As a result of these studies, leaders in the industry have initiated groundbreaking changes to their procedures so that more fish will survive – and be in better physiological condition – following angling tournaments.
Over the past several decades sport fishing tournaments have moved toward the practice of releasing fish, alive and unharmed, at the end of each event. But until now there has been little scientific evidence for designing the most effective "live release" procedures. With funding from Shimano Canada Ltd. and a Natural Sciences and Engineering Research Council (NSERC) Collaborative Research and Development grant, Dr. Tufts and his Queen's team have discovered new ways to improve handling procedures for fish at tournaments, which will set key benchmarks in this area.
"There's a growing awareness in fisheries management that people can enjoy the sport in a way that is ecologically responsible," says Dr. Tufts. "In our lab at Queen's we are working with important fresh water species, such as bass and walleye, to determine the physiological impact of catch and release fishing, and devise ways to ensure survival of the maximum number of fish."
Dr. Tufts' research into "Physiological Changes in Largemouth Bass Caused by Live-Release Angling Tournaments in Southeastern Ontario" is featured in the current issue of the North American Journal of Fisheries Management.
Experiments conducted by Dr. Tufts' research group have identified that the weigh-in process at the end of these events is one of the most critical times for fish caught by tournament anglers. Throughout the traditional weigh-in procedure, potential dangers to fish arise from their confinement in water-filled bags while waiting to be weighed, as well as their exposure to air during the actual weigh-in.
At high water temperatures, the concentration of oxygen in the containment bag decreases quickly, while the rate of oxygen consumption by the fish (its metabolic rate) rises. Whenever fish are removed from water, the structures in the gills that exchange gases – the lamella – will also collapse, which inhibits the uptake of oxygen.
As a result of Dr. Tufts' research, Shimano Canada Ltd. has now incorporated the following changes into their live-release procedures on the Canadian Fishing Tour, one of Canada's highest profile tournament circuits:
- Fish are transferred immediately from containment bags to a weigh-in basket, submersed in well-aerated water to ensure proper oxygenation while waiting to be weighed.
- Oxygen levels and water temperature in all holding tanks, as well as live-release boats, are continuously monitored.
- Fish are now weighed while submersed in oxygenated water, without exposure to air.
The Queen's research shows that bass or walleye kept in water during the new weigh-in process maintain 150% and 65% higher energy stores respectively, than fish weighed in air. "These results indicate that fish kept in water during the weigh-in process are in much better physiological condition and should be able to resume their normal physical activities much more quickly after they have been released," says Dr. Tufts.
As well, he adds, it is possible that the results obtained by weighing the fish in water are more accurate since there is now no error associated with fish flopping on the scales.
"It's encouraging to see a commercial leader in this area seeking solid scientific information to guide their procedures for releasing fish in the best possible condition," says Dr. Tufts. "As researchers we hope the benefits from this partnership will spread throughout the fishing industry in North America."
Contacts:
Nancy Dorrance, Queen's News & Media Services, 613.533.2869
Nancy Marrello, Queen's News & Media Services, 613.533.3227