Some years back, if you'll allow me just the one pun, FADs were all the rage in sport and gamefishing circles around Australia. Gamefish anglers in Australia and New Zealand were demanding them and in some cases fisheries departments were delivering the goods. In the absence of government backing in some areas, gamefishing clubs and even private individuals began building and deploying their own FADs.

What was the object of all of this activity? To catch more fish, of course, and in the case of most of this effort, more billfish and tuna. This early experience in the use of FADs in the Australian gamefishing scene proved that they certainly worked, and over a wide range of areas and conditions. Off southern Queensland, central New South Wales and Perth, FADs of various designs were deployed and reports of great fishing poured in.

Since those halcyon days, government interest has waxed and waned - mainly waned. Nevertheless, a number of clubs have continued their efforts, often with great success, and recently at least one state fisheries department is again about to embark on a comprehensive FAD program. So it's timely to look at the development of FADs Down Under and around the world, and to think about what the future may hold. At the same time, it is worth considering the other side of the FAD coin - the commercial use of expendable FADs in the global commercial tuna fishery.

WHAT'S A FAD?
The term FAD is an acronym for Fish Aggregating Device, or Fish Attracting Device, as some prefer. Many objects seem to attract and aggregate fish, including such 'devices' as jetties, pontoons, shipwrecks and so on. However, the term FAD has come to mean a floating object of some kind that has been physically placed in the water with the intention of attracting fish.

Even though a naturally floating log is a great fish attractor, it's not a FAD because it wasn't put there by humans. Neither are buoys which mark fish traps or shipping channels, because their primary purpose is not to attract fish (even though they often do so very successfully). On the other hand, bunches of palm fronds anchored offshore by large rocks, as used by many Pacific Islanders, are definitely FADs and are used to great effect in subsistence fisheries.

In the minds of most anglers, FADs are anchored, but that doesn't have to be the case. Major parts of the world's tuna industry are based on drifting FADs. To make the job of finding surface fish much easier, fleets of sophisticated purse seining vessels scatter huge numbers of simple free-floating FADs equipped with radio transmitters, tracking their movements and planning their entire fishing campaigns around their locations.

A BRIEF HISTORY
The first observations that floating objects attract a variety of fishes were no doubt very early. Maybe prehistoric fishermen noticed that drifting logs and seaweed were usually good places to fish near, or that rafts and canoes themselves attracted fish. Whatever the chain of events, it is a fact that FADs have been around for at least 2000 years. As long ago as 200AD, the Roman author Oppian, writing about fishing in the Mediterranean, recorded: "The fishermen gather reeds and tie them together in bundles which they let down into the waves and underneath they tie a heavy stone by way of ballast. All this they let sway gently in the water, and straight away the shade loving tribes of the Hippurus [mahi mahi] gather in shoals and linger about delightedly rubbing their backs against the reeds. Then the fishers row to them to find a ready prey, and bait their hooks and cast them, and the fish seize them, hastening therewith their own destruction."

Today, simple FADs similar to those described by Oppian are still very much in use around various islands of the Indian and the Pacific oceans and the Caribbean, and variations on this simple theme are the basis of modern FADs.

In the Philippines, simple, cheap FADs are called payaos (see illustration) and such are the numbers used that the catches of mainly yellowfin tuna around them constitute a substantial fishery by world standards. These simple bamboo rafts with their dangling palm leaves and cheap anchoring devices have been adapted by other island countries throughout the region, to the extent that simple FADs are now an integral part of fishing in numerous developing countries.

Contrary to what many anglers might imagine, the main driving force behind the development of modern FADs has not been motivated by recreational fisheries, but rather for artisanal or commercial fishing purposes. Knowing that cheap, expendable FADs can enhance the fisheries of developing countries, programs were instituted by international agencies such as the South Pacific Commission (SPC - now called the Secretariat of the Pacific Community) based in Noumea. The aim was to design and construct large, serious FADs that would be more permanent and be available to more fishers.

In Hawaii, the development and maintenance of a FAD program is seen as an important role of the State Government, primarily to provide access to fish for subsistence and for small-scale commercial fishers. Beginning in 1980, the Hawaiian Department of Land and Natural Resources placed 26 FADs of various designs around the main Hawaiian islands in depths ranging to 2500 metres.

