Recently quite a few studies have been looking at the survival rates of popular angling species. The results have been encouraging and some key issues have been identified to help ensure the health of your released fish.
One of the most elaborate studies on Australian species to date was carried out by NSW Fisheries at Botany Bay in February this year. Named the Botany Bay Catch and Release Research Challenge the study looked at the survival rates of various species in the area including flathead, bream, trevally and snapper. More than 200 recreational anglers participated in the event.
The anglers were divided into two groups. Group 1 placed their two largest flathead, bream or trevally in a live well. These fish were then presented to researchers who tagged the fish and recorded capture methods and other data on each individual fish. After this the fish were transported to the large sea cages at nearby Kurnell where they were released. The way the fish were handled in group 1 approximately represented the way fish are handled in live weight in style competition. Group 1 caught 124 fish.
Group 2 anglers had researchers on board and immediately after being caught fish were tagged and data was recorded. A marshal boat equipped with a large live would then collect the fish for quick transportation to the cages for release. These fish more closely represented the species that anglers would normally throw straight back ie undersized, over bag limit, or fish otherwise destined for release. Group 2 recorded 232 fish.
Two control groups of fish were netted and then handled in a similar fashion to groups 1 and 2 above. This helped scientists get an even more accurate picture of the real survival rates.
All the fish were then watched for 10 days after which the bream in group 1 worked out to have an adjusted survival rate of 92 per cent. Group 1 Trevally had an adjusted survival rate of 55 per cent. "Adjusted" simply means that the control group was taken into account when working out the final figures.
Group 2 had adjusted survival rates as follows: bream 72 per cent, trevally 98 per cent, snapper 69 per cent.
Dusky flathead showed a high mortality rate because the cages didn't suit the way flathead lay on the bottom. Future experiments will feature flathead specific cages.
The above project is far from over, more analysis of the results is currently taking place. The project is funded by recreational fishing licences. This is a huge effort by NSW Fisheries and there was also a massive amount of volunteer work carried out by local fishing clubs.
At first look at the above figures I feel that they are very encouraging, especially when some pathetic rumours have circulated claiming that most released fish die! I do believe there is even more hope though survival rates can be easily be much higher than those recorded at Botany Bay. Firstly, most anglers who release a fish put it straight back in the water, which certainly means a higher survival rate than the above experiment.
It is also well known that experienced anglers who know how to handle fish enjoy much higher fish survival rates.
Proof of this is in the popular bream competitions where the survival rates are close to 99%! It must be recognised that this rate is in actually slightly lower as only live fish score so anglers very occasionally do not bring in a specimen that looks a bit sickly.
Some species are much more hardy when it comes to being hooked, handled and put in tanks. Not surprisingly the trevally in the Botany Bay experiment survived much better when they were placed quickly in an area where they could free roam. A fast swimming species like trevally will always suffer when being kept still in a small tank. Perhaps a tuna tube or the like is the go for species that cannot sit still in an aerated tank.
One of the main aims of the experiment was to determine how to enhance survival rates. There were many other variables recorded eg were the fish caught on lure or bait. If caught on bait what bait was used, etc. This data has proven very valuable and NSW fisheries recommends the following to achieve higher survival rates.
* Bring the fish in quickly - a long fight stresses a fish and it is more likely to die.
* Cut the line rather than removing hooks from gut or gills.
* Use barbless hooks - unhooking is easier if you flatten barbs on hooks, or use single hooks on lures.
* Avoid lifting the fish from the water. If you must lift it out of the water, wet your hands.
* If you put the fish down to take the hook out, put it on a smooth, wet surface, or a piece of vinyl-covered foam. Fish skin is easily injured.
* Don't use a net to pick the fish up, unless it is of knotless mesh. Knotted polypropylene landing nets damage a fish's skin and eyes.
Upon release, help a fish regain equilibrium, by holding it upright in the water and moving it to and fro for a while.
Next week I'll look at other research that has been carried out on catch and release survival rates. Until then see you on the water.
Rob Paxevanos
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