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Life or death in the fast lane: dolphin mother‐calf separation during tuna purse‐seine sets
Author(s) -
Edwards Elizabeth F.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1176.10
Subject(s) - fishery , fishing , biology , tuna , stock (firearms) , demography , geography , fish <actinopterygii> , archaeology , sociology
Dolphin stocks in the eastern tropical Pacific Ocean, reduced 70–80% due to fishery‐related mortality 1960–1990, are not recovering despite near‐zero fishery mortality since 1991. Because mortality records show that 75–95% of killed lactating females are not killed with a nursing calf, the fishing process appears to separate mothers and calves, so that unobserved mortality of calves may be important to the lack of stock recovery. A suite of studies investigated this question from a number of perspectives, including review of physiological and behavioral development in dolphin calves, mathematical analysis of dolphin drafting hydrodynamics, and empirical studies of swim development in dolphin calves from birth through two years. In toto, these studies show that the sustained high‐speed swimming and accompanying aerial respirations characteristic of dolphins evading purse‐seine sets creates conditions under which dolphin calves will have great difficulty sustaining a drafting relationship with the mother, and that developmental limits are likely to prevent calves from maintaining an association with the mother while swimming independently. Effects are strongly age‐related, with youngest calves at greatest risk for separation.