The program continued and was transferred to the Hawaii Institute of Marine Biology, University of Hawaii, in 1996 and at last count it was monitoring 55 surface and four subsurface FADs. The latter are fully submerged, with the buoy tens of metres below the surface to lessen drag from surface currents and to avoid collisions with ships.

As a matter of interest, the life expectancy of the Hawaiian FADs has continued to increase with better and better designs devised through trial and error. Surface FADs in Hawaii now have an average life expectancy of three to four years, while subsurface models can now be expected to last for five to six years, which is a very impressive record.

While commercially-orientated FAD programs around the world have developed steadily, often with government support and funding, FAD programs aimed at recreational use have developed in a rather patchy fashion, with some fisheries departments in the US and Australia embracing the idea and providing FADs for angler use. Official support has been mostly transient, though, and these days it is mostly fishing clubs that do the hard yards and raise the funds to construct and deploy FADs.

One exception to this story has been NSW Fisheries. Having undertaken a detailed study of FADs in the 1980s, the Department is about to embark on a new program. Funded by the Saltwater Licence Trust Fund, and beginning later this year, the program will run for two years and deploy at least 10 FADs off the NSW coast. Angling success will be closely monitored by the use of logbooks, and scientific monitoring and sampling will also take place with hopefully a long-term program to become a reality in years to come.

TYPES OF FADS
FADs come in all shapes and sizes, from the most simple bamboo and palm versions to complicated 'industrial strength' structures which, in places like Hawaii and Okinawa, may be anchored in water as deep as 4000 metres.

The design of FADs has evolved through time, but all have three elements in common - a float, a tethering rope and an anchoring device. Other elements added to increase the life of the FAD to make them easier to find, or to attract more fish, include lengths of chain, both near the float and near the anchor, subsurface streamers, netting or mesh attached to the chain to increase its visual aspect, and radar reflectors and lights on the buoy.

One feature of FADs that has evolved over time is the flotation device or buoy, or more specifically, its shape. Early commercial designs consisted of large, often elaborate rafts made from several 44-gallon drums lashed together. It was soon found that these bulky objects created enormous resistance to water currents, resulting in high loss rates. Continuous experimentation proved that cylindrical or spherical objects provided far less resistance to currents, and hence were not nearly so prone to loss.

As mentioned, NSW Fisheries operated a serious FAD program in the early 1980s and went through this type of sequence of designs. Several elaborate models involving large rafts topped by solar panels, lights and radar reflectors were trialed. The final design, which proved to be successful in the strong currents on the continental shelf off Sydney, was the essence of simplicity. Consisting of a 30cm by 4m long PVC pipe, the buoy was foam-filled with some cement poured in at the other end so that it floated with half its length above and half below the waterline.

It is not difficult to construct a FAD, but deploying it can sometimes be fraught with problems.

Perhaps my favourite FAD story involved some keen club anglers who decided to place a simple FAD off Coffs Harbour for their own use. The buoy was a simple 'off-the-shelf' model, while the anchoring device was the essence of simplicity - an old car-engine block.

Having carefully assembled the FAD, our friends loaded it onto their boat and duly arrived at the predetermined spot. They placed the float in the water first, made sure the rope would deploy without looping around feet, arms or objects, and with great effort hoisted the engine block onto the gunwale and pushed it over with an almighty splash. The rope whipped around madly like a snake, but their precautions were well made and everything went according to plan. That is, until the rope came taut, and in an instant the buoy was pulled violently under the surface before disappearing quickly, vertically, and forever from view!

The lesson here was that depth sounders are not always as accurate as one might wish and it always pays to have a little more rope than might seem necessary!

WHICH FISH LIKE FADS?
For reasons not fully understood, FADs are particularly attractive to pelagic fishes. Around the world, by far the most common 'FAD fishes' are mahi mahi (dorado), which more than any other species appear to like nothing better than hanging around flotsam and jetsam in the ocean. This habit, by the way, has saved the lives of many a castaway drifting at sea in liferafts. Mahi mahi nearly always appear under the raft, and if they can be caught, provide food and moisture in otherwise desperate situations.

