Suivi biologique d'une réserve marine de la Côte Bleue (Golfe de Marseille, Méditerranée, France)

The “Côte Bleue” marine parc, located between Fos and Marseilles (French Mediterranean coast), includes two fisheries reserves at Carry-le-Rouet (85 ha, created in 1983) and Cape Couronne (210 ha, created in 1996), both provided with anti-trawling and production artificial reefs. The biological survey of Cap-Couronne reserve has been repeated with the same protocol every three years since 1995 and took into account the initial state of communities before protection. This programme aims at assessing (i) the ecosystem restoration, (ii) the benefits of this protection regime for sustaining the resources exploited by the low-tech small fisheries. It includes visual censuses of fish assemblages and standardized fishing operations made by professional (trammel net) and amateur (hook-and-line) fishermen within and outside the reserve. Both methods attest that the abundance and the individual size of the most valuable fish species are markedly increasing, and that the behaviour of these species tends to be more natural. After five years of protection, the reserve fish stocks are still in a replenishment stage, but the greater abundance of large-sized individuals of targeted species and changes in their behaviour suggest that the reproductive success of those species will increase significantly and will benefit the fishing activities outside the reserveLe Parc Marin de la Côte Bleue, situé entre Fos et Marseille, gère deux réserves intégrales, à Carry-le-Rouet (85 ha, créée en 1983) et au cap Couronne (210 ha, créée en 1996). Ces deux réserves sont aménagées avec des récifs artificiels de protection anti-chalut et de production et font l'objet de suivis biologiques depuis leur création. Le programme de suivi de la réserve de Cap-Couronne a été répété trois fois selon le même protocole depuis 1995 avec un point zéro de l'état des peuplements avant l'application des mesures de protection et d'aménagement. Ce programme a pour objectifs : (i) la mise en évidence de la régénération de l'écosystème littoral ; (ii) l'évaluation des acquis de la protection d'une zone bien définie pour une gestion concertée des ressources halieutiques au bénéfice de la petite pêche artisanale. Il comprend des recensements visuels des assemblages de poissons et des pêches standardisées réalisées avec des pêcheurs professionnels (filet trémail) et amateurs (lignes). Les deux méthodes d'évaluation montrent que l'abondance et la taille individuelle des poissons les plus recherchés sont en nette augmentation, et qu'il y a une restauration de leur comportement naturel. Après cinq ans de protection, le peuplement ichtyologique de la réserve est encore en phase de restauration, mais l'augmentation observée du nombre de gros géniteurs d'espèces de forte valeur commerciale et l'amélioration de leur comportement permettent de prédire un accroissement du succès reproductif de leurs populations dans la réserve, au bénéfice de l'exploitation halieutique en périphérie

Histology of Tritia mutabilis gonads: using reproductive biology to support sustainable fishery management

The mutable nassa, Tritia mutabilis, a marine gastropod that is widely exploited on the Adriatic coast is an important source of income for small-scale fishermen in the Mediterranean Sea, particularly in the Gulf of Lion. However, the lack of knowledge on the ecology and biology of this species limits our capacities to propose and produce an effective management plan. As a result, stocks are currently declining, especially in Italy. In order to optimize a management plan for this fishery, we designed a study to better characterize the reproductive biology of T. mutabilis, using gonad histology and performing a regular monitoring of population size frequency. The average shell height of individuals during the breeding period was 24 ± 2.7 mm for males and 30 ± 3.7 mm for females. The presence of small females (10 mm) and large males (32 mm) in the whole sample challenged previous assumptions regarding protandry (sex change from male to female). The size at first maturity was estimated for males and females at 17.5 mm and 24.4 mm shell height, respectively. In Italy, current management measures include a minimum conservation reference size of 20 mm in shell height. Therefore, it is likely that many individuals that did not reproduce are being caught, which could partly explain the decline observed, despite conservation measures introduced more than ten years ago. Overall, our study provides some baseline information to establish, in consultation with fishermen, management measures for this small-scale fishery in France

Study of a Mediterranean reef fish assemblage. Comparisons of population distributions between depths in protected and unprotected areas over one decade

