Baleen Whales

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Baleen whales undergo the longest annual migrations of any animal (Rice and Wolman 1971, Stone et al. 1990, Rasmussen et al. 2007). The function has generally been accepted as an evolutionary response to the need to feed in colder waters and reproduce in warmer waters (Corkeron and Connor 1999, Learmonth et al 2006). The location of feeding and breeding grounds along migration routes were initially inferred from stomach contents of stranding data and whaling logs (e.g., MacKintosh 1945, Scammon 1874, Pike 1962, Reeves et al 2004). Migration studies were rare before the 1960s because baleen whale populations were severely depleted by commercial whaling (Johnson and Wolman 1984, Mizroch et a1. 1984, Butterworth et al 2002). Studies increased …show more content…
However these methods were costly and years of data would be needed to make statistical inferences. In the 1960’s Kooyman (1965) developed the first time-depth recorder to study the physiological diving capabilities of Weddell Seals in the Antarctic. Argos receivers became operational on NOAA satellites in 1978 making it possible to determine the location of a tagged animal anywhere on the Earth’s surface. Combined photograph identification and passive acoustic monitoring, this has provided a number of tools for advancing understanding of baleen whale biology, including migration patterns (Katona et al. 1980, Clapham et al. 1992, Kooyman, …show more content…
In the late 1970’s, PDO was linked a biotic regime shift in the northeast Pacific (Francis et al. 1998, Hare and Mantua 2000). Rugh et al. (2001) found a ~7 day delay in the southbound migration of grey whales after 1980, coincident with the shift. In a longer-term study, Ramp et al. (2015) found that humpback and fin whales in the Gulf of St. Lawrence (Canada) moved their migration arrival time up roughly one month earlier over 27 years, correlating with changes in sea surface temperature (SST; a proxy for primary productivity) and sea ice. Once on foraging grounds, whales may stay longer. Hauser et al. (2016) found that Chukchi beluga whale had significantly delayed migrations (2-4 weeks) from the Beaufort and Chukchi Seas over 19 years, as regional sea ice freeze-up timing became later in the Beaufort, Chukchi, and Bering

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