King Threadfin Concerns-Brisbane River

By Stefan Sawynok
Infofish Australia

Stocks of king threadfin in the Brisbane River are at risk of serious decline.

Commercial catches were jusaw BobThorntonst over 56 tonnes in the past 4 years, which is well in excess of historical harvests. In the 2014-2015 season alone (with three months of data still to come in), there has been 22 tonnes harvested. Just how many more threadfin are available in the system is unknown, but based on similar system’s stocks, they will be getting closer to exhaustion. There has been limited evidence of strong spawning that would refresh stocks and heading into El Nino there is lower chance of successful spawning.Mathew Hubbard from Brisbane River Fishing was the first to raise alarm bells having observed commercial fishers fishing around Nudgee. Mathew posted photos on Facebook of threadfin taken from the river, generating a lot of discussion and in the process reaching nearly 76,000 people.
Bob Thornton with Threadfin caught as a part of winter tag and release monitoring of the river.


Infofish Australia has been monitoring the commercial catch for over a year, but with a dip in the 2014 catch, it wasn’t clear the take was too high until April-May. Up until March, Brisbane has been the second largest king threadfin fishery in the state. A meeting on the 15th July, attended by many Brisbane fishers, highlighted the need for urgent action in order to avert an inevitable decline.


The real problem isn’t the commercial fishing so much as the absence of an early warning system to provide a buffer against such problems. The Crystal Bowl in Rockhampton serves this purpose and efforts are underway to develop the Crystal Bowl in Brisbane, but it’s early days.

The Brisbane River fishery is a unique recreational fishery in that the major predators, being snapper, king threadfin and mulloway, are catch and release for the majority of fishers. The age profile of fishers is also much younger than most other river systems. It’s no coincidence that the dominant Generation Y fishers are favouring Facebook over the dinner plate.

King threadfin are a fast growing species, reaching around 90cm within 5 years, making them a very attractive sportfishing species. With the emphasis on photos for Facebook, the locals have a renewable resource that drives regular spending at tackle and boating stores.
With no other major populations nearby, in the past, Brisbane fishers have often travelled to Maryborough, Rockhampton or the Cape for a threadfin fix.

Suntag, in partnership with local businesses, are driving the effort to collect data and are increasingly having to use their own funding to do so.   In 2014/15 Recreational businesses donated over $65,000 in time and materials to monitor the Brisbane region. Through that effort, it is hoped that in the future such issues can be detected early enough that conflict between sectors and rapid wind ups of fishing effort are avoided.