M
Mike
Well-known member
- Joined
- Nov 10, 2006
- Messages
- 5,441
There is no doubt that there are many positives associated with good tailrace fisheries, but what seems to be lost among anglers at times is that not all tailrace fisheries need to be coldwater fisheries in order to be good and not all tailrace fisheries are necessarily going to be good. Habitat is still very important. Discharges need to maintain suitable water temperatures, suitable water quality, and favorable flows that match the channel size and provide reasonable depths. Tailraces also need to have good physical habitat; flow, temperature, and other water quality parameters are not necessarily enough.
The problem with some tailraces is that the physical habitat declines over time as the tailrace becomes wider and shallower. This means that the fishery can also decline and that previously successful management techniques, such as fingerling vs adult stocking, may no longer work or be appropriate.
Impounding a stream or river disrupts natural fluvial processes downstream from the impoundment. Sediment that would have been transported downstream is instead trapped in the impoundment. Much of that sediment would have been cast up on the flood plain and contributed to stream bank maintenance. Without the benefits of the sediments, tailraces are subject to becoming wider and shallower. And, of course, bank destabilization can be exacerbated if and when high flows occur more frequently than occurred pre-impoundment, whether they are associated with operational activities at the dams or just increasing development (and runoff) in the drainage basin. Additionally, the impoundment and tailrace may change more than just fluvial ecology; they may change avian ecology (over time may increase avian predator densities throughout the year) as well, which in turn may have direct impacts on tailrace fisheries with limited deep habitat.
While I am not attempting to discuss all aspects of tailrace fisheries here, I thought just a few of the aforementioned items might stimulate some thought and other comments on tailraces. I am not interested in participating in a point/counter-point discussion on such a complex topic.
Finally, let's bear in mind that "resource first" is not necessarily the same as "trout first." Changing a tailrace from warmwater to coldwater, and potentially damaging a perfectly good warmwater fish population, could easily be interpreted as being contrary to "resource first" guidance. Some anglers prefer good warmwater fishing.
The problem with some tailraces is that the physical habitat declines over time as the tailrace becomes wider and shallower. This means that the fishery can also decline and that previously successful management techniques, such as fingerling vs adult stocking, may no longer work or be appropriate.
Impounding a stream or river disrupts natural fluvial processes downstream from the impoundment. Sediment that would have been transported downstream is instead trapped in the impoundment. Much of that sediment would have been cast up on the flood plain and contributed to stream bank maintenance. Without the benefits of the sediments, tailraces are subject to becoming wider and shallower. And, of course, bank destabilization can be exacerbated if and when high flows occur more frequently than occurred pre-impoundment, whether they are associated with operational activities at the dams or just increasing development (and runoff) in the drainage basin. Additionally, the impoundment and tailrace may change more than just fluvial ecology; they may change avian ecology (over time may increase avian predator densities throughout the year) as well, which in turn may have direct impacts on tailrace fisheries with limited deep habitat.
While I am not attempting to discuss all aspects of tailrace fisheries here, I thought just a few of the aforementioned items might stimulate some thought and other comments on tailraces. I am not interested in participating in a point/counter-point discussion on such a complex topic.
Finally, let's bear in mind that "resource first" is not necessarily the same as "trout first." Changing a tailrace from warmwater to coldwater, and potentially damaging a perfectly good warmwater fish population, could easily be interpreted as being contrary to "resource first" guidance. Some anglers prefer good warmwater fishing.