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Unwanted or weed fish in aquaculture pond may affect the growth and development of cultured fish species. The current investigation aimed to assess the piscicidal effect of five commercial toxicants on weed fish, Nile tilapia (Oreochromis niloticus) for a short period. The fish was exposed to four concentrations (0.5, 1.0, 1.5, and 2.0 ppm) of dimethoate, pyrethroid lambda-cyhalothrin, cypermethrin, malathion, and Chillas along with control (without any toxicants) during a 48-hour static bioassay. Fish mortality and physicochemical parameters i.e., pH and dissolved oxygen (DO) of water were checked after every 8 hours. The pH of water varied from 3.46to 6.5 and DO range 2.70-5.66 during all experiments. After 48 hours of exposure, the maximum fish mortality was achieved by dimethoate (4.15, 8.30%), cypermethrin (4.16, 8.32%), malathion (4.0, 8.00%), and Chillas (4.0, 8.00%) at the highest applied concentration (2.0 ppm). While pyrethroid lambda-cyhalothrin showed the highest mortality at 1.5 ppm (4.16) with 8.32% as well as on 2.0 ppm (4.16, 8.32%). In conclusion, pyrethroid lambda-cyhalothrin was observed as the best toxicant as piscicide causing overall higher mortality on all applied concentrations. However, the long-term experiment is further needed to clarify the mortality trend and optimization of toxicants in a long-term experiment.

The toxic unit and additive index approaches were used to understand how 2 pesticides, 3‐trifluoromethyl‐4‐nitrophenol (TFM) and 2,5‐dichloro‐4‐nitrosalicylanilide (niclosamide; Nic), interact in mixtures. Our first objective was to determine whether the interaction was strictly additive or greater than additive at doses comparable to those used to control invasive sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes, and our second was to compare the utility of the toxic unit and additive index models for determining how TFM and Nic interacted. Typically, TFM is mixed with Nic (1–2%, w/v) to increase its potency and reduce TFM use. However, there is little information on how the 2 chemicals interact. Using a well‐studied, resident nontarget fish, the rainbow trout (Oncorhynchus mykiss), we conducted toxicity tests with TFM, Nic, and TFM:Nic (100:1, w/v; TFM/1% Nic) mixtures over 12 h to determine if the interaction was strictly additive, less than additive (antagonistic), or greater than additive (synergistic). The toxic unit and additive index approaches indicated synergistic interactions at environmentally relevant concentrations, suggesting that both are valid approaches for predicting how TFM and Nic interact. The toxic unit approach was simpler to conceptualize and to calculate, and we recommend that it be used when describing how TFM and Nic, and other similar organic compounds, interact with each other in aquatic ecosystems. Environ Toxicol Chem 2021;40:1419–1430. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Histopathological manifestation of castor bean seed as fish toxicant upon gastro-intestinal system of Tilapia (Oreochromis mossambicus) was investigated parallel with mohua oil cake as haemotoxic piscicidal agent in outdoor experimental tanks. Castor seed bean was proved to be an effective piscicide with activity potential comparative with mohua oil cake though the mortality rate was higher and quicker in the later. As plant derived toxicant castor bean exhibited strong histopathological lessions in intestinal mucosa and liver whereas, mohua oil cake exhibited severe respiratory distress to the test fish. Significant reduction of dissolved oxygen and concurrent increase in BOD1 of water under both the piscicides aggravated the distress of the test fish.

