Subject: Case Study-Trapped Whale. What to do?
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Mon, 12 Sep 1994 15:01:48
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Subject: Case Study-Trapped Whale. What to do?
From: SMTP%"MARMAM@UVVM.BITNET" 12-SEP-1994 14:17:25.68
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Subj: Management Options for River Whale
Date: Fri, 9 Sep 1994 21:03:32 -0500
Reply-To: Marine Mammals Research and Conservation Discussion
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From: Bill Fulton <FULTON@decus.org.au>
Subject: Management Options for River Whale
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Introduction
------------
Attached is an update on the 10m long Brydes whale
_Balaenoptera edeni_ which has been swimming 17 km up
the Manning River in Australia since August 16th.
The team, led by the National Parks and Wildlife
Service, would appreciate the suggestions of Marmam
readers as to the best management options at this
stage.
Current Status
--------------
The whale remains by its own choice in a 3km-long
stretch of the river which is 300m wide and contains
a deep narrow channel with abundant small fish
and prawns (shrimp). It gives an outward appearance
of being healthy and vigourous and appears of normal
weight. Definite feeding behaviour has been observed
including lunges with baleen exposed.
The water is clean and tidal, with salinity ranging
from 20 to 30 parts per thousand depending on the
direction of the tide. (Sea water is 35 ppt.) Water
temperature is 18-19 degrees celsius.
Constant monitoring has been in place throughout,
with baseline data on respiration and movement now
available.
It is not known whether the whale meant to be in
the river or, now that it is there, whether it is
interested in leaving the river at this time.
A sandy bar at the river mouth is covered with
1.8 to 2.4 metres of water at high tide and could
possibly be a barrier.
The whale is just upstream from a pile driver in
sporadic use Monday to Saturday. An alternative
exit route is available via a narrower channel.
The whale visits the mouth of that channel but
has never been seen to enter it.
We are just beginning a series on experiments to
determine our ability to influence the whale's
movement without unduly stressing or alarming it.
One experiment will involve a curtain of bubbles
created by pumping compressed air into a riverbed
hose punctured along its length.
Another will involve a row of floats 1m apart,
each suspending a short length of cotton sheet
weighted with a handful of gravel (not a physical
barrier and not a danger for entanglement).
Management Options
------------------
Comments of the relative merits of our various
options (or other options you could suggest)
would be valuable.
Option A
No action unless it strands.
Option B
Continue cautious experiments for a further week. Then scale back operations for
some weeks, awaiting developments and further insight. Develop strategies for
possible later intervention.
Option C
Try to herd the animal out of the river at this time
using boats and/or loud underwater percussion
noises.
Your thoughts on this would be much appreciated and will assist with decision ma
king with regard to managing this incident.
Bill Fulton
ORRCA
fulton@decus.org.au