Shark Depredation and Unwanted Bycatch in Pelagic Longline

Fiji Pelagic Longline Tuna Fishery
A3.5. Catch and Discard Rates of Target and Bycatch
Species
The data in Table 3 were provided by the Secretariat of the Pacific
Commission’s Oceanic Fisheries Programme (SPC OFP) which has
compiled observer programme data provided by the Fiji Government.
It is important to note that observer coverage is very low, particularly
for 1999 to 2004, hence may not be representative. Observer coverage
ranges from 4.51% to 0.34% of hooks observed out of the total fishing
effort per year (Lawson, Pers. comm.).
The data in Table A3.4 come from catch logsheets completed by vessels
and provided to the Fiji Fisheries Department as a condition of the
licence. Logsheets do not provide full coverage of activities and have been
extrapolated by the Fisheries Department to account for missing data.
According to SPC data, over the five years for which observer
programme data are available, sharks formed 3 - 10% of the catch
per effort and 8 to 25% of the weight of the catch per effort.
According to the Fiji Fisheries Department’s data in 2004, sharks
comprise 6% of the total catch by weight that year while SPC indicated
that sharks comprised 14%. Another contradiction is that, according
to a 1999 study, sharks formed a major portion of the tuna longline
fishery at that time. The data supplied by observers on local vessels
showed that sharks comprised > 25% (by number) of the total catch,
most of which was discarded (Swamy, 1999). However, these data do
not reflect what proportion of this catch was retained or discarded.
SPC Observer Programme Data for 1999 and 2002 to 2005 (Table
A3.5) indicate that, of the sharks that were observed being caught,
78 to 90% were finned and 82 to 94% were discarded. A significantly
larger proportion of the shark catch was alive when hauled to the
boat, most of the small proportion of sharks that were discarded were
dead at that stage.
Tables A3.6 to A3.8 indicate catch, mortality and discard rates for
the three most commonly caught shark species as indicated by SPC
observer programme data. According to the data the three most
commonly caught species in order of most to less common are: Blue
Shark (Prionace glauca); Oceanic Whitetip Shark (Carcharhinus
longimanus); and Silky Shark (Carcharhinus falciformis).
The data for each of the three species reinforce the pattern indicated
by observer data which is that sharks are mostly alive when hauled
in and mostly dead when discarded. This is contradicted by the
interview results which state that the sharks are almost always dead
when hauled to the boat.
The interviews with fishermen also gave different results for the most
commonly caught sharks. According to the interviews with fishermen
that only fish in Fiji Waters, sharks that are typically caught are:
Makos, Brown Sharks and Blue Sharks. One interviewee indicated
that Brown and Blue sharks are the most destructive to their target
catch, the rest of the interviewees were not sure. According to the
interviewees, sharks are caught at a rate of roughly one to two sharks
per set (2300 to 2500 hooks).
One interviewee commented that due to the fact that the length of
their fishing trips are limited to around 9 days due to ice supplies
they catch fewer sharks than Chinese and Japanese longliners which
can stay are sea for much longer periods of time.
Table A3.2. Target Species (Tuna – Albacore, Bigeye, Yellowfin), Sharks and
“Other” observed catch, Fiji Pelagic Longline Tuna Fishery Catch Data, 1999
and 2002-2005, for all fish caught regardless of whether retained or
discarded. Source: SPC Observer Programme Data.
1999
No. /100 hooks % Kg/100 Hooks %
Tuna 1.756 49 33.473 46
Sharks 0.3581 10 17.9829 25
Other 1.4837 41 21.0125 29
Total 3.5978 72.4684
2002
No. /100 hooks % Kg/100 Hooks %
Tuna 1.803 54 32.03 67
Sharks 0.0885 3 3.8017 8
Other 1.4646 44 12.236 25
Total 3.3561 48.0677
2003
No. /100 hooks % Kg/100 Hooks %
Tuna 1.323 62 24.414 62
Sharks 0.0819 4 4.3062 11
Other 0.7346 34 10.392 27
Total 2.1395 39.1122
2004
No. /100 hooks % Kg/100 Hooks %
Tuna 1.774 74 30.487 72
Sharks 0.1463 6 5.8829 14
Other 0.4633 19 6.2142 15
Total 2.3836 42.5841
2005
No. /100 hooks % Kg/100 Hooks %
Tuna 1.916 72 33.461 73
Sharks 0.1072 4 4.7502 10
Other 0.6489 24 7.6622 17
Total 2.6721 45.8734
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