[MARMAM] New paper on possible stock structure of Pacific coast bottlenose dolphins

Richard Defran rh.defran at gmail.com
Mon Jul 13 15:15:13 PDT 2015

Dear Colleagues,

We are pleased to announce the publication of a new paper on possible stock
structure  of coastal bottlenose dolphins off
California and Baja California, Mexico.

“Defran, R.H., Marthajane Caldwell, Eduardo Morteo, Aimée Lang, Megan Rice
and David W. Weller. 2015. Possible stock structure of coastal bottlenose
dolphins off Baja California and California revealed by
photo-identification research. *Bulletin of the Southern California Academy
of Sciences*: Vol. 114 (1).”

Boat-based photo-identification research has been carried out on bottlenose
dolphins in eastern North Pacific coastal waters off northern Baja
California, Mexico and southern and central California, USA from 1981 to
2001. Within these waters, bottlenose dolphins routinely travel back and
forth between coastal locations while generally staying within a narrow
corridor extending only 1–2 km from the shore. Inter-area match rates for
616 dolphins photo-identified between 1981–2000 in four California coastal
study areas (CCSAs) of Ensenada, San Diego, Orange County and Santa Barbara
averaged 76%. To explore possible southern range limits for these dolphins,
photo-identification surveys were carried out in the coastal waters off San
Quintín, Baja California, Mexico between April-August 1990 (*n*=8 surveys)
and July 1999 to June 2000 (*n*=12 surveys). The 207 individual dolphins
identified off San Quintín were compared to the 616 dolphins identified in
the CCSAs. The inter-area match rate between San Quintín and the CCSAs was
3.4% (*n*=7 dolphins). This low rate contrasts sharply with the much higher
average match rate of 76% observed between the CCSAs. These differences in
match rates suggest that both a California coastal stock and coastal
Northern Baja California stock may exist, with only a limited degree of
mixing between them.

A PDF copy of this paper is available for free download at:

or by request from rh.defran at gmail.com


 R.H. Defran and co-authors
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