Tropical species heading south?

As the world continues to experience extremes of weather the once scoffed at notion of global warming and resulting climate change has seemingly been accepted into the mainstream psyche. Scientists continue to tell us the planet is warming, droughts and natural disasters are becoming more common, and sea levels are on the rise.

Amongst these gloomy predictions anglers in southern Australia may have brightened to claims by some weather boffins that the East Australian Current was increasing in strength and might result in tropical sportfish, such as marlin and dolphinfish, being regularly caught in southern waters – usually well off the fish’s regular migration routes.

And some Victorian fishos might well be studying climatic theories more closely after recent seasonal events. Fishing World writer Steve Cooper recently wrote on a Victorian website about the amazing tuna fishing experienced by anglers in the offshore waters from Port Fairy to Port MacDonnell. It all started back in 2006 when at the time these waters began to yield southern bluefin tuna weighing from 80kg to 130kg. Even bigger tuna were hooked and lost. Even more significant though was the fact that no one had ever caught tuna of this size before in Victorian waters. Since then, the tuna have kept running, and this season, the fishing has been an absolute blinder.
The bluefin began running about six weeks earlier and there were more of them. Consistent with recent seasons, the big 100kg-plus tuna arrived in late March and are still being caught.

Each year around autumn as the East Australian Current pushes warm water to its extreme southern reaches weird and wonderful catches make fishing report headlines. Cobia turn up in Sydney’s Botany Bay (two weeks ago) and as far down the coast as Batemans Bay, as occurred a couple of years ago. During the ’70s fishos regularly encountered mangrove jacks, and the odd giant herring, in suburban Sydney lagoons.
The capture of an 18kg Spanish mackerel off the Drum and Drumsticks rock ledge at Jervis Bay by (my brother-in-law) Brett Richards in the early ’90s personally highlighted the influence of these warm water currents. Around the time sailfish too had been encountered off these southern NSW rock ledges.

Maybe these sort of migrations have been happening all along but have largely gone unnoticed? Steve Cooper writes that trawler operators out of Portland have been saying for years that the big tuna were offshore. It is now believed anglers only began hooking these big SBT when they began venturing much farther offshore.
Dolphinfish, also called mahi mahi, is a tropical sportfish, yet these have become semi-regular captures in the same waters. Coincidence? According to Steve Cooper he’s heard of trawler-boat fishermen who’ve been encountering these fish for more than 25 years off the Victorian coast.

So as the world’s sea temperatures appear destined to rise who knows what Victorian and even Tasmanian fishos will be catching in 100 years time? Food for thought…

Mick Fletoridis

Had any encounters with pelagic fish a long way from their usual migration range? Drop a comment below.


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