How to tell the age of dusky flathead

Recreational anglers like nothing more than catching a few flathead, drifting for the fish, throwing soft-plastic lures for them, even tempting the ambush predators on salt-water fly gear.

Perhaps no other fish is as central to our catch, especially given the popularity of estuary fishing where flathead often reside.

But what do we know about flathead and, in particular, the dusky flathead that's such a keen target and even the basis of the annual Flathead Classic fishing competition on the Gold Coast?

To help learn appreciate the flathead's biology, NSW DPI researchers recently produced a graph that allows anglers to estimate the age of dusky flathead they catch.

The graph is split into 5cm length classes ,with the most common age for each size class highlighted.

The shaded area is the spread of ages for each size class. For example, a flatty of between 50cm and 54cm is most likely to be 4 years old but could be a minimum of 1 or a maximum of 7 years old.

The variation is mainly due to the different growth of the sexes, as females flathead grow much faster than males after 2 years of age.

Females also reach much larger sizes than males. The maximum size for females duskies is about 100 cm, but for males is just 60 cm. So consider releases the bigger breeders.

The oldest female flatty so far recorded in NSW was 16 years old (and 88.5 cm), the largest was 98.5 cm (and 13 years old), while the oldest and largest male was just 11 years old and only 61.5cm.

The data has come from more than 5000 dusky flathead collected from NSW waters over the years from the Clarence in Northern NSW to Wallaga Lake on the South Coast.

Next time you catch a nice dusky flathead, use the graph to estimate its age. And, as we touched on, most thinking anglers release the big girls to fight another day and help populate our waterways with more flathead.

This article was prepared with information from NSW DPI. There's a bit more on the growth and reproduction of dusky flathead here.

Photo Credit: Gun  angler Ian "Big E" Phillips with a massive NSW South Coast flathead, pic courtesy of NSW Fisheries; and underwater photo by Shayne McKee.