Results of the blue whiting otolith exchange

At the Blue Whiting Assessment Working Group, it was agreed to carry out an otolith exchange programme to solve the ageing problems pointed out by ACFM. A sample of 115 otoliths from Division IXa was exchanged, and seven countries are taking part in the exchange, although it has not yet been completed. One otolith from each fish was sectioned and the other preserved in aqueous solution. In the whole otoliths a tendency to lose one or two early rings was observed, and in the sectioned otoliths the presence of false rings was the cause of misreading. A combination of both methods would probably improve the age determinations, but is unfortunately time consuming. The agreement between the readers was in general low, from both sliced and whole otoliths.The ANOVA with a significance level of 5% showed that the mean age of the sample is different for various readers, and the Tukey test showed that there are no significant differences between three readers, at the same significance level. Considering the importance of ageing in the .assessment, new investigations are needed to improve the agreement, and it is suggested that further samples are exchanged, or that an otolith workshop should be convened

Acoustic abundance estimates of blue whiting off the Spanish Atlantic coast in march-april 1991

This document describes the abundance and distribution whiting from an acoustic survey on the Spanish continental shelf (Divisions VIIIc and IXa2). The total biomass was 171 thousand tonnes, corresponding million fish. of b1ue Atlantic estimated to 4800 Only young fish were recorded in the whole area surveyed, with similar length and age distribution to those found in the fishery (Ages 0-5). Older fish were not detected in this area, at least in the spawning season. A comparison of the distribution and densities of blue whiting observed in this survey with those recorded in 1984 show that the distribution pattern in this area is quite stable

Abundance estimation and distribution of sardine in Northern Spain (north of IXa and VIIIc divisions)

Since 1986, an acoustic survey programme have been carried out for assessment of sardine: stock in Atlantic waters of the Iberian Peninsula. Sardine abundance estimated by length and age groups and oceanographic conditions in Galician and Cantabrian waters from 1986 to 1993 were studied. The biomass decreased after 1986 despite the occurrence of two very good year classes 1983 (the strongest ever recorded since 1976) and in 1987. The 1991 recruiting year c1ass seems to be a good one in the 1993 survey.Depuis 1986, un programme de sondage acoustique a été fait pour l'evaluation du stock de sardines dans les eaux atlantiques de la Peninsule Iberique. L'abondance de sardines, estimée par des groupes de taille et d'age, et les conditions oceanographiques dans les eaux de la Galicie et de la mer Cantabrique a été étududiée depuis 1986 jusqu'à 1993. La biomasse a diminué après 1986, malgre la presence de deux bonnes années 1983 (la plus forte jamais registrée depuis 1976) et 1987

Mesh size and effort changes in multispecies fisheries in ICES Divisions Vlllc and IXa.

Different simulations varying trawl mesh size and effort changes for several fishing units in ICES Divisions VIllc and IXa were carried out. Landings included in the analysis represent most of the catches in the southern area defined as the management unit for hake, megrim; monkfish, horse mackerel, blue whiting and mackerel. Three Nephrops stock s in Divisions Vlllc and IXa are also included. These species are mainly exploited by Spanish and Portuguese fleets, using various fishing gears to exploit different fractions of the populations, and for this reason nine fishing units were used in the analysis

Cambios de malla y esfuerzo en las pesquerías multiespecíficas en aguas atlánticas de la península Ibérica

Se han realizado diferentes ensayos de cambios de malla y esfuerzo para varias unidades pesqueras de las divisiones VIIIc y IXa del CIEM (Consejo Internacional pqra la Exploración del Mar). Los desembarcos incluidos en este análisis representan la mayoría de las capturas de las especies de merluza, gallos, rapes, jurel, lirio y caballa en la zona sur, definida como unidad de gestión. Están también incluidos tres stocks de cigala de estas divisiones. Dichas especies son las principales especies explotadas por las flotas española y portuguesa, que usan diferentes tipos de artes para explotar diferentes fracciones de las poblaciones. Por esta razón en el presente análisis se utilizaron nueve unidades pesqueras.Different simulations varying trawl mesh size and effort changes for several fishing units in ICES Divisions VIIIc and IXa were carried out. Landings included in the analysis represent most of the catches in the southern area defined as the management unit for hake, megrim, monkfish, horse mackerel, blue whiting and mackerel. Three Nephrops stocks in Divisions VIIIc and IXa are also included. These species are mainly exploited by Spanish and Portuguese fleets, using various fishing gears to exploit different fractions of the populations; for this reason, nine fishing units were used in the analysis.Versión del editor0,000

Age determination procedures for pelagic and benthic species from ICES area in Spanish Institute of Oceanography (IEO)

This handbook presents a summary of the age estimation procedures used in Spanish Institute of Oceanography (IEO) for some of the main commercial small and medium pelagic species and benthic species of the Spanish fleet. It provides information about the sampling program, otolith extraction and preparation, and the age estimation criteria. A summary of the information related to the age accuracy, validation and corroboration of each species is also presented, as well as that related to the age precision, quality control and verification

Age determination procedures on small and medium pelagic species in Spanish Institute of Oceanography (IEO)

This handbook presents a summary of the age estimation procedures used in Spanish Institute of Oceanography (IEO) for some of the main commercial small and medium pelagic species of the Spanish fleet: anchovy (Engraulis encrasicolus), sardine (Sardina pichardus), mackerel (Scomber scombrus), chuck mackerel (Scomber colias), horse mackerel (Trachurus trachurus), Mediterranean horse mackerel (Trachurus mediterraneus) and blue whiting (Micromesistius poutassou). It provides information about the sampling program, otolith extraction and preparation, and the age estimation criteria. A summary of the information related to the age accuracy, validation and corroboration of each species is also presented, as well as that related to the age precision, quality control and verification