Thousands of Dead Fish Pulled from Lake Davis (16,000 gallons of toxin poured in by state)

[The Straight Story]

Thousands of Dead Fish Pulled from Lake Davis

PORTOLA (AP) -- California officials have completed the grim task of collecting fish killed in last month's poisoning of a Sierra Nevada lake to exterminate the northern pike.

California Department of Fish and Game crews gathered nearly 50,000 pounds of fish since September 21st, when 16,000 gallons of a toxic chemical were poured into Lake Davis near Portola.

Northern pike, which wildlife experts believe were carried to Lake Davis by anglers from outside the state in the 1980s, decimated the lake's famous trophy trout.

California first poisoned Lake Davis in 1997 but pike reappeared 18 months later.

http://www.news10.net/display_story.aspx?storyid=34420

[acmavm]

1. WTF? Does anyone besides me think this is crazy? Too bad about the

'prize' trout, I'm sorry. But to poison the lake?

[niyad]

2. I thought I was the only one-- how on earth is poisoning the lake going to help the trout? or any

of the other aquatic denizens? do people swim in this lake?

[Adsos Letter]

3. LOTS of folks protested this the first time we went through it...

[Submariner]

4. As a fisheries biologist I have used Rotenone before

It is not a toxic chemical that can harm humans by absorption in the skin. It only affects the gill functions of fish to smother them and is used regularly by state fish & game departments to rid lakes and ponds of undesirable fish species.

The northern pike is a voracious predator that upsets the natural biodiversity of water bodies they are introduced. Once it dissipates the lake/pond can be restocked with native species.

It is too bad that it has to be done, but idiot sport fishermen not knowing what they are doing to the local ecology bring this burden to the state biologists that have to remedy the problem with rotenone.

[niyad]

5. thank you for that information.

[msmcghee]

6. You are correct.of course. Thanks. Esp. about rotenone not being . .

. . a toxin in the usual sense. As one would expect from a fisheries professional. It has no effect on humans, or any animals that don't have gills. Also, Northern Pike are not indigenous west of the Rocky Mountains / continental divide. On this side of the divide aquatic ecosystems have evolved since the last ice age around trout / salmon / char species.

Idiots from the mid-west prairie states keep planting species like Northern Pike and Walleye Pike in our waters where they are totally unmatched to the existing food base, aquatic insects, crustaceans, etc. The only way to restore the balance is to kill all the fish in the lake and then try to restore things by planting native species. Like most man-made problems - real solutions are difficult and complicated and will not be resolved by reacting to emotional catch phrases like "poisoning the poor fish".

Brown trout that have been planted here though are also not native to this region. Cutthroat, rainbow, bull trout are. Large mouth bass is another widely planted non-native species. I heard they were brought out in buckets from the east during the railroad expansion by crews who would toss them into ponds along railroad right-of-way - so they could fish for their dinner in the future.

[Submariner]

7. Striped bass were also shipped from the east coast

and transplanted into the San Francisco Bay and Sacramento River drainages as a food fish source in the 1800's when, as you say, railroads stretched to the west coast.

You're spot on about brown trout. They are very aggressive and will out-compete rainbow trout and brook trout for food. The rainbows will become especially stunted in growth if brown trout are in the system.

I was surprised to see Northern Pike in the tundra ponds of southwest Alaska (Lake Iliamna) region a few years back. They have out-competed Dolly Varden and other salmonid species in many of Alaska's interior watersheds.

[acmavm]

8. Factsheet: Rotenone

Rotenone
A recent study linking rotenone – a pesticide with a ‘natural’ image, commonly used in organic farming and gardening – to Parkinson’s disease, has increased demand for a level playing field in the safety assessment of pesticides. The current regulatory system, designed for synthetic agrochemicals, impedes research into, and registration of, least toxic, relatively benign pest control substances.

<snip>

Acute toxicity
Rotenone is classified by the World Health Organisation as a moderately hazardous, Class II(18). The LD50 for rats (the amount of the chemical lethal to one-half of experimental animals) is between 132 and 1,500 mg per kilogram(19). One factor in this wide variation may be the differences in the plant extracts used(20).
The acute oral toxicity of rotenone is moderate for mammals, but there is a wide variation between species(21). It is less toxic for the mouse and hamster than for the rat; the pig seems to be especially sensitive. Recent studies have shown that in rats, rotenone is more toxic for females than males. It is highly irritating to the skin in rabbits(22), and to the eyes. In rats and dogs exposed to rotenone in dust form, the inhalation fatal dose was uniformly smaller than the oral fatal dose(23).
Rotenone is believed to be moderately toxic to humans with an oral lethal dose estimated from 300 to 500 mg/kg(24). A lowest lethal dose of 143 mg/kg has been cited in a child(25). Clinical experience seems to indicate that children, in particular, are rather sensitive to the acute effects of rotenone(26).
Human fatalities are rare, perhaps because rotenone is usually sold in low concentrations (one to five per cent formulation), and because its irritating action causes prompt vomiting. If the dust particle size is very small, and can enter deep regions of the lungs, rotenone’s toxicity when inhaled may be increased. Acute local effects include conjunctivitis, dermatitis, sore throat, congestion, and vomiting. Inhalation of high doses can cause increased respiration followed by depression and convulsions(27). On the basis of rabbit studies, absorption through the intact skin is low(28).

http://www.pan-uk.org/pestnews/Actives/rotenone.htm