Calling all fisherman. Reward! Acoustic loggers lost in NW Madagascar.

June 25, 2016

Prepared by Melinda Rekdahl, WCS
25 June 2016

As part of the WCS-led component (MG-6) of the GEF Dugong and Seagrass project in northwest Madagascar, a deployment of 6 acoustic loggers was carried out from the 20th to the 26th of April 2016 (see news article here). The deployments were based on the results of seagrass mapping and community interview surveys. Three loggers were deployed at sites around Nosy Komba and Ambaro Bay (see google map) in areas adjacent to seagrass beds where water depth was sufficient to prevent the loggers being exposed during low tide (between 5 to 9 meters – low tide).

Given the high number of artisanal fisherman in both locations, there was concern that the loggers may be stolen or tangled in the fisherman’s gear.

In order to try to mitigate this risk, the loggers were deployed with a subsurface float and heavy anchor system (20kg concrete blocks), so that they wouldn’t be visible at the surface and would not be easily dragged. The loggers were also labeled carefully with WCS contact details in case they were tangled in the fisherman’s nets and removed by the fisherman. Additionally, before deployment, local communities were alerted of the deployments (although not the exact location) in the hopes that they would not disturb the recorders or contact WCS if they became entangled in their nets.

The recorders were set to record continuously at 48 kHz and it was planned to retrieve the recorders in a mission between the 22nd and 23rd of May 2016 in order to change batteries and download the data before re-deploying.

Before this date there was a report from fisherman after the first deployment that one of the recorders in Ambaro Bay became entangled in a fisherman’s nets and dragged away from the original position.

The fisherman contacted WCS but unfortunately didn’t follow up and meet the WCS staff to help them to locate the recorder. The attempt to recover this recorder failed and there were an additional 2 recorders that were unable to be recovered, 1 in Nosy Komba and 1 in Ambaro Bay, during the May mission.

We are actively working to try and locate the lost loggers by posting a reward and notice at three local radio stations (Ambanja, Nosy Be and Ambilobe) to the local fisher communities.

A radio message will be released 3 times a day starting on the 30th of May until end of June but to date these efforts have not generated any information. Efforts to contact the fisherman who dragged one of the loggers are also ongoing but due to the isolation and poor network coverage in the zone this is proving unfruitful for the time being.

Based on these experiences we have concluded that Ambaro Bay has very challenging conditions for deployment as there is very low visibility (less than 1 meter) and therefore a high chance of losing the recorders if they become entangled in fishermans’ nets.

Therefore we have made the decision not to redeploy in Ambaro Bay as the risk of further losses is too high.

Similarly, we have decided to postpone or cancel the deployment of loggers in Nosy Komba until we can assess whether we can work with the fisherman communities in Nosy Komba to check on the recorders and work with WCS to ensure they remain in the area.