THE marine food chain goes something like this: sun, phytoplankton, zooplankton, shrimps, sprats, forage and demersal fish, pelagics and apex predators. Remove any one link and the whole web collapses.
It's against this premise we can thank our lucky stars the foreign-owned factory ships that eyed our blue mackerel fisheries a few years back were sent packing. Consider, on the other hand, the jack mackerel fishery in the Southern Pacific.
A similar fish to our small mackerel species, the jack mackerel has been plundered to the point of collapse.
Where stocks were estimated at 30 million tonnes two decades ago, they have been reduced to 3 million tonnes today. A University of British Columbia oceanographer, Daniel Pauly likened the overfishing to the last of the buffaloes. "When they're gone, everything will be gone ... this is the closing of the frontier," he said.
Factory ships from around the world have descended on the waters off Chile and Peru for years and unleashed their massive nets. While a staple of some cultures, jack mackerel mainly ends up as fishmeal to sate the aquaculture industry.
The largest of the factory ships, the Russian-flagged Lafayette, a rebuilt 50,000-tonne oil tanker, is longer than two football fields. The mother ship sucks fish from its fleet of super trawlers using giant hoses. The mackerel, as many as 1500 tonnes a day, are frozen in blocks.
When the ship set sail for the Southern Pacific at the end of November, its target was to catch 300,000 tonnes of fish. That's twice what Hong Kong consumes in a year.
Meanwhile, delegates from 20 countries have gathered to try to stop the plunder. Australia and New Zealand have initiated a South Pacific Regional Fisheries Management Organisation to apply unilateral leverage on the renegade factory ships.
Thankfully, our fisheries managers had the good sense to prevent factory fishing of our blue or slimy mackerel stocks after a trial some year ago.
Game fishers hunting around the slimy mackerel schools off Port Stephens have enjoyed world-class marlin fishing. The stellar fishing is directly attributable to the abundance of baitfish.
Charter skipper Scott Thorrington said it was still going "nuts" when we spoke to him on Friday.
"There's bait everywhere, oodles of slimy mackerel, and they're the key to the fishery. You can see the marlin rounding up the bait and smashing it," Thorrington said from behind the wheel of his boat Flying Fisher.
Then our call was cut short by the wail of a fishing reel and yet another marlin hook-up.
In last weekend's Lake Macquarie Billfish Bonanza, Thorrington tagged an incredible 17 marlin using 24 kilogram tackle. However, he ended up playing bridesmaid to winning boat Diversion whose crew tagged 17 marlin using lighter 15 kilogram tackle.
There are plenty of fish for the frying back inshore.
Broken Bay and Pittwater are littered with surface fish including Australian salmon, bonito and frigate mackerel. Flathead are lurking beneath the feeding schools and bream are starting to gather.
The rain should help the school jewfish in the Hawkesbury. Blue swimmer crabs are hot one day and skulking the next, but there are big whiting over the flats in Brisbane Water.
Harbour guide Craig McGill conveys another amazing shark story. An angler was fighting an Australian salmon from his boat anchored off Clifton Gardens when a big bull shark launched from the water, grabbed the jumping fish, and landed back down with an almighty splash.
Otherwise, the action includes kingfish to 80 centimetres, abundant salmon, tailor, bonito and frigate mackerel. The flathead are lining up over the flats in North Harbour.
Southside guide Scotty Lyons has been scoring plenty of salmon, tailor and bonito in Botany Bay.
Offshore, Lyons and crew landed an impressive bag of morwong reminiscent of the kind of catches my grandfather made in the good old days.