The link is no longer available, but I posted info a while back about the mortality of trout parks in Missouri. They are stocked sections of streams with varying regulations. Some sections allowed fly-only, artificial lures as well as bait. These numbers are based on actual results from fishing day in and day out and based on how many trout must be restocked to maintain the section fished:
Afishinado wrote:
From Mike’s writings, I believe that he cites some studies that claim bait, fly, and artificial lure mortality rates are similar. This article is from a recent study in Missouri, where they have "trout parks", which are heavily stocked, and have areas segregated for bait, artificial lures, and flies. This is a perfect laboratory for studying mortality rates under realistic conditions. They studied mortality on a long-term basis through all months of every season. Many of the other studies I’ve read, were for a short-term and involved only few hundred anglers and fish. In these SR areas, many thousands of anglers catching many thousands of fish under actual conditions led them to their conclusions. One other note, since it is a pay-to-fish area, and trout are very expensive to raise, the Missouri Dept. of Conservation has a financial interest to protect. Here are their conclusions:
“Studies conducted by fisheries biologist across the country for the past 40 years, and most recently right here in Missouri, have documented that anglers can improve trout fishing just by changing what is on the end of their line. These studies have shown that trout caught and released using bait are five times more likely to die than trout caught and released using artificial lures or flies. In the trout management areas of Missouri, where minimum size limits require anglers to release sublegal size trout, the effects of bait fishing can have a detrimental effect on the fish population. Up to 80% of the sublegal size fish can die before they reach legal size of 15 or 18" in these areas.
Trout, like many other fish, use their sense of smell and taste when selecting food items. When a trout bites a food item, the scents released from the food can trigger the trout to hang onto its prey even more aggressively than if the smell and taste cues were not present. Unfortunately, this can lead to the hook penetrating very sensitive parts of the fish such as gills, esophagus, or even the heart located just under the skin in the lower rear part of the mouth.
Natural, prepared, and scented baits are often fished passively, meaning the bait is left to set on the stream or lake bottom, or suspended below a float, until the fish ingests it and begins to swim off. By this time the hook is usually deep in the fish's mouth. Because artificial lures and flies don't release scents, and because they are fished more actively by pulling them through the water, the time between biting and hooking is reduced, and the hook does not end up as deep in the trout's mouth. Therefore, if trout are to be released, their chances of survival are much greater if anglers use artificial lures or flies.
The use of artificial lures or flies when trout fishing will reduce catch and release mortality, resulting in more and larger fish for all anglers.”