Global Conservation Priorities for Marine Turtles

Abstract

Where conservation resources are limited and conservation targets are diverse, robust yet flexible priority-setting frameworks are vital. Priority-setting is especially important for geographically widespread species with distinct populations subject to multiple threats that operate on different spatial and temporal scales. Marine turtles are widely distributed and exhibit intra-specific variations in population sizes and trends, as well as reproduction and morphology. However, current global extinction risk assessment frameworks do not assess conservation status of spatially and biologically distinct marine turtle Regional Management Units (RMUs), and thus do not capture variations in population trends, impacts of threats, or necessary conservation actions across individual populations. To address this issue, we developed a new assessment framework that allowed us to evaluate, compare and organize marine turtle RMUs according to status and threats criteria. Because conservation priorities can vary widely (i.e. from avoiding imminent extinction to maintaining long-term monitoring efforts) we developed a “conservation priorities portfolio” system using categories of paired risk and threats scores for all RMUs (n = 58). We performed these assessments and rankings globally, by species, by ocean basin, and by recognized geopolitical bodies to identify patterns in risk, threats, and data gaps at different scales. This process resulted in characterization of risk and threats to all marine turtle RMUs, including identification of the world's 11 most endangered marine turtle RMUs based on highest risk and threats scores. This system also highlighted important gaps in available information that is crucial for accurate conservation assessments. Overall, this priority-setting framework can provide guidance for research and conservation priorities at multiple relevant scales, and should serve as a model for conservation status assessments and priority-setting for widespread, long-lived taxa.

Impacts of fisheries bycatch on marine turtle populations worldwide: toward conservation and research priorities

“…To evaluate relationships between bycatch impact scores and RMU risk scores, we adapted the scaling evaluation approach used by Wallace et al (2011) to assess risk and threat criteria for marine turtle RMUs. Weighted median BPUE, mortality rate, and body size values were scored using a comparable low-medium-high scale (numeric values 1 to 3; see Table 2 for values).…”

Movement patterns of marine turtles in the Mediterranean Sea: a review

“…Just a few leatherback turtles enter the Mediterranean from the Atlantic and they can be found all over the basin, although they do not breed in the Mediterranean . The other two species have Mediterranean populations recognised as regional management units, with the green turtle unit being considered at high risk (Wallace et al 2011). The main identified threats at sea to these two Mediterranean populations are incidental catch in fishing gear, collision with boats and intentional killing (Tomás et al 2008;Casale 2011), which as a whole represent a high level of threat (Wallace et al 2011).…”

“…The other two species have Mediterranean populations recognised as regional management units, with the green turtle unit being considered at high risk (Wallace et al 2011). The main identified threats at sea to these two Mediterranean populations are incidental catch in fishing gear, collision with boats and intentional killing (Tomás et al 2008;Casale 2011), which as a whole represent a high level of threat (Wallace et al 2011). The impact of other potential threats on the populations, like chemical contaminants (D'Ilio et al 2011) and debris (e.g.…”

A critical review of the Mediterranean sea turtle rescue network: a web looking for a weaver

“…Green turtles face a measurable risk of extinction worldwide and therefore qualify for the IUCN Endangered status under Criteria A2bd (Seminoff 2004). The Mediterranean population is genetically distinct from Atlantic populations and belongs to a separate regional management unit (RMU) , which is recognized to face high threats and a high risk of extinction (Wallace et al 2011). A total of 339-369 females are nesting in the entire Mediterranean (Broderick et al 2002).…”

“…The resident Mediterranean loggerhead population is genetically isolated (Carreras et al 2011) from individuals of the two Atlantic RMUs migrating to Mediterranean foraging grounds and is considered to face high threats (Wallace et al 2011). Bycatch rates are estimated at up to 200,000 loggerheads per year, leading to more than 50,000 deaths annually through direct interaction alone (Casale 2008, Lucchetti and Sala 2010, Casale 2011.…”