Differences in Mediterranean fish communities of two rocky coastal areas, one inside an integral marine reserve and the second outside the reserve, near Banyuls-sur-Mer, France, were compared using underwater visual census after a 12-year interval. In 1980, the community structure in and outside the marine reserve was studied at two depths (Bell, 1983). In 1992, We used the same methodology to assess if variations occurred in this fish community between these two samplings. In both 1980 and 1992, water depth affected the relative abundance of fish communities and the number of species was roughly maintained in both sites. However, there were several other important qualitative and quantitative variations in the fish fauna over this period: (1) The abundance of species has decreased in the integral reserve whereas it has been maintained outside the reserve; (2) Nine species are more abundant in the integral reserve and nine others are more abundant outside the reserve. Among the species vulnerable to fishing, such as Labrus merula, Symphodus tinca, Mullus surmuletus, Diplodus sargus, D. vulgaris, Scorpaena porcus, Oblada melanura, 6 of them are more abundant inside the integral reserve and 4 others are more abundant outside; (3) The demographic structure of vulnerable species inside the reserve has changed: only the proportion of large fish (30 to 40 cm length) compared to medium (15 to 30 cm) and small (0 to 15 cm) fishes was higher in the integral reserve. The prohibition of recreational and professional fisheries and scuba diving has the fish community in the integral marine reserve in 1992 enhanced less than in 1980. The impoverishment of the fish density in the integral reserve between these two periods is difficult to understand in regard to the stability of the fish density outside the reserve. These results stress the need for a more regular and more extensive survey of the fish assemblage in and around the marine reserve of Cerbère-Banyul

Quantification de la dissipation de la houle par une forêt de structures souples dites basées sur la nature

International audienc

Quantification de la dissipation de la houle par une forêt de structures souples dites basées sur la nature

International audienc

Un exemple de mise en place de solutions dites NBS/SSE : le projet CATCHSED

International audienc

Quantification de la dissipation de la houle par une forêt de structures souples dites basées sur la nature

International audienc

Suivi biologique d’une réserve marine de la côte bleue (Golfe de Marseille, Méditerranée, France)

The “Côte Bleue” marine parc, located between Fos and Marseilles (French Mediterranean coast), includes two fisheries reserves at Carry-le-Rouet (85 ha, created in 1983) and Cape Couronne (210 ha, created in 1996), both provided with anti-trawling and production artificial reefs. The biological survey of Cap-Couronne reserve has been repeated with the same protocol every three years since 1995 and took into account the initial state of communities before protection. This programme aims at assessing (i) the ecosystem restoration, (ii) the benefits of this protection regime for sustaining the resources exploited by the low-tech small fisheries. It includes visual censuses of fish assemblages and standardized fishing operations made by professional (trammel net) and amateur (hook-and-line) fishermen within and outside the reserve. Both methods attest that the abundance and the individual size of the most valuable fish species are markedly increasing, and that the behaviour of these species tends to be more natural. After five years of protection, the reserve fish stocks are still in a replenishment stage, but the greater abundance of large-sized individuals of targeted species and changes in their behaviour suggest that the reproductive success of those species will increase significantly and will benefit the fishing activities outside the reserve.Le Parc Marin de la Côte Bleue, situé entre Fos et Marseille, gère deux réserves intégrales, à Carry-le-Rouet (85 ha, créée en 1983) et au cap Couronne (210 ha, créée en 1996). Ces deux réserves sont aménagées avec des récifs artificiels de protection anti-chalut et de production et font F objet de suivis biologiques depuis leur création. Le programme de suivi de la réserve de Cap-Couronne a été répété trois fois selon le même protocole depuis 1995 avec un point zéro de l’état des peuplements avant l’application des mesures de protection et d’aménagement. Ce programme a pour objectifs : (i) la mise en évidence de la régénération de l’écosystème littoral ; (ii) T évaluation des acquis de la protection d’une zone bien définie pour une gestion concertée des ressources halieutiques au bénéfice de la petite pêche artisanale. Il comprend des recensements visuels des assemblages de poissons et des pêches standardisées réalisées avec des pêcheurs professionnels (filet trémail) et amateurs (lignes). Les deux méthodes d’évaluation montrent que l’abondance et la taille individuelle des poissons les plus recherchés sont en nette augmentation, et qu’il y a une restauration de leur comportement naturel. Après cinq ans de protection, le peuplement ichtyologique de la réserve est encore en phase de restauration, mais l’augmentation observée du nombre de gros géniteurs d’espèces de forte valeur commerciale et l’amélioration de leur comportement permettent de prédire un accroissement du succès reproductif de leurs populations dans la réserve, au bénéfice de l’exploitation halieutique en périphérie.Jouvenel Jean-Yves, Bachet Frédéric, Harmelin J.G., Bellan-Santini Denise. Suivi biologique d’une réserve marine de la côte bleue (Golfe de Marseille, Méditerranée, France) . In: Revue d'Écologie (La Terre et La Vie), tome 59, n°1-2, 2004. pp. 243-251

