Part I: Seals teeth and whales ears - Scott Polar Research Institute ...

Of the six divisional collections of teeth made in 1957 and 1958, only division IV
in 1958 showed a significant difference between the mean ages of control and
commercial samples. The age frequencies for all areas combined were similar for
commercial and control samples. The mean ages for 33 control samples of the catches
by divisions from 1953 to 1964 when sealing ended are shown in figure [3
monitoring paper]. (Samples were not available from 1952 (collection lost) and 1962
(no catch)). This graph shows unexpectedly low mean ages for 1959 and 1960. The
most likely explanation I can think of, is that these age readings may have been
wrong. (I was not involved in the age determinations after [1958?}. The oil yields in
these years were the highest recorded over the whole series (2.17 and 2.20 barrels per
seal) suggesting the mean ages should have been higher than those recorded. (In
1953-55 and 1959-60 when mean ages were similar, the oil productions averaged
respectively 1.94 and 2.19 barrels per seal). I concluded that the mean age of the bulls
on the beach increased over the period 1952 to 1961 to about 7 7 years and levelled
off. This was very close to my 1951 target of 7.5 years for the average age of bulls on
the beaches.
The samples from individual divisions suggested that bull elephant seals don’t
necessarily return to breed in the areas in which they were born. If this were so then
the age pattern of the annual samples would have been different: thus, in each
division the sample taken in a year following a closed year should have a much
higher age than the sample taken before the closed year. This was not so and I
believed that the adult male component of the herd tended to be distributed about
the island according to the availability of cows. This implied that a large proportion
of the stock of adult bulls (possibly cruising offshore) acted as a reservoir from which
places on the breeding beaches, left vacant by the killing of dominant males, were
filled. Thus, the mean age of the catches from division II [with the exception of 1955],
was lower than in other divisions. Mean ages of samples from division IV were in
general much higher in the earlier years of sustained management; and those from
divisions I and III were intermediate. What this suggested was a relatively greater
surplus of adult males in division IV and possibly a continued relative deficit in
division II. A large difference noted between the mean ages of samples from
Divisions I and II in 1954 and 1955 might then be explained by a movement of
surplus males from Division IV, which was closed to sealing in 1955. Possibly it was
only by such immigration of males from under-exploited areas that the stocks in
over-exploited areas had survived. It was possible to rectify this by further
adjustments to divisional quotas and alterations were made to quotas from 1957
onwards.
The final few years. Albion Star (South Georgia) Ltd. took over the sealing licence from
CAP in June 1960, together with the three remaining sealing vessels, Albatros, Dias
and Petrel. But at the end of the 1961/62 season sealing was suspended. “The
decision was bound up with the falling price of both whale and seal oil and the
company’s increasing difficulty in obtaining a viable whale catch. Sealing thus
followed suit, for that industry was carried on as a subsidiary to the whaling aspect
and it was not considered an economic proposition to man the sealers and the land
factory exclusively for sealing operations.” There was no sealing or whaling in 1962.
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