Catch and release is a vital part of salmon management to protect future stocks. Research has shown that anglers can avoid unwanted salmon deaths, but it does require a responsible level of care to achieve this.
Good technique means more salmon spawning and more fish to catch in the future.
To see your fish swim off strongly adds to the elation of landing a salmon but seeing it die after release is a terrible comedown.
If you handle a salmon poorly, it may die later when you can’t see it, from exhaustion, internal damage or infection. Technique is important.