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

so far. In fact the average oil yield increased by a third of a barrel during these years,
due to this. Also the effects of the other changes (lower quota and a minimum size
regulation) led to selection of larger males. It was also partly associated with the
cessation of autumn sealing and slight improvements in factory methods. However
an increase in the average age of the catch suggested that the improved oil yield was
probably a result of the altered regulations. In the absence of full carcass utilisation it
might have been expected to fluctuate around 2.1 barrels per seal, unless the average
age of the catch continued to rise, the sealing season advance or oil extraction in the
factory improve.
Age composition of the catch. My collections in 1951 had revealed an average age of the
catch of 6.64 ± 0.34 years from samples mainly from division III. From 1952 annual
tooth samples were collected and returned by the sealers, for estimation of age
composition. This was a very important element in the new regime. I was still
closely involved, though writing my thesis, but the early history of the tooth
collections illustrates some difficulties of remote control of operations at the other
end of the world. The first annual collection (1952) was unfortunately lost in transit
and in 1953 the collection wasn’t subdivided according to the divisions worked. But
from 1954 onwards the collections were satisfactory. In 1956 Nigel Bonner, a biologist
who had earlier worked for a year on fur seals at South Georgia (in the Bay of Isles),
was recruited as the Sealing Inspector that my plan had called for. (I think the
Falkland Islands Government was waiting to see whether my proposals were
practicable!) (Nigel became a good friend and filled this post for some seven seasons.
Later he led the Seals Research Division in one of the Natural Environment Research
Council’s (NERC) institutes, and then joined the British Antarctic Survey, as head of
Life Sciences and some years later became my Deputy Director)). I was able to help
him get started and we worked on the first collections together to standardise the
methods. Some 1767 teeth were collected between 1953 and 1958, and Nigel made
control collections in 1957 and 1958, totalling 439 teeth. Nigel Bonner and/or me
aged all these teeth, in my case in my spare time for which I received a small
honorarium. The FIG was doing very well in terms of the costs of the monitoring
operation called for under the regulations!
The great majority of the teeth collected were entirely suitable for age
determination. Comparisons of the frequency distribution of ages in the commercial
samples (1955-58) and the Control Sample (1957-58) showed they were in near
perfect agreement. But just how representative were the samples (5%), of the total
catches? I have described the sealing methods elsewhere. The sealers work
intermittently, at times in haste under great pressure from time or conditions, at
others more leisurely. I expected that the teeth would be collected during the least
fraught periods of a sealing trip, when there was more time available. When these
collections were proposed in 1951 I believed, from having worked with the sealers,
that they would be conscientious and the bias if any would be small; this proved
correct. As an additional safeguard Nigel arranged for the required number of teeth
representing 5% of the number caught on each trip, to be returned to the sealing
inspector after each trip. This prevented them making up the required number by
intensive collection at the end of the season.
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