JONATHAN LOVELL鈥橲 ambition is to be a rancher. But he has no interest in
cows, horses or prairies, and no cowboy boots or ten-gallon hat. In fact, a
ten-gallon tank and waders are more likely. Because Lovell鈥檚 dream is to be a
fish rancher鈥攐r at least to show that fish ranching has a commercial
future. Unfortunately, like the handful of other biologists who share his
enthusiasm for free-range pisciculture, Lovell finds himself struggling to be
taken seriously. Be honest. What was your reaction to the term 鈥渇ish ranching鈥�?
I laughed. So do many others.
The reaction might be fair, except that conventional fishing or fish farming
aren鈥檛 exactly brilliant ideas either. Despite their radar systems and fancy
nets, today鈥檚 fishermen are no more than sophisticated hunter-gatherers. And
when hunter-gathering goes industrial, you鈥檙e in a world of trouble.
Fish farming offers a more controlled way of operating. Just tip a few feed
concentrates into the pens, then haul in as many salmon or whatever as the
market requires. Just like offshore factory farming. In fact, so like it that it
comes with precisely the same drawbacks: disease, pollution and public dislike
of a product which lacks the taste and texture of its wild counterpart.
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The clever part of ranching is that it combines the virtues of the two
conventional enterprises while avoiding their drawbacks. And before you start
worrying about how an aquatic cowboy rounds 鈥檈m up to bring 鈥檈m in, Lovell has a
cunning alternative. Although roaming free for most of their lives, his fish
would be trained to come 鈥渉ome鈥� in response to a particular sound. When their
time was up they wouldn鈥檛 have to be pursued with boats and nets. Fire off a
burst of the appropriate noise and they鈥檇 come swimming to you. Surrender
themselves, as it were.
Lovell was a fisherman himself, with his own boat in Cornwall, before he gave
up in search of something better. He became interested in a system called
acoustic ranching in aquaculture, or ARIA. The ARIA principle can be
demonstrated in a modest fish tank. Several such tanks occupy space in Lovell鈥檚
laboratory at the University of Plymouth鈥檚 Institute of Marine Studies. At one
end of each one is a separate compartment fitted with an underwater speaker
that鈥檚 linked to a computer. At the click of a mouse, the behaviour of the 15 or
so fish drifting lazily back and forth at the other end of the tank suddenly
changes. They form a shoal swimming purposefully towards the compartment,
straight to the source of the sound, which happens to have roughly the
characteristics of the cod mating call.
The reason for their enthusiasm is soon apparent, and it鈥檚 nothing to do with
the amorous nature of the sound. Once the fish have entered the compartment,
another click opens a trapdoor to release food. When there鈥檚 nothing left to
eat, the fish resume their aquatic meandering. What Lovell has demonstrated is a
classic conditioning experiment, in the style of Pavlov鈥檚 dogs, where the source
of a specific sound becomes associated with the presence of food. His first
experiments were on mullet; he鈥檚 since shown it can work for bass, carp and
goldfish. 鈥淲ith two feedings a day you can train a fish to respond to a sound in
just two weeks,鈥� he says. 鈥淎nd they can remember that sound for at least four
months, maybe longer.鈥�
The question is, can this acoustic conditioning be scaled up to become a
realistic alternative to other fishing methods? Lovell is not the first
biologist to have heeded the ARIA call鈥攐r to have found that progress is
slow. The European veteran is Jens Balchen, Emeritus Professor of Engineering
Cybernetics at the Norwegian University of Science and Technology in Trondheim.
He鈥檚 been working on acoustic conditioning for 30 years, he says, adding
ruefully that 鈥済etting the principles adopted is taking a long time鈥�.
Outside the tanks, progress has been encouraging. In 1980 a Japanese group
trained bream to come to a feeding station when summoned. Experimenting in an
inland sea, they managed to recapture a substantial number of their fish after
five months of freedom. Working almost 20 years later with cod in an Icelandic
fjord, another group used a sound conditioning system over some 17 months. The
fish retained their conditioned behaviour for at least eight months after the
last feeding. Several of these schemes have prompted optimistic conclusions
about ARIA鈥檚 potential鈥攂ut none has spawned a commercial project.
Norway is still leading the way in field trials. Jens Balchen was one of the
first researchers to experiment on conditioning as a way of controlling fish
behaviour鈥攁nd among the followers of this pioneering work is one of his
former PhD students, Jo Arve Alfredsen, also from Trondheim. He鈥檚 built a couple
of conditioning machines and tested them in various locations along the
Norwegian coast. One of them is housed in a PVC cylinder a metre long and 25
centimetres in diameter. Mounted upright about a metre and half above the
seabed, it contains a feed hopper and delivery system, a device to generate the
conditioning signal, and various timers. Alfredsen watches the behaviour of the
fish using an underwater TV camera.
