Giant Trevally - Caranx ignobilis
Did you know? Giant Trevally will sometimes trail seals or sharks and use them to ambush prey.
Sustainability and stock status
A decline in Giant Trevally numbers has been noted in Hawaii around inhabited regions, with both catch data and ecological studies presenting this decrease in numbers. However in Australia there doesn't seem to be a current concern for the sustainability of "GTs"
With most recreational fishing groups promoting a catch and release practice for the giant trevally, sustainability looks stable for the immediate future in Australian waters. However careful fish handling techniques should still be used by anglers to not damage the fish. Supporting the fish's weight, using barbless hooks and restricting the time the fish spends out the water are all important to continue it's sustainability.
The giant trevally can be found from the Central Coast of NSW all the way around the northern half of Australia to Perth in WA. The GT inhabits a wide range of offshore and inshore marine environments. It is a pelagic fish found throughout the water column but is mostly located in association with the bottom, or with structure, including coral and rocky reefs, shore faces, bombora or drop-offs and channels. They will also venture onto flats, headlands and shallow water to hunt and reproduce.
Juvenile to sub-adult giant trevally are known to enter and inhabit estuaries in Australia. In these estuaries, the giant trevally is found from highly dirty water to clean. These young fish eventually move to inshore reefs as they mature, before again moving to deeper offshore reefs.
Biology, behavioural characteristics and time of year
The giant trevally reaches maturity at about 60cm in length and three to four years of age. The species grows to 1.7m in length and 80kg in weight. The Giant Trevally can be recognised by its steep head profile, strong small sharp plates called "Scutes" on the straight, rear portion of the lateral line and silver colour with occasional dark spots, however large males can be black. It is the largest species of Trevally in Australian waters.
The power of this species is immense, especially in the larger sized fish. It is known to hunt individually and in schools. They are mostly active during the day, especially at dawn and dusk and can be caught throughout the year.
Fishing gear and techniques
Perhaps pound for pound the ultimate sports fish, the GT will need some serious gear if you want to land a trophy size specimen. Best baits are whole fish, live or dead with a super strong 6/0 to 10/0 forged hook. But if you are a true sports fisherman then Flies, Jigs, Soft plastics and Surface lures like Poppers will present you with the greatest challenge and excitement to catch this fish.
Depending on the size of the fish and the type of habitat you’re in gear will vary, but typically offshore fishing for large GTs will require a heavy action spin rod with a fast taper and length of between 7 to 9 feet, with a robust 4500 to 6500 saltwater spinning reel and a braid mainline up to 55kg (120lb) and Monofilament or Fluorocarbon leader up to 90kg (200lb). Plus Heavy Duty terminal tackle.
I have had the challenging experience of hooking juvenile GTs while fishing for Bream. Trying to stop one amongst structure was a bit like trying to stop a truck with ribbon.
Killing and cooking
At large sizes GTs can have Ciguatera which is a toxic food-borne illness, so send them to a taxidermist and not the table if you're going to keep one. GTs in smaller sizes are ok to eat and some say they are good table fare. However Australian anglers who target the species don't often keep fish.
If you do want to keep some then use the iki jime method for dispatching and then place in an ice slurry.