Are fisheries regulations influencing the biology and reproduction of the surmullet Mullus surmuletus Linnaeus, 1758 on the south-eastern coasts of France (NW Mediterranean)?

International audienceThe surmullet Mullus surmuletus Linnaeus, 1758 is one of the main target and high valuespecies for small coastal fisheries in the North-Western Mediterranean. Morphometric andreproduction indices of surmullet were determined in fisheries regulated and non-regulatedzones neighbouring the Port-Cros National Park (South-Eastern France) in autumn 2019 andspring 2020. Total length of individuals ranged between 12 and 32 cm, with a mode (?)between 17 and 23 cm. Significantly larger individuals were measured in the regulated fishingzones than in non-regulated ones, and in autumn rather than in spring. Females dominated inall zones and seasons, particularly in size classes > 24 cm in spring. Higher gonado-somaticindex and more advanced gonadal development stages were observed in both sexes in springthan in autumn. Higher percentages of individuals with mature gonads and high gonado-somatic index were found in the fisheries regulated zone, engendering a higher reproductivepotential. These results highlighted the importance of fisheries management with regard to thelife-history traits of targeted fish species.Le rouget de roche Mullus surmuletus est l'une des principales espèces cibles etcommerciales des pêcheries côtières artisanales de la Méditerranée nord-occidentale. Lamorphométrie et les indices de reproduction du rouget ont été déterminés dans les zones depêche réglementées et non réglementées autour du Parc National de Port-Cros (Sud-Est de laFrance) à l'automne 2019 et au printemps 2020. La longueur totale des individus variait entre12 et 32 cm, avec un mode entre 17 et 23 cm. Des individus significativement plus grands ontété mesurés dans la zone de pêche réglementée comparativement aux zones non réglementées,et en automne par rapport au printemps. Les femelles dominaient dans toutes les zones etsaisons, en particulier dans les classes de taille > 24 cm au printemps. Un indice gonado-somatique plus élevé et des stades de développement gonadiques plus avancés au printempsqu’en automne ont été observés chez les deux sexes. Des pourcentages plus élevés d'individusavec des gonades matures et un indice gonado-somatique élevé ont été trouvés dans la zone depêche réglementée, induisant un plus fort potentiel reproducteur. Ces résultats mettent enévidence l'importance de la gestion des pêches sur les traits d'histoire de vie des espèces depoissons ciblés

Are fisheries regulations influencing the biology and reproduction of the surmullet Mullus surmuletus Linnaeus, 1758 on the south-eastern coasts of France (NW Mediterranean)?

International audienceThe surmullet Mullus surmuletus Linnaeus, 1758 is one of the main target and high valuespecies for small coastal fisheries in the North-Western Mediterranean. Morphometric andreproduction indices of surmullet were determined in fisheries regulated and non-regulatedzones neighbouring the Port-Cros National Park (South-Eastern France) in autumn 2019 andspring 2020. Total length of individuals ranged between 12 and 32 cm, with a mode (?)between 17 and 23 cm. Significantly larger individuals were measured in the regulated fishingzones than in non-regulated ones, and in autumn rather than in spring. Females dominated inall zones and seasons, particularly in size classes > 24 cm in spring. Higher gonado-somaticindex and more advanced gonadal development stages were observed in both sexes in springthan in autumn. Higher percentages of individuals with mature gonads and high gonado-somatic index were found in the fisheries regulated zone, engendering a higher reproductivepotential. These results highlighted the importance of fisheries management with regard to thelife-history traits of targeted fish species.Le rouget de roche Mullus surmuletus est l'une des principales espèces cibles etcommerciales des pêcheries côtières artisanales de la Méditerranée nord-occidentale. Lamorphométrie et les indices de reproduction du rouget ont été déterminés dans les zones depêche réglementées et non réglementées autour du Parc National de Port-Cros (Sud-Est de laFrance) à l'automne 2019 et au printemps 2020. La longueur totale des individus variait entre12 et 32 cm, avec un mode entre 17 et 23 cm. Des individus significativement plus grands ontété mesurés dans la zone de pêche réglementée comparativement aux zones non réglementées,et en automne par rapport au printemps. Les femelles dominaient dans toutes les zones etsaisons, en particulier dans les classes de taille > 24 cm au printemps. Un indice gonado-somatique plus élevé et des stades de développement gonadiques plus avancés au printempsqu’en automne ont été observés chez les deux sexes. Des pourcentages plus élevés d'individusavec des gonades matures et un indice gonado-somatique élevé ont été trouvés dans la zone depêche réglementée, induisant un plus fort potentiel reproducteur. Ces résultats mettent enévidence l'importance de la gestion des pêches sur les traits d'histoire de vie des espèces depoissons ciblés

Are fisheries regulations influencing the biology and reproduction of the surmullet Mullus surmuletus Linnaeus, 1758 on the south-eastern coasts of France (NW Mediterranean)?

International audienc

Marine reserve spillover: Modelling from multiple data sources

International audienceThe functional formof spillover,measured as a gradient of abundance of fish,may provide insight about processes that control the spatial distribution of fish inside and outside theMPA. In this study,we aimed to infer on spillover mechanism of Diplodus spp. (family Sparidae) from a Mediterranean MPA (Carry-le-Rouet, France) from visual censuses and artisanal fisheries data. From the existing literature, three potential functional forms of spillover such as a linear gradient, an exponential gradient and a logistic gradient are defined. Each functional form is included in a spatial generalized linear mixed model allowing accounting for spatial autocorrelation of data. We select between the different forms of gradients by using a Bayesian model selection procedure. In a first step, the functional form of the spillover for visual census and artisanal fishing data is assessed separately. For both sets of data, ourmodel selection favoured the negative exponentialmodel, evidencing a decrease of the spatial abundance of fish vanishing around 1000 m from the MPA border. We combined both datasets in a joint model by including an observability parameter. This parameter captures how the different sources of data quantify the underlying spatial distribution of the harvested species. This enabled us to demonstrate that the different sampling methods do not affect the estimation of the underlying spatial distribution of Diplodus spp. inside and outside the MPA. We show that data from different sources can be pooled through spatial generalized linear mixedmodel. Our findings allow to better understand the underlying mechanisms that control spillover of fish from MPA

Improving the management of Hyères saltmarshes (Provence, France) using an ecosystem-based approach

International audienc

Species-based or ecosystem-based approaches to conservation pratices: Lessons from the Port-Cros National Park (south-east France, Mediterranean Sea).

International audienceFor almost 60 years, the management policy of the Port-Cros National Park (PCNP) has steadily progressed, in phase with human impacts, changes in doctrines and goals in the field of nature conservation, what was socially acceptable at a given time, a very active Scientific Council and a gradual shift from species-centered to ecosystem-based management. Here, we illustrate problems faced by a national park, together with responses or practices that are suited, or not, to an ecosystem-based approach. PCNP’s doctrine has been to explain that the abundance of species fluctuates naturally, and that we must not be too hasty to intervene, that nature sometimes does things better than humans, that a national park is neither a zoo nor a botanical garden, and the purpose is not to artificially increase the species diversity. The management approach of the PCNP can constitute a source of lessons for nature protection and management