Carbon dioxide (CO2 ) has been approved by the US Environmental Protection Agency as a new aquatic pesticide to control invasive Asian carps and other aquatic nuisance species in the United States. However, limited CO2 toxicity data could make it challenging for resource managers to characterize the potential risk to nontarget species during CO2 applications. The present study quantified the toxicity of CO2 to 2 native riverine fishes, bluegill (Lepomis macrochirus) and fathead minnow (Pimephales promelas), using 12-h continuous flow-through CO2 exposure at 5, 15, and 25 °C water temperatures. Resulting survival indicated that bluegill (median lethal concentration [LC50] range 91-140 mg/L CO2 ) were more sensitive to CO2 than fathead minnow (LC50 range 235-306 mg/L CO2 ) across all water temperatures. Bluegill were also more sensitive to CO2 at 5 °C (LC50 91 mg/L CO2 , 95% CI 85-96 mg/L CO2 ) than at 25 °C (LC50 140 mg/L CO2 , 95% CI 135-146 mg/L CO2 ). Fathead minnow showed an opposite response and were less sensitive at 5 °C (LC50 306 mg/L CO2 , 95% CI 286-327 mg/L CO2 ) relative to 25 °C (LC50 235 mg/L CO2 , 95% CI 224-246 mg/L CO2 ). Our results show that CO2 toxicity can differ by species and water temperature. Data from the present study may inform decisions related to the use of CO2 as a control tool. Environ Toxicol Chem 2020;39:2247-2255. Published 2020. This article is a U.S. government work and is in the public domain in the USA.

Purpose This study aims to evaluate the effect of Piper betle leaf extract towards the acute-lethal toxicity, LC50 of red Nile tilapia juveniles (Oreochromis niloticus). Design/methodology/approach Ten red Nile tilapia juveniles per tank (in triplicate) were used as an experimental fish for the LC50 bioassay. Five different concentrations of P. betle extract; 80 ppm, 90 ppm, 100 ppm, 110 ppm and 120 ppm, were tested on the red Nile tilapia juveniles and one tank was acting as a control. The progress of the LC50 and lethal time of fish mortality were observed and recorded within the random interval of 96 h. The value for LC50 was determined as 100 ppm of P. betle leaf extract. Higher number of fish mortalities was observed when concentration higher than 100 ppm was tested on to the red Nile tilapia juveniles. Findings Data obtained shows that the P. betle concentration of 120 ppm accelerated the fish mortality period. Originality/value However, adaption of P. betle extract occurred after 50 h, as there was no fish mortality observed within the time.

Rotenone ([2R-(2α,6aα,12aα)]-1,2,12,12a-tetrahydro-8,9-dimethoxy-2-(1-methylethenyl)-[1]benzopyran[3,4-b]furo [2,3-h][1]benzopyran-6(6aH)-one) is a naturally occurring compound derived from the roots and stems of Derris, Tephrosia, Lonchocarpus and Mundulea plant species. Since its discovery at the end of the 19th century, rotenone has been widely used as a pesticide for controlling insects, ticks and lice, and as a piscicide for management of nuisance fish in lakes and reservoirs. In 2000, Betarbet et al. reproduced most of the behavioural, biochemical and pathological features of Parkinson's disease (PD) in rotenone-treated rats. Since that time, rotenone has received much attention as it would be one of the environmental neurotoxins implicated in etiopathogenesis of PD. Moreover, it represents a common experimental model to investigate the underlying mechanisms leading to PD and evaluate the new potential therapies for the disease. In the current general review, we aimed to address recent advances in the hazards of the environmental applications of rotenone and discuss the updates on the rotenone model of PD and whether it is implicated in the etiopathogenesis of the disease.

Rotenone, a naturally occurring isoflavone compound, is applied to water as a piscicide to manage undesired fish populations in lakes, ponds, rivers and in aquaculture. A rapid and sensitive method based on solid-phase extraction (SPE) combined with large-volume sample stacking with polarity switching (LVSS) and micellar electrokinetic chromatography (MEKC) has been developed for the identification and quantification of rotenone in lake water. Several experimental parameters for MEKC, LVSS and SPE were investigated to achieve the optimum conditions necessary for the analysis. The optimized conditions which included a background electrolyte containing 20 mM sodium borate and 25 mM sodium dodecyl sulfate (SDS) at pH 10 were used to successfully detect rotenone within 17 min. Using a combined SPE and LVSS approach, the rotenone signal was enhanced by 1000-fold compared with a normal capillary electrophoresis analysis, and limits of detection and quantification obtained were 3 and 10 μg L−1, respectively. The calibration curve was linear for rotenone concentration over the range of 10–100 μg L−1 and the method was highly reproducible with the relative standard deviation of the peak areas and migration times for method intra-day repeatability (n = 6) found to be 5.4% and 0.6%, respectively. Quantitative recoveries ranging from 85 to 88% were obtained in the lake water matrices. The potential of the proposed method to be used for quantitative determination of rotenone at trace level concentrations in water samples was demonstrated by analyzing lake water samples including surface (1 m) and bottom (13 m), which makes it a suitable practical method for analyzing rotenone residues in water.