The list of other FAD-associated species reads a little like the who's who of popular gamefish. In tropical and subtropical waters, they include skipjack, yellowfin and bigeye tuna, wahoo, cobia and mackerels (if close to shore), most of the trevally family, and of course, sailfish and marlin.

Most of the pelagic sharks also join the party, including blues, oceanic whitetips and makos.

Possible exceptions to FAD loving fishes appear to be spearfish and broadbill swordfish, but I'll stand corrected by any first-hand experience out there.

In more temperate waters, yellowtail kingfish become the primary FAD fish, along with albacore (usually in deeper water around the anchor rope or chain) and, at times, southern bluefin tuna.

An entourage of other less familiar species of fish are also attracted to floating flotsam and jetsam, and therefore, to FADs. A current study by PhD student Tim Dempster, who has made countless dives on wave-recorder buoys off Sydney, recorded a total of 14 'FAD-associated' species of fish. These include the usual suspects - mahi mahi and yellowtail kings - but also two species of oceanic triggerfish (leatherjackets), silver drummer, pilot fish (the striped fish which hang around sharks), two species of drift fish, sergeant major, yellowtail (yakkas), juvenile silver trevally, amberjack and rainbow runner.

In fact, the juvenile members of quite a few members of the trevally family find FADs attractive. This may relate to a mechanism for dispersal used by such species, in that juveniles might seek to accompany floating driftwood or weed moving with prevailing currents.

The species found around FADs off Sydney would naturally be different from those associated with buoys in the tropics,but nevertheless, the same families do tend to be found near FADs right around the world.

Whole pelagic communities will be attracted to FADs, which happens to result in one of the downsides of purseseiners setting their nets on free floating logs and drifting FADs. Whereas shooting a net around a free-swimming school of tuna nearly always results in a 'clean' catch of the target species, setting these huge, all-encompassing nets on logs or FADs almost certainly takes a large bycatch of unwanted fishes, including species such as billfish, triggerfish, rainbow runner and sharks.

The bycatch of marlin by purse seiners can add up to large numbers of discarded fish, while in the case of blue sharks, the quantity of discarded bycatch by purse-seiners throughout the world is nothing short of staggering.

HOW DO THEY WORK?
Having established that FADs have been around since the year dot, it may come as a surprise to find out that we still don't really know how they actually work in attracting and holding fish.

Of course, that doesn't mean that there aren't plenty of theories. For example, one of the more common reasons given for why fish are attracted to floating objects, including FADs, is to seek shade. To me this seems most unlikely, since pelagic fishes spend the vast proportion of their time in the open and the amount of shade offered by a log or
a buoy would be minimal. Another widely held theory is that FADs attract predatory fishes, such as tuna and billfish, because that is where baitfish congregate. Ironically, one reason given for baitfish staying near FADs is in order to avoid predators!

Some experiments and observations suggest that the second theory may be stronger than the first. When small, movable FADs were deployed off South Carolina in the USA, they duly attracted schools of baitfish similar to Australian yellowtail, along with predators such as little tuna and wahoo. These assemblages of fish were observed to have little if any interaction with each other until, that is, the FAD was removed. When this happened, a feeding frenzy instantly occurred, with the predators having a field day on the panicked baitfish. Other studies on gut contents of predatory fishes around FADs have found that the stomachs are usually empty, or if they contained any items, they were not the baitfish species associated with the FADs where the predators were caught.

So what is really going on here? It appears that baitfishes do use floating objects to avoid predation, possibly provoking an avoidance or 'flinch' response which pelagic predators probably have to avoid collision with physical objects which are usually not part of their open ocean environment.

But why would predatory fishes find FADs so attractive, especially considering that a single small FAD may attract thousands of tuna at a time?

The answer appears to be for orientation to a relatively fixed object in time and space. The open ocean is largely a featureless void, and even though pelagic fishes obviously feel at home in such an alien world, many species will fixate on solid objects, apparently using it as a point of reference from which to conduct regular feeding or foraging forays.

FISH BEHAVIOUR
Ultrasonic tracking of tuna tagged near FADs has helped to reveal some fascinating insights into their behaviour in relation to FADs and why they are attracted to such objects in the first place.

Dr Kim Holland of the University of Hawaii attached acoustic transmitters to juvenile yellowfin and bigeye tuna caught near FADs and tracked them for up to 48 hours. He found that sub-adult yellowfin tuna tend to spend daylight hours around the FADs, but left them at night, venturing as far as 8km away only to return at dawn.

