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

Results of the First Exchange on Pouting Otoliths 2015

El documento muestra los resultados obtenidos en el primer intercambio ibérico de lectura de otolitos de faneca (Trisopterus luscus

Northern Shrimp (Pandalus borealis) Stock on Flemish Cap According to 1988-1996 surveys

Shrimp was regularly caught in Flemish Cap bottom trawl surveys from 1988 to 1996. Sampling results were previously published: Escalante et al., 1990; Mena, 1991-1992; Sainza, 1993a-1993b-1994-1995 and del Rio, 1996. The whole information is now reviewed to document the evolution of the stock abundance and structure during the period. This was a singular time period because of the active fishery started in April 1993

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

Preliminary results on Northern hake from the “Spanish Discard Sampling Programme”

The “Spanish Discard Sampling Programme” was started in 1988, however it has not had a continuous implementation in time. Results on Northern hake discard were obtained sampling the Spanish trawl fishery operating in the Northern hake distribution area. Discarding strategy varies between fleets, depending mainly on the target species of the fleet. Differences along the time series were probably due to market changes more than to the abundance of the species. In the years with a higher sampling quality, 2003 and 2004, the total level of Northern hake discard was estimated to be around 5% in weight and between 11-15% in number, respectively. Discards were compounded by ages from 0 to 3, mainly ages 1 and 2

Maturity Ogives Analysis of European Hake from Southern Stock

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Time scale ovarian maturation in Greenland halibut

In this paper possible evidence of a prolonged ovarian development phase in Greenland halibut is presented. The reproductive cycle in this species has been originally described based on the assumption that this phase should last about one year. The results of several years of analysis showed that there is more than one year between the mean age of females at the onset of the ovarian development and the mean age of actually spawning females. Two possible interpretations of this fact are discussed: the ovarian development phase (vitellogenesis) could last more than one year, and individual spawning does not necessarily occur on an annual basis as a consequence, or the incidence of non-spawning females every year could be very high. Both possibilities have important implications for the species’ reproductive potential and stock dynamics of this valuable deep water resource

Guía práctica para el estudio del crecimiento de especies demersales en el Área ICES

Versión revisada 05-02-2015En el documento se presenta una síntesis de los métodos empleados para estudiar el crecimiento y la edad, mediante estructuras calcificadas (otolitos y vértebras), de las especies ícticas de interés comercial para la flota española en el área del ICES. El estudio de estas especies forma parte del requerimiento que la Comisión Europea ha establecido para el Programa Español de Recopilación, Gestión y Uso de Datos Pesqueros (PNDB) en base a los desembarcos nacionales, según establece la normativa vigente de la Unión Europea (UE). En este Programa está involucrado el Instituto Español de Oceanografía (IEO), y entre otros el proyecto BIODEMER, desarrollado en el Centro Oceanográfico de Vigo. Las especies objeto de estudio en este proyecto son: merluza ("Merluccius merluccius"), abadejo ("Pollachius pollachius"), congrio ("Conger conger"), faneca ("Trisopterus luscus"), gallineta ("Helicolenus dactylopterus"), locha ("Phycis blennoides"), maruca ("Molva molva"), maruca española ("Molva macrophthalma"), mendo ("Glyptocephalus cynoglossus"); incluyendo las especies de descarte: arete ("Chelidonichthys cuculus") y goyeta ("Microchirus variegatus"). Para complementar este documento se ha adjuntado el anexo: Fichas técnicas de Biología y crecimiento de 11 especies demersales en el área ICES, en el que se detallan para cada especie los protocolos aplicados en la interpretación de la edad. Para cada caso se incluye una revisión de la bibliografía existente, así como de los talleres e intercambios realizados sobre estudios de crecimiento y edad