Received: from opus.hpl.hp.com by jr.hpl.hp.com with ESMTP (1.37.109.24/15.5+ECS 3.3+HPL1.1) id AA028364399; Thu, 26 Aug 1999 14:53:19 -0700 Return-Path: <bdow@cisco.com-DeleteThis> Received: from hplms26.hpl.hp.com by opus.hpl.hp.com with ESMTP (1.37.109.24/15.5+ECS 3.3+HPL1.1) id AA251594397; Thu, 26 Aug 1999 14:53:17 -0700 Received: from mail1.cisco.com (mail1.cisco.com [171.68.225.60]) by hplms26.hpl.hp.com (8.9.1a/HPL-PA Relay) with ESMTP id OAA09960 for <wind_talk@opus.hpl.hp.com-DeleteThis>; Thu, 26 Aug 1999 14:53:17 -0700 (PDT) Received: from cisco.com (dhcp-h21-253.cisco.com [171.68.192.253]) by mail1.cisco.com (8.8.6 (PHNE_14041)/CISCO.SERVER.1.2) with ESMTP id OAA17756 for <wind_talk@opus.hpl.hp.com-DeleteThis>; Thu, 26 Aug 1999 14:50:06 -0700 (PDT) Message-Id: <37C5B7E9.91BB8022@cisco.com-DeleteThis> Date: Thu, 26 Aug 1999 14:55:53 -0700 From: Bob Dow <bdow@cisco.com-DeleteThis> Reply-To: bdow@cisco.com-DeleteThis Organization: Cisco Systems, Inc. X-Mailer: Mozilla 4.04 [en]C-CISCOIS (Win95; U) To: wind_talk <wind_talk@opus.hpl.hp.com-DeleteThis> Subject: Sharks at Ano Nuevo Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit
For fun I sent a few questions to Burney Le Boeuf, the
researcher who did the white shark tagging project described
in Discover magazine, July. Here is his answer:
Dear Bob,
The type of study we are doing is slow going but in two
years we have learned some things that may be of interest
and relevant to sharks in the water near Ano Nuevo.
How does the population vary during the year? We see white
sharks in the waters off Ano Nuevo from mid-October through
December. They may stick around longer than that but winter
weather makes it difficult to look. We see evidence of
recent white shark attacks on elephant seals from the fall
through January. It is thought that white sharks go
southern California waters to breed in Spring and Summer.
How concentrated are they at Ano Nuevo and do they stray to
Waddell? We have seen up to seven white sharks at one time
feeding on an elephant seal.
We monitor the sharks in an area of about 1 1/2 square
kilometers. We know they go out of our range at times (not
specific to time of day, as they are as active at night as
during the day) but we don't know where they go.
How many are there? Hard to say. We tagged six in one
year. One thing is clear, most of these sharks were
patrolling off Ano Nuevo every day for the six weeks that
our radio acoustic buoys were in place.
Is it the same crew every year? Sean Van Sommeran tagged a
female (named Top Notch after a notch in her dorsal) with a
sphagetti tag in 1995; she has been seen every fall since
then. Last year, we followed her movements daily for five
weeks before the weather shut us out. She was present for
most of day every day. That is, she spent most of her time
patrolling close to the island for a seal meal. We could
never confirm beyond a doubt that she made a seal kill. She
was 18 feet 6 inches long.
Would it be possible to set up a shark sensor for Waddell?
It would be possible to move our RAP buoy system to Waddell,
moor it, tag one or more sharks with ultrasonic tags, if
they are present, and track their movements in the area. Is
it practical? The waves may be too great in the area. We
need to work in calm waters and hope the buoys ride the
rough times. It would be expensive to duplicate the system,
i.e., provide another system besides the one at Ano Nuevo.
I would stress a couple of more points. White sharks patrol
near Ano Nuevo Island (and probably other seal rookeries) so
I think they are more apt to be encountered here than at
other spots along the coast. I would give the island a wide
berth. Near the island, if there are white sharks present,
our sense is that they will quickly investigate objects on
the surface. After all, this is their table. This may
include pieces of plywood, surfboard, an old wetsuit, etc.
They will spend a lot of time checking out a plywood cut out
in the shape of a seal. They will circle it, poke it, nose
it and even lift it in their mouths and release it without
biting it. A shark might spend up to 20 minutes doing this.
We have not seen a white shark take a full bite out of the
plywood model.
I hope this helps.
Burney Le Boeuf
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