Tuna Wranglers

Series: Deadliest Catch – Tuna Wranglers

Tuna Wranglers
Tuna Wranglers

While waiting for Season 2 of Deadliest Catch to arrive, Tony and I watched this. It’s just two 45 minute episodes, and it concerns the tuna fishermen off South Australia. It’s another Discovery Channel offering.

Complete aquaculture of tuna (rearing them from larval stages to adult) has proved difficult for several reasons. Tuna are extremely active – they have incredibly fast metabolisms, eat prodigiously, and swim long distances (their bodies are maginficently put together for swimming). Simulating their natural environment in a pen is almost impossible (much like rock lobster). They require high-energy food, and lots of it, making farming them an expensive proposition. They are also notoriously reluctant to spawn in captivity, which defeats the purpose of farming them! The fish are delicate and manhandling them to extract eggs manually or check their state of sexual maturity decreases their value on the open market. Finally, there are concerns that fish that escape from captivity may act differently to wild fish, and carry parasites and viruses that could decimate wild populations should they become exposed to them.

Southern bluefin tuna are thus caught on the continental shelf south of Australia when they weight 15-20 kilograms (at an age of about 2 years). They are transferred from the giant purse seine nets into holding pens while out at sea, and the pens are then towed back to Port Lincoln in South Australia – very slowly. There the tuna are transferred to farm pens (ranches!), and fattened up for a couple of years until they weigh 30-40 kilograms. The fish are then caught – by hand, by divers, to avoid damaging them – in the pens, flash frozen, and shipped to Japan. This is big money – a large, perfect tuna (unbruised and unmarked) fetches thousands and thousands of dollars in Japan.

The fishing process is fascinating – the ships can be out for weeks at a time. One ship looks for the tuna and baits them (throws sardines overboard to move the school in the direction desired), another deploys the purse seine nets around the school of tuna, and a third boat transfers the tuna from the nets to holding pens, and tows the pens full of live tuna back to port. A spotter plane also looks for tuna sunbathing near the surface – they need the sun to warm them in order to allow them to digest their food as fast as possible. We loved the CGI animations showing the fishing process.

The pens are essentially giant nets, closed at the bottom, with floats around the rim. Divers have to check the nets for breakages, monitor the conditions of the fish, and (occasionally) deal with sharks who bite their way in, understandably attracted to a giant floating lunchbox of tuna goodness. They either shoot them (last resort) or wrestle them out of the pen by hand. Bronze whalers are the most common invaders. The underwater footage of the pens and of the divers working in them is magnificent – crystal clear water, thousands of incredible, sleek fish, and a sense of space yet security. The divers are tethered to the surface so that they can maintain radio contact with the boat (they wear full face masks) and for air supply, or free dive. There are many ways to get tangled on things, so if they’re on scuba they wear their cylinders (for emergencies) upside down with the pillar valve pointing downwards to minimise that risk. As some of the divers said, they can’t believe they get paid to dive, because they enjoy it so much.

This is a fascinating look at the tuna fishing process, and eye-opening as far as the amounts of money that are spent to find, catch and rear these incredible fish. In comparison to the crab fishermen of Alaska, the fishing process is child’s play in terms of safety and working conditions. The deck hands on the bait boat don’t seem to do anything more physically strenuous than toss handfuls of sardines overboard once the tuna have been located. Boredom seems to be the biggest challenge.

Tuna can only be spotted when the sea is flat, and while the ocean south of Australia is cold and temperamental, in general the Bering Sea where the crab fishermen make a living makes it look like my bathtub – before I climb in! The most dangerous part of the whole trip is entering Lincoln Bay with the incoming tide, site of Dangerous Reef where Peter Gimbel and company found great white sharks during the filming of Blue Water, White Death.

The question of the scarcity of bluefin tuna, and the impact that the current fishing practices are having on these incredible fish is not dealt with in this series at all. I imagine it’d put a SERIOUS damper on all that Australian enthusiasm…

You can get the DVD here.

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Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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