silverfox
Well-known member
- Joined
- Oct 4, 2006
- Messages
- 1,928
I don't think predation is the biggest issue. It may be one, but likely not the biggest. If the stream can support wild reproducing brook trout, then all of the environmental factors should allow the long-term survival of stocked trout. Assuming their instinct to survive is strong enough.
Most of the research I've read indicates that "presence" is the issue. Competition for habitat, competition for food, and aggression all cause stress to brook trout. To the point that the brook trout's behavior is modified, changes in foraging rate, growth rate, increased risk of disease from stress, and impacts to reproductive success are all impacted by the presence of nonnative trout.
Otherwise, as Mike said, the other biggest issue (probably THE biggest) is incidental mortality. These stocked streams would see little to no angling pressure if they weren't stocked. This is why I've always had a hard time believing the line that "stocking isn't the limiting factor." It is having an impact in many (most?) cases. Is it the only impact? No. Is it a multiplier? I say yes. Regardless, it certainly isn't helping the brook trout population. Isn't one of the tenets "to enhance?" No matter how you slice it, stocking over brook trout is far from enhancement.
So you've got increased angling pressure = more incidental mortality, and then, especially in a brook trout stream with increased voluntary C&R, you've got remnant stocked fish competing w/ the brook trout. Add in some wild naturally reproducing brown trout, and some habitat problems, water quality problems, temperature problems = extirpated brook trout, or severely suppressed populations anyway.
Most of the research I've read indicates that "presence" is the issue. Competition for habitat, competition for food, and aggression all cause stress to brook trout. To the point that the brook trout's behavior is modified, changes in foraging rate, growth rate, increased risk of disease from stress, and impacts to reproductive success are all impacted by the presence of nonnative trout.
Otherwise, as Mike said, the other biggest issue (probably THE biggest) is incidental mortality. These stocked streams would see little to no angling pressure if they weren't stocked. This is why I've always had a hard time believing the line that "stocking isn't the limiting factor." It is having an impact in many (most?) cases. Is it the only impact? No. Is it a multiplier? I say yes. Regardless, it certainly isn't helping the brook trout population. Isn't one of the tenets "to enhance?" No matter how you slice it, stocking over brook trout is far from enhancement.
So you've got increased angling pressure = more incidental mortality, and then, especially in a brook trout stream with increased voluntary C&R, you've got remnant stocked fish competing w/ the brook trout. Add in some wild naturally reproducing brown trout, and some habitat problems, water quality problems, temperature problems = extirpated brook trout, or severely suppressed populations anyway.
