Subject: Info: Why dorsal fins on captive whales curl

Michael Williamson (whe_william)
Mon, 14 Feb 1995 21:38:03

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Date: Tue, 14 Feb 1995 21:26:00 -0500 (EST)
From: Michael Williamson <WHE_WILLIAM@FLO.ORG>
Subject: Info: Why dorsal fins on captive whales curl
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From:	SMTP%"MARMAM@UVVM.BITNET" 14-FEB-1995 19:07:13.39
To:	WHE_WILLIAM
CC:	
Subj:	Re: Orca dorsal fins
 
Date:         Tue, 14 Feb 1995 15:12:28 -0800
Reply-To:     Marine Mammals Research and Conservation Discussion
              <MARMAM@UVVM.BITNET>
Sender:       Marine Mammals Research and Conservation Discussion
              <MARMAM@UVVM.BITNET>
Comments:     Warning -- original Sender: tag was rbaird@SOL.UVIC.CA
From:         Jaap v/d Toorn <jaap@TFS.COM>
Subject:      Re: Orca dorsal fins
X-To:         Marine Mammal List <marmam@uvvm.uvic.ca>
To:           Multiple recipients of list MARMAM <MARMAM@UVVM.BITNET>
 
> I am searching for literature or personal information as to why the
> dorsal fins of male Orcas loose their vertical orientation in
> captivity.  Is it a physiological condition of the tissues?
>
> __________
>
> Dr. Jan Hodder                         jhodder@oimb.uoregon.edu
> Oregon Institute of Marine Biology     Phone: 503-888-2581
> University of Oregon                   FAX: 503-888-3250
> Charleston OR 97420 USA
>
 
I am not sure if this has actually been documented, but I have heard
the following possible explanations for this phenomenon:
1) Because killer whales in captivity tend to swim in
counterclockwise patterns around their pools, (at least in the
northern hemisphere) there is an uneven distribution of pressure on
the dorsal fin. If dorsal fins all droop in the same direction,
that would support this hypothesis.
2) Differences in diet may cause physiological changes, that can make
the dorsal fin less rigid.
 
A combination of the two is also a possibility. Note that drooping
dorsal fins are also found in wild killer whales.
 
Jaap
 
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Jaap van der Toorn                                         jaap@tfs.com