11-18-2009, 07:03 AM
[url "http://www.und.nodak.edu/org/ndwild/carp.html"]http://www.und.nodak.edu/org/ndwild/carp.html[/url]
First, lets look at your posted article, which is a good one. It is a plan to restore a lake that is in a similar situation as UL. A few quotes from the intro of your article stand out.
" Their long lifespan (up to 15 years or more) and potential to reach a large size (up to 20 pounds or more) allow fish from strong year classes to grow steadily, rapidly at first, but more slowly later on as they become large and exceed natural limits of their food supply.
Eventually the reservoir is full of large, old carp whose reproductive success is poor, because the reservoir's carrying capacity for carp is reached. Although few young carp are added to the population, the damage was done when the strong year classes were produced."
Does this sound familiar?
Then:
" They can grow rapidly, and quickly reach a size too large for predation. This rapid growth permits a carp to live most of its 15 or more years without risk of predation. The carp's high fecundity (reproductive capacity) up to 2 million eggs in a 20-pound female and its adaptability to spawn in different situations gives it an edge over many native or preferred species. "
Then the article describes that the first line of carp removal was placing barriers to congregate carp during the spawn and treating the carp with rotenone. They then describe reducing numbers even further using drawdowns of the lake during spawning and rotenone bait stations. Only at the point when the carp population is low, yet the reproductive potential still present, does the paper describe using predation to keep the carp population low. (as you quoted yourself) However, predation was NOT used to initially drop the carp numbers in your paper.
This is basically also the JSRIP plan too. Once the aquatic vegetation is re-established, and there will be an expected spike in predatory fish species already there, whch hopefully will impact the very young carp fry and allow the other species (hopefully) to be able to compete better with the carp. The aquatic vegetation also will hopefully also allow the Junie fry to survive better naturally too.
A few more random points,
RE"Think strawberry. How many times was it poisoned? And what are the Cutts doing in there now?? "
Good example of a native (well, nearly native, Bear lake) fish introduced to control a prey species that co evolved with predatory cutts. (Utah chub) The match should work well. Additionally, when the cutts cannot eat fish, they can switch to smaller food sources and survive fine. I have caught a very large number of cutts up there this fall on my 3 trips and many of these were barfing up daphnia as I was unhooking them.
Contrast that to a system where there are too many predators, which is the common result of walleye or pike introductions in the West. All of the food is gobbled up and then crasho! Bad fishing for all species.
As for Yuba, besides being the poster lake for predator-prey crashes over the years, your own article explains what has happened there, you have a very large number of big carp that are simply too big for any predator, including pike to control. It wont matter if you plant more pike. Maybe if they could get the carp down by other means, then plant pike, you may have a chance, but Yuba has defied the best laid plans of many biologists over the years, and isn't going to change in its difficulty to manage.
Finally, from the second article.
"Combined methods such as rotenone treatment followed by stocking with carp predators succeeded at restoring clear waters for a year or two, but there is little information indicating success in the long term."
Believe me, the DWR would be all over predatory control of carp if they thought it would work. They did look at this along with many other possibilites when formulating the UL recovery plan.
P:S I do have some hope for a herpes vrus that controls carp though. i do't know if it was seriously considered at the time of the recovery plan, but may show promise.
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First, lets look at your posted article, which is a good one. It is a plan to restore a lake that is in a similar situation as UL. A few quotes from the intro of your article stand out.
" Their long lifespan (up to 15 years or more) and potential to reach a large size (up to 20 pounds or more) allow fish from strong year classes to grow steadily, rapidly at first, but more slowly later on as they become large and exceed natural limits of their food supply.
Eventually the reservoir is full of large, old carp whose reproductive success is poor, because the reservoir's carrying capacity for carp is reached. Although few young carp are added to the population, the damage was done when the strong year classes were produced."
Does this sound familiar?
Then:
" They can grow rapidly, and quickly reach a size too large for predation. This rapid growth permits a carp to live most of its 15 or more years without risk of predation. The carp's high fecundity (reproductive capacity) up to 2 million eggs in a 20-pound female and its adaptability to spawn in different situations gives it an edge over many native or preferred species. "
Then the article describes that the first line of carp removal was placing barriers to congregate carp during the spawn and treating the carp with rotenone. They then describe reducing numbers even further using drawdowns of the lake during spawning and rotenone bait stations. Only at the point when the carp population is low, yet the reproductive potential still present, does the paper describe using predation to keep the carp population low. (as you quoted yourself) However, predation was NOT used to initially drop the carp numbers in your paper.
This is basically also the JSRIP plan too. Once the aquatic vegetation is re-established, and there will be an expected spike in predatory fish species already there, whch hopefully will impact the very young carp fry and allow the other species (hopefully) to be able to compete better with the carp. The aquatic vegetation also will hopefully also allow the Junie fry to survive better naturally too.
A few more random points,
RE"Think strawberry. How many times was it poisoned? And what are the Cutts doing in there now?? "
Good example of a native (well, nearly native, Bear lake) fish introduced to control a prey species that co evolved with predatory cutts. (Utah chub) The match should work well. Additionally, when the cutts cannot eat fish, they can switch to smaller food sources and survive fine. I have caught a very large number of cutts up there this fall on my 3 trips and many of these were barfing up daphnia as I was unhooking them.
Contrast that to a system where there are too many predators, which is the common result of walleye or pike introductions in the West. All of the food is gobbled up and then crasho! Bad fishing for all species.
As for Yuba, besides being the poster lake for predator-prey crashes over the years, your own article explains what has happened there, you have a very large number of big carp that are simply too big for any predator, including pike to control. It wont matter if you plant more pike. Maybe if they could get the carp down by other means, then plant pike, you may have a chance, but Yuba has defied the best laid plans of many biologists over the years, and isn't going to change in its difficulty to manage.
Finally, from the second article.
"Combined methods such as rotenone treatment followed by stocking with carp predators succeeded at restoring clear waters for a year or two, but there is little information indicating success in the long term."
Believe me, the DWR would be all over predatory control of carp if they thought it would work. They did look at this along with many other possibilites when formulating the UL recovery plan.
P:S I do have some hope for a herpes vrus that controls carp though. i do't know if it was seriously considered at the time of the recovery plan, but may show promise.
[signature]