A Snapshot of the Tropical Tuna Purse Seine Large-Scale Fishing ...

and aggregate FHV, respectively. The Developing:Developed ratio of capacity increased
to 1.67:1.0 in vessel numbers.
Table 4. Distribution of large-scale tropical tuna purse seiners (mostly targeting tropical tunas) by flag at
the end of 2011. The entries represent the number of vessels and their estimated combined FHV.
Flag Vessels FHV(m3) Flag Vessels FHV(m3) Flag Vessels FHV(m3)
ANT 3 4400 GIN 3 2025 PHL 76 56933
AUS 7 4110 GTM 6 10402 PNG 10 8839
BLZ 7 9308 IDN 41 23703 RUS 7 6121
CHN 12 16258 IRN 8 11660 SLB 5 2147
CIV 1 871 JPN 36 45614 SLV 4 7892
COL 11 12566 KIR 6 9377 SYC 8 18826
CPV 5 4530 KOR 58 69392 THA 4 3950
ECU 69 66711 MEX 40 47145 TUV 1 1937
ESP 40 63974 MHL 10 11376 TWN 34 45448
FRA 36 40386 NIC 6 8722 USA 38 57711
FSM 7 5865 NZL 5 6129 VEN 24 27922
GHA 15 17332 PAN 17 23006 VUT 18 28760
Total 678 781349
Developed 254 332764
Other 424 448585
Oth:Dev 1.67 1.35
4. Discussion
Using the information available from the tRFMOs we estimate that, towards the end of
2011, there were 1,664 purse seine vessels authorized to fish for tunas worldwide, with
a combined fish hold volume exceeding one million cubic meters. The estimate of the
number of vessels is probably of reasonable accuracy. However, the estimate of fishing
capacity needs to be viewed with caution because it is largely based on extrapolations.
Restricting the list to large-scale vessels, defined here as ≥335 m 3 FHV (approximately
273 tonnes FCC), reduces the number of purse seiners to 854, with a combined FHV of
870 thousand m 3 . Further restricting the list to those large-scale vessels that target
tropical tunas (based on the limited information available) brings the number down to
678 vessels with 781,000 m 3 FHV.
Interestingly, by trimming down the initial list to only large-scale purse seiners that
target tropical tunas, there is a 59% reduction in the number of vessels but only a 24%
reduction in the overall fishing capacity as measured by fish hold volume. This is likely
due to the fact that the RFMO vessel registers contain many small coastal purse seiners
(see Figure 1). Many of these are purse seiners operating in the Atlantic Ocean that
catch bluefin tuna occasionally (purse seining for bluefin in the Mediterranean is only
allowed for one month each year, and presumably most of these target other non-tuna
species during the rest of the year).
The number of large-scale purse seiners targeting tropical tunas estimated here (678
vessels) needs to be seen as an approximation. We have made efforts to exclude vessels
that do not usually target tropical tunas. However, it is possible that in some RFMOs
these vessels could begin to target tropical tunas more actively, depending on their
fishing prospects for other species.
Hamilton et al. (2011) calculated that there are at least 580 industrial-scale tuna purse
seine vessels in the canned tuna industry, based on RFMO registers as of November
2010. This number is lower than the numbers calculated by us for the tropical tuna
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