Changes in occurrence and abundance of northern / southern flatfishes over a 20-year period in a coastal nursery area (Bay of Vilaine) and on the eastern continental shelf of the Bay of Biscay

Abstract

SUMMARY: Several works have demonstrated trends in the distribution of fish species relative to global warming. This study investigated whether similar trends have occurred for selected flatfish species on the continental shelf of the Bay of Biscay. These species were used as indicators and changes in their populations were studied in a coastal nursery ground where flatfish juveniles are concentrated as well as on the entire shelf. Previous studies analysing changes in sea surface temperature for the continental shelf indicate that winter warming occurred in the 1980s and 1990s. Sixteen autumn cruises conducted since 1981 in the Bay of Vilaine nursery area and 11 autumn cruises since 1987 over the entire shelf provided data on a nearly annual basis for the abundance of benthic fish. The four most common flatfish species were selected and their occurrence and yearly abundance were analysed with regard to specific biogeographic ranges and climate change. Similar results were obtained for juveniles on a nursery scale and for all age groups on the entire shelf. Although sole (Solea solea) showed irregular yearly variations, northern winter spawners such as plaice (Pleuronectes platessa) and dab (Limanda limanda) exhibited significantly high abundance during the 1980s, followed by a continuing low level and ultimately zero catches. On the other hand, the wedge sole (Dicologoglossa cuneata), a southern summer spawner, showed an increasing trend in the late 1990s. Diversos trabajos han demostrado tendencias en la distribución de especies de peces relacionadas con el calentamiento global. Este estudio se investigó si han ocurrido tendencias similares en especies seleccionadas de peces planos en la plataforma continental del Golfo de Vizcaya. Esas especies fueron usadas como indicadores y los cambios en sus poblaciones fueron analizados tanto en un área costera de concentración de juveniles como en toda la plataforma. Estudios previos de los cambios en la temperatura superficial del mar en la plataforma continental, indican la ocurrencia de periodos de calentamiento de invierno en los años 1980s y 1990s. 16 campañas de otoño realizadas desde 1981 en el área de crecimiento de la Bahía de Vilaine y 11 campañas de otoño efectuadas desde 1987 en toda la plataforma continental proporcionaron datos en una base casi anual de la abundancia de peces bentónicos. Se seleccionaron las cuatro especies de peces planos más comunes y su presencia y abundancia anual fueron analizadas con respecto a sus rangos biogeográficos específicos y al cambio climático. Se obtuvieron resultados similares para los juveniles en su área de crecimiento y para todos los grupos de edad a escala de toda la plataforma continental. Aunque el lenguado (Solea solea) mostró variaciones anuales irregulares, la solla (Pleuronectes platessa) y la limanda (Limanda limanda) que se reproducen en invierno mostraron una abundancia significativamente más alta durante los 1980s, seguida de una disminución continua y por último capturas nulas. Por el contrario, el lenguad...

Climate change impacts on coastal and pelagic environments in the southeastern Bay of Biscay

“…In a study focusing on flatfish in the area of Bay of Villaine, Désaunay et al (2006) found a decrease in northern spawners such as plaice and dab, whereas southern spawners, such as wedge sole, increased.…”

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“…Geographical shifts in the distribution of many shelf-sea fish communities around the British Isles have been well documented. Broadly speaking, these changes can be viewed as a response to warming sea temperatures, so as to maintain individuals in a preferred temperature range (Hedger et al 2004, Perry et al 2005, Poulard & Blanchard 2005, Desaunay et al 2006, Heath 2007, Dulvy et al 2008. In some areas, this is manifested as a poleward shift in distribution or a move into deeper water.…”