A Plea to Redirect and Evaluate Conservation Programs for South America’s Podocnemidid River Turtles

Páez, Vivian P.; Lipman, Alison; Bock, Brian C.; Heppell, Selina S.

doi:10.2744/ccb-1122.1

Cited by 25 publications

(36 citation statements)

References 70 publications

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“…Another common practice in turtle conservation programs, removing eggs from natural nests, is also not recommended. This practice can negatively affect egg and hatchling survivorship (Frazer , Crouse , Páez et al , Ahles and Milton , Hart et al ). However, the introduction of a large number of hatchling females (by artificially raising nest temperatures) may alter the genetic and ecological structure of the population (Mrosovsky and Godfrey , Lovich ).…”

Section: Discussionmentioning

confidence: 99%

Boosting female hatchling production in endangered, male‐biased turtle populations

2017

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In turtle species with temperature-dependent sex determination, hatchling sex ratios skewed toward males could threaten populations where females are vulnerable to harvest. We tested the efficiency of black plastic covers in producing more female hatchlings from nests of the six-tubercle Amazon River turtle (Podocnemis sextuberculata) at the Mamirau a Reserve, Amazonas, Brazil, during September to November 2003. Covered nests produced 37% more females and midnest average temperatures were 18 C higher than control nests. Incubation period was 3 days shorter, but survivorship was 12% lower in nests with black plastic. This technique could be an inexpensive, local alternative for short-term sex-ratio manipulation in endangered male-biased populations with temperature-dependent sex determination.

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Section: Discussionmentioning

confidence: 99%

Boosting female hatchling production in endangered, male‐biased turtle populations

2017

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“…Both eggs and adults of P. unifilis have been exploited since the pre‐colonial period (pre 18th century) and are still consumed by indigenous and riverine communities across Amazonia (Smith, ; Harju, Sirén & Salo, ). Dramatic intensification of overharvesting of aquatic species through the 20th century (Antunes et al ., ) has generated a widespread ‘fishing‐down the food chain’ process across Amazonian waterways (Castello et al ., ; Antunes et al ., ), with surviving freshwater turtle populations manifesting dramatic declines in body size (Castello et al ., ; Páez et al ., ; Antunes et al ., ). Based on current human population densities and access to rivers, a precautionary analysis of P. unifilis populations predicts severe (≥50%) and rapid (<50 years) future losses across 60% (5.3 M km 2 ) of the pan‐Amazonian range (Norris et al ., ).…”

Section: Methodsmentioning

confidence: 97%

Nest removal by humans creates an evolutionary trap for Amazonian freshwater turtles

et al. 2019

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Nest‐site selection exerts a fundamental maternal effect on offspring fitness in oviparous species. In many freshwater turtles, females do not care for their eggs after oviposition but rather rely on a nest's micro‐environment to incubate developing embryos although linkages between oviposition choices and overall fitness remain poorly evaluated. We tested predictions derived from multiple hypotheses to examine nesting patterns of the yellow‐spotted river turtle Podocnemis unifilis, a species imperiled by egg harvesting by humans throughout its range, based on data collected from 73 nesting sites along 118 km of river in the eastern Brazilian Amazon. Nesting area size largely explained nest‐site selection by turtles, but only weakly explained turtle egg harvesting by humans. Despite the wide availability of alternative nesting habitats, turtles do not appear to be capable of avoiding hazardous nesting sites associated with increased egg harvesting by humans. Because signals used by female turtles to select nesting areas are apparently not sufficient for avoiding nesting along rivers accessible to humans, direct conservation action will be vital for persistence of these and likely other Amazonian freshwater turtles.

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“…The conservation and commercial exploitation of Podocnemis unifilis in Brazil contrasts with other South American countries. Conservation actions primarily aimed at protecting nests were initiated at a time of military rule (early 1970's) and have continued through democratization (1970's -1980's) and into the 21 st century (Alho 1985;Páez et al 2015;Vogt 2008 constructed at the ICMBio base, located at the entrance of the Falsino River (Fig. 1).…”

Section: Background On River Turtle Management Approachesmentioning

confidence: 99%

“…Amazon river turtles generates high expectations for, and sharp debate about governance-effective management approaches necessary to ensure the conservation of these species (Páez et al 2015). The most commonly adopted management approaches for Amazon river turtles involve actions around the protection and conservation of nesting areas, nests and hatchlings during this critical life phase when individual turtles are highly concentrated on exposed river sands accessible to people (Harju et al 2017;Mittermeier 1978;Páez et al 2015;Vogt 2008). Nesting areas emerge episodically with seasonal lowering of river levels and can shift from one season to the next so are typically common-pool resources for which management actions necessarily include a variety of governance Manuscript to be reviewed mechanisms to ensure compliance (Salo et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Peer Review #2 of "Community involvement works where enforcement fails: conservation success through community-based management of Amazon river turtle nests (v0.3)"

2018

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Law enforcement is widely regarded as a cornerstone to effective natural resource management. Practical guidelines for the optimal use of enforcement measures are lacking particularly in areas protected under sustainable and/or mixed use management regimes and where legal institution are weak. Focusing on the yellow-spotted river turtles (Podocnemis unifilis) along 33 km of river that runs between two sustainable-use reserves in the Brazilian Amazon as an illustrative example, we show that two years of patrols to enforce lawful protection regulations had no effect on nest harvesting. In contrast, during one year when community-based management approaches were enacted harvest levels dropped nearly threefold to a rate (26%) that is likely sufficient for river turtle population recovery. Our findings support previous studies that show how community participation, if appropriately implemented, can facilitate effective natural resource management where law enforcement is limited or ineffective.

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A Plea to Redirect and Evaluate Conservation Programs for South America’s Podocnemidid River Turtles

Cited by 25 publications

References 70 publications

Boosting female hatchling production in endangered, male‐biased turtle populations

Boosting female hatchling production in endangered, male‐biased turtle populations

Nest removal by humans creates an evolutionary trap for Amazonian freshwater turtles

Peer Review #2 of "Community involvement works where enforcement fails: conservation success through community-based management of Amazon river turtle nests (v0.3)"

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