Approche quantitative de la fonction de nourricerie jouée par les ...

Chapitre 4 : Impact of vegetation structure dynamics and usage on the nursery function of
West European tidal salt-marshes.
a)
b)
P BMSM
A BMSM
P BDA
A BDA
P BMSM
A BMSM
P BDA
A BDA
0
0
3
1
2
6
3
9
4
12
Dissimilarity
5
15
Dissimilarity
Figure 29 : Classification Ascendante Hiérarchique des CPUE (a) numériques et (b) pondérales (Méthode
de Ward, distance euclidienne) printanières et automnales des peuplement de poissons capturés dans les
marais salé de la baie de l’Aiguillon et de la baie du Mont Saint-Michel en 2003.
5. Discussion.
Studies of coastal nursery areas usually use fishing gear such as beam trawls (Le Pape
et al. 2003a; Parlier et Feunteun 2004 ). However, in order to study the colonisation
mechanisms of European salt marshes, a combination of fyke nets and gill nets is generally
used because of the temporary flooding conditions and the water depths rarely exceeding a
few tens of centimetres (Laffaille et al. 2000a; Parlier 2002). It is also impossible to use even
small boats on the drainage creeks. The capture technique used in this study was designed to
decrease the selectivity of the fishing gear by using a combination of different gears. The gill
nets placed upstream of the mixed gear were intended to catch large-sized fish rather than
pelagic species which are capable of jumping over the barriers formed by gill nets, whereas
the fyke nets were intended to catch small-sized benthic or pelagic fish.
6
18
7
137