PROCEEDINGS OF THE FOuRTH INTERNaTIONal FISHERS FORum

9
8
7
6
5
4
3
2
1
0
Fig. 6. Number of fish caught by age by purse seiners (FAD and
schooling fish) and longliners, Atlantic bigeye, 2005.
Number of Vessels
Number of Fish (Millions)
1000
800
600
400
200
2005
PS FAD
PS Schooling
LL
0 1 2 3 4 5 6 7+
Age
0
1979 1982 1985 1988 1991 1994 1997 2000 2003
Indian Atlantic Pacific World
Fig. 7. Number of Japanese active large longliners by ocean.
Fishing capacity
In many studies, it was demonstrated that the world fishing
capacity exceeds that needed to catch tuna resources at
its maximum sustainable yield (MSY). Such excess in the
capacity makes it very difficult for the administrators to
take any management measures (catch/effort control). Many
organizations, including the FAO, recommend freezing the
fishing capacity and reducing it in the future.
Following the recommendations, the large longline fleets,
particularly in the industrialized countries, are being
reduced. This result is through the efforts of the respective
governments of the longline fishing nations. A good
example is shown in Figure 7. However, it is also an effect
of the declining stock of big tuna, due to the very large
catch of juveniles by seiners. On the other hand, the fishing
capacities of purse seiners and coastal longliners have been
and still are increasing (see Figure 8).
Particularly the purse seine vessels are getting larger and
larger, as seen in Figure 8.
As FAD fishing is very productive with less operating cost,
it is getting more and more popular, resulting in more waste
of stocks by discards, less yield per recruit and lowering the
MSY levels.
Status of resources
The table below indicates the results of most recent tuna
stock assessments by RFMOs.
Number of Vessels
600
500
400
300
200
100
Number
Capacity
0
1981 1986 1991 1996 2001
Fig. 8. Number and carrying capacity of the world purse
seiners. Bigeye is the most important species for longliners, but,
as they are caught in such a significant numbers at their juvenile
stage by purse seiners, the large fish available to longliners has
been greatly reduced. Even if the stock as a whole is not overfished,
the yield per recruit as well as the total biomass have
been greatly reduced due to the ongoing harvest of juveniles.
Consequently the MSY is also reduced. In the eastern Pacific, when
longliners alone were fishing bigeye, MSY was estimated at about
140,000 mt, but, at present, with FAD purse seine fishing occurring,
it is estimated at 70,000 mt.
6
5
4
3
2
1
0
Holding Capacities (100,000 cubic m)
BLUEFINS
SOUTHERN
BLUEFIN
BIGEYE
YELLOWFIN
ALBACORE
SKIPJACK
ATLANTIC
EAST WEST
NORTH
EAST
SOUTH
WEST
EAST
EAST
NORTH
PACIFIC
WEST
CENTRAL
WEST
CENTRAL
SOUTH
Overfished and overfishing occurring
Not overfished but overfishing occurring
About MSY level and no overfishing
Can increase yield sustainably
INDIAN
It is noted that most of the stocks are near the MSY levels
and many are in a state of overfishing (means the catch is not
sustainable and fishing mortality rate needs to be reduced).
Some are still in optimal or under-exploited, but some are
definitely over-exploited.
Industry Perspectives on the Status of Latin American and Global Longline Fisheries
31