Bluefin Tunas for the science
Inside the story about the Giant Blue
Fin Tunas expedition in the Tasman Sea
all, it has to be said that in the southern hemisphere there is not a
single Bluefin tuna species. There are the Southern Bluefin tuna,
Thunnus maccoyii (Castelnau, 1872) and the Pacific Bluefin tuna,
Thunnus orientalis (Temminck & Schlegel, 1844). They’re strictly
related with each other and with the Northern, or Atlantic Bluefin tuna,
Thunnus thynnus, and they’re really difficult to identify one from
another only on external characters.
Obviously, this takes nothing out of the magnificence and the difficulty
of spearfishing fishes like those captured in our expedition, but… Which
one has been caught?
have the same oceanic, pelagic existence, the first one widely distributed
in all oceans south of latitude 30°S, the second one primarily in the
northern hemisphere. Both can be found in New Zealand waters, even if a
recent scientific paper affirms that only a very narrow percentage (0,3%)
of the Bluefin there can be correctly identified, by DNA methods, as T.
orientalis, being T. maccoyii the Bluefin species more widely
Southern Bluefin tuna (T. maccoyii), was identified by body size
and colour of the caudal keel, the median caudal keel being yellow in
adults. Later researches found however that in large specimens this
identification method was not reliable.
exploitation by commercial fishing started in the 1950, and till somewhat
recent years was at the base of the tuna bought for sashimi in the
Japanese market. Due to high pressure by professional fishermen and to the
fact that reaches sexual maturity only around four or five years, the
stock is now in a depleted status.
not as a surprise therefore that for field identification Japanese fishing
skippers have firstly identified Pacific Bluefin tuna by the presence of a
muscular protrusion in the dorsal abdominal cavity, present only in T.
maccoyii but not in T. orientalis. Unfortunately, this can be
observed only when the gills are removed, not a good practice when the
principal aim is to preserve as much as possible the body integrity and
weight for possible records.
to have a more elongated body and can reach a bigger size. Just some days
before our expedition, an American marine biologist in a trip measured and
estimated the weight of a fish taken by reel at 420kg! T. maccoyii,
while smaller, seems to have a stockier body.
all thing considered, and thanks to the correct practice of taking good
measurements of the fish and precise weight, we’re able to probably asses
all the capture to T. orientalis. Plotting the FL (Fork-Length)
numbers for Craig Clasen’s (244 kg - 537,93 lbs) and Eric Walker’s (228 kg
- 502,65 lbs) fish for the known body relationship in T. maccoyii
against T. orientalis the result is pretty evident. The difference
from the predicted weight in T. maccoyii is respectively 146 kg -
321,87 lbs and 125 kg - 275,58 lbs. The difference instead for T.
orientalis is only 25 kg - 55,12 lbs and 16 kg - 35,27 lbs
respectively. Moreover, some of those missing kilos/lbs can be explained
as body fluid lost between the time of capture and that of weighting.
Text and pictures by Riccardo Andreoli
Vanuatu, Port Vila, near the
Mamas Market. A friend of mine is eagerly telling me: - “I was really
thinking of you when I was there. When the water is cold like now, there
they take giant wahoos. Monster wahoos! Sometimes up to seventy kilos!”.
For some unknown reason my
salivation glands are drying up and my hands start shaking. On the spot I
decide: - “OK, when do I leave?”.
One day and a half later I’m
wobbling in midair inside a minuscule plane, only six seats, the drone of
the two engines covering everything else in it.
Below it, slow developing of
dream south pacific landscapes. Rugged coastlines with corals just under
the surface, minute drop-offs in crystal clear water, the sand cobalt blue
just beneath them. Green islands with apparently no trace whatsoever of
human life, near the ocean slender coconut trees dancing in the wind and
powerful, old giant trees inland. At the stops, in grass-and-dirt landing
lanes, hugely grinning people ceremoniously shakes my hand, swarms all
over the plane, opens the tiny baggage hold, takes everything out and
repacks with new bags. Then we’re bumping again on the dirt ready to take
off for the next island and its miniature cluster of human life.
My destination finally, the
aerodrome a concrete hut with a rusty corrugated metal roof and no trace
of glass on its three windows. My contact, Joshua, is waiting for me but
it’s immediately clear that he has no idea at all of what I want to do
apart a generic “fishing”.
