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Project OUTCOMES

ACTIVITY 1.1. Establishment of a reference library for the identification of sea cucumber species

This activity was eventually canceled bue to data collection issues in early 2018 following change in fishery context.

ACTIVITY 1.2. Improve biological and genetic knowledge of sea cucumber species

In December 2017, after the official opening of the sea cucumber fishery in October 2017, the SFA had announced that there would be a total ban on the harvesting of H. nobilis, one of our target species of the SEACUSEY project. Therefore, it was decided that we would remove this species from our sampling efforts, and concentrate on the three most targeted species: Holothuria “pentard”, white teatfish H. fuscogilva, and sanpye Thelenota ananas.

• Activity 1.2.1. Study of size at sexual maturity

This SEACUSEY activity was initiated at the start of December 2017, during the predicted spawning season of the three species. A first sampling campaign was carried out in early February by the Project Officer, members of the SFA research team, and M. Léopold on board R/V L'Amitié. During this campaign biological samples and biometric measurements (i.e. individual weight, length and width) of 70 specimens belonging to Holothuria “pentard” and white teatfish H. fuscogilva were collected (see the video). The team discovered that sanpye Thelenota ananas were not found at all within this first study site. This may have been due to fishers specifically targeting the other two high value species.

A second sampling campaign was carried out in early March, whereby the team traveled to the Amirantes region. During this campaign, biological and biometric measurements of 31 specimens belonging to Holothuria “pentard” were collected. The team discovered that Thelenota ananas and H. fuscogilva were in low numbers, or not found at all within this region at the time.

Overall, it was seen that the collection of gonad samples remained lower than expected (i.e. 93 samples of Holothuria “pentard” and 9 samples of white teatfish H. fuscogilva), making it possible to carry out statistical analyses only for Holothuria “pentard”. Ms. Salomé Cahuzac, a biodiversity Masters student from the University of Marseille, France did a two-month internship with SFA and IRD in March and April 2018, specifically recruited for the gonad sampling phase of SEACUSEY project. Her responsibilities included macroscopic analyses of the gonad tubules of Holothuria “pentard” and H. fuscogilva to determine the size at sexual maturity. See Report S. Cahuzac, Size at maturity, pentard, Seychelles.

From the samples that were collected, the size at maturity of pentard was estimated at 30 cm (+- 2 cm). This study provided the first data on the reproductive biology of this species. The results provide guidance for further research investigation and fishery management. They will also be used to develop a protocol to aid future studies of this nature at the SFA. The study will be published in the SPC Bêche-de-Mer Bulletin in 2019.

 

Ms. Cahuzac performing macroscopic observations on a gonad sample

• Activity 1.2.2. Study of the intraspecific genetic structure

Before the harvesting ban of black teatfish H. nobilis, specimen samples of all four harvested species were taken during a cruise on the professional fishing vessel L'Escapade in July 2017. The samples were transferred to the University of La Réunion, and later to a French company specializing in the development of microsatellite markers. Those markers are now available for the four species.

 

DNA sampling of the three authorized species commenced during biological sampling cruise in February 2018 (see the video), followed by the second cruise in March. It was becoming apparent that sampling campaigns using R/V L'Amitié were not as frequent as was hoped. This was due to logistical constraints, as well as rough weather conditions persisting. Therefore, the Project Officer enlisted the help of some of the fishermen in the fleet to help with the DNA collection of the sea cucumber species during their commercial trips. Constant meetings and training exercises were held by the Project officer and at sea in order to prepare the fishermen for the data collection. Adding to this, the project officer also collected salted DNA samples when vessels returned to port for discharging their catch.

Through these exercises, we were able to gather 950 DNA samples: 437 samples of Holothuria “pentard”, 348 samples of white teatfish H. fuscogilva and 165 samples of sanpye Thelenota ananas from eight regions around Seychelles.

DNA analysis was carried out by H. Magalon at the University of La Réunion, consultant N. Oury in La Réunion, and C. Fauvelot at the IRD France. Results showed that was a single stock of Pentard and white teatfish, although small, significant genetic variability was observed across sampling sites for the latter species (see more results  Seacusey project_Activity 1&2_session4_12 09 2018). This difference likely occurred due to the overall low abundance of white teatfish throughout Seychelles. There were too few sanpye samples for conducting a robust analysis for that species.

ACTIVITY 2.1. Estimate and map sea cucumber resource abundance using fishery-dependent data

• Activity 2.1.1. Estimate resource abundance of the main target species

Two surveys of the L’Amitié research vessel were conducted on June 16-17 and July 4-18, 2017, north of Praslin Island, to conduct an experimental sea cucumber fishery. Three professional fishermen, a professional skipper, the research division of the SFA and the IRD participated. A student was hosted on the IRD and the SFA to accompany this operation.

The experiments made it possible to measure the catches of each of the fishermen according to a sea cucumber density gradient under real conditions. A statistical model was developed based on experimental fishing data and underwater visibility parameters. See Rapport_SEACUSEY_CAQUELARD_Julie_2017.pdf.