His experiments have shown that several wild species, including saithe, cod
and whiting, can be conditioned to come to a feeding station. But he admits that
the results do depend partly on local circumstances. 鈥淚f the fish can get a lot
of food elsewhere, they take less notice of my machine and its signals. But if
there are few other sources, they learn the combination of food and sound very
辩耻颈肠办濒测.鈥�
Balchen remains optimistic, however. 鈥淚 have no doubt that the use of
acoustic conditioning is commercially feasible,鈥� he declares. By way of evidence
he points to one way they made use of the method to recapture stored fish. 鈥淭he
main saithe fishery is in October. So much is caught that it鈥檚 beyond the
capacity of the freezing industry. So it can be stored live by closing off a bay
with an electric fence, and then recapturing the fish using acoustic
肠辞苍诲颈迟颈辞苍颈苍驳.鈥�
Lovell would like to begin the ranching process one stage earlier. His idea
is to condition tens of thousands of fry while they鈥檙e in a hatchery. Only then
would he release them into the wild. 鈥淚n our pilot project we鈥檇 get young bass
from a hatchery, take them to an enclosed bay, and put them into a fenced-off
area about ten metres by ten,鈥� he says. 鈥淚nside this area we鈥檇 feed them at dawn
and dusk, and continue to play the conditioning signal.
Once the fish had adapted to their new environment, probably over a minimum
of two weeks, we鈥檇 release them鈥攂ut continue offering food twice daily in
conjunction with the signal.鈥� The fish would get enough food to make it worth
their while swimming to the sound source鈥攂ut much less than they鈥檇 need if
confined within a conventional farm. In an enclosed bay there鈥檇 be no danger of
the fish swimming out of range of the signal. But Lovell suspects that even in
open waters, if the fish knew they had a dependable source of food at a
particular location they might not bother to migrate.
In the US, fish ranching hasn鈥檛 attracted much attention. But a group at the
University of Massachusetts at Dartmouth is interested in how it might be
adapted as part of a plan to reinstate an estuary fish population. 鈥淲e have a
badly polluted estuary here in New Bedford Harbor,鈥� says Ed Baker of the School
for Marine Science and Technology. 鈥淭he fines levied against the polluters are
going to be used to restore the marine habitat and the fish population.鈥� Baker
fears that fish reared in a hatchery won鈥檛 manage too well when introduced to
their new home. His thought is that acoustically conditioned fish, able to count
on a predictable meal, will be better able to survive the period of adaptation
to natural food sources and life in the wild.
Lovell鈥檚 own tests have so far been confined to a laboratory fish tank. He
was aiming to run a larger trial this spring in Plymouth Sound鈥攂ut has
been thwarted by lack of money. Another of his pilot schemes has been endorsed
by the European Union鈥攂ut, so far, without a guarantee of funding.
Undaunted, he too remains convinced of ARIA鈥檚 commercial viability.
So does Alfredsen. 鈥淪ea ranching will come in the future. But there are many
legal aspects which have to sorted out. For example, who has the right to
harvest the fish?鈥� The problem, in other words, of poaching. What鈥檚 to stop
someone coming along with a sound generator and luring your carefully nurtured
fish into their traps? Fish rustling, if you like.
Lovell hoped that as long as he could mark his fish, they鈥檇 remain his
property. William Howarth, professor of environmental law at the University of
Kent, disagrees. 鈥淎s soon as fish are released into the wild, rights of property
over them are relinquished. That鈥檚 a principle which goes back to the 18th
century. And it鈥檚 a peculiarity of English law that there鈥檚 a distinction
between captive farm animals, which you can reclaim if they stray into your
neighbour鈥檚 field, and animals which are by nature wild. Fish, even marked ones,
fall into this second category.鈥�
But Lovell has a fallback position. 鈥淚n the case of bass we鈥檇 be aiming to
harvest them at 24 centimetres, which is actually below the minimum landing size
for wild fish. If someone else took them they鈥檇 be breaking the law.鈥� This
would, of course, depend on Lovell himself having been granted special
permission to pull out undersized fish in a particular locality.
But there鈥檚 still one last obstacle before anyone will put serious money into
pilot projects. 鈥淔ish farmers do not want to do anything which is new. They want
to do exactly what the others do,鈥� says Balchen. 鈥淚f one of them begins
listening to me, the others become very disturbed,鈥� he adds.
鈥淚t鈥檚 like schooling behaviour in the fish themselves.鈥�
If he鈥檚 right, Lovell and the rest of the would-be ranchers might turn this
behaviour to their advantage. Get one fish farmer seriously involved, and all
the rest may come swimming along, fearful of missing their place in the new and
perhaps profitable shoal.