Informe de los resultados de la Acción Piloto de pesca experimental de Palometa (Brama brama). Ref.: API-AP-4/2000 en aguas exteriores al litoral gallego (NW de la Península Ibérica)

Pesquerías ICES. Centro Costero de Vigo. 15/9/200

Report of 4th Exchange on European hake age readings

In 2002 the ICES WGSSDS showed the difficulties in the assessment of hake due to uncertainty on age estimation of older fish which has led the WG to use a plus group at age 8. To solve these problems an otolith exchange was recommended between readers involved in the assessment and focused mainly on older fishes. Preliminary results of the fourth hake otoliths exchange, conducted in 2003, indicate that the age estimation criteria used up to age 3 was the one adopted previously, however, for older fishes, otolith interpretation presents a higher complexity. The results indicate that the precision of age readings has decreased and a strong bias has been found in age readings of older fishes. Thus, the values of APE and CV in (%) for all readers are 41, and 45 respectively, while the values for assessment readers are 24 and 32. The comparison of these results with those from the previous exchange in 2001 shows the difficulty of this task, and to solve these problems a specific international workshop will be carried out

Study of the growth pattern of juvenile European hake (Merluccius merluccius L.) using whole otoliths and length frequency distributions from commercial catches and groundfish surveys

A review of length distributions of commercial landings from bottom trawls, small gillnetters and groundfish surveys in Galicia has led to a new hypothesis about the individual growth of young hake from the Southern Stock (ICES Divisions VIlle and IXa). According to this new hypothesis, hake grow to about 20 cm in the first year of life and up to 35-40 cm during the second. This is in contrast with the more widespread belief that hake grow to about 15 em and 24 during the first and second years of life respectively. Consequences of the new hypothesis are that landings of hake from trawls and small gillnetters would be mainly composed of 1 year old hake and that they would reach first maturity at age 3. An interpretation of the pattern of otolith rings consistent with this hypothesis is that 6 months after birth a first hyaline ring is formed, probably associated with the change from pelagic to demersal life and that another hyaline zone with opaque rings evbedded in it is formed during the first winter. Although this study refers to hake from the Southern stock, it is possible that these conclusions are applicable also to hake from the Northern stock (ICES Divisions VIIIa,b, Sub-areas VI,VII and IV )

Studies on age determination and growth pattern of the wedge sole Dicologoglossa cuneata (Moreau, 1881) in the Spanish waters of the Gulf of Cadiz (southwest Iberian Peninsula)

The wedge sole Dicologoglossa cuneata (Moreau, 1881) is a typical coastal soleid which is considered as one of the main target species in the demersal fishery of Spain's southern Atlantic region. This paper presents a study on the growth pattern of wedge sole in the Gulf of Cadiz. Age was determined by observing and analysing whole otoliths (sagittae), thereby obtaining the mean lengths at age for males and females in the year 1993 (from 15-20.9 cm TL and 1-4 years for males; from 15.9-23.6 cm TL and 1-6 years for females). In addition, the growth parameters for both sexes were obtained according to the Von Bertalanffy equation: L∞ = 24 cm, K = 0.343 and t0 = -1.384 for males; L∞ = 27 cm, K = 0.296 and t0 = -1.520 for females (showing growth differences growth between the sexes). These were compared with results reported by other authors for other areas of the species's distribution range. Through the interpretation of the otolith and its edge, a sequence of annual rapid- and slow-growth rings was observed; otoliths with an opaque edge (rapid growth) showed the highest percentages in the period from May to October. Mean otolith diameters for each of the estimated ages were calculated, as well as the body length/otolith diameter relationship: a = -12.631 and b = 61.033 (r² = 0.70).La acedía Dicologoglossa cuneata (Moreau, 1881) es un soleido típicamente costero, considerado como una de las especies objetivo de las pesquerías demersales de la región suratlántica ibérica. En este trabajo se estudia el patrón de crecimiento de la acedía del golfo de Cádiz. La determinación de la edad se realizó mediante la lectura de otolitos enteros (sagitta), obteniéndose las tallas medias por clase de edad para machos y hembras del año 1993 (entre 15 y 20,9 cm de longitud total y de 1 a 4 años para machos; de 15,9 a 23,6 cm de longitud total y de 1 a 6 años para hembras). Por otra parte, se estimaron los parámetros de crecimiento para ambos sexos según la ecuación de Von Bertalanffy: L∞ = 24 cm, K = 0,343 y t0 = -1,384 para machos; L∞ = 27 cm, K = 0,296 y t0 = -1,520 para hembras, presentando ambos sexos un crecimiento diferente. Estos resultados se compararon con los obtenidos por otros autores en otras áreas del rango de distribución de la especie. Mediante la interpretación del otolito y su borde, se observa una sucesión anual de anillos de crecimiento lento, formados durante el periodo invernal, y otros de crecimiento rápido, que muestran los porcentajes más altos en el periodo de mayo a octubre. Se calcularon los diámetros de los anillos para cada una de las edades estimadas, así como la relación longitud total del pez - diámetro del otolito, obteniéndose una ecuación lineal en la que a = -12,631 y b = 61,033 (r² = 0,70).Instituto Español de Oceanografí

