Links between demersal species distribution
pattern and hydrographic structures
in the bay of Biscay and Celtic Sea
Francisco Sânchez
(1) , julio Gil (l) , Ricardo Sânchez (1) ,
Jean-Claude Mahé
(2) , Philippe Moguedet (3)
(1) Instituto Espanol de Oceanografía, Apdo 240, 39080 Santander, Espana
(2) Ifremer Lorient, 8 rue Francois Toullec, 56100 Lorient, France
(3) Ifremer La Rochelle, BP 7, 17137 L’Houmeau, France
f.sanchez@st. ieo.es
Abstract
Demersal species distributions were studied in relatictn to the dynamics
and water masses patterns in the bay of Biscay and (.eltic Sea. Welldefined mesoscale et clonic-anticyclonic patterns and their links with the
hake recruitment distribution are described. In addition, the characteristics of bottom water masses have been examined in relation with the
distribution of two species of megrim.
Introduction
The SESITS (Southwestern European shelf international trawl surveys)
project, with financial contribution of the European Commission, provided the co-ordination and standardization of the methodology of the
bottom trawl surveys carried out by the research institutes Ifremer, IKO
and Ipimar. The standard abundance indices of target species were estimated from conversion coefficients obtained by means of gear calibration experiments. Also, the simultaneous hydrographic data record in
the area made it possible to study the effect on species distribution.
ln the SESITS area, the distribution of water masses over the continental
shelf is driven bv the Poleward Current, continental freshwater discharges and meteorological conditions. Thus, the various combinations
of these varying situations cause different distributions of water masses
in autumn. Basically, three distinct situations are possible in the Cantabrian Sea:
- shelf region invaded by waters that are warmer and lighter than those
occupting the shelf break;
- cold waters nearby the coastal region shaping a well-defined front between
these and warmer shelfbreak waters and an intense mesoscale activity;
- wide upwelling discontinuously occupying large portions of the shelf
area, leaving mesoscale anticvclonic eddies to whirl around and drift far
from the shelf break.
173
pattern and hydrographic structures
in the bay of Biscay and Celtic Sea
Francisco Sânchez
(1) , julio Gil (l) , Ricardo Sânchez (1) ,
Jean-Claude Mahé
(2) , Philippe Moguedet (3)
(1) Instituto Espanol de Oceanografía, Apdo 240, 39080 Santander, Espana
(2) Ifremer Lorient, 8 rue Francois Toullec, 56100 Lorient, France
(3) Ifremer La Rochelle, BP 7, 17137 L’Houmeau, France
f.sanchez@st. ieo.es
Abstract
Demersal species distributions were studied in relatictn to the dynamics
and water masses patterns in the bay of Biscay and (.eltic Sea. Welldefined mesoscale et clonic-anticyclonic patterns and their links with the
hake recruitment distribution are described. In addition, the characteristics of bottom water masses have been examined in relation with the
distribution of two species of megrim.
Introduction
The SESITS (Southwestern European shelf international trawl surveys)
project, with financial contribution of the European Commission, provided the co-ordination and standardization of the methodology of the
bottom trawl surveys carried out by the research institutes Ifremer, IKO
and Ipimar. The standard abundance indices of target species were estimated from conversion coefficients obtained by means of gear calibration experiments. Also, the simultaneous hydrographic data record in
the area made it possible to study the effect on species distribution.
ln the SESITS area, the distribution of water masses over the continental
shelf is driven bv the Poleward Current, continental freshwater discharges and meteorological conditions. Thus, the various combinations
of these varying situations cause different distributions of water masses
in autumn. Basically, three distinct situations are possible in the Cantabrian Sea:
- shelf region invaded by waters that are warmer and lighter than those
occupting the shelf break;
- cold waters nearby the coastal region shaping a well-defined front between
these and warmer shelfbreak waters and an intense mesoscale activity;
- wide upwelling discontinuously occupying large portions of the shelf
area, leaving mesoscale anticvclonic eddies to whirl around and drift far
from the shelf break.
173