Double the cost of a license and it'll still be cheap. In some limited circumstances, it may be prohibitive for casual fishermen and famililies, but this is not illiberal. For one, young children are already exempted, so a structure already exists to mitigate the effect on economically marginalized families.
From the many horror stories we review in this forum and my own experience, it appears to me that our major problem is not one of regulation, but of abuse and lack of enforcement. In 30 years of fishing in Alberta, I've had my license checked once, and that was in Fish Creek Park. Were I of a different frame of mind, I could easily do without one and have no fear of getting caught. What is the real problem: the fisherman in the pool below you interrupting your solace, or the trio of bait chucking louts on the cliff above tossing their beer cans about and hitting you up for weed?
In the past, our population density was low enough that these people would not have a catastrophic impact. But with our economic growth and the influx that came with it, I fear that this is no longer the case. Therefore, I believe that we should pay more to use this resource, that being the only way to conserve it.
At the end of the day, if you're trying to convince someone to conserve something, the real problem is that it is too cheap.