Tahiti peninsulaOn Tahiti Iti, several management and conservation systems for coral reef ecosystems areas have been created in various associated municipalities. Our team have been working since 2019 on the two municipalities of Taiarapu-Est and Taiarapu-Ouest. We (i) support the optimization of the applicable measures and (ii) strengthen management committee’s empowerment to set up an adaptive management.
© Ewen Morin
inhabitants in 2017
of protected marine area
Tahiti Iti, located in the south-east of the island of Tahiti, is made up of two municipalities: Taiarapu-Est and Taiarapu-Ouest. Several Regulated Fishing Areas (ZPR) or rāhui have been implemented along the coasts of the peninsula.
In 2014, the municipality of Teahupo’o at Fenua Aihere opens the way with the classification of a portion of its marine area as a “protected area of managed natural resources”, a category created by the Environmental Code of French Polynesia. From 2018, the associated municipalities of Pueu, Afaahiti and Tautira have created, in turn, ZPRs. With these measures, municipalities regulate fishing practices: in some areas all fishing is prohibited – whatever the species or the technique used – in others certain practices are authorized by way of derogation: this is the case by example of fishing for ature (Selar crumenophthalmus) with a large net, authorized only a few hours during the day in Tautira.
These areas are managed by committees, established to monitor ZPR and formulate management proposals. These measures aim to guarantee a sustainable use of marine resources.
On the Tahiti peninsula, our team focuses on (i) production and analysis of data relating to the ecological and stocks state, (ii) on design of improved scenarios and on (iii) management committees’ empowerment or training.
WHAT WE HAVE DONE
Assess water quality and management strategies
In 2020, we conducted a survey to collect each month ecological data to analyze water quality in different places around Tahiti Iti. So, we led on each site diurnal underwater visual counting of fish; record of the cover percentage of different substrate categories; water temperature, salinity, pH and dissolved oxygen concentration were also measured.
In addition, based on a study carried out in Palau indicating that “taro fields and mangroves protect coral reefs by trapping sediments” we have developed a protocol to measure sediment trapping capacity of different types of terrestrial environments (taro plantation, mangroves, heavily anthropized areas, etc.). Fiffty cylindrical sediment traps were deployed in all sites and retrieved monthly.
Sedimentation is one of the biggest threats facing coral reefs[…] This paper documents the filtering effects of cultivated wetland, namely that of taro (Colocasia esculenta) fields. […] The results showed that the taro fields have the capacity to trap up to 90 % of sediments.
Analysis of these data will allow comparisons to be made between different sites to assess the effectiveness of ZPRs and effects of different types of coastal development on sediment pollution. Results should allow us to design new scenarios to improve management strategies.
Better known cultivated taro diversity
We carried out a survey to identify different taro species cultivated on the peninsula and to characterize exchanges linked to this plant, which is culturally very important in French Polynesia and throughout the Pacifi. We sought to identify the reasons that motivate farmers to choose one specie over another: we aim to identify the most resilient species to climate change. We also compared the varietal diversity cultivated with consumer preferences to assess the interest or relevance of expanding cultivation of certain species identified as resilient.
Designing scenarios to preserve or manage coral reef ecosystems at the watershed scale is essential to increase the effectiveness of measures limited to the maritime area. The association of taro plantations adjacent to the Managed Marine Areas could be considered in ZPR optimization scenarios.
WHAT WE PLAN TO DO
En 2021, we will focus our efforts on Tautira and Teahupo’o to implement a ZPR and rāhui monitoring protocol based on fish size. We will experiment with a collaborative approach to collect commercial fish sizes. Involving men and women who fish in data collection is relevant for several reasons:
Mobilize and collect local ecological knowledge to gain efficiency in designing and implementing monitoring protocol;
Promote legitimacy of the project, taking into account social organization and cultural practices or values;
Transmit new skills and knowledge locally to ensure, over the long term, the autonomy of management committees in the collection and analysis of data.
In addition to data collection, local communities will be trained in the design and implementation of ecological and fisheries monitoring.