Murray cod and tom yum whets appetite

Just this week I was presented with two huge cutlets from a just-caught Murray cod. Beautiful they were, thick glistening skin, slightly pink flesh, thick and juicy. I placed them carefully in the fridge, not really sure what to do with them.

Saturday, 5am: Like many 50 to 59 year olds we rise early to the local ABC radio station. And Saturday is my favourite morning show because it will be Scott Levi and his Big Fish program. It's not that I'm a keen angler, having little patience for fishing. What I like is the joy his team have in their pastime, that's the important thing, enjoying what you are doing. Their topic today was the Murray River cod. See it just worked out that I would gain valuable knowledge and from there be able to truly appreciate this native fish.

Most of what they are talking about is based on Dr Stuart Rowland's NSW fisheries research paper on the decline of the Murray cod (which you can find on the Murray-Darling Basin Authority website, mdba.gov.au).

There is something about this fish that is so wrapped up in our history and our psyche. A little background distilled from Dr Rowland's paper - the Murray cod is endemic to the Murray-Darling basin. A slow-growing freshwater fish, the largest that is found solely in freshwater.

The ultimate survivor, cod find themselves at the top of the food chain, the only problem with being here is that you get our attention. Know what I'm saying, great white sharks?

They feed seemingly on anything, yabbies, fish and mussels being their main food source along with more unusual fare like water dragons, turtles, ducks, mice and snakes. Gosh, they seem to be able to eat anything - even possums and kookaburras, reportedly. This undiscriminating appetite means they should be easy to catch.

The earliest explorers and settlers were all amazed at the abundance, size and ''delicacy'' of the river cod. As far back as the 1830s these fish were being caught near Yass. When you look at the ebbs and flows of the waterways in the Murray-Darling basin it is quite amazing that this fish can survive and prosper through the droughts that leave these huge river systems just a series of ponds and then the huge floods like we've seen in recent years.

As is our penchant, we bring species to the very brink of extinction before thinking, ''Hang on we might need them''. The cod were in serious decline due to fisheries which squandered this marvellous fish first by de-snagging the rivers, which technically removed the logs and rocks that cod use to protect themselves. Then they used devices such as drum and gill nets to catch them in great numbers to feed growing towns and cites.

This practice went on for more than 100 years until it was final dismantled in 2001 - yes, just the last decade. Other practices such as arsenic poisoning from the runoff from sheep dips, siltation from farming, cold water pollution and migration barriers from damming the rivers haven't helped either. Neither did the introduction of redfin and carp, both species of fish which survive off the same food source as the cod. Can't imagine what the Aboriginal people were thinking watching all this happen. They had been looking after this fish just fine for 25,000 years, believing the cod to have formed the Murray river system and all the native fish.

We came to our senses, granted mainly because the cod got to such low numbers that it wasn't financially viable any more. We got the point and started to look at alternatives to fishing them into extinction. Hatcheries to restock, a ban on commercial fishing plus bag limits, closed seasons, managing migration upstream and translocation of the species to new systems like the Yarra. Basically caring about this iconic fish has helped, along with its own amazing survival skills, to bring it back to almost sustainable numbers once again. By all accounts, it's one of the greatest recoveries of an ancient species of fish but there is still a way to go.

And don't think me too hypocritical either in tucking into one for lunch. The folk who caught this 10-kilogram fish did so with bread and also caught 20 huge carp. That's a good thing. Thus armed with my newfound knowledge I'll enjoy lunch and reflect on this amazing Australian fish that has people like Dr Rowland, NSW fisheries and our Aboriginal traditional landowners looking after its welfare and survival hopefully for another 25,000 years. This is top of the tree for river fish and I can't think of a better way to have it than how the fishermen who caught this prepared the cod, a south-east Asian tom yum.

Tom yum of Murray cod with broccolini

1 litre water

400g cod back bone, left in largish sections

3-4 red shallots, peeled and halved

3 stalks lemongrass, trimmed of woody ends, halved lengthways, cut into 30mm pieces

8 large kaffir lime leaves, torn in half

2 thick slices of galangal, about 5mm thick

2 large cutlets Murray cod cut into 50g chunks, with some skin on each piece

1 bunch broccolini, blanched in boiling water, chilled, cut each branch in half

1 bunch coriander, leaves picked over, roots rinsed and reserved

mixed chillies, large and small, red and green, sliced thinly

4-6 limes, juiced to yield about 80-100ml

60ml fish sauce

Bring a pot of water to the boil and blanch the cod bones. Remove after 20 seconds and tip out the water. Bring one litre of water to a low simmer. The water should be barely moving (about 85C). Add the cod bones and simmer for 20 minutes, remove and discard the bones.

With the handle of a knife or in a mortar, bash the shallot, lemongrass, galangal and coriander roots separately, just enough to squash, add to the stock and simmer for 15 to 20 minutes. Add the fish and broccolini, remove from the heat, cover and let steep for a few minutes until the fish is just cooked.

Meanwhile, set up four bowls with the coriander leaf, chilli, lime juice and fish sauce. Have extra of everything to serve, so you can individually adjust your bowl.

Divide the soup contents among the four bowls and serve immediately. A beautiful fragrant hot and sour soup.

>> Bryan Martin is winemaker at Ravensworth and Clonakilla.