Prix moyen mensuel des especes demersales en France et a Boulogne-sur-Mer : etude econometrique de la periode 1974-1983

The landed prices of the four main demersal species (whiting, saithe, haddock, cod) in France vary based on the amount landed, the average weight of the fish, imports and seasonal factors. Adapting an econometric model to the period 1974-1983 makes it possible to differentiate the four species as regards the determination of prices. - Cod seems like the key species, around which the prices of the three other species are determined. The visible consumption of cod is the highest (around 60,000 tonnes per year, more than half of which is imported). The average landed price depends to some degree on the landed and imported amounts: rises of 10% of landed amounts and imported amounts cause a direct drop of 3% and of 1.5% respectively in the landed price. The structure of intake by size has little effect on the formation of the prices for cod; large-size fish obtain a price slightly higher than small or medium-size fish. - Cod seems like a substitute for the three other species. The variations in the average price of cod influence in a positive way the price of the three other species, especially that of haddock. The price of none of these three species is perceptibly subjected to the fluctuations of imports, which are moderate when compared with landings. - The price of saithe is not much influenced by the average weight of the landed fish; an increase of the landings of small-size (size 4) fish leads to a moderate drop in prices. - The prices of haddock and especially of whiting are perceptibly affected by the size of the fish; an increase of 10% in the average weight of landed fish leads to a rise of 2.5% and of 8% respectively of the landed prices. - Whiting is, among the four species, the one whose price is most linked to the amount landed: a rise of 10% of intake causes a drop of 4% to 5% of the price. The influence of the landed amounts on the price is moderate in the case of saithe and relatively weak in that of haddock. - Finally, the prices of each of the species drop during the summer period. These analyses, an indispensable item for assessing the various strategies for managing the fisheries in the mid or long term, remain primarily explanatory tools, founded on past observations. They are not forecasting methods, operational for the short-term needs of fishing and fish-trade companies.