Fishing for statistics
By David Bancroft
Research undertaken in the Wooli River is helping scientists understand the survival rate of fish released after being caught by anglers.
Done with the assistance of volunteer anglers in Wooli, the scientists have examined how well fish recover after being hooked.
The results, to date, have been encouraging, but vary from species to species and on other factors such as where hooks lodged.
As a result of research already conducted, it is estimated the short-term survival rates of popular species such as snapper are (67 per cent), yellowfin bream (72-100 per cent), trevally (63-98 per cent), sand whiting (93 per cent) and mulloway (69-92 per cent) after being released.
Now scientists will spend three years researching the factors that contribute to the survival rates of various fish species after they are released.
The project, worth close to $1million, is funded jointly by the NSW Department of Primary Industries (DPI) and the Saltwater Fishing Trust ? one of two independent bodies which invest funds from fishing licences into projects to promote recreational fishing.
Minister for Primary Industries Ian Macdonald said research over the past 18 months provided an accurate estimate of short-term survival, but fish may not experience all of the factors that contribute towards mortality such as a reduced ability to feed, susceptibility to predators and increased stress.
NSW Fisheries Conservation Technology Unit senior research scientist, Matt Broadhurst, said catch and release had become popular.
"Fishing is worth a lot to the local economy, and this is a key issue because a lot of anglers release," he said.
"Survival rates depend a lot on the species and whether the hook is in the mouth or in the stomach."
He said hooks, even stainless steel hooks, eventually broke down and were passed by the fish.
"We don't know yet whether they pass through the front or the back end," he said.
"We will now look at what happens in the wild. We are going to attach radio transmitters and map out where they are going and see if their pattern of behaviour changes."