Larval development and growth of the European hake <i>Merluccius merluccius</i> in the northwestern Mediterranean

Abstract

SUMMARY:The larval growth and development of the European hake, Merluccius merluccius, was studied from field larvae. Larvae were collected in the northwestern Mediterranean on three cruises carried out during the peak spawning months (November 1998, September 1999 and November 1999. Like other species of the genus, these larvae are characterised by a well-developed anterior part of the body, head and trunk region. Nevertheless, yolk sac larvae are much more slender than larvae at notochordal flexion stages. In the present study we analysed the allometric relationships between several body measurements and body length. This is the first attempt to infer larval growth of Merluccius merluccius by means of sagittal otolith analysis. Our results show the change in the otolith shape from a lenticular otolith in early larvae to an almond-shaped otolith in larger larvae. Otolith diameter showed a power relation with larval size, with no significant differences between seasons. In spite of the sea surface temperature differences between the three periods of larval collection, the early growth estimates showed no significant differences. This was explained by the similarity in the temperature at the depths at which the larvae are located. Absolute growth rates in length were estimated by relating daily growth increments in otoliths and larval size (standard length). When using the whole larval size range the values obtained were similar to those found for other Merluccius species. Nevertheless, the present data evidenced that growth for larvae younger than 12 days is very low, showing a significant increase thereafter. This indicates that length is probably not the best parameter for describing the growth of hake larvae in the first days of life, as allometric analysis suggested.Keywords: hake, Merluccius merluccius, morphometric, larval growth, larval development, otoliths, age.RESUMEN: DESARROLLO Y CRECIMIENTO LARVARIO DE LA MERLUZA EUROPEA MERLUCCIUS MERLUCCIUS, EN EL MEDITERRÁ-NEO NOROCCIDENTAL. -Se estudió el crecimiento y desarrollo larvario de la merluza europea, Merluccius merluccius, a partir de larvas capturadas en el mar. Las larvas se pescaron en el Mediterráneo noroccidental en tres campañas que se realizaron durante los meses de máxima puesta (Noviembre 1998, Septiembre 1999 y Noviembre 1999). Como otras especies del mismo género, estas larvas se caracterizan por tener la parte anterior del cuerpo, la cabeza y el tronco, bien desarrollada. Sin embargo, las larvas lecitotróficas son mucho más alargadas que las larvas en estado de flexión del notocordio. En este estudio, analizamos las relaciones alométricas entre algunas medidas del cuerpo y la longitud del mismo. Es la primera vez que se realiza un estudio del crecimiento larvario de Merluccius merluccius por medio del análisis de los otolitos sagitta. Nuestros resultados muestran que hay un cambio en la forma del otolito, pasando de forma lenticular en larvas pequeñas a forma almendrada en larvas de mayor tamaño. El diámetro del otolito se relaciona con la...

Distribution and abundance of fish larvae in the northern Ionian Sea (Eastern Mediterranean)

“…Patterns of larval fish distribution originate from complex spatial and temporal interrelationships that are strongly affected by the seasonality and duration of their meroplanktonic existence (Olivar et al 1998;Koutrakis et al 2004;Palomera et al 2005). Several studies have focused on how biological processes such as high food concentrations, low predator stocks, and certain hydrographic features regulate the distribution and abundance of planktonic organisms, including fish larvae Somarakis et al 2000Somarakis et al , 2006, even if biological-physical interactions are considered to be more important than purely biological forcing mechanisms (Cuttitta et al 2004;Sabates 2004).…”

Environmental influences on the recruitment process inferred from otolith stable isotopes in Merluccius merluccius off the Balearic Islands

“…Hake complete their settlement to the bottom in around the second month of life (ca. 57.5 d and 3.5 cm; Morales-Nin & Moranta 2004, Palomera et al 2005, and are progressively grouped in nursery areas, where pre-recruits and recruits form patches (Maynou et al 2006). However, there is still a lack of knowledge on how the environmental conditions affect early life stages of this species and the consequent recruitment success.…”

A morphohistological and histochemical study of hatchery-reared European hake, <i>Merluccius merluccius</i> (Linnaeus, 1758), during the lecitho-exotrophic larval phase

“…In European hake larval development, prey capture became guaranteed early, because of the early development of gut, jaws, fins, swim bladder, teeth and sensory organs (Mas-Riera 1991, Palomera et al 2005, Bjelland and Skifftesvik 2006, Morote et al 2011, Sánchez et al 2011. During the endo-exotrophic feeding phase of hake larvae, gut widening takes places, which is a factor as important as mouth size for determining the ingestion of prey.…”

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