Shark Depredation and Unwanted Bycatch in Pelagic Longline

Australia Longline Tuna and Billfish Fishery
Table A1.1. Statistics of Australia’s pelagic longline fishery
Vessel characteristic min. max. average sample size
Number of crew per vessel 2 6 4 35 vessels
Trip length (days) 1 30 4.47 178 trips
Set length (hours) 0.25 6 3.327 531 sets
Sets per trip 1 21 3.057 174 sets
Branchline length (m) 5 28 19 26 vessels
Buoyline length (m) 4 20 11.9 26 vessels
Distance between branchlines (m) 10 60 38.15 46 vessels
Distance between hook and weight (cm) 200 800 473.2 16 vessels
Number hooks between buoys 5 30 8.44 46 vessels
Mainline length (km) 25 100 61.4 28 vessels
Minimum hook depth (m) 12 80 32.74 44 vessels
Maximum hook depth (m) 30 350 76.85 44 vessels
Number of hooks per set 90 1940 956.6 513 sets/46 vessels
evaluation (to occur within 12 months of the management plan being
implemented) to establish ecological sustainability. Such a process
may present the complication of how to maintain a shark reference
point whilst exploiting a target species catch rate increase, should
such an opportunity be identified through stock status evaluation.
A1.8.3. Finning at sea prohibition
Shark finning was banned in Australia in response to concerns over
sustainability, the need to prevent finning of protected species, and
the issues of waste and cruelty. In 1991 Australia banned finning,
unless the carcass was retained by foreign vessels fishing inside the
AFZ. However, for domestic vessels this requirement was not applied
until 2000. Prior to the ban in 2000, shark finning was a widespread
and common practice judging from the estimates of Rose and
Mc Laughlin (2001). The ban was introduced as an amendment to
the permit condition of pelagic longline concession holders that
disallowed possession, carrying and landing of shark fins unless
attached to the trunk of the shark.
Without finning regulations, shark fins unlike most fish products,
can be easily carried in large quantities even by small fishing vessels
without refrigeration. The requirement for fins if retained, to remain
on the carcass until offloaded in port has essentially put an end to
finning, with the exception of those from the small numbers of sharks
that are primarily retained for meat. It has also assisted to ensure that
the protected shark species are less likely to be killed if caught and
their fins retained. But, despite this there are essentially two main
motivating factors; economic return or hook recovery, that actually
largely control the fate of sharks irrespective of the management
processes that exist and in Australia there are a considerable number
and complexity of these.
So, a combination of the shark retention trip limits and the
prohibition of finning sharks at sea has greatly increased the
likelihood of the preference being, to, if possible not actually catch
sharks in the first instance. In those fisheries that have such shark
management regulations there is therefore likely to be some interest
in any practical measures of assistance to achieve this.
An additional impact of the carcass retention trip limit and finning
prohibition is that now with such a low fin volume, the consequential
inefficiencies in marketing further reduces incentive to retain any
sharks or bother to remove fins from those that are retained primarily
for their meat.
A1.8.4. Prohibited use of a wire trace
Wire was used by pelagic longline fishers in Australia, as it is in
other fisheries, for two primary reasons: (i) to deliberately increase
retention rates of sharks with the intention of retaining them or parts
thereof, and/or (ii) to reduce gear loss by sharks and other species
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