RE: Effects of Rotenone

[David Williams]

Title: Message

It's my understanding that the sunfish are thought to have washed out of some farm pond upstream, then made their way into the lake chain.  When a lake is rotenoned, some sunfish survive by hiding in the weeds and finding oxygen sources.  The survivors, since rotenone breaks down quickly, naturally repopulate the lake again.  The concentration of rotenone necessary to kill all the sunfish would likely kill everything else, vertebrates and invertebrates alike.  The choice seems to be to either continue a chemical treatment process every few years then restock or find a predator that will keep the sunfish population in check.  Personally, I would love to see more aggressive planting of brown trout. (Just imagine browns which have converted from an insect to a fish diet.  Think Hebgen Lake-sized browns.)  Having said that, there often is a problem for every solution-brown trout escaping into the Columbia where they begin to prey on salmon and steelhead fry/smolts.  Tiger trout might be a partial answer since they are supposed to be sterile, thereby limiting any damage they could do if they found their way into the Columbia.     David Williams The Williams Lawfirm 425.990.8800 [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Uncle Brad and Elly Sent: Saturday, May 15, 2004 1:04 PM To: [EMAIL PROTECTED] Subject: Re: Effects of Rotenone how does the undesirable species get into these lakes in the first place? does some unscrupulous individual/s carry in buckets of sunfish? what do they get out of it ? is sunfish supposed to be fun to fish for ? or did sombody just have an aquarium that they just didn't want to take care of anymore? if these are the reasons then the sunfish are a symptom rather than the real problem. BjR ----- Original Message ----- From: Don Kelly To: [EMAIL PROTECTED] Sent: Saturday, May 15, 2004 11:24 AM Subject: Re: Effects of Rotenone I surely don't think we're trying to help any fish, including trout, by poisoning them.  We're strictly trying to please sport fisherman by getting rid of the less desirable species (all trout and insects killed are an unavoidable bit of collateral damage) and restocking the more desirable species.   Regards,   Don Kelly ----- Original Message ----- From: Mark Steudel To: [EMAIL PROTECTED] Sent: Saturday, May 15, 2004 9:54 AM Subject: RE: Effects of Rotenone Hmmm, it seems just from this FAQ, that the fish we are trying to help are the most susceptible to this chemical. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dan Hall Sent: Friday, May 14, 2004 11:25 PM To: [EMAIL PROTECTED] Subject: Effects of Rotenone My interest in the effects of rotenone on insect life was sparked by the list discussion of the basin lakes so I did a web search and came up w/ this Oregon Dept of Fish and Wildlife site which answers many questions about this chemical.  It is an insecticide which has a profound effect on the treated water.    Dan   http://www.dfw.state.or.us/ODFWhtml/InfoCntrFish/DiamondLake/Rotenone.html     Excerpted claims:   Q. How does rotenone affect the environment? A. Rotenone is non-persistent so there is no accumulation in the water, soil, plants, or surviving animals. Because it breaks down so rapidly, its environmental significance does not extend beyond one year. For example, populations of aquatic invertebrates that have been reduced may take from several months to one year to recover to their former numbers. Surviving organisms will grow and reproduce at an accelerated rate due to reduced competition. While adult frogs and other amphibians would not be seriously affected, tadpoles and juvenile salamanders probably would be killed. For these species, it would be the next breeding season before more animals would be produced and the populations would be slower to recover. Q. How soon can we expect fishing to improve after a rotenone treatment? A. Fish stocking can begin as soon as biologists determine that it is safe to re-introduce fish. Generally, small fish are stocked because they are cheaper. This means more can be stocked but a longer time will be required for them to grow to catchable size. Depending on the growing season, most waters will have good fishing within two to three years after treatment. As a general rule, aquatic invertebrate populations return to pre treatment levels within several months to one year. Q. Is rotenone a selective pesticide? A. Although rotenone has some toxicity to all oxygen breathing animals, it is selective to fish at the concentrations used by fishery biologists. In general, most common aquatic invertebrates are less sensitive than fish to rotenone but some of the zooplankton are equally sensitive. Snails and clams are quite tolerant. With respect to fish, trout and salmon are the most sensitive, sunfish are less sensitive and catfish are the most resistant. Q. How does it work? A. Rotenone does not "suffocate" fish as was long believed. Instead, it inhibits a biochemical process at the cellular level making it impossible for fish to use oxygen in the release of energy needed for body processes. Q. Is it cost effective? A.  A Washington State researcher estimated that for each dollar spent on rotenone and stocked trout, anglers gained between $32 to $105 worth of fishing. On non treated trout lakes, the gain from fish stocking alone was between $10 to $15.