This sample is too amall to form the basis of any generalisation about the effect 
of fur seals on the Japanese commercial fisheries. The stomachs represent short periods 
at only two collecting points, the vicinity of Esan-misaki, Hokkaido, and the waters off 
Iwate Prefecture in northern Honehu. They cannot be considered as being typical of the 
food habits of the seals throughout their stay in the wintering area. Nevertheless they 
suggest that, despite the well-worn adage that the Japanese use anything and everything 
that comes from the sea, an appreciable part of the food of fur seals consists of species 
currently of no commercial importance in Japan, and unlikely to become so in the future. 
True, the squid and the pollack which formed the principal items in the three 
stomachs from Hokkaido watere are of considerable importance to the Japanese economy, 
though none of these species is taken commercially in the United States and Canada. But 
74 percent of the contents of the 19 Iwate stomachs was a lantern fish (Diaphus ep.) never 
before recorded as a fur eeal food, and of negligible economic importance in Japan. Being 
a deep-water, offshore fish which comes to the surface only on dark nights, Diaphus seldom 
is taken by Japanese fishermen; when it does appear in their catches in quantity, it is 
used mainly for fertilizer and almost never for human food. Of the various equids found 
in the Iwate stomachea only one, Doryteuthes bleekerj, is an edible species of good quality, 
the others being used for fertilizer and stock feed only. Offshore populations of tiny 
squids such as Watasenia, which observations indicate to be a very common food of fur 
seals, dolphins, and porpoises, are practically newer fished commercially, 
It must also be remembered that most of the Japanese fishing operations for the 
squid and fish they accuse the seals of consuming are carried on within 10 miles of the 
coast, rarely more than 15 miles off, and that the fur seals very seldom come this close 
in (cf p 32). The fisheries farther offshore where the fur seals congregate are concerned 
mainly with dolphins, tuna, and sharks, large species which the seals are not mown to 
bother, although they are commensalate with then. 
The only figure used by the Japanese in their estimate of fur seal damages to 
their fisheries (p 25) which is not open to serious question is their aseumption that each 
seal consumes about five pounds of fish products per day. They based this figure alleg- 
adly on the amount fed to captive hair seals in the Tokyo zoo, but subsequent evidence 
indicates it to be reasonable and perhaps conservative. The average weight of the seals 
collected off Japan in 1949 was 53 pounds, and the stomach of a 50-pound seal is moderately 
filled by about 3.0 pounds of fish. A pregnant female weighing 110.5 pounds, collected off 
Iwate Prefecture, had consumed 7.9 pounds of Diaphus comprising about 110 individual fish. 
Another mature female weighing 89.6 pounds, killed unusually close inshore near Hosoura, 
had eaten 5.0 pounds of the squid Doryteuthes, composed of all or part-of 29 individuals. 
A young male weighing 62.0 pounds had consumed 2.6 pounds of pollack and squid. How many 
timee daily a seal may fill its stomach to repletion in nature is unknown. Mre Belle 
Benchley, Executive Secretary of the Zoological Society of San Diego, California, states 
(in 1it.) that if captive fur seals are allowed to gorge, as they probably do in the wild, 
digestion appears to be slower than when they are fed smaller quantities and they may fast 
for 24 hours before feeding again. Captive seals one year old in the San Diego Zoo consume 
an average of four pounds of fish per day. Yearling seals weigh roughly from 25 to 50 
pounds. This evidence indicates that a mature seal may eat from five to eight pounds daily 
and small seals from three to five pounds, taking into consideration the number of fish 
killed "playfully", with only a bite or two taken from them. Hence the Japanese. estimate 
that seals consume about five pounds of fish and squid per day ie well within the limits 
of the available evidence. 
Their other figures used in obtaining their estimate of damages were all greatly 
exaggerated. As shown previously, their estimate of the number of seals in Japanese waters 
was far too high, and by no stretch of the imagination can all the seals’ food be consid- 
ared of economic importance. Their third postulate, that each seal spends 180 days in 
Japanese waters, ie equally questionable. While some seals may be found in the area con- 
stantiy from November to May, the bulk of them spend the first part of this period several 
hundred miles off the coast, beyond the range of the Japanese fishing vessels. 
40 
