Sunday, April 17, 2011

Saturday's Scribe - A fishy tale

As our appetite for seafood rises, so too does our need to understand changes to the fish we eat. How much do you know about the state of your plate? Take our quiz, but don't make a meal of it!

1. What kind of shark often ends up as the fish in your fish and chips?
a) School shark b) Grey nurse c) Bull shark d) Hammerhead

2. Omega-3 fatty acids are found in cold water oily fish. Which of is the best source of omega-3s?
a) Sardines b) Salmon c) Red snapper d) Tuna

3. Which fish should you limit your consumption of due to high mercury levels?
a) Sea perch b) Swordfish c) Shark d) All of the above

4. Each year every Australian eats nearly 25 kilograms of seafood. More than half of this is imported mainly from Thailand, New Zealand, China and Vietnam. What kind of imported fish do we eat the most of?
a) Frozen fish fillets b) Canned fish c) Fresh fish fillets d) Frozen prawns

5. What proportion of the world's fish stocks - species of fish in a designated fishing area - are overfished?
a) Less than 10 per cent b) Around 20 per cent c) Around 60 per cent d) Over 90 per cent

6. The orange roughy is classed by the Australian government as an overfished species which means that there are inadequate numbers of breeding age fish in some fisheries to sustain the species into the long term. At what age does an orange roughy start to breed?
a) < 5 years b) 5- 20 years c) 20 - 35 years d) Over 35 years

7. Which species of freshwater fish is not native to Australia?
a) Murray cod b) Rainbow trout c) Sooty grunter d) Barramundi

8. What is the world's largest fish?
a) Swordfish b) Sperm whale c) Whale shark d) Blue marlin

9. In order to work out sustainable yields, scientists need to understand what factors?
a) Birth rate b) Mortality c) Breeding age and size d) All of the above

10. You're at the local fish shop deciding what to cook for dinner. Which would be the best meal to make from a sustainable seafood industry perspective?
a) Deep sea perch with chips and salad b) Sea bream with mash and asparagus c) Bluefin tuna steak with a lemon butter sauce d) Flathead with lemon cous cous and wilted greens

See answers below:
Answer 1:
A - School shark

School shark along with other species of shark including gummy shark, whiskery shark, saw shark, dog sharks and wobbegongs are often sold as flake in your local fish and chip shop. The Australian government currently lists school sharks as overfished in the area covered by the Commonwealth's Southern and Eastern Scalefish and Shark Fishery.

Answer 2:
A - Sardines

While all of the fish on the list are good sources of omega-3s, sardines are the best sources of omega-3. Sardines also don't contain high levels of mercury, which can accumulate in the fatty tissue of longer-lived fish and fish that live higher up the food chain.

Answer 3:
D - All of the above

Food Standards Australia and New Zealand advises that pregnant women, women planning pregnancy and young children should limit their intake of shark (flake), broadbill, marlin and swordfish to no more than one serve per fortnight with no other fish to be consumed during that fortnight. For orange roughy (also sold as sea perch) and catfish, the advice is to consume no more than one serve per week, with no other fish being consumed during that week.

Answer 4:
B - Canned fish

In 2008-9 Australia imported more than 54,000 tonnes of canned fish, over 40,000 tonnes of fish fillets and nearly 13,000 tonnes of fresh, chilled or frozen prawns. Most of our canned fish, mollusc and crustacean imports come from Vietnam and China.

Answer 5:
C - Around 60 per cent

According to CSIRO's Dr Beth Fulton, 64 per cent of all known fish stocks are overfished around the world.

Answer 6:
C - 20 - 35 years

The orange roughy, also known as deep sea perch, orange ruff or red roughy, doesn't mature until it is aged between 20 and 35 years old. Commonwealth fishery stocks of orange roughy in the eastern, southern, and western zones are currently classified as overfished. They are also classed as overfished in the neighbouring South Tasman Rise Trawl fishery which is jointly managed with New Zealand.

Answer 7:
B - Rainbow trout

Rainbow trout are native to North America and were first introduced to Australia in 1894. Murray cod are endemic to the Murray-Darling basin; sooty grunters, otherwise known as black bream are found in northern Australia; and barramundi are widespread along the northern Australian coast.

Answer 8:
C - Whale shark

The largest of all fishes is the whale shark which can grow up to 18 metres in length, although 4 -12 metres is more common. The maximum size for a blue marlin is 5 metres, while a swordfish is 4.5 metres. The sperm whale is a mammal and is not a fish.

Answer 9:
D - All of the above

Determining sustainable levels of fishing requires an understanding of the life cycle of the species in question; including the age at which the fish starts to breed; the birth rate or how quickly the population can increase; and the rate of mortality from natural predation, disease and old age.

Answer 10:
D - Flathead with lemon cous cous and wilted greens

Deep sea perch (also known as orange roughy), sea bream (jackass morwong or silver perch) and bluefin tuna are classified as overfished in Australian fisheries.

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