Piscicides, Toxicants, and Explosives

Reasons for using toxicants: Control undesirable fish in favor of sport species; e.g. suckers or carp Eradicate exotic species; e.g., snakehead Eradicate competitors Control fish diseases Restoration of endangered species

Toxicants for fish sampling Piscicides: fish poisons Only four registered with EPA: 1.Rotenone 2.Antimycin 3.Two lampricides TFM (3-trifluromethyl-4nitrophenol) Bayer 73 (2-aminoethanol salt of 2',5- dichloro-4'-nitrosalicylanilide) Must be applied by a certified pesticide applicator.

Most common; derived from root of derris plant (a legume) Blocks oxygen uptake across gills - > suffocation 1 gal/acre-ft = 3 ppm 2.5-5% liquid Powder form: difficult to get into suspension; shelf life is limited Toxic ~10 days at 70-75ºF (longer at colder temperatures) Effectiveness is function of species, size, water temperature, pH, O 2, suspended matter Rotenone

Pros and Cons of Rotenone Samples entire community Low selectivity Works well in shallow areas Immediate detoxification with potassium permanganate (KMnO 4 ) Most fish are ‘sacrificed’ Negative public perception Non-target species: swine, zooplankton, many invertebrates Drinking water concerns Potassium permanganate toxicity

Cove rotenone sampling-most common in SE U.S. Administration of rotenone-mixing with prop wash.

Protocol for rotenone cove sampling: 1.determine cove volume 2.set block net (typically 3/8" mesh w/ 1/4" mesh float collar) pre-dawn or previous day 3.apply dilute solution w/pump at net and deep areas first; hand-spray littoral zone 4.Three day pickup and data collection schedule: day 1: species, length, weight day 2: species, length day 3: species

Block seine contains floating dead fish.

Collecting poisoned fish.

Evaluation of Cove Rotenoning Pro: allows estimation of standing crop (lb/acre or kg/ha) Biases: typically conducted in late summer, so may not get true species composition or true size structure for populations Scuba shows that 75% of total number and 95% of biomass will surface in 3 days Use is declining because of concerns over fish mortality

Stream Rotenoning Primarily in warm water streams Use block nets Determine velocity and make calculations Use potassium permanganate, KMnO 4, drip at lower end to detoxify

Antimycin Antibiotic from the fungus Streptomyces Sold as Fintrol Inhibits respiration at cytochrome level Toxicity decreased by high alkalinity, temperature, sunlight Detoxified with potassium permanganate Affects fish selectively: can be used to ‘clean out’ catfish ponds, as it will eliminate cyprinids, catostomids, percids and centrarchids

Lampricides

Lampreys ascend streams to spawn

Injecting lampricide into sediments to reach ammocoetes.

Explosives

Sampling with Explosives Detonating cord (PrimaCord), dynamite Typically used only when any other technique is difficult to apply – e.g., too much debris, timber, etc., cannot use seines, gill nets, or hoop/trap nets – low conductivity--cannot use electrofishing – remote area limits amount of gear Safety!! Likely will be quite a few requirements