No trace of shoes around,
calloused feet on the soft brown soil, the tree wall of the jungle ten
meters away. Everyone has in his hand an unsheathed huge “jungle knife”,
“machete” in other places in the world. My mammoth baggage is placed
inside an old truck and we drive to the village, dodging trees branches
whipping past just over us.
Incanted place, a vast, well
mowed central meadow, a ring of wooden huts with coconut leaves roofs.
Children all around running in it. Simple village games, a tin can used as
a sled, a toddler inside with a stellar smile, tugging it a three years
old girl constantly chattering at him.
My house is a long hut just on
the border of the meadow, the bedroom with a real bed, the walls festooned
with a flamboyantly blue killing whales cloth.
We speak at length, Joshua and I,
in the fast approaching night. He’s curious about my Tuna gun, about my
tales of Blue Waters fish, about Italy. He says that I’m not the first
Italian arriving there but “only” the second one. I’m curious about his
village life, about what he catches when fishing, and how big and where.
He confirms what till then was only a supposed truth: wahoos are really
big here, sometimes village fishermen actually take fish bigger than
seventy kilos. And, above all, the correct time is NOW! Almost
unbelievable. It seems I always arrive at a place only to discover that
the right “season” is not at this time but it has been or it will be, of
course in some short months.
A petrol lamp with its gold,
wavering light is ceremoniously presented for the night. I sleep like a
baby. Tomorrow we’ll go fishing!
The scheduled time is six thirty
but it’s impossible to sleep so late. Children, disappeared in their homes
at dusk are playing and running at first light, here around five and
We’ve a long walk in the jungle
before reaching the boat so we’re five, all carrying something of my bulky
gear. Sound of bare feet squishing the damp soil, green light filtering
down from the leaves canvas thick above us, the Tuna Gun heavy on my
shoulder. Sometimes a jungle knife swinging and cutting with a thud a more
obtrusive branch. Twenty minutes of walk, dodging here and there massive
tree roots snaking underfoot, we arrive at the boat. It’s inside a
mangrove thicket, brown water around its thick contorted roots.
Around what’s evidently a
shipwright site. Two canoes at different completion stages, long white
wood ribbons and chips all over the place. The boat we use is the
characteristic pacific longboat, seven meters long with an outboard
engine. Soon, giving ample berth to surfacing coral reefs, we’re in the
ocean. We’re on the leeward side of the island, the wind is here
only a buffeting presence, the surface almost flat. That’s, till we remain
near the coastline. When we turn our prow out we start dancing, the water
flying aboard in sheets and sprays. They have no instrument at all
onboard, they have to try, patiently, here and there before finding the
fish. So we go around on the ocean, I well cocooned in my wetsuit,
waiting, they trolling simple bright plastic lures. After a while anyway
it’s evident that wahoos are probably patrolling the other side of the
island, where the wind is whistling, the waves strong blue walls.
We round the cape, the prow more
and more out of the water, crashing down with a resounding bang on the
flat keel. Still no fish. It’s only where the waves start dancing around,
their froth ends without order, confused, colliding against each other,
almost surely a deep underwater mount, that one of the lines becomes
taught. The fisherman shout: - “Wahoo!” and starts fighting the fish.
It’s a big one, it’s necessary a second pair of strong arms only for
keeping a springing tension on the line. As planned, I jump into the
water, the gun ready, the flasher in my hand. A moment only for clearing
the bubbles from the mask and the boat is already drifting away, fast. But
under my feet there’s the school! Wary metal-grey shapes, suspicious eyes
looking up scrutinizing that unknown thing just crashed inside their
realm, then swinging to those strange vibrating plates ten meters deep,
then up to me again. One fin in the air, I dive. Softly, slowly. I do not
look at them, at all. I start swimming in the direction all their heads
point to. Oh, I know well their ways. In western Africa I fought them,
distrustful, powerful warriors, for long months days in days out.
Only, when I judge I’m almost as
deep as they were, I look over my shoulder. And there it is. A good one,
judging from the relative size inside the school. Not, certainly not, one
of the biggest. Under me nothing but the blue-grey of the shifting sun
rays, now and then dulled when a fast tropical cloud scuttles around.
I move my body away from it, the
gun starting however to point in its direction. At the last possible
moment I look directly at it, I take aim, I correct for the parallax of
the short point, I confidently pull the trigger. A good shot, I can only
suppose and hope, because in a fraction of a second the Wahoo is not there
anymore. I’ve no idea if the spear really landed where I directed it, on
the left side just behind the pectoral fin. I do not know how big it
really is but it’s certainly putting up a convincing show of bulkiness.