This information can assist FAD designers to determine how far apart FADs should be. Acoustic transmitters attached to the fish also relay information about their depth. Kim has also shown that small bigeye tuna spend more time closer to the surface around FADs than when they are in free schools away from the FADs.

More recent work has shown some further fascinating results. Also working in Hawaii, Californian biologist Dr Peter Klimley has gone one step further by putting electronic receivers inside FADs and monitoring the visits of yellowfin tuna which had been previously implanted with 'passive identification transponder' (PIT) tags.

The 'listening posts' inside the FADs recorded when individual fish were near. Retrieved records showed that tuna would return often to the same FAD, but rarely to other nearby FADs; they normally stayed near a FAD for less than one hour, but sometimes more than 10 hours; and that they would arrive at the FAD and leave it at the same time each day (or often, once in the day and once at night). Some fish even returned to the same FAD after absences of nearly six months, but the long-term returnees were not as faithful to their original FADs.

Often, two tuna tagged at the same time would stay together for weeks, as evidenced by their leaving and returning to the same FAD or FADs at the same time. This strongly suggests not only that tuna remain in the same school for extended periods, but that they use the FADs as landmarks or points of reference over extended periods.

PROS AND CONS
Whenever anglers think of FADs they think of fish, especially the potential for making it easier to locate and catch them. However, not everyone necessarily thinks that FADs are such a good idea.

One oft-heard anti-FAD argument is that they make it far too easy to find and catch fish, especially for novice fishermen. They argue that if there is only a limited amount of fish in a given area at a given time, they will tend to artificially concentrate near FADs. Thus, the fish are prone to being fished out rapidly by anyone with a boat and knowledge of a FAD's position.

For this reason, and others, FADs are sometimes vandalised or destroyed, a factor which must be considered when planning a deployment program.

In Hawaii, the issue of whether or not FADs are beneficial is an ongoing debate. Apart from the usual 'fish depletion' argument, another point made by some charter captains is that FADs attract large schools of skipjack tuna well away from their usual wider grounds where the big blue marlin hunt and feed. It's suggested that this may affect the behaviour and movements of the marlin, thereby reducing the likelihood of success on the average charter.

Then there is the issue of who owns a FAD, or more to the point, who owns the fish which are attracted to it. Fishing clubs, private individuals, charter operators or commercial fishing companies might all construct and deploy their own FADs, but do they have the right to stop others from fishing near them? Probably not, but rest assured that such arguments do take place.

When a government department deploys FADs, can it ban fishing by one group in the vicinity of the FAD, but not another group for which it was primarily constructed and which may have provided the funds for its construction? In the latter case, it may well be within the legal powers of government to legislate the use of FADs, but I would imagine there would be some interesting challenges along the way.

In reality, and looking at the history of FAD deployment and use in Australia and other countries, the use of FADs is generally sorted out by the user groups. Since pelagic fishes come and go on a regular basis, the question of ownership of the fish themselves rarely arises.

Finally, the use of drifting FADs in commercial tuna fisheries needs to be mentioned on the 'con' side of any discussion about FADs.

As mentioned, large numbers of highly sophisticated tuna purseseine vessels from developed countries around the world are now regularly deploying thousands of expendable radio-equipped drifting FADs as a routine part of their fishing campaigns in all three major oceans. No doubt the use of this incredible array of FADs, which can be pinpointed via satellites, has dramatically increased the efficiency of these vessels, which now account for the bulk of the world's tuna catch.

Scientists believe that, at present, the use of this method to catch skipjack tuna is not so much of a problem, since stocks are considered to be under-exploited. However, there are some concerns about the sustainability of current fishing pressure on yellowfin tuna, and even bigger concerns about bigeye tuna. Both species are also prone to increased exploitation rates by the use of FADs. And to make matters worse, the bycatch of other species of fish associated with these FADs is a secondary issue which rarely attracts much attention.

At present, there are no international regulations dictating what methods may be used in the tuna fisheries of the world. Fortunately, international management of tuna fisheries is finally on the horizon, so let's hope this situation is monitored and taken into consideration in the not too distant future.

If not, the next passing FAD might be the last.