These<strong>in</strong>clude the compressible rib cage and lungs, aslower heartbeat while div<strong>in</strong>g, a shunt<strong>in</strong>g <strong>of</strong> theblood away from limbs and toward the heart andbra<strong>in</strong>, and a high content <strong>of</strong> oxygen-b<strong>in</strong>d<strong>in</strong>g prote<strong>in</strong>—themyoglob<strong>in</strong>—which prevents musclesfrom oxygen deficiencies (Geraci, 1986a). In captivity,only shallow depths are available comparedwith great depths <strong>in</strong> the wild. Yet, it is importantto provide animals with habitats as large and deepas possible to encourage div<strong>in</strong>g and rapid swimm<strong>in</strong>g.Adaptations <strong>of</strong> the epidermis reduce turbulence,and the streaml<strong>in</strong>ed shape <strong>of</strong> their bodiesallows dolph<strong>in</strong>s to swim fast. Recent studies havedemonstrated that realistic maximum swimm<strong>in</strong>gspeeds for dolph<strong>in</strong>s are lower than previouslyreported, which were based on sparse data andimprecise measurement techniques. Bottlenosedolph<strong>in</strong>s, false killer whales, and short-beakedcommon dolph<strong>in</strong>s have reached maximum speedsbetween 28.8 and 29.5 km/h, and long-beakedcommon dolph<strong>in</strong>s can atta<strong>in</strong> the speed <strong>of</strong> 24.1 km/h (Rohr et al., 2002; Anonymous, 2003). Cruis<strong>in</strong>gspeed <strong>of</strong> bottlenose dolph<strong>in</strong>s is on average 6 km/h(Anonymous, 2003).<strong>Cetaceans</strong> become sexually mature at differentages, depend<strong>in</strong>g on their species, but <strong>in</strong>dividualsseem to reach sexual maturity when they obta<strong>in</strong>a certa<strong>in</strong> size, rather than a certa<strong>in</strong> age. Gestationperiod varies from 7 to 12 months for dolph<strong>in</strong>sand up to 18 for larger species such as the killerwhale (Schroeder, 1995). Calv<strong>in</strong>g <strong>in</strong>tervals varyfrom one to six years. Gestation, calv<strong>in</strong>g <strong>in</strong>terval,and life spans are longer for larger species. Theharbour porpoise, for example, is expected to livefor up to 24 years (Read, 1999), the bottlenose
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6. Life Support Systems 353sometime
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6. Life Support Systems 355al., 199
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7. Food and Fish House 365in its se
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8. Husbandry 373Figure 8.3. Milk sa
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8. Husbandry 375reintroducing a new
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8. Husbandry 377Rescue and Rehabili
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8. Husbandry 379Appendix II include
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8. Husbandry 381& R. J. Harrison (E
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Appendix 383Dolphinarium YaltaDolph
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Appendix 385Aomori Prefectural Asam
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