Histology of Tritia mutabilis gonads: using reproductive biology to support sustainable fishery management

The mutable nassa, Tritia mutabilis, a marine gastropod that is widely exploited on the Adriatic coast is an important source of income for small-scale fishermen in the Mediterranean Sea, particularly in the Gulf of Lion. However, the lack of knowledge on the ecology and biology of this species limits our capacities to propose and produce an effective management plan. As a result, stocks are currently declining, especially in Italy. In order to optimize a management plan for this fishery, we designed a study to better characterize the reproductive biology of T. mutabilis, using gonad histology and performing a regular monitoring of population size frequency. The average shell height of individuals during the breeding period was 24 ± 2.7mm for males and 30 ± 3.7mm for females. The presence of small females (10 mm) and large males (32 mm) in the whole sample challenged previous assumptions regarding protandry (sex change from male to female). The size at first maturity was estimated for males and females at 17.5mmand 24.4mmshell height, respectively. In Italy, current management measures include a minimum conservation reference size of 20mmin shell height. Therefore, it is likely that many individuals that did not reproduce are being caught, which could partly explain the decline observed, despite conservation measures introduced more than ten years ago. Overall, our study provides some baseline information to establish, in consultation with fishermen, management measures for this small-scale fishery in Franc

All shallow coastal habitats matter as nurseries for Mediterranean juvenile fish

International audienceCoastal zones are ecosystems of high economic value but exposed to numerous disturbances, while they represent nurseries for many fish species, raising the issue of the preservation of their functions and services. In this context, the juvenile fish assemblages of all types of habitats present in shallow coastal zones were studied on the south-east coast of France using underwater visual censuses in warm (June–July 2014) and cold (April 2015) periods. A total of fourteen habitat types were characterized, which could be grouped into three broad categories, rocky substrates (natural and artificial), sedimentary bottoms with all levels of granulometry, and seagrass beds including Cymodocea nodosa and Posidonia oceanica meadows; the ecotones or interfaces between the three broad habitat categories were individualized as particular habitat types. The abiotic and biotic descriptors of the 14 habitat types individualized did not vary with time, except for a higher cover percentage and canopy height of macrophytes in the warm period, which increased the three-dimensional structure of some habitats. The taxonomic composition and density of juvenile fish assemblages were analyzed using both multivariate and univariate descriptors, after grouping the 57 fish species recorded into 41 well-individualized taxa. Juvenile fishes were recorded in all habitat types, with higher mean species richness and abundance during the warm than the cold period. The richest habitats in terms of both fish species richness and abundance were the natural rocky substrates and the interfaces between Posidonia beds and the other habitats. Although juvenile fish assemblage composition differed among habitat types and between periods, the most abundant fish species were Atherina sp., Sarpa salpa , Gobiidae, Symphodus spp., Pagellus spp. and several Diplodus species, which colonized 7 up to 14 different habitat types (depending on taxa) during their juvenile life. Most species settled in one or a few specific habitats but rapidly colonized adjacent habitats when growing. This study provided evidence of the role of all types of shallow coastal habitats as fish nurseries and their varying pattern of occupation in space and time by the different juvenile stages. It highlighted the importance of the mosaic of habitats and interfaces for the complete development of all juvenile life stages of fishes, and for the preservation of a high diversity of coastal fish assemblages and fisheries resources in the Mediterranean Sea