My colleagues and I are pleased to report that the following paper has been
recently published.
Thomas A. Jefferson, Dagmar Fertl, Jaime Bolaños-Jiménez, and Alexandre N.
Zerbini. 2009. Distribution of common dolphins (Delphinus spp.) in the western
Atlantic Ocean: a critical re-examination. Marine Biology 156:1109–1124.
Abstract:
Due to indications that misidentification (largely confusion among dolphins of
the genera Delphinus and Stenella) in the past had led to erroneous assumptions
of distribution of the two species of common dolphins (Delphinus delphis and D.
capensis) in the western Atlantic Ocean, we conducted a critical re-examination
of records of the genus Delphinus from this region. We compiled 460 ‘plottable’
records, required support for confirmation of
genus and species identifications, and found many records lacking (and some
clearly misidentified). When we plotted only the valid records (n = 364), we
found evidence of populations in only three areas, and apparent absence
throughout much of the tropical/subtropical regions. Off the east coast of the
US and Canada, D. delphis is found from the Georgia/South Carolina border
(32°N) north to about 47–50°N off Newfoundland. Since the 1960s, they have
apparently been absent from Florida waters. There is no evidence that dolphins
of the genus occur in the Gulf of Mexico. Reports of common dolphins from most
of the Caribbean Basin are also rejected, and the only place in that region
where they are confirmed to occur is off central-eastern
Venezuela (a coastal D. capensis population). Off eastern South America, common
dolphins appear to be restricted to south of 20°S. There is a coastal
long-beaked population found in the South Brazil Bight, and one or more
short-beaked populations south and offshore of this (ranging south to at least
northern Argentina). The results are very different from commonly-accepted
patterns of distribution for the genus in the Atlantic. Most areas of
distribution coincide with moderate to strong upwelling and common dolphins
appear to avoid warm, tropical waters. This study shows that great care must be
taken in identification of similar-appearing long-beaked delphinids, and that
uncritical acceptance of records at face value can lead to
incorrect assumptions about the ranges of the species involved.
pdf copies are available upon request from me (see email information below).
Regards,
Dagmar Fertl
dfe...@gmail.com
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