Migrations, Famille et Vieillissement en Guadeloupe

L’enquête « Migrations, Famille et Vieillissement », conçue par une équipe de chercheurs de/associés à l’Ined (Institut national d’études démographiques), est la première enquête Ménage de grande ampleur spécifiquement dédiée aux départements et régions d’outre-mer (Drom). Elle analyse et mesure les mutations sociodémographiques à l’œuvre dans chacun d’entre eux (Marie, 2011). Outre les thématiques centrales que sont les migrations, le vieillissement, la famille et leurs transformations, elle aborde une série de thèmes « secondaires » tout aussi essentiels à la connaissance de ces territoires et à l’examen de leurs spécificités (pratiques linguistiques et religieuses, discriminations, état de santé, etc.). Cette enquête combine représentativité territoriale et comparabilité nationale, voire internationale. Son ambition est également politique : elle a été pensée comme un instrument d’aide à l’élaboration et à la mise en œuvre locale de politiques sociales et sanitaires adaptées. Forte des enseignements des premières éditions conduites en 2009-2010 en Martinique, Guadeloupe, Guyane et La Réunion, puis à Mayotte en 2015-2016 (Marie et al., 2017), cette enquête a été reconduite en 2020-2021 (MFV-2) dans les quatre Drom « historiques » : Guadeloupe, Martinique, Guyane et La Réunion. Le questionnaire réactualisé vise à approfondir la connaissance des dynamiques à l’œuvre dans chacun de ces territoires et des changements qui s’y sont opérés ces dix dernières années, avec l’ambition d’en donner une vision prospective

High fidelity of sea turtles to their foraging grounds revealed by satellite tracking and capture-mark-recapture: New insights for the establishment of key marine conservation areas

Movement ecology studies are essential to protect highly mobile threatened species such as the green turtle (Chelonia mydas), classified as an endangered species by the IUCN. In 2019, the South Atlantic subpopulation has been downlisted to ‘Least Concern’, but the maintenance of this status strongly relies on the pursuit of research and conservation, especially on immatures, which contribute to the demographic renewal of this subpopulation. Identifying marine areas used by immatures is therefore crucial to implement efficient measures for the conservation of sea turtles in the Caribbean. We analysed data of capture-mark-recapture of 107 (out of 299) immatures recaptured at least once in Martinique, and satellite tracked 24 immatures to investigate their site fidelity and habitat use. Our results revealed a strong fidelity to foraging grounds, with mean residence times higher than 2 years, and with a high degree of affinity for specific areas within the coastal marine vegetation strip. Home ranges (95% kernel contour) and core areas (50% kernel contour) varied from 0.17 to 235.13 km2 (mean ± SD = 30.73 ± 54.34 km2) and from 0.03 to 22.66 km2 (mean ± SD = 2.95 ± 5.06 km2), respectively. Our findings shed light on a critical developmental area for immature green turtles in the French West Indies, and should help to refine Regional Management Units and reinforce the cooperative network aiming at ensuring conservation of the species at international scale

Fine scale geographic residence and annual primary production drive body condition of wild immature green turtles ( Chelonia mydas ) in Martinique Island (Lesser Antilles)

The change of animal biometrics (body mass and body size) can reveal important information about their living environment as well as determine the survival potential and reproductive success of individuals and thus the persistence of populations. However, weighing individuals like marine turtles in the field presents important logistical difficulties. In this context, estimating body mass based on body size is a crucial issue. Furthermore, the determinants of the variability of the parameters for this relationship can provide information about the quality of the environment and the manner in which individuals exploit the available resources. This is of particular importance in young individuals which growth quality might be a determinant of adult fitness. Our study aimed to validate the use of different body measurements to estimate body mass, which can be difficult to obtain in the field, and explore the determinants of the relationship between body mass and size in juvenile green turtles. Juvenile green turtles were caught, measured, and weighed for six years (2011-2012; 2015-2018) at six bays in the west of Martinique Island (Lesser Antilles). Using different datasets from this global database, we were able to show that the body mass of individuals can be predicted from body measurements with an error of less than 2%. We built several dataset including different morphological and time-location information to test the accuracy of the mass prediction. We show a year and north-south pattern for the relationship between body mass and body measurements. The year effect for the relationship of body mass and size is strongly correlated with net primary production but not with sea surface temperature or cyclonic events. We also found that if the bay locations and year effects were removed from the analysis, the mass prediction degraded slightly but was still less than 3% on average. Further investigations of the feeding habitats in Martinique are still needed to better understand these effects and to link them with geographic and oceanographic conditions