Hydro-plankton characteristics and their relationship with sardine and anchovy distributions on the French shelf of the Bay of Biscay

Abstract

SUMMARY:The spatial pattern in hydro-plankton and fish distributions and their relationship were analysed based on the spring 2000 fisheries acoustic survey. The importance of this survey was that it was a multi-disciplinary platform which collected an extensive set of parameters in the hydro-plankton leading to a potentially finer description of hydro-plankton conditions and fish habitats. More than 50 variables were measured on a grid of stations, in four compartments of the ecosystem: hydrology, nutrients, primary producers and meso-zooplankton. First, a joint analysis of all hydro-plankton compartments was performed using multiple factor analysis (MFA). The method was used to estimate a compromise factorial space common to all compartments in which the stations were grouped by hierarchical clustering. The groups were represented spatially and a strong spatial pattern was evidenced. The fish and their spawned eggs were sampled along transect lines using acoustics and CUFES (continuous underway fish egg samplers). The distribution of the fish and their eggs was analysed in relation to the hydro-plankton groups of stations and difference in fish density across hydro-plankton conditions was tested by a pair-wise multiple comparison procedure. Anchovy was associated with a lesser number of hydro-plankton conditions than sardine. Eggs of both species were also associated with a lesser number of conditions than the fish. Finally, the gain provided by using the extensive set of hydro-plankton parameters for mapping large-scale hydro-plankton conditions was analysed in comparison with the situation in which a small set of parameters was available. The extensive set of parameters allowed more hydro-plankton conditions to be identified but only in the coastal area and not on the shelf. Size fractionated chlorophyll was determinant for tracking river plume hydro-plankton condition. However, the fish did not respond to the variety of the coastal hydro-plankton conditions. Keywords: spatial pattern, multiple factor analysis, habitats, hydro-plankton, fish-environment relationship. RESUMEN: CARACTERÍSTICAS HIDRO-PLANCTÓNICAS Y SU RELACIÓN CON LAS DISTRIBUCIONES DE SARDINA Y ANCHOA EN LAPLATAFORMA FRANCESA DEL GOLFO DE VIZCAYA. -Este artículo analiza la relación espacial entre los peces pelágicos y su medio ambiente utilizando datos de la campaña acústica francesa del año 2000. Esta campaña fue multidisciplinaria y permitió la colección de una lista extensa de parámetro en el hidro-plancton. Mas de 50 variables fueron muestreadas sobre la misma red de estaciones. Estas variables se agrupan en cuatro compartimientos del ecosistema: hidrología, nutrientes y materia en suspensión, bacterias y fitoplancton, mesozooplancton. En primer lugar se hizo una análisis conjunto a todas las variables reagrupadas en los cuatros compartimientos aplicando el método MFA (Análisis Factorial Múltiple). El método permitió estimar el espacio factorial común a todos los compartimientos en el que se hizo un agrupamiento de las estaciones. Los grup...

Essential habitat for sardine juveniles in Iberian waters

“…However, they contrast with what was observed for the eastern Mediterranean and the Bay of Biscay. In the former case, sardines were associated with warmer waters (Giannoulaki et al 2011), while in the latter no preferences were observed in relation to hydrographic conditions (Petitgas et al 2006).…”

“…Sardine is a small eurythermic and euryhaline clupeoid, distributed in the northeastern Atlantic Ocean from the southern Celtic Sea and the North Sea to Senegal, and across the western and northern Mediterranean Sea (Parrish et al 1989). It generally inhabits waters with temperatures ranging from 8 to 24°C and salinities ranging from 30 to 38 psu (Petitgas et al 2006). Sardine populations support important fisheries across their distribution area (Whitehead 1985).…”

Underwater acoustics for ecosystem-based management: state of the science and proposals for ecosystem indicators

“…These have combined acoustic with oceanographic data (e.g. Paramo & Roa 2003, Petitgas et al 2006, Peltonen et al 2007, Lebourges-Dhaussy et al 2009, Zwolinski et al 2010 or with satellite-based environmental data (Bellido et al 2008, Giannoulaki et al 2008, Tugores et al 2010, Zwolinski et al 2011. Habitat characteristics and fish densities have been mapped at comparable extents and resolutions in coral reef and other coastal ecosystems by integrating the output of several sonar systems on multibeam hydrographic survey vessels (Kracker et al 2011).…”

Overview of recent progress in fisheries acoustics made by Ifremer with examples from the Bay of Biscay

“…The day-time geographic distribution of anchovy in the Bay of Biscay in May was found to be associated with turbid, nutrient-rich coastal waters in the Southern part, while the distribution of sardine during the same period was unrelated to water mass characteristics (Petitgas et al 2006). As a consequence, the day-time geographic distribution of sardines is more variable between years but also more widespread (Massé 1996;Massé and Gerlotto 2003).…”

“…factors structured at the regional scale. The spatial distribution of anchovy at the mesoscale (dozen of km) displayed significant correlation with plankton communities commonly found in river plumes and in the southern coastal areas of the Bay of Biscay (Petitgas et al 2006). Moreover, small pelagic species generally undergo regional scale migrations, thought to be evolutionary adaptations to seasonal changes in food availability or search for spawning habitats favourable for offspring survival (Fréon et al 2005).…”