Dear friends and
collegues:
We are pleased to
let you know that a new paper: Local decline in abundance of bottlenose
dolphins (Tursiops truncatus) in the Bay of Islands, New
Zealand is currently available through early online access in the
Marine Mammal Science website. Altenratively, I can email PDF's upon
request.
Abstract
Regional
populations of bottlenose dolphins (Tursiops truncatus) around New
Zealand are genetically isolated from each
other and the species was recently classified as
nationally endangered based on relatively small population sizes and
reports of high calf mortality. Here, we
estimate the abundance and trends in one of these regional populations, the Bay of Islands, using a
photo-identification database collected from
1997 to 1999 and from 2003 to 2006, containing a total of 3,841 records
of 317 individual dolphins. Estimates of
abundance obtained with the robust design fluctuated widely but showed a significant decline in the
number of dolphins present in the bay over
time (7.5% annual rate of decline). Temporary emigration was random and fluctuated considerably (c = 0.18, SE =
0.07 to c = 0.84, SE = 0.06). Apparent
survival was estimated at 0.928 (CI = 0.911–0.942). Seasonal estimates (26 seasons) obtained in POPAN also showed a significant
decline in abundance (5.8% annual rate of
decline). Despite the decline observed in local abundance, dolphins continue to be found regularly in the Bay of
Islands, suggesting that fewer dolphins
use the bay on regular basis. Consequently, it seems that a change in
habitat use, mortality and possibly low
recruitment could underlie the apparent local
decline.
Kind
regards
Gaby
Gabriela Tezanos-Pinto
BSc (hons), PhD
Adjunct Research
Associate
Coastal-Marine Research
Group
Institute of Mathematics and Natural
sciences
Albany Campus, Massey
University