Results of Exploratory Deep-sea Fishing Survey in the Galician Bank: Biological Aspects on Some of Seamount-associated Fish (ICES Division IXb)

Since October 1998 to October 1999 an experimental survey, comprising 12 monthly fishing trips were carried out in Galician Bank (ICES Divisions IXb) by two commercial trawlers of the Spanish fleet. The aims of this survey were to explore the fishing resources of studied area and to know the species community associated to this seamount. A total of 297 valid hauls were made during 309 hours of fishing and yielded a total catch of 45 145 kg in the depth strata studied (650-1200 m). The community of species in the area prospected presented high species richness. A total of 106 species were made up of 70 teleosts, 11 sharks, 3 rays, 2 chimaeras, 11 crustacea, 6 molluscs and 3 equinoderms The most important species captured were teleosts: H. mediterraneus, M.moro, L. eques, A. bairdii, E. telescopus, T. cristulata and L. piscatorius, followed for deep sharks: D. licha, D. calceus and crustacean: Ch affinis. The yields obtained for the whole series of fishing trips were low being the values obtained by order of importance: 30.3, 14.0, 13.1, 11.7, 4.8, 4.2, 2.5 kg/h and 1 kg/h for the teleosts; 2.0, 1.7, kg/h for sharks and 1.2 kg/h for crustacean. The results indicate, in general, there were no differences in depth distribution of the species characterised by the presence or absence of certain species and also, a seasonal variation in the abundance of the most important caught

Hake age estimation: state of the art and progress towards a solution

Since 1992, northern and southern hake (Merluccius merluccius) stock assessments have used age data based on otolith analysis. Age data for stock assessment is provided by different institutions, which implies a quantification of age‐reading precision to estimate assessment quality indicators. During this period, considerable effort has been made to improve the precision of age data by means of successive agereading calibration exercises, exchanges, and workshops in 1997, 1999, 2001, and 2004. This goal was partly achieved, and experts recently agreed on standard criteria (Piñeiro and Saínza, 2003) that allowed an acceptable precision to be reached for ages up to 3 years (Piñeiro et al., 2004). However, these criteria have never been validated, and recent mark ‒ recapture experiments are not in line with ageing results based on the standard criteria. Given the impact of bias in age estimation on stock assessment results, consequent management advice, and concern about the state of the hake stocks (ICES, 2007a, 2007b), a report on the current state of the art is needed. The main goal of this report is to present a synthesis of the work carried out over the years by researchers involved in providing age data for stock assessment, mainly on age‐reading calibration exercises, and current knowledge regarding the growth and ageing of this species. This report also includes recommendations for future work aimed at achieving validated age‐reading criteria