Regional resource limitation in the
eastern Levantine Basin was predicted to protract the growth of members of the
Israeli sub-population of the common bottlenose dolphin (CBD), compared to CBD
sub-populations of similar adult size. Growth curves were fitted to
length-at-age data available for 24 male and 26 female CBD stranded or
incidentally caught along the Israeli coastline between 2000 and 2009. The
obtained model growth constants were compared to those of other CBD
sub-populations from the southeastern coast of the United States and a
correlation to regional seawater primary productivity was sought. As in other
sub-populations, local CBD females initially grow faster than males for
approximately 3–4 years and remain longer until around eight years old,
after which males surpass them in length. Yet the steep early growth of females
as well as its high rate of decay was found to be extreme compared to other CBD
sub-populations, with 99% of the asymptotic length being reached at the age of
six years. A positive correlation between seawater primary productivity and
early growth rate as well as growth decay constants could be demonstrated for
CBD males from Texas, Florida and Israeli coasts. Females of the same
sub-population presented a non-monotonic relationship to primary productivity.
Early female attainment of physical maturity in an ultra-oligotrophic region was
unpredicted and is not readily explained. It may accompany early reproductive
maturation, selected for as partial compensation for lower lifelong reproductive
success.
If interested, the following
Taylor & Francis link will last 50 free downloads, after which PDF
copies may be requested
from me.
Cheers,
Dani
Dan H. Kerem,
PhD
IMMRAC (Israel Marine Mammal
Research & Assistance
Center)
The Recanati
Institute for Maritime Studies
The Charney School for Marine Sciences
The University of
Haifa
Mt. Carmel, Haifa 31905
Israel
http://maritime2.haifa.ac.il/eng/DK.asp
http://immrac.org
Phone: 972-4-8249449
Fax: 972-4-9240493
e-mail:
dankerem@research.haifa.ac.il