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

parent vessel. When carcasses were abundant in a small area a long wire cable was
brought ashore; a number of smaller wires were spliced into it ending in wooden
toggles which were threaded through the flipper holes in the blubber rafts. The
ship’s winch was then used to tow the load out to the ship. The carcasses were left to
rot at the water’s edge, and be eaten by scavengers like giant petrels, skuas, gulls and
rats - the most wasteful feature of the industry.
Requirements for achieving maximum sustainable yield.
Although Harrison Matthews (later FRS) travelled with the sealers and wrote
about the sealing industry in 1929, his account was largely anecdotal. The sealing
regulations were predominantly ad hoc and apparently not based on any scientific or
quantitative findings until I reported on my work in 1951. Several factors were then
considered to devise the best method of sustainably harvesting this natural resource
in order to exploit it to the fullest reasonable extent – indefinitely – while conserving
the population.
The catching season. The commercial basis of the industry was the blubber oil, and the
yield per seal varied seasonally. Elephant seals are virtually absent from land from
May to August and various components of the herd are absent at other times. The
factory output statistics show that over the thirty-year period 1929-1958, the average
oil production per male seal fluctuated greatly over the months when they were
taken. For four months, during May – August they are foraging and fattening up at
sea, and not surprisingly the highest blubber oil production per animal was found in
August/September (c.2.3 barrels/seal), at the beginning of the breeding season. It
progressively declined through October (c.2.1) and November (c.1.8). Then they
remain at sea through December to February and when they hauled out again in
March and April respectively the blubber oil produced averaged c.1.8 and c.1.7 per
seal. In years when sealing took place in January and February the average oil yield
was about [1.2] barrels/seal. This suggested that the bulls were about twice as fat at
the beginning of the breeding season than in the moulting season. These figures were
probably influenced by two main factors: a change in physical condition associated
with the stress of the breeding season and the utilisation of the fat reserve in the
blubber associated with that fasting period. Probably it also represented a
progressive change in the size and age composition of the catch, because in general
the oldest and largest males are the first to haul out (see chapter 17).
Possibility of utilising carcasses for other products. It had always been the practice of
elephant sealers to take only the blubber and skin from which to extract blubber oil,
leaving the carcasses to rot on the beaches – providing food for scavengers. The
blubber and skin together account for some 40% of the body weight, so the wastage
of protein and oil was considerable. As early as 1926 – the year of my birth - it had
been demonstrated that the extra oil from the carcass could increase the yield by as
much as 26%. Fifteen large male elephant seals taken in September of that year
produced on average 2.00 barrels of oil from the blubber and 0.52 barrels from the
rest of the carcass. Later experiments in 1947 and 1948 gave an increased oil
production of 22-25% on full utilisation and 58-65 kg of meal per carcass. In 1954 the
company estimated that full utilisation of the carcass should produce 16% more oil
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