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Activity : Environmental models

Sub-activity 1: Multi-oscillatory system approach

Work in progress as per 29th June, 2006 on Octopus Vulgaris.

From A. P. Solari (Universidad de Las Palmas de Gran Canaria)

Currently, we are working on the dynamics of Octopus vulgaris (Cuvier, 1797) based on our new, non-linear framework [1-7] and discuss our results in relation to “classical” approaches such as those proposed by Beverton-Holt [8], Ricker [9] and the logistic equation.

We are using data from several sources:

(a) Population series are both from FAO (CECAF landings, years 1962-2001) and Spanish IEO (catch and effort from Moroccan areas, years 1976-1999);

(b) Further series from localized geographical points (island of La Palma and Gran Canaria) and Northern Chile (a control, for discussion) are incorporated, as well;

(c) Environmental descriptors such as NAO, pressure data from Azores, Optimum Interpolated Sea Surface Temperature (Reynolds v. 2, OI SST), Sea Surface Temperature Anomaly (Kaplan) and some other geophysical variables (climatic and other proxies) are being incorporated into the approach. Also, we will further do an exploratory analysis on recently released automatic buoy data from the US Air Force in order to determine possible further external descriptors.

The grounds for the modelling work on this case study have been put forward and discussed and, as far as our criteria are concerned, some of the results may be highly promising and contribute to determine sustainable catch ranges –at least- in the short term (4-8 years).

We (J. J. Castro and A. P. Solari) have met up E. Balguerías twice at the IEO in Tenerife to discuss the ongoing work.

We are expecting some Moroccan catch and effort data with higher spatial resolution to further advance the tasks ahead.

Finally, we also did an exploratory approach on the European sardine (put forward at the Senegal meeting in June 2006).


[1] Solari, A. P., J. M. Martin-Gonzalez and C. Bas (1997). Stock and recruitment in Baltic cod (Gadus morhua): a new, non-linear approach. ICES Journal of Mar. Sc. 54:427-443.

[2] Bas, C., A. P. Solari and J. M. Martin-Gonzalez (1999). Considerations over a new recruitment model for exploited fish populations. Royal Academy of Sciences and Arts, Vol. LVIII Nr. 5:157-183.        

[3] Castro, J. J., A. P. Solari, J. M. Martin-Gonzalez and C. Bas (1999). Recruitment to the fishery of the skipjack tuna Katsuwonus pelamis in the Canary Islands area: application of a new conceptual framework. Report to the Ministry of Fisheries and Agriculture, Canarian Government, Grant Order Nr. 540 to the Las Palmas University Foundation. (In Spanish).

[4] Solari, A. P., J. J. Castro and C. Bas (2003). On skipjack tuna dynamics: similarity at several scales. In "Scales in Aquatic Ecology. Measurement, analyses and simulation". Edited by Laurent Seuront (CNRS, France) and Peter G. Strutton (Monterey Bay Aquarium Research Institute, USA). CRC Press.

[5] Solari, A. P., J. J. Castro, S. Souissi, E. Balguerías, V. Hernández-García and C. Bas (2004). On the dynamics of the common Octopus (Cuvier, 1797). Presented at the European CEPHSTOCK Workshop, Imperial College, London (31st August-2nd Sept. 2004).

[6] Solari, A. P., J. J. Castro, S. Souissi, E. Balguerías, V. Hernández-García and C. Bas (2004). On the dynamics of the common Octopus (Cuvier, 1797): towards a new framework.In review process.

[7] Castro, J.J., E. Balguerías, C. Bas y A. P. Solari (2006). Sobre la dinámica del pulpo común, Octopus vulgaris (Cuvier, 1797): hacia un nuevo marco teórico. Report the Ministry of Education, Culture and Sports of the Canarian Autonomous Government. April, 2006.

[8] Beverton, R. J. and S. J. Holt, 1957. On the dynamics of exploited fish populations. Ministry of agriculture, fisheries and food (London). Fisheries investigation series 2 (19).

[9] Ricker, W. E., 1954. Stock and recruitment. J. of the Fisheries Research Board of Canada, 11:559-623.



Sub-activity 2: Environmental variability in production models

This activity aims at developing a Bayesian analysis of surplus biomass production models, accounting for environmental effects. Application will mainly concern the Mauritanian octopus stock (Octopus vulgaris). The flexibility of the Bayesian modelling framework (Meyer and Millar 1999; Millar and Meyer 2000; Rivot et al. 2004) will allow us to develop two axes:

a) To incorporate multiple sources of information and data in the model, and to simultaneously account for measurement errors and process uncertainty in the production function (in relation with the activity “data-poor models”);

b) To model the influence of environmental fluctuations on the stock dynamics. In particular, it will be tested if the introduction of environmental covariates (i.e. upwelling index) may explain a significant part of the inter-annual variability of the production (Fréon 1991) and improve the fitting of the model to the data and improve the predictions.

Application case study:  Mauritanian octopus

Coordinator : Etienne Rivot

Fréon, P. 1991. L'introduction d'une variable climatique dans les modèles globaux de production. In Pêcheries Ouest Africaines. Variabilité, instabilité et changement. P. Cury et C. Roy (Eds), Paris pp. 395-424.
Meyer R. and Millar R.B. 1999. BUGS in bayesian stock assessments. Can. J. Fish. Aquat. Sci., 56: 1078-1086.
Millar R.B. and Meyer R. 2000. Non linear state-space modeling of fisheries biomass dynamic using Metropolis-Hastings within Gibbs sampling.
J. R. Statist. Soc., Sery  C (Applied Statistics), 49: 327-342.
Rivot, E., Prévost, E., Parent, E., and Baglinière, J.L. 2004. A Bayesian state-space modelling framework for fitting a salmon stage-structured population dynamic model to multiple time series of field data. Ecological Modelling, 179: 463-485.

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Persons involved in the case studies
Abdelmalek Faraj , Biology Emmanuel Chassot , Fisheries scientist
Didier Gascuel, Fisheries scientist Cheik Abdallahi Inejih , Biology
Ibrahima Diallo, Biology Jose J. Castro , Biology
Aldo P. Solari, Dynamics of fishery resources Didier Jouffre , Biology
Eduardo Balguerias, Biology Modou Thiaw, Biology
Etienne Rivot, Fisheries Scientist Nicolas Bez, Geostatistics science

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