The results of this study were communicated at the 10th WIOMSA conference held in Tanzania from 30 October to 4 November 2017. Please read the abstract Léopold&al2017_WIOMSA abstract.pdf

The model was transposed to logbook data that is routinely collected by the SFA to estimate and map the abundance of sea cucumber resources in the Seychelles using BDMer 3.0 tool.

Dive profile monitoring

The next step of the study was to accurately estimate commercial CPUE. To date, CPUE estimates have indeed been based on ‘total dive time’ that is recorded in the logbooks. However, this estimate fails to take into consideration the actual time spent fishing, as safety stops. The project looked at ways to improve this estimate.

Over 2018, six commercial sea cucumber divers from three fishing vessels were given pressure recorders that were attached to their BCDs. These recorders accurately mapped the depth profile of 621 dives.

F. Rakotonjanahary, a student at the Institut halieutique et des sciences marine, University of Toliara (Madagascar) from June to September 2018, contributed to build a statistical model to better estimate the actual fishing time (see his report Rapport_stage_seychelles_Nov2018_Fidele).

This model predicts effective fishing time per dive based on depth and total dive duration, which suggests that "true" fishing time (and therefore CPUE) can be estimated at reasonable accuracy using logbook data if skippers make accurate declarations (see a presentation of that activity during the national workshop Seacusey project_Activity 3_session2_12 09 2018).

• Activity 2.1.2. Development of the BDMer 3.0 information system

The specifications of the BDMer 3.0 information system were defined by the IRD, according to the needs expressed by the SFA. This information system is intended to facilitate the routine estimation of the abundance of exploitable sea cucumber resources using fishing records. The procedure is as follow. For each dive, catch data are first converted into density estimates using the statistical models described above based on catch records per species, total dive time, depth, and number of divers. Statistical inference is then used to derive abundance estimates. G. Lahitsiresy Max, a student at the Institut halieutique et des sciences marine, University of Toliara (Madagascar) from June to September 2018, mapped 180 zones according to depth (10-50 m), sea bottom substrate, and fishing areas (see his report Rapport_Max LAHITSIRESY). These zones were used as statistical strata in the statistical procedure in BDMer 3.0.

The computer developments were carried out at the IRD center in New Caledonia. They were partly completed during M. Dubois's internship in April-August 2018 (see Rapport_de_stage_DUBOIS_MORGAN). S. Fiat (IRD New Caledonia) visited SFA in July 2018 to install the data server and a preliminary version of the system. The final version of the tool was made available in December 2018 following numerous interactions with SFA. Only SFA has access rights to the system.

 

 

BDMer 3.0 now allows for 1) estimating total abundance of sea cucumber stocks per species, 2) mapping sea cucumber catches in each dive location, and 3) mapping sea cucumber density in dive locations and zones as displayed below.

 

ACTIVITY 2.2. Define resource management measures at appropriate spatial scale

During the project, regular meetings were held with partners and associates in the industry. Specifically M. Léopold and A. Ebrahim met with Mr. Paul Morin, chairman of the AMSSI, and Mr. Marcus Quatre, chairman of the newly-formed Seychelles Sea Cucumber Harvesting Association (SCHA) (and also a skipper on board sea cucumber vessel ‘Brizare’). At a meeting in January 2018, they were briefed on the project objectives, and were presented with a poster that demonstrated the outcomes of the first phase of the project. Mr. Morin and Mr. Quatre expressed their gratitude and enthusiasm of the activities of SEACUSEY.

Project partners also regularly met with the Deputy CEO of the SFA, Mr. Calvin Gerry. The deputy CEO was briefed on the overall project outcomes and procedures. The project objectives were well received, and it was made clear at these meetings that the SFA will continue to endorse the activities of the project into future seasons of fishing. Mr Gerry has since communicated about the SEACUSEYresearch program at the national management advisory committee (MAC) for sea cucumber fisheries, that was held several times in 2018. The project has complemented the expertise provided by the MRAG in July 2017 based on the analysis of the fishing sheets and the VMS data available on the trips of licensed vessels. In April 2018, the project partners highlighted that by strengthening the fishery’s technical capacities and optimizing management costs, the project will support the SFA’s management role in collaboration with the sector’s stakeholders. Over the longer term this will inform discussions about the relevance of a future national sea cucumber fishery co-management plan.

It was also proposed that a national workshop be hosted in the Seychelles on September, 12th 2018 before the fishery reopens. The aim of the workshop was to evaluate the outcomes of these actions and possible extensions that could be considered with other countries in the region. The overall collaborative research process was also presented (see presentation Seacusey project presentation_session1_12 09 2018 and the video of the genetic and biological sampling on-board l’Amitié). The new data management system (cf. Activities 2.1 and 2.3) was presented (see the presentation here). A total of 40 participants attended the workshop, including members of the fishery sector, government staff, consultants, and local medias. The stakeholders’ contribution provided useful guidance for future collaborative action (download the Report National workshop_12 09 2018, the Poster for National Workshop_FINAL and the flyer of the workshop here). Visit Seychelles NATION’s communication at http://www.nation.sc/article.html?id=260404

Stakeholders expressed their thanks and appreciation for the research work that was undertaken during the project. They expressed the need for continuation of the research work as 18 months is quite short to carry out a comprehensive study on the sea cucumber fishery.