A study has found catch-and-release sportfishing practices that leave salmon with injuries, particularly to their eyes, cause higher mortality than earlier research suggested.

Scott Hinch, who led the study by researchers at the University of British Columbia, said mortality among chinook salmon could be as high as 40 per cent, depending on environmental conditions and injuries sustained during capture and release.

At the same time, the years-long research that was supported by the Sport Fishing Institute of B.C. found that a series of changes in anglers91裸聊视频� practices could boost salmon survival.

Hinch said it may be as simple as using smaller hooks, avoiding landing nets and handling fish as little as possible.

91裸聊视频淵ou can make those decisions as an angler, you know, make sure that when you are releasing, you91裸聊视频檙e doing it the best way possible,91裸聊视频� said Hinch, associate dean and professor in the university91裸聊视频檚 department of forest and conservation science.

91裸聊视频淚91裸聊视频檓 not sure how this will flesh out in the near term, but I certainly would like to see all our recommendations, in some fashion, become regulations,91裸聊视频� he added.

The study found chinook salmon caught off the east coast of Vancouver Island that were released in good condition had short-term mortality rates between zero and eight per cent over the course of the study, while good-condition coho were less resilient with 17 per cent short-term mortality.

But different injuries, environmental conditions and fishing practices could affect survival significantly.

The research, which involved tagging and tracking more than 1,500 salmon off B.C.91裸聊视频檚 coast, found injuries to eyes, fins and scales reduced survival rates for chinook by 15 to 20 per cent within 10 days of release.

Eye injuries were linked to a further 20 per cent mortality boost after 40 days.

91裸聊视频淪o (it) could be as high as 40 per cent mortality, depending on the context, depending on how the fish was injured,91裸聊视频� Hinch said in an interview.

He said previous studies were shorter term, generally observing fish in holding pens for a few days and finding mortality of five to 10 per cent.

The new study shows certain types and sizes of fish don91裸聊视频檛 respond well to the practice, and catch-and-release is 91裸聊视频渘ot the panacea91裸聊视频� for salmon91裸聊视频檚 woes, Hinch said.

Still, he said the findings allowed researchers to identify practical solutions to help boost survival rates while supporting the long-term sustainability of salmon populations struggling with the effects of climate change and habitat degradation.

The study found a 91裸聊视频渟trong size effect91裸聊视频� on survival, with smaller coho and chinook both suffering higher mortality rates than larger fish. Every one-centimetre decrease in length was associated with a six per cent increase in coho mortality about three days after release.

91裸聊视频淚f you have to make a decision of whether you91裸聊视频檙e going to keep the fish or not, and it91裸聊视频檚 legal to keep, and it91裸聊视频檚 got a serious eye injury, maybe you keep that one even though maybe it91裸聊视频檚 not quite as big as the one you were hoping to get,91裸聊视频� Hinch said.

The researchers recommend that anglers use smaller hooks and avoid flashers 91裸聊视频� a shiny type of fish attractor 91裸聊视频� as well as treble and tandem-hook setups, all of which are linked to higher mortality.

The list of best practices also includes landing fish as quickly as possible and avoiding landing nets, even those marketed as 91裸聊视频渇ish friendly,91裸聊视频� Hinch said.

91裸聊视频淏oth chinook and coho, when those nets are used to bring them out of the water, into the boat, they still get their fins damaged. Their fins split, regardless of what the webbing material is made of,91裸聊视频� he said. 91裸聊视频淎nd we showed pretty clearly that when you start damaging the fins 91裸聊视频� the poorer the survival outcomes were.91裸聊视频�

If a net must be used, the report says anglers should ensure it91裸聊视频檚 loose, and salmon should remain in the water throughout the process to minimize exposure to air.

The study was largely funded through the B.C. Salmon Restoration and Innovation Fund, a joint initiative with Ottawa, while a steering committee involved the federal Fisheries Department and members of the Sport Fishing Institute of B.C.

Members of the sport fishing institute helped with some of the field work, and Hinch was set to present the paper at the group91裸聊视频檚 annual conference on Friday.

91裸聊视频淭hey are a strong supporter of our recommendations,91裸聊视频� said Hinch, adding the Fisheries Department has also expressed interest in adopting them.

Hinch said the study also revealed a link with climate change and warming waters, as salmon will start struggling in water temperatures of 18 C and higher.

91裸聊视频淲hen you start to capture fish in those temperatures and you91裸聊视频檙e making them struggle 91裸聊视频� and then you91裸聊视频檙e exposing them to air, possibly, depending on your practices, that can have really strong negative outcomes,91裸聊视频� he said. 91裸聊视频淭he temperature is the facilitator that makes air exposure and handling even more lethal.91裸聊视频�

The findings have led the researchers to suggest that anglers avoid catch-and-release altogether when water temperatures hit 18 C or warmer.

91裸聊视频淚t91裸聊视频檚 simple things 91裸聊视频� but we have to then enact them, and hopefully there91裸聊视频檚 enough goodwill and understanding among anglers,91裸聊视频� Hinch said. 91裸聊视频淚91裸聊视频檓 pretty sure there is, because I91裸聊视频檝e worked with a lot of them now, and they all want to do the right thing.91裸聊视频�

Brenna Owen, The Canadian Press