Berliner Ring 19, D-24211 Preetz, Federal Republic of Germany.
CAPTURE-RECAPTURE ESTIMATES OF HECTOR'S DOLPHIN ABUNDANCE AT BANKS PENINSULA, NEW ZEALAND
Article first published online: 26 AUG 2006
Marine Mammal Science
Volume 21, Issue 2, pages 204–216, April 2005
How to Cite
Gormley, A. M., Dawson, S. M., Dawson, S. M., Slooten, E. and Bräger, S. (2005), CAPTURE-RECAPTURE ESTIMATES OF HECTOR'S DOLPHIN ABUNDANCE AT BANKS PENINSULA, NEW ZEALAND. Marine Mammal Science, 21: 204–216. doi: 10.1111/j.1748-7692.2005.tb01224.x
- Issue published online: 26 AUG 2006
- Article first published online: 26 AUG 2006
- Received: 14 May 2004 Accepted: 17 November 2004
Vol. 28, Issue 2, 437, Article first published online: 19 APR 2012
- Hector's dolphin;
- Cephalorhynchus hectori;
Capture-recapture techniques have been extensively used to estimate survival rates of Hector's dolphins at Banks Peninsula, but not abundance. We analyzed nine seasons of photo-identification data using a model-fitting approach in the computer program MARK, and then used MARK's estimates of capture probabilities to calculate the abundance of distinctive individuals. We extrapolated these estimates to include unmarked individuals using five seasons of data on the proportion of identifiable individuals in this population, obtained from “random photography.” This capture-recapture approach suggests a 1996 population of about 1,100 (CV = 0.21). This is very similar to the 1997 line-transect estimate of about 900 (CV = 0.28), especially considering that the two techniques do not necessarily measure the same thing. An important advantage of the capture-recapture approach stems from the inherent versatility of photo-ID data. If the sampling design is appropriate, an unbiased abundance estimate can be achieved as a spin-off from work directed at other questions. However, in our view, line-transect estimates are easier to interpret because the sampling design is explicit.