Data/hora: 06/06/2024 13:52:35

Provedor de dados: 	5	
País: 	France	
Título: 	Etude comparative des coefficients de conversion utilisés pour estimer le poids vif des captures des flottilles de pêche de l'Union	
Autores: 	Caillart, Benoït; Borel, Gidas; Merrien, Claude.	
Data: 	1996-12	
Ano: 	1996	
Palavras-chave: 	European Union; Fleet of fishing; State of stocks; Quota; Statistic; Fish caught; Conversion coeffcient; Union européenne; Flotille de pêche; Etat des stocks; Quota; Statistique; Capture; Coeffcient de conversion.	
Resumo: 	Conversion coefficients are the factors used in estimating the live-weight equivalent of fish caught. Live weight is the only measure used in catch statistics, being the basis in particular for monitoring the drawdown of quotas and estimates of the state of stocks. The study looked first at how figures on catches in live-weight equivalent are gathered, validated and calculated in three Member States, namely Denmark, France and the United Kingdom. These three countries employ related methods involving the database storage of sales data together with details of the presentation of the fish. The information in logbooks is mainly used as a cross-check on the sales data. If sales data are not available, logbook details are entered raw in the catch databases. The liveweight equivalent is estimated by retrieving the presentation data from sales declarations and multiplying them by the actual conversion coefficient. Problems can arise where a vessel sells its catch in another country because then the conversion coefficients of that country are used. The coverage of the statistical systems in all three countries seems satisfactory. In France and the UK, catches by small-scale local fishermen who do not sell through quayside auctions are the only ones not covered. The study attempted to ascertain the origins of the conversion coefficients in the three Member States. Most of those using them were unaware how the coefficients had arisen. It was found that those being used in 1995 went back to 1945 in Denmark and the end of the 1960s in France, and had virtually not been reviewed since. They also seem to have been taken over from other Member States and so not to be based on the results of scientific work done at home. The MAFF in the UK had undertaken a scientific revision which led to the inclusion, at the end of the 1980s, of conversion coefficients estimated on the basis of tests. A brief survey of the origin of the coefficients in other Member States showed that they went back equally far, and had arisen in the same complicated way, as in France and Denmark. In order to identify the most sensitive coefficients, a study was made of the most common presentations of fish on landing. A review of the figures from all three Member States indicated that by far the predominant presentation in landings of quota species is 'gutted', although the UK sees significant landings of monkfish and crayfish as 'tails'. Among the more processed forms, 'headless' accounts for only a small fraction of catches, while filleting on board factory ships only concerns a few vessels. However, the coefficients used for fillets have considerable importance because these factory ships operate in waters of countries with which the Union has fishery agreements (Norway) and where tight controls on catches are mandatory. A database containing the coefficients used in all Member States was set up in order to be able to compare figures. This helped to pinpoint major differences, in particular for species like monkfish, cod, whiting, pollack and haddock. Assuming that in principle all methods of gutting are the virtually same and that all the countries fish the same stocks, proposals for harmonising the conversion coefficients have been made based on the scientific material available. Various coefficients have been proposed for immediate introduction, with the proviso that they will need revising in the next few years. A method is proposed for revising these coefficients. The most suitable method is by stratified sampling, taking account of size, time of year and major fishing zone involved. By weighting the results according to the essential characteristics of exploitation (size patterns in catches, catches per quarter and catches by fishing zone) is should be possible to devise coefficients that can be applied in all Member States. The cost of sampling for quota species has been put at about ECU 650 000.	
Tipo: 	Text	
Idioma: 	Francês	
Identificador: 	http://archimer.ifremer.fr/doc/1996/rapport-1640.pdf	
Relação: 	http://archimer.ifremer.fr/doc/00000/1640/	
Formato: 	application/pdf