Landing nets in catch-and-release fisheries are recommended to shorten fight time, reduce handling time and to protect fish from harm when handling the fish.
However, not all nets are the same and just one — rubber mesh nets with large mesh — rose to the top as the best option for landing salmonids, according to a recent study that compared four types of nets, as well as the use of bare hands. On the Lower Columbia, recreational fishermen often must release wild-spawned salmon and steelhead they catch while pursuing hatchery fish. White sturgeon also are sometimes scheduled for catch-and-release fisheries.
“Our study on brook trout was conducted to find the most fish friendly landing net that anglers can use for landing brook trout,” said researcher Robert Lennox, a PhD student in the Department of Biology at Carleton University in Ottawa, Ontario in Canada. “We found that rubber mesh nets with large mesh were the best option after comparing fin fraying, scale loss, and mucous loss of brook trout landed with different net types and with bare wet hands.”
That’s even though the brook trout landed in nets were handled for longer than the fish handled with bare hands. Nets keep the fish safe from drops that occur when using bare hands that can cause bruises or lesions. The study was conducted at Lake Collins in Quebec with anglers fishing with light spinning rods and barbed treble hooks out of boats.
“When used to hold fish in the water and remove hooks quickly, rubber nets with large mesh can improve the condition of brook trout released by anglers in catch-and-release fisheries,” Lennox concluded.
“Influence of Landing Net Mesh Type on Handling Time and Tissue Damage of Angled Brook Trout” was published online Nov. 14 in the North American Journal of Fisheries Management.
Anglers and fisheries managers should be aware of how choices affect fish health, Lennox said.
“Net mesh that is small or not constructed from rubber are prone to damaging the fish and should be avoided,” he said. “Managers should recommend anglers use nets properly (i.e. to hold fish in the water and reduce air exposure) and anglers should select nets that are least damaging to fish, which we suggest are rubber meshed nets with large holes.”
The study compared handling time and instances of fin fraying, scale loss, and mucous loss sustained by brook trout landed by four net mesh types — large rubber, nylon, polypropylene, and rubber coated — or bare wet hands.
Specifically, the nets tested were a large 25 millimeter (about 1 inch) mesh knotless rubber net, a small 2 mm (less than 0.1 of an inch) micromesh knotless nylon net, a large 40 mm (1.57 inches) mesh knotted polypropylene net and a small 6 mm (0.23 inches)mesh knotless rubber coated nylon net. Bare hands were also included because anglers will often use this method of catch and release.
Study results found that the polypropylene mesh resulted in the greatest extent of fin fraying, whereas the bare wet hands method, nylon mesh, and rubber coated mesh resulted in the most scale loss.
Some nets — nylon and rubber coated — had extended handling times compared to bare wet hands because of hook entanglement in the netting. However, using bare wet hands to land the trout resulted in higher odds a trout would be dropped into the bottom of the boat.
“We concluded that the large rubber mesh was the least damaging to Brook Trout,” the study says. “Changes to angler practices such as using appropriate landing tools can benefit fish welfare in catch-and-release fisheries.”
Poor net design can lead to prolonged air exposure and handling of fish. Fin fraying can lead to “compromised post-release swimming ability and fin rot,” the study says. Scale or mucous loss “can render a fish more susceptible to infection and disease.”
Significant fin fraying (more than five times that of bare hands) was caused by the polypropylene mesh net.
The knotless nylon mesh had the highest frequency of scale loss. Similar in frequency for scale loss was bare hands and rubber coated nylon mesh.
The knotless nylon mesh most frequently caused mucous loss, about 1.5 times the loss of bare hands. The large rubber mesh had the lowest mucous loss.
The longest handling time was with knotless nylon mesh, largely because of the frequency of hook entanglements. Bare wet hands had the shortest handling time, but the frequency of dropping the brook trout was nearly four times higher for bare wet hands than any of the net types.
Treble hooks did not have a significant effect on mortality compared with single hooks, but they did increase handling time and air exposure.