dFADs threaten marine life in the Indian Ocean

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dFADs threaten marine life in the Indian Ocean

August 27, 2019 - 15:40
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Drifting fish aggregating devices (dFADs) are threatening the marine environment in the Indian Ocean. In 2015, marine conservationist Lucy Martin worked with the Island Conservation Society (ICS), a non-governmental organisation in the Seychelles, on a large survey to find out how big a problem dFADs actually were.

Chubs cluster under a drifting fish aggregating device (dFAD) in St Francois Atoll, Seychelles Islands. dFADs are often discarded and left to drift in the sea, eventually getting stuck on reef, damaging corals, or ensnaring marine life such as sea turtles. Photo by Lucy Martin.

Text by Lucy Martin

A dFAD is a floating raft equipped with solar-powered batteries, a fish finder and a GPS system. They enable vessels to track the location and quantity of schooling tuna. Usage of this fishing practice has been accelerating since the 1990s, and nowadays, mass-produced dFADs follow the ocean currents, signalling the best fishing grounds. Made of scrap netting and long ropes, dFADs work by creating shade—the shelter of which attracts small fish in the vast open ocean. This, in turn, attracts larger fish. After a period of about five months, the volume of available food brings a tuna feeding frenzy. The industry then uses purse-seine nets that circle the shoal, close at the bottom and bring in the whole catch.

Discarded and drifting

In response response to campaigning by turtle conservation groups, a change to dFAD design was encouraged in 2012 in order to avoid entanglement of these marine reptiles in the hanging nets. However, what my colleagues and I found in 2015 was that dFADs were being carelessly discarded at the fishing grounds and left to drift around the ocean until they hit shallow coastal waters, like that of the Outer Islands in the Seychelles where I live.

Many of these Outer Islands are atolls, and I found that the impacts of dFADs entering this sensitive ecosystem were many. The seabed outside the atoll—with pristine coral reefs—would be the first to take a hit; the net and rope attached around coral heads and would anchor dFADs, then rip colonies off the seabed in strong currents, swell or wind. Once freed from the seabed, dFADs would move onto seagrass flats and uproot plants and marine organisms. Eventually, the train wreck of damage made it into the lagoon or onto the beach. All this while, marine life became ensnared and died. The synthetic materials used were persistent and therefore so was the threat.

Survey and removal

In the 2015 survey, ICS and I quantified the damage being done and started more intensive removal of dFADs. Since then, I have moved into ecotourism and run a PADI dive centre. Here, I organise dFAD removals with guests and promote the Project AWARE Dive Against Debris Speciality in which I regularly remove dFADs with students.

Reductions and FAD Watch

Since the issue has been highlighted, reductions in dFAD quotas have been made, and the industry is looking into biodegradable dFADs. A collaboration with Spanish Tuna Purse Seiner Fishing Representatives, named FAD Watch, has been initiated to attempt to intercept dFADs before they hit the reefs. All of the advancements are big improvements, but there is still a lot that needs to be done.

Watch this space to read Martin’s first-hand accounts of dFAD removals, as well as the problems and conservation successes revolving around dFADs, in an upcoming issue.

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