Subject: Info: Harp Seal population info

Michael Williamson (whe_william)
Mon, 28 Mar 1995 09:58:24

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Date: Tue, 28 Mar 1995 09:59:59 -0500 (EST)
From: Michael Williamson <WHE_WILLIAM@FLO.ORG>
Subject: Info: Harp Seal population info
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From:	SMTP%"MARMAM@UVVM.BITNET" 27-MAR-1995 19:44:24.67
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Subj:	Harp seal population dynamics
 
Date:         Mon, 27 Mar 1995 20:35:27 AST
Reply-To:     Marine Mammals Research and Conservation Discussion
              <MARMAM@UVVM.BITNET>
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From:         Y6IM@acad1.UnbSJ.CA
Organization: UNB Saint John
Subject:      Harp seal population dynamics
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To:           Multiple recipients of list MARMAM <MARMAM@UVVM.BITNET>
 
 
In reply to Anne Doncaster's query on my quotes (from newspaper
reports) on harp seal population - I stand corrected.  Maybe the
newspaper misplaced the decimal (most probably).  The numbers ARE NOT
from 3 to 27 million, but from 2.7 - 3.5 million animals (p=95%).
The annual production of seal pups is: 580,000 (+/- 39,000).  All
this data is from a 1990 census.  Adding on 5 years times 580,000 (I
have no data on pup mortality rates), the current population may be
from 5.6 to 6.4 million animals (minus pup mortality).  The
current harvest quota is for 186,00 adult seals/year.  The following
is three other references to check out, and then a forwarded response
from the seal research side of Department of Fisheries (Canada).
 
Dave R.
-----------------------------------------------------------------
 CURRENT CONTENTS / Search: Find WORD HARP SEAL POPULATION
 
 
AArticle 1
   Author: ESTEP, K W; MACINTYRE, F; NOJI, T T; STENSHOLT, B;
                ORITSLAND, T.
           Affiliation: INST MARINE RES,POB 1870/N-5024
            BERGEN//NORWAY/
           Affiliation: INST MARINE RES,POB 1870/N-5024
            BERGEN//NORWAY/
           Affiliation: UNIV AMSTERDAM,INST TAXONOM ZOOL,EXPERTISE
            CTR TAXONOM
           IDENTIFICAT/1090 GT AMSTERDAM//NETHERLANDS/
    Title: SEAL SIZES AND HABITAT CONDITIONS ASSESSED FROM AERIAL-
            PHOTOGRAPHY AND VIDEO ANALYSIS
   Source: ICES JOURNAL OF MARINE SCIENCE V 51 N 3 1994 pp. 253-261
 
 Abstract:   Image analysis was used to assess ice conditions and
size seals in still-camera and video images automatically,
collected during an exploratory survey conducted in the
West Ice (Greenland Sea) in spring 1990, to determine the
feasibility of using these techniquem, to examine the distribution of
breeding harp and hooded seals and the environmental conditions under
which seals are found.  Images from a Sony CCD video camera and a
still-photo aerial camera provided excellent resolution, while a Dage-
MTI camera proved to be totally inadequate, due to excessive lag and
auto-iris failure.  Use of image analysis in future surveys will
allow large amounts of data, including environmental conditions, seal
sizes, and automatically prepared seal distribution maps, to be
collected quickly from video and still-camera surveys.  It is expected
that the application of these techniques to future surveys will
increase the understanding of seal populations and their relationship
to their environment.
 
 AArticle 3
   Author: STENSON, G B; MYERS, R A; HAMMILL, M O; NI, I H; WARREN, W
                G; KINGSLEY, M C S.
           Affiliation: FISHERIES & OCEANS CANADA,SCI BRANCH,POB
            5667/ST JOHNS
           A1C 5X1/NF/CANADA/
           Affiliation: FISHERIES & OCEANS CANADA,SCI BRANCH/MONT
            JOLI G5H
           3Z4/PQ/CANADA/
           Affiliation: HONG KONG UNIV SCI & TECHNOL,DEPT
            BIOL/KOWLOON//HONG
           KONG/
    Title: PUP PRODUCTION OF HARP SEALS, PHOCA-GROENLANDICA, IN THE
            NORTHWEST ATLANTIC
   Source: CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES V 50 N
            11 1993  pp. 2429-2439
 
