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 Scientists place
conventional
plastic tags on tuna which provide information on growth,
fishing mortality, natural mortality and movements
when recaptured. These important population
parameters are used to estimate the status of tuna stock and the impacts of
fishing. Another form of tagging, using electronic tags, provide detailed
information on fish movements in relation to their environment. The
comprehensive information obtained from electronic tags is intended to improve our
knowledge on fish behaviour and their vulnerability to the various fishing
gears.
There are two types of electronic tag: “sonic” and “archival”.
 Sonic tags
transmit a radio signal that is received at a “listening
station”; these tags will be used to detect
the
presence/absence of tuna in the
vicinity of FADs equipped with
listening stations.
Archival tags are small
computers that record depth, ambient and fish temperature and light levels.
These tags will be used to study the vertical and horizontal movements of tuna.
Both sonic
and archival tags are placed inside the fish belly
Large-scale tagging
experiments are required to provide the level of information necessary for tuna
stock assessments. The last major tagging programme was undertaken by SPC 14
years ago and it is now fundamental that we update our information on fishery
exploitation rates and population size to reduce the existing uncertainty in
stock assessments.
The first phase of the next Regional
Tuna Tagging Programme is scheduled to start at the end of 2006 in Papua New
Guinea (PNG). About 20% of the annual regional tuna catch is taken in PNG waters
and a significant portion of the PNG catch is taken from vessels using fish
aggregating devices (FADs). Both conventional and archival tagging data will
provide critical information on the impact of FADs on tuna vulnerability and will
improve estimates of population parameters required for regional stock
assessment models for skipjack, yellowfin and bigeye tuna. The output from this
project will directly benefit PNG tuna fisheries management, and by extension
the region.
The objective of the PNG
tagging project is to release 30,000 tuna tagged with conventional plastic tags,
and about 600 tuna with electronic tags. To ensure the success of the
project, cooperation of all stakeholders involved in tuna fisheries is
essential. The more tags returned to the SPC, the more accurate information we
will obtain and thereby be in a position to provide the best scientific advice
for future tuna fisheries management.
Please send us any of the
tags that you find, with the necessary information of the tagged
fish (see details below). You will receive a reward for each tag
returned:
a reward of US$10 is
provided for a conventional tag (or, if preferred, a project cap
or T-shirt).
a reward
of US$50 for a sonic tag
a reward
of US$250 for an
archival tag
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