This activity aims to test and make available assessment methods adapted to data-poor situations. Three methods will be considered:

a) The application of VPA in the case of a low number of years of catch data available: the pseudo-cohort corrected analysis (Laurec and Santarelli-Chaurand, 1986). This method allows to take into account changes in fishing effort (non equilibrium conditions). It will also be used in complement of the activity “length/age conversion” in order to test the sensitivity of diagnoses to growth parameters estimates.

b) The application of “Catch Survey Analysis” (Collie and Sissenwine, 1983; Mesnil, 2003) to catch, effort and recruitment time series. This model allows to include a priori recruitment variability in a situation where all catch at age are unknown.

c) The application of surplus production models both fitted with pseudo-equilibrium methods (Fox, 1975) and dynamic methods based on constraints or in a Bayesian context (linked with the “Environmental models” activity). This application should allow to analyze the consistency and complementarity of the two approaches.

Case studies: Bobo, Hake, Sardinelle, Octopus

Coordinator: Didier Gascuel

References

Collie, J.S., Sissenwine, M.P., 1983. Estimating population size from relative abundance data measured with error. Can. J. Fish. Aquat. Sci. 40, 1871-1879.

Fox, W.W., 1975. Fitting the generalized stock production model by least-squares and equilibrium approximation. U.S. Fishery Bulletin 73, 23-37.

Laurec, A. and Santarelli-chaurand, L. 1986. Analyse rectifiée des pseudo-cohortes : Analyse des données des cohortes à partir d'une année de structures démographique des captures ; correction des variations d'effort et/ou de recrutement.: IFREMER, Rapport interne, Ronéo, 19pp.

Mesnil, B., 2003. The Catch-Survey Analysis (CSA) method of fish stock assessment: an evaluation using simulated data. Fisheries Research 63 (2), 193-212.

Matériel

Articles scientifiques

Rapports et documents techniques

Persons involved in the case studies

Didier Gascuel, Fisheries scientist	Nicolas Bez, Geostatistics science
Emmanuel Chassot , Fisheries scientist	Ebaye Ould Sidina, Biology
Aboubacar Sidibe, Biology	Youssouf Hawa Camara, Biology
Didier Jouffre , Biology	Etienne Rivot, Fisheries Scientist
Eduardo Balguerias, Biology	Ibrahima Diallo, Biology
Cheik Abdallahi Inejih , Biology	Ana Ramos, Biology
Modou Thiaw, Biology	Abdelmalek Faraj , Biology

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