 Abstract:   Northwest Atlantic harp seal, Phoca groenlandica, pup
production was estimated from aerial surveys flown off eastern
Newfoundland (''Front'') and in the Gulf of St. Lawrence (''Gulf'')
during March 1990. One visual and two independent photographic
estimates were obtained at the Front; a single photographic estimate
was obtained in the Gulf. Photographic estimates were corrected form
is identified pups by comparing black-and-white photographs with
ultraviolet imagery. Estimates were also corrected for pups absent
from the ice at the time of the survey using distinct age-related
developmental stages. Stage durations in the Gulf appeared consistent
with previous studies but were increased by 30% to improve the fit to
staging data collected at the Front. The best estimate of pup
production at the Front was obtained from the visual surveys. A total
of 467 000 (SE = 31 000) pups were born in three whelping
concentrations. The photographic estimates were comparable.  Pup
production estimates for the southern (Magdalen Island) and
northern (Mecatina) Gulf whelping patches were 106 000 (SE = 23 000)
and 4 400 (SE = 1300), respectively. Thus, total pup production was
estimated to be 578 000 (SE = 39 000).
 
AArticle 5
   Author: BJORNDAL, T; CONRAD, J M; SALVANES, K G.
           Affiliation: NORWEGIAN SCH ECON & BUSINESS ADM,CTR
           FISHERIESECON/BERGEN//NORWAY/
           Affiliation: CORNELL UNIV,DEPT AGR ECON/ITHACA//NY/14853
    Title: STOCK SIZE, HARVESTING COSTS, AND THE POTENTIAL FOR
            EXTINCTION - THE CASE OF SEALING
    Source: LAND ECONOMICS V 69 N 2 1993 pp. 156-167
 
 Abstract:   Starting in the 1960s, considerable opposition to the
Canadian and Norwegian harp seal hunt off Newfoundland developed. It
was alleged that the seal hunt was unethical and that the seal
population had been seriously depleted. The purpose of this paper is
to analyze the production function for the seal hunt based on data
for the Norwegian seal hunt. Particular attention is paid to the
question whether free entry to the fishery will cause
overexploitation. This depends critically on the characteristics of
the production function, in particular the extent to which harvesting
costs depend on stock size.
------------------------------------------------------------------
Date sent:      Mon, 27 Mar 1995 13:20:10 -0330 (NST)
From:           STENSON@nflorc.nwafc.nf.ca
To:             Y6IM@acad1.UnbSJ.CA
Subject:        Re: Research on Harp seals
 
Dear Dave:
 
We are doing a lot of research on harp seal- fisheries interactions. We have
projects on abundance, diet and distribution on both harp and hooded seals. The
most recent estimate of harp seals numbers was based on a 1990 pup production
survey. Pup production was estimated to be 580,000 (Newfoundland and Gulf of
St. Lawrence). The reference is:
 
Stenson. G. B., R. A. Myers, M. O. Hammill, I-H. Ni, W.G. Warren and
M.C.S.Kingsley. 1993. Pup production of harp seals, Phoca groenlandica, in the
northwest Atlantic. Can. J. Fish. Aquat. Sci. 50:1993.
 
Based on this, Peter Shelton constructed a population model which estimated
total population at 3.1 million (95%C.I. 2.7-3.5 million). This can be found in
the 'grey literature':
 
Shelton, P.A., N.G. Caddigan and G.B. Stenson. 1992.
Model estimates of harp seal population trajectories in the Northwest Atlantic.
CAFSAC Res. Doc. 92/89.
 
A brief description of the status of harp and other seals in the NFLD area can
be found in:
 
Stenson,G.B. 194. The status o fpinnipeds in the Newfoundland Region. NAFO Sci.
Coun. Studies 21:115-119.
 
The same issue has a paper on diets of harp seals off NFLD:
Lawson, J.W., G.B. stenson and D.G. McKinnon. 1994. Diet of harp seals (Phoca
groenlandica) in Divisons 2J and 3KL during 1991-93. NAFO Sci. Coun. Studies
21:143-154.
 
The upshot is that harp seals  ON AVERAGE eat a small amount of Atlantic cod
(~3% of their diet) but there are a lot of harp seals and they spend a fair bit
of time in our waters. Therefore, they proably eat a reasonable amount of cod
(given the lot stock levels). However, the IMPACT this consumption has on the
prey is a much more complex issue (requiring a lot of information on the
mortality of the prey, other predators, etc.) and we are NOT in a position to
say ONE WAY OR ANOTHER what the impact is.
 
I hope this informaiton is
what you were looking for.
 
Garry Stenson