Tracking foraging green turtles in the Republic of the Congo: insights into spatial ecology from a data poor region

Abstract

Globally, marine turtles are considered threatened throughout their range, and therefore conservation practitioners are increasingly investing resources in marine protected areas to protect key life history stages and critical habitats, including foraging grounds, nesting beaches and inter-nesting areas. Empirical data on the distribution of these habitats and/or the spatial ecology and behaviour of individuals of many marine turtle populations are often lacking, undermining conservation efforts, particularly along the Atlantic coast of Africa. Here we contribute to the knowledge base in this region by describing patterns of habitat use for nine green turtles Chelonia mydas tagged with satellite platform transmitter terminals at a foraging ground in Loango Bay, Republic of the Congo, one of only a few documented mainland foraging grounds for marine turtles in Central Africa. Analyses of these data revealed that core areas of habitat use and occupancy for a wide range of size/age classes were restricted to shallow waters adjacent to Pointe Indienne in Loango Bay, with most individuals showing periods of high fidelity to this area. These data are timely given the Congolese government recently announced its intention to create a marine conservation zone to protect marine turtles in Loango Bay. Despite the small sample size of this study, these data exemplify the need for comprehensive strategies that span national jurisdictions, as we provide the first documented evidence of linkages between green turtle foraging sites in Central Africa (Loango Bay, Republic of the Congo) and Southern Africa (Mussulo Bay, Angola).

Network analysis of sea turtle movements and connectivity: A tool for conservation prioritization

“…Finally, to better normalize data with timestamp irregularities and tags programmed to record locations on different schedules, we subsampled each track to retain just one location per day (De Solla et al, 1999). The highest quality record of the day was chosen; the first occurrence of the high‐quality points was retained if multiple locations of the same highest quality level was recorded for one day (per Metcalfe et al, 2020; Witt et al, 2010). All types of sea turtle movements from one point to another were used in this study, such as those described by Dingle and Drake (2007) as short‐ and long‐distance migrations, ranging, foraging, commuting, or seasonal movements “between habitat regions.”…”

Missing Data in Sea Turtle Population Monitoring: A Bayesian Statistical Framework Accounting for Incomplete Sampling

“…This is a globally significant marine region characterised by intense seasonal upwelling of cold-water nutrients, resulting in some of the most productive coastal and offshore waters (net primary productivity > 300 gCM -2 y -1 ) in the world (Sherman and Hempel, 2008). Consequently, this region is a biodiversity hotspot (Polidoro et al, 2017) hosting globally important populations of marine vertebrates (Wallace et al, 2010;Wallace et al, 2011), with the Republic of the Congo supporting important nesting beaches for populations of olive ridley and leatherback turtles, as well as important foraging grounds for juvenile green and hawksbill turtles (Godgenger et al, 2009;Metcalfe et al, 2020). In 2011, longterm data gathered by Wildlife Conservation Society (WCS) and Renatura Congo, in partnership with the Ministère de l'E ́conomie Forestière, resulted in all sea turtle species being classified as highly protected (Arretén°6075 du 9 avril 2011 determinant les espèces animales inteǵralement et partiellement proteǵeés).…”

Movements of green turtles from foraging areas of the United Arab Emirates: regional habitat connectivity and use of marine protected areas

“…Foraging areas can change seasonally, and fidelity to these sites across years can be high (Mingozzi et al 2016). Foraging areas can also host mixed age-classes of sea turtles (e.g., in the Republic of the Congo; Metcalfe et al 2010) and this distribution is likely regulated by resource availability and competition. Expanding on the potential results from satellite tracking post-nesting female turtles, satellite tracking studies from foraging areas have the incremental ability to (a) document links from foraging areas to unknown nesting destinations (e.g., Dutton et al 2018); (b) document round trip foraging-nesting-foraging migrations (e.g., Limpus and Limpus 2001); (c) document use of multiple foraging areas (e.g., Casale et al 2012a); (d) document movements of male turtles (e.g., James et al 2005); and (e) of juvenile turtles (e.g., Hart and Fujisaki 2010), along with similar habitat use, migratory corridor and habitat connectivity data.…”