Using expert opinion to identify and determine the relative impact of threats to sea turtles in Mozambique

Abstract

Although robust and consistent long‐term datasets are lacking, it is commonly accepted that sea turtle populations face significant human threats while using Mozambique's coastal habitats. While multiple threats have been identified, their relative impact – and thus the ability to prioritize limited conservation resources – is poorly known. To obtain a better understanding of these threats, information from experts was elicited through a semi‐structured survey using open and closed‐ended questions. Experts in research, conservation and management of sea turtles were identified and asked to identify key threats and to complete pairwise comparison matrixes to determine the relative weight (w) of each threat (13 criterion, n = 24 questions). Weights for the perceived impact of threats were calculated from scores given in the pair‐wise matrix using the analytic hierarchy process. Responses (n = 18) to open‐ended survey questions were thematically coded and discussed according to common themes (e.g. extent of knowledge, limitations, conservation management tools) identified. Bycatch from commercial trawling (w = 13.65), artisanal fishing (w = 12.30) and hunting of nesting turtles (w = 11.33) were the top threats identified, in order of relative impact. While two of the three top threats are widely distributed and likely to be logistically and resource intensive to address, the top‐scoring threat, ‘bycatch from commercial trawling', is a clearly defined target for conservation intervention. Given a lack of baseline or published data, soliciting expert opinion was an efficient way to identify emergent threats, along with the success and limiting factors influencing sea turtle conservation in a developing nation. The methodology and technique implemented here are transferable. Expert surveys can provide valuable insights in locations with similar socio‐economic environments and limited empirical data to help clarify the relative impact of various threats.

Global challenges and priorities for interventions addressing illegal harvest, use and trade of marine turtles

“…Obtaining reliable information on illegal activities is challenging, and the opinions of experts evolve over time (Martin et al, 2011). The perceptions we have reported may have been subject to biases, including from field experiences, areas of expertise, and the degree of both of these (Donlan et al, 2010; Williams et al, 2019). Expert knowledge is likely to be influenced by a range of factors that are unique to the individual experts, making it difficult to achieve impartiality.…”

“…However, overexploitation and shifts from subsistence to commercial use, motivated by nutritional values, perceived health benefits, valued material properties (e.g. of the carapace and its scutes) or revenue from trade (Frazier, 2005; Barrios-Garrido et al, 2017) threaten the conservation of marine turtles (Donlan et al, 2010; Williams et al, 2019) by depleting their populations. For example, international market demands during the 1950s–1970s caused the collapse of all marine turtle populations in Mexico (Mancini & Koch, 2009, and references therein).…”

Investigating the Distribution of Foraging Habitat for Loggerhead Sea Turtles, Caretta caretta, in the Mediterranean Sea

“…Bycatch has been also recognized as a major problem worldwide for all the sea turtle species [34]. For example, trawl fishery has been identified as the main source of mortality for neritic adult loggerheads in the southwest Atlantic region [35] and the top-ranked threat for all the sea turtle species hosted in Mozambican waters [36]. Even though many attempts to mitigate the consequences of fisheries bycatch have been made (e.g., through awareness campaigns for fishermen or adaptations to fishing tools; [12]), the problem still persists, highlighting the necessity to enhance trans-boundary and multidisciplinary collaborations towards the establishment of the appropriate measures and strengthening the conservation efforts for sea turtles.…”

Modeling the emergence of migratory corridors and foraging hot spots of the green sea turtle

“…In the SWIO, direct take and coastal fisheries bycatch are a major threat (Bourjea, ). Looking at the model results, we could infer that high levels of bycatch and direct take reported along the east African coasts (see review in Bourjea, ) of Mozambique (Gove, Pacules, & Gonçalves, ; Kiszka, ; Williams, ; Williams, Pierce, Hamann, & Fuentes, ), Tanzania (Moore et al, ; Muir, ), and Kenya (Mueni & Mwangi, ; Okemwa et al, ) might probably affect all sea turtle nesting populations of the region, and more specifically nesting populations from the north of the Mozambique Channel.…”