Subject: Great Barrier Reef humpbacks (fwd)

Mike Williamson (pita@www1.wheelock.edu)
Mon, 4 Oct 1999 08:35:29 -0400 (EDT)

From: MARMAM Editors <marmamed@UVic.CA>
Reply-To: Marine Mammals Research and Conservation Discussion
     <MARMAM@UVVM.UVIC.CA>
To: MARMAM@UVVM.UVIC.CA
Subject: Great Barrier Reef humpbacks (fwd)

Forwarded message:
From: Phil Clapham <phillip.clapham@noaa.gov>

Recently, an abstract of the following paper was presented here:

Chaloupka M, Osmond M (1999)  Spatial and seasonal distribution of
humpback whales in the Great Barrier Reef region.  In: Musick JA (ed)
Life in the slow lane: ecology and conservation of long-lived marine
animals.  American Fisheries Society Symposium 23: 89-106.

This paper draws various conclusions about (and in some cases gives
quantified estimates for) the distribution, reproductive rates and
population growth of humpback whales in the GBR area.  Among other
things, it draws inferences about the location of calving grounds, and
states that population growth and juvenile recruitment are "low and
variable".

I would like to request that the authors provide MARMAM readers with
more information about the data on which this is based.  This work
appears to be a version of a paper presented at IWC two years ago, which
was based (if I remember correctly) on opportunistic sightings of
humpbacks by largely untrained observers; this is presumably the reason
for the line in the abstract which states "These sightings were
SUPPOSEDLY of humpbacks..." (emphasis added).

If this is indeed the case, I am curious as to how the authors can
justify undertaking calculations of crude birth rate, calving interval,
calving rate, interbirth interval and population growth.  Inexperienced
and untrained observers produce unreliable data, particularly concerning
identification of mothers and calves.  To use such data to derive
quantitative estimates of important population parameters (when one
cannot even be certain of the species identification, as the abstract
implies) is potentially very misleading.

Phil Clapham

--

Phillip J. Clapham, Ph.D.
Large Whale Biology Program
Northeast Fisheries Science Center
166 Water Street
Woods Hole, MA 02543

tel (508) 495-2316
fax (508) 495-2066
Internet: phillip.clapham@noaa.gov




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