The line has raced away so fast I
was not able to take hold of it. On the surface the 35 litres float is
already whipping away as fast I’ve ever seen it, almost totally submerged
inside a thick foam wave.
The boat is not anywhere near, I
start swimming, the big gun in front of me to break the worst of the
waves. Every twenty seconds, on the top of a big one, I kick out so to
see around. The float is crazy, never seen something like this. It’s
almost out of sight, it has abruptly changed direction three times in a
minute, it’s still bobbing frantically up and down. I chase it, swimming
powerfully, searching to find the best streamlined position. Long minutes
alone in the ocean till the engine noise signals the boat is here again.
By the time they’re near me I’m almost at the float. It’s stopped now. The
little eight litre float is still fully submerged but the big one is flat
on the surface. Without even thinking about it I grab the line and pull.
The weight at the other end is comforting, the wahoo still there. It’s not
struggling anymore, it’s a dead weight. The moment I see the outline of
the fish, still almost invisible on the dark background, I take a deep
breath and, still slowly pulling, I dive. I compensate swallowing, as I
can, my hands are busy just now. I arrive at the fish, wait some moments,
when, breathing, it opens its gillplates, I effortlessly slid my hand
inside. And it’s THEN, when I thicken my hold around its throat, I realize
how big it’s. Its head is easily twice mine!
I slowly swim to the surface
towing the bulky shape of the fish with me. When I arrive the boat is
here, eager hands grab the fish, I jump aboard. The wahoo is flat on the
bottom, giant, the fishermen shouting for the marvel to see that bizarre
chap rained down from the blue really taking a fish out here, so far away
from the reef bottom, and so good a fish!
I try, but it’s too heavy to lift
it in the prancing boat. The pictures are an uncertain compromise between
balance and the desire to show this magnificent wahoo.
Back to land, after several
regrettably not-so-close encounters with whales, the fishermen here
avoiding them because, and they’re dead certain about it, they scare out
the wahoos. “But, why” - I ask – “certainly they do not eat wahoos”. “We
do not know why.” – is the answer – “Perhaps the sound?”. It really could
be, isn’t it?
The way is long returning to the
village. Two fishermen cut a strong young tree, easily braid some coconut
leaves to make a couple of improvised ropes, and they transport as a
trophy the fish hanging from the pole. And old sinewy fishermen found on
the beach ceremoniously but very firmly take my gun and march proudly
toward the village.
There’s no way there for
weighting the fish. The only scale in the island is the one at the airport
but weighting would mean for all of us, above all for those carrying the
fish, almost half an hour of walk on wandering jungle tracks to reach it
and twenty and more minutes then back to the village. It’s not so an
important thing to ask them, even willing, to do. Above all, I feel it’s
not a polite thing to ask, only out of curiosity.
At the village, children running
all around, staring up to the dangling fish, men shouting. The joy and the
marvel for the event obvious. Those four in the boat start describing the
catch, really enjoying themselves. Each one has a little crowd around him.
A bit embarrassing, I only took a fish.
Much of the joy I believe is
revealed later. Here, as in almost all Vanuatu, the old ways are still
strong. The sharing of what one have with all the community, the village
in first place, a normal fact of life.
Throughout the evening a regular
procession of men, young sometimes, but more commonly old ones arrive at
the hut where, on a shelf, above the reach of the dogs, the two wahoos are
kept. Most have under one arm a knife of some sort. They arrive,
ceremoniously they bow, shake my hand, say something that is lost for my
ignorance, and then they proceed to cut themselves a fat steak of fish. A
solemn nod, they disappear into the night. A snug sensation of belonging,
of being accepted, warms up inside me. Even now, as far as it can be,
truly half a world away, I’m not able to think at the village without
discovering that glow still kindled inside me.
How big it was, you ask? Well, I
was reduced to a guess, a well educated, better, a mathematical one, but a
guess nevertheless. I took a Fork-Length measurement with my ribbon meter,
always with me exactly for these reasons, and I inserted it in a
well-known mathematical formula, a couple of species specific constants in
it to adapt to any known kind of fish. The length was 188 cm, the
calculated weight 44,92659948 kg.
Anyone feel free to guess the real weight. It could be less. Or it could