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It’s not all bad though: we can farm fish. How? Well, like fields of sheep on land, fish-farmers make fields of fish in the sea. The fish are surrounded by big nets and are fed until they’re big and fat and ready to eat.

But we need to be careful with the fish farms. Keeping the fish in a crowded space can make them sick and sometime the sickness can spread to the wild fish. It is a bit like a cold spreading around to all the kids at school. Also, heaps of wild fish need to be caught and turned into food to feed the farmed fish. Around 10 kilograms of wild fish are needed to grow one kilogram of farmed fish. Where will all these little fish come from?

Aquaculture – fish-farming – has filled some of the gap in declining wild catches. Production grew 20 times between 1980 and 2011. It is now pushing 50% of all seafood production and getting close to overtaking the total wild catch. It has the potential to take pressure off wild stocks and make big dollars for the investors.

But like everything it has it’s challenges. If poorly managed, aquaculture can actually damage wild stocks and ecosystems. What do the farmers do with all the fish poo? Does it just pile up on the ocean floor?

Likewise, crossbreeding between escaped domestic fish and wild stocks can weaken the genetic make-up of the wild ones. As luck would have it, natural habitats are often destroyed to set up fish farms.

Even fish can’t always breathe underwater

‘Dead zones’ containing too little oxygen for fish to breathe are growing as global temperatures increase.

Warmer water dissolves less oxygen, so as temperatures rise, oxygen vanishes from oceans. Marine biologists are warning that if dead zones continue expanding, oceanic “deserts” could massively deplete marine life and fish stocks.

A recent study by some scientists from the University of Copenhagen suggests that unless we drastically reduce our carbon emissions these dead zones in our oceans could expand and fish could vanish from huge stretches of the ocean.

What can you do?

Here are some practical tips:

* Buy sustainable seafood. Avoid long-living endangered species like Flake (shark) and Orange Roughy. When you buy fish and chips the fish is flake – get mum and dad to ask for the flathead instead – there’s heaps of them and they taste better. The Australian Marine Conservation Society (AMCS) has a handy ‘Sustainable seafood guide’ with all the information you need about different species.

* Fish fairly. If you go fishing don’t be a fool with fish. Only catch what you can eat and release the rest. The idea of ‘filling up the freezer’ went out with Stubbies shorts, Crest Lager and terry toweling sun hats with the tiny brim (ask your granddad about this – you are too young to remember).

* Shop wisely. Cut down on packaging and products with toxic ingredients that end up in our waterways.

* Don’t litter – every bit of rubbish you drop in the street ends up in a waterway after the next big rain. You’re a dope if you rubbish Australia.

* Keep storm-water clean. Oil, antifreeze, fertilizers, paint and other chemicals find their way into the waterways – don’t let dad or uncle John pour them down the storm-water drain or sink!

For these tips and more, visit the Australian Marine Conservation Society.


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