ESR 26:87-92 (2014)  -  DOI: https://doi.org/10.3354/esr00621

NOTE
Critically low abundance and limits to human-related mortality for the Maui’s dolphin

Rebecca M. Hamner1,2,*, Paul Wade3, Marc Oremus2, Martin Stanley4, Phillip Brown4, Rochelle Constantine2, C. Scott Baker1,2

1Marine Mammal Institute and Department of Fisheries and Wildlife, Oregon State University, Hatfield Marine Science Center, 2030 SE Marine Science Drive, Newport, Oregon 97365, USA
2School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
3National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, 7600 Sand Point Way NE, Seattle, WA 98155, USA
4New Zealand Department of Conservation, Auckland Conservancy, Private Bag 68908, Auckland 1145, New Zealand
*Corresponding author:

ABSTRACT: The New Zealand endemic Maui’s dolphin Cephalorhynchus hectori maui is characterized by several life history traits thought to be important predictors of extinction risk in marine mammals, including a slow rate of reproduction, small geographic range, small group size, and coastal distribution. We continued the genetic monitoring of the remnant population of Maui’s dolphins using DNA profiles to identify 39 individuals from 73 skin biopsy samples collected during dedicated boat surveys in the austral summers of 2010 and 2011. Using a 2-sample, closed-population model with the genotype recapture records, we estimated the current abundance to be N = 55 individuals approximately age 1+ (95% confidence limits = 48, 69; coefficient of variation = 0.15). The endangered species potential biological removal that would permit the recovery of the Maui’s dolphin was calculated to be 1 dolphin every 10 to 23 yr. Despite this, the Maui’s dolphin is not necessarily doomed to extinction. It appears to be maintaining an equal sex ratio and connectivity within its remnant range and has the potential for rescue by interbreeding with Hector’s dolphin C. h. hectori migrants.


KEY WORDS: Abundance · Genotype mark-recapture · Potential biological removal · Cephalorhynchus hectori maui · Critically endangered · Cetacean · New Zealand


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Cite this article as: Hamner RM, Wade P, Oremus M, Stanley M, Brown P, Constantine R, Baker CS (2014) Critically low abundance and limits to human-related mortality for the Maui’s dolphin. Endang Species Res 26:87-92. https://doi.org/10.3354/esr00621

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