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Stock assessments
of the major targeted tuna species in the western and central Pacific Ocean
are undertaken periodically by the Oceanic Fisheries Programme (OFP) of the
Secretariat of the Pacific Community in collaboration with scientists
participating in the Standing Committee
on Tuna and Billfish (SCTB). Assessments have been
completed for South Pacific albacore (Thunnus alalunga), bigeye (Thunnus
obesus), skipjack (Katsuwonus pelamis) and yellowfin (Thunnus
albacares) tunas.
The OFP has adopted
a common methodology for all of its formal tuna stock assessments. The
methodology, known as MULTIFAN-CL, has been developed by
Dr.
David Fournier Fournier
et al. 1998; Hampton and Fournier 2001). Fishing
effort data are used in the model as independent variables. The
parameterization of the model is constrained using Bayesian priors, where
appropriate - MULTIFAN-CL
methodology] (pdf 185k).
The statistical
fitting procedure of MULTIFAN-CL allows approximate confidence intervals to
be determined for model parameters and for quantities of interest that are
functions of the model parameters. The latter may be defined biological
reference points, such as FMSY and BMSY, against which
the status of the stock is assessed.
The assessments in
this section give background information on the biology and fisheries, the
sources of data and processing methods used, the most recent results using
the MULTIFAN-CL model and our conclusions regarding the current status of
the stocks. The data files used in the MULTIFAN-CL model can be made
available for independent review or analysis by interested scientists. Any
data requests, questions, comments or suggestions regarding any of the
material in these pages should be directed to Dr.
John Hampton, Principal Fisheries Scientist, OFP.
Some simulation
testing of MULTIFAN-CL has been undertaken [Ianelli
2000] (pdf 1,134k) and is the subject of
continuing research in the OFP.
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