The film Tuna Wranglers (Discovery Channel, 2007) gives you a lot of useful information about the bluefin tuna fishing industry in Australia. But with an American-accented narrator and a goofy cowboy theme, the film does a pretty fair job of alienating an Australian viewer.

It's a documentary, but it's not a great documentary. Drama here is very often manufactured for effect, an unfortunate measure which ultimately devalues the material and makes you regret the hokey, down-home narrative that drives the story forward. Tuna fishermen make good money. They're not in it for the love of it. It's not "in their blood", as the narrative imputes at one stage near the end of the film.

In the film we get to see Marcus Stehr, an owner of the Stehr Group which is one of the major players in Australia's tuna industry. Marcus' German-born father, Hagen Stehr, founded the company in 1969, when tuna was still fairly abundant in the waters off South Australia.

It's in the waters of the Great Australian Bight that the action takes place. All the main elements of fishing are described on video, from the bait boat which attracts and herds the school of tuna, to the spotter plane, to the divers who manage the catch in enormous nets that are towed out to sea and back, and that contain the juvenile bluefin before they are unloaded to holding pens off the boats' home town of Port Lincoln.

Once the catch are brought to the small port located at the mouth of Spencer Gulf, a Fisheries boat draws up alongside and inspectors board the main boat. They sample the catch by hooking and weighing 40 fish. This gives them an average weight. Then a camera is set up at the mouth of the holding pen before the fish are herded into it. An inspector counts the number of fish. This number is multiplied by the average weight to establish whether the catch exceeds the Stehr Group's annual allocation.

Unfortunately, we didn't get to see the inspector's decision. It was removed by the film's editor. For Marcus Stehr and his crew, exceeding the catch is a problem because it means they must tow the excess fish back out to sea and release them.

But the fishermen already have some idea while still out at sea about the size of the catch. Once the fish have been encircled by the purse seine net and its bottom has been cinched, completely enclosing the fish, and the fish have been transferred to the transportation enclosure, the lead diver enters the enclosure and visually gauges the size of the fish.

If the lead diver says the fish are large enough to be profitably taken, the boats either go for the next catch or return to port.

Tuna, especially bluefin tuna, are scarce. Each fish, we're told, is worth about US$70,000. A full complement of fish can be worth US$20 million. Most of the tuna is exported to Japan.

Of course, the film completely sides with the fishermen and conservation of the fish gets no mention at all. The boys' undertaking is given an heroic cast in the narrative. They're sea-going cowboys who wrangle sharks out of the nets by hand and endure months at sea. The film says nothing about the scarcity of the fish.

It should. The film is ultimately a lost opportunity. Given a less sensational tone and a more challenging script, it could have advertised the downside of harvesting tuna from the Southern Ocean. Instead, it merely glorifies a bunch of very ordinary guys who just happen to be fishermen.