High waves from cyclone Yasi at Whitsundays.
High waves from cyclone Yasi at Whitsundays. Zac Bailey

Ciguatera outbreak in Spanish mackerel traces back to Yasi?

SO SUDDENLY ciguatera poisoning from mackerel is a real issue. Why here and why now?

Concerned fishos this week learned of another outbreak of ciguatera when nine people were treated in hospital after eating a 25kg Spanish mackerel caught off Scotts Head, on the Mid North Coast, last weekend.

That follows the case at Evans Head reported last month and a number of others from the Gold coast,

The Adreno Spearfishing Facebook page also reports three staff members received a small dose of ciguatera from a mackerel of 7kg taken from the Gold Coast last weekend.

The NSW Food Authority has issued advice to avoid eating mackerel heavier than 10kg - about 115cm fork length, according to the Australian National Sportfishing Association conversion tables.

That measurement sits pretty well with the 10.6kg fish we weighed on Wednesday, but most seasoned mackerel fishos know that some fish are long and slender and some are deep, thick and weigh heavier.

This measurement puts the age of the mackerel in question at more than four years, according to G R. McPherson's paper Age and Growth of the Narrow-barred Spanish Mackerel in North-eastern Queensland Waters (Australian Journal of Marine and Freshwater Resources1992, P43).

According to Fisheries NSW, migrations of Spanish mackerel extend along the entire east coast of Queensland (and the Gulf of Carpentaria) although permanent resident populations also to exist. Resident fish disperse from reefs after spawning 'while migrating fish can move up to 1000 nautical miles south into NSW waters'.

OK, a scientist I am not, but here's my pitch.

Cyclone Yasi devastated the North Queensland heartland of the Spanish mackerel, the Barrier Reef and inshore waters between Cooktown and Mackay, in early February, 2011.

The maze of reefs around the Palm Passage, east of Cardwell, are major Spanish mackerel spawning grounds in October to December; I've fished them with a seasoned mackerel pro and they are enormously prolific.

According to the ARC Centre of Excellence for Coral Reef Studies it took about nine months for corals to become re-established and in many areas over the intervening period, there was a heavy growth of algae over the dead coral.

To me, that's a prime window for the proliferation of the ciguatera dinoflagellate that can live in this algae.

Scroll forward three years to a dry summer in south-east Queensland and northern NSW and an active Eastern Australia Current, and you get conditions for an ideal southwards migration of Spanish mackerel.

Last year I feasted on mackerel up to 20kg but this year, I'm going to eat just a tiny bit of that 10.6kg fish and see how I feel about dining out on the rest.



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