Satellite tracking of Fish Aggregating Devices helps island states govern waters, collect ocean data.

Fish aggregating devices can be made from anything and come in varying sizes. Many, like these anchored FADs, include palm fronds that hang over the edges of the FAD to attract fish. Image Credit: PNA Tuna

In recent decades, the use of fish aggregating devices (FADs) has risen dramatically. While it’s unknown why marine pelagic species can be attracted to these man-made floating rafts, it is known that FADs can make fishing a great deal more efficient.

The extent of ‰ÛÏghost fishing‰Û caused by FADs is disputed. Loose netting is typically the cause of unintended fish kills. FADs encourage fish ‰ÛÒ including juveniles and non-target species ‰ÛÒ to congregate, and fishing vessels use purse seine nets to capture all fish aggregated beneath FADs.

However, because FADs are more expensive to recover than to abandon, it is estimated that hundreds of thousands of these floating devices are adrift in the world’s oceans. Many of them run aground or become entangled on reefs, while others may continue to snag and kill marine life. It’s estimated that hundreds of thousands of additional FADs of varying sizes are set adrift in the world’s oceans each year.

The Parties to the Nauru Agreement (PNA), a group formed in 1982 of eight island nations ‰ÛÒ the federated states of Micronesia, Kiribati, Marshall Islands, Nauru, Palau, Papua New Guinea, Solomon Islands and Tuvalu ‰ÛÒ are working together to address these issues and track FADs. Since 2010, the PNA members have been implementing within their waters a requirement that all fishing vessels report, and since 2016 are required to register, the satellite tracking buoys used, and provide data feeds so that every FAD can be tracked, even if it changes hands or is discarded.

According to Maurice Brownjohn, commercial manager at the PNA office in the Marshall Islands, geo-orbiting communication satellites receive buoy data in a prescribed format transmitted from each buoy at least twice daily and then transmit the data to their respective satellite buoy service provider via land and earth stations around the globe.

The service provider then provides near-real time data to the respective vessel and company office with a copy by email to the Fisheries Information and Management System (FIMS) åÊin the standard North Atlantic Format to allow automation of data receipted into FIMS.

Such buoys not only enable the fishing boats to track their FADs, but increasingly provide a raft of data that can improve catch efficiency. The newer generation buoys are able to ascertain fish species, size, and biomass, which helps the fishing companies ‰ÛÏsee‰Û how many fish are underneath a FAD. This helps determine which FADs are the most productive.

‰ÛÏThe fishery is changing from a fishing operation to a cherry-picking operation,‰Û said Brownjohn.

Purse seine vessels and gear in this Google Earth image shows the paths of FADs belonging to just three vessels (typically vessels have about 100 FADs each) fishing in PNA waters over the course of six months. Image Credit: PNA Tuna

Historically about 30,000 FADs were released into PNA waters annually (about 120,000 FADs are deployed globally each year); recent data indicates that FADs released every year has more than doubled in recent years. Currently about 50 percent of the world’s skipjack tuna comes from PNA waters.

However, Brownjohn says there’s an argument that FADs can actually improve the health of fisheries, rather than damage them.

‰ÛÏIt is possible that mass deployment of FADs could be a solution, not a problem,‰Û he said. ‰ÛÏIf only large aggregations were targeted, the controversial non-target by-catches could be reduced relatively.‰Û

‰ÛÏAdditionally, we are increasingly working on electronic catch reporting. It gives us the means to link the FAD to the catch in real time, by species and by tonnage. This is giving us a much better indication of the impact of FADs and we’re learning more about the fishery.‰Û

Now that PNA has the data on all FADs in compliance in its waters, the organization is able to track marine debris, such as when FADs become wrapped around a reef or wash up on a beach. This allows the organization to identify the owner of the device so it can be removed. Prior to FAD tracking it was nearly impossible to identify who owned which FAD, and knowledge of FAD operations was minimal.

However, there are issues with FADs no matter how they’re tracked. First, there’s always the issue of by-catch when using FADs and purse seine nets. In PNA waters, the primary species for which scientists have urged a drastic reduction in by-catch is bigeye tuna. For this reason, in PNA waters there is an annual three-month FAD usage closure. However, Brownjohn said his organization has noticed that fishing vessels appear to release FADs outside the PNA boundary up to a month before the closure ends so that when the closure lifts the FAD has drifted into place and is already productive. This has served to undermine the conservation impact of the FAD closures.

Another problem that’s become apparent is that some fishing companies are not accurately reporting all of their FADs. The organization estimates that about two-thirds of all FAD buoys are currently not reporting to PNA, on direction of the fishing companies in breach of the terms of fishing in 2016. PNA is working on a solution to this issue, Brownjohn said. Failure to accurately report FAD usage can result in a fishing vessel being ejected from PNA waters in future.

Brownjohn noted that this FAD data has always been available to individual boats, but no one has used it all on an aggregated basis. PNA is in the early days of using the buoys’ data, including fishery and oceanographic data, but Brownjohn thinks such an application for the buoys will only grow.

‰ÛÏI’ve got 11,000 FADs on the screen at the moment. If you have thousands of buoys in the water, you have a massive amount of fishery management data, but additionally oceanographic data including seas surface temperature twice a day,‰Û he said. ‰ÛÏThis information should be invaluable for oceanographic applications.

Kelley Christensen is Earthzine’s science editor

See also, from The Pew Charitable Trusts, “Widely Used Fishing Aid Is Polluting Ocean and Needs Better Management“