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International Journal of Marine Science 2013, Vol.3, No.24, 187-192
http://ijms.sophiapublisher.com
188
Ocean Tuna Commission (IOTC) based on nominal
catch data of tuna from Indian Ocean and Indian EEZ.
3 Results
3.1 Tuna production in Indian Ocean
In Indian Ocean, tuna catches increased rapidly from
about 237,986 tones (T) in 1980 to 654,754 t in 1995.
They have continued to increase up to 2005; the catch
was 1,318,648 t forming about 26% of the world catch.
However, since 2006 onwards there was a decline in
tuna catch and in 2010 the catch was only 1,257,908 t
(Figure 1). The principal species caught in the Indian
Ocean is skipjack and yellowfin. The catch of bigeye
has also increased to around 150,000 t, due to
increased targeting of tunas by longliners for
Sashimi
market and the use of FADs in the surface fishery.
Although the catch of yellowfin tuna increased
gradually in the past five decades, its relative
importance decreased rapidly. Skipjack constituted
about 38% of the total catch, yellowfin 26%,
kawakawa 10%, bigeye 9%, albacore 3% and blue fin
1%. Purse seiners account for about 36% of the total
tuna catch followed by gillnetters 31%, long liners
15%, bait boat 10%, pole and line 7% and the
remaining by other gears (1%) as shown in Figure 2.
In 2008 Indian Ocean tuna production declined to
1,148,911 t with estimated landed value of US$ 2.5
billion. Present decline in production of the Indian
Ocean tuna fisheries may have serious ecological and
socioeconomic consequences in the region. Analysis
of landing data clearly indicated that overexploitation
of targeted species threatens the sustainability of tuna
populations. Though there had been substantial
increase in the production of tunas in the Indian Ocean,
the fast pace of development has ignored several
patterns which are vital to sustain the tuna production
in the capture fisheries. Information on a few of these
vital parameters is either not available, and for a few
other parameters, the available information has not
been properly utilized. The IOTC has implemented
certain measures to improve compliance of conservation
and management measures. However, many of the
member countries do not provide the required
information needed to monitor the compliance of
fishery management regulation.
3.2 Stock status
Estimates of total and spawning stock of yellowfin
tuna (YFT) biomass continue to decline, probably due
to overexploitation during 2003-2006. IOTC recommends
maximum sustainable yield (MSY) of YFT should not
exceed 3, 00000 t (IOTC, 2011). The preliminary
estimate of bigeye catches in 2010 (1, 04,549 t) is
optimal and current estimate of MSY is 11, 0000 t.
Albacore, which is also slightly overfished, has MSY
estimates ranging from 28,260 to 34,415 t in 2010,
with the annual average of catch around 40,988 t over
the past five years (IOTC, 2010, 2011).
Figure 1 Trends in tuna catch in Indian Ocean from 1950-2010
Figure 2 Gear-wise contribution of tuna in Indian Ocean from 1950-2010