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66 
sustainable catch from the resource is probably somewhat less than 
100,000 M.T., and thus it is likely that some slight overfishing of 
the yellowfin tuna stocks of the Atlantic Ocean is now occurring. 
Although varying significantly, the catch of skipjack has increased 
substantially from 1964 to a high in 1974 of 113,000 M.T. Scientists 
working with the Commission believe that substantially more skipjack 
could be taken from this fishery. 
Bluefin tuna, a species of the more temperate zone, has signifi- 
cantly declined in catch from 1964 through 1974, from about 38,000 M.T. 
to about 16,000 M.T. In response to reduced catches of bluefin tuna 
in the Atlantic, recommendations by ICNAF made in 1974, resulted in 
regulations being applied in several fisheries for bluefins. As a 
result, the catch level in 1975 is below that which otherwise would 
have been reached. It is the consensus that the current levels of 
fishing mortality for this species in the Atlantic are very high for 
such a potentially long-lived fish. The strong implication is that 
reduced fishing would improve the yield from the bluefin tuna stock. 
The albacore tuna catches in the North Atlantic Ocean, which also 
come under the purview of this Commission, have declined slightly from 
1964 to 1974. Incomplete scientific evidence indicates that the stock 
north of the equator is approaching its optimum level of exploitation. 
- With respect to the southern stock of albacore (i.e., south of the 
equator), it would appear from the relatively incomplete scientific data 
that have been collected, that this stock is relatively more heavily 
exploited than the North Atlantic longline fishery for the same species. 
Further increases in effort will very likely cause a decrease in the 
sustainable yield. Thus, with respect to albacore tuna in the Atlantic 
Ocean, it appears that the fishery has expanded to its upper limit and 
that increased effort will probably bring about a reduced return at a 
considerably higher cost. 
Several other species of tuna are taken in the Atlantic, the major 
one being the bigeye tuna. The catch of this species has about doubled 
from 1964 through 1974. Preliminary scientific data indicate that the 
catch of bigeye tuna in the Atlantic probably can be expanded by a 
small amount, but that the stock is being fished to close to its maximum 
level of productivity. 
Other tuna species (i.e., large bill fishes: marlins and sword 
fishes) incidental to the tunas taken by the longline fleet, are also 
fished in the Atlantic. The data from Commission records appear to be 
incomplete with respect to the effects of fishing on these species. 
A committee has been set up to study the status of the stocks of smaller 
tunas. 
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