The invasion of the Laurentian Great Lakes of North America by sea lampreys (Petromyzon marinus) in the early 20th century contributed to the depletion of commercial, recreational and culturally important fish populations, devastating the economies of communities that relied on the fishery. Sea lamprey populations were subsequently controlled using an aggressive integrated pest-management program which employed barriers and traps to prevent sea lamprey from migrating to their spawning grounds and the use of the piscicides (lampricides) 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide to eliminate larval sea lampreys from their nursery streams. Although sea lampreys have not been eradicated from the Great Lakes, populations have been suppressed to less than 10% of their peak numbers in the mid-1900s. The ongoing use of lampricides provides the foundation for sea lamprey control in the Great Lakes, one of the most successful invasive species control programs in the world. Yet, significant gaps remain in our understanding of how lampricides are taken-up and handled by sea lampreys, how lampricides exert their toxic effects, and how they adversely affect non-target invertebrate and vertebrates species. In this review we examine what has been learned about the uptake, handling and elimination, and the mode of TFM and niclosamide toxicity in lampreys and in non-target animals, particularly in the last 10 years. It is now clear that the mode of TFM toxicity is the same in non-target fishes and lampreys, in which TFM interferes with oxidative phosphorylation by the mitochondria leading to decreased ATP production. Vulnerability to TFM is related to abiotic factors such as water pH and alkalinity, which we propose changes the relative amounts of the bioavailable un-ionized form of TFM in the gill microenvironment. Niclosamide, which is also a molluscicide used to control snails in areas prone to schistosomiasis infections of humans, also likely works by uncoupling oxidative phosphorylation, but less is known about other aspects of its toxicology. The effects of TFM include reductions in energy stores, particularly glycogen and high energy phosphagens. However, non-target fishes readily recover from sub-lethal TFM exposure as demonstrated by the rapid restoration of energy stores and clearance of TFM. Although both TFM and niclosamide are non-persistent in the environment and critical for sea lamprey control, increasing public and institutional concerns about pesticides in the environment makes it imperative to explore other means of sea lamprey control. Accordingly, we also address possible "next-generation" strategies of sea lamprey control including genetic tools such as RNA interference and CRISPR-Cas9 to impair critical physiological processes (e.g. reproduction, digestion, metamorphosis) in lamprey, and the use of green chemistry to develop more environmentally benign chemical methods of sea lamprey control.

Comparative evaluation of mahua (Bassia latifolia) oil cake (MOC) and castor bean (Ricinus communis) seed (CBS) was tested as piscicides for tilapia (Oreochromis mossambicus) and panchax (Aplocheilus panchax), and residual toxicity test was done on Labeo bata. Delayed response of CBS compared with MOC was evident as first and total mortality of tilapia was encountered at 4th and 10th hour of application, against 26 hr and 42 hr in panchax respectively. Susceptibility of the test fish to the piscicides was highly variable as tilapia was more susceptible than panchax under both the piscicides tested especially in CBS. Residual toxicity decreased polynomialy over time (R² ≥ 0.99) and reduced to below 10% on day 13–14 in both MOC and CBS treatments. Both MOC and CBS contributed positively to the nutrient pool of water in which CBS provided more nitrogen compared with MOC. N: P ratio of water in CBS treatment increased exponentially to more than 18 indicating phosphorus limitation.

Mortality and behavioral alterations are monitored as the sensitive endpoints in toxicological studies and may be applied as useful biomarkers to assess piscicidal pollution in aquatic environment. Present study assesses acute toxicity of the piscicide, mahua oil cake (MOC), and its effect on the behavioral responses of the freshwater grapsid crab, Varuna litterata, under laboratory conditions. To determine the LC50 values, a 4-day acute static renewal toxicity test was done where 10 adult male crabs (mean length 2.870 ± 0.379 cm; mean weight 9.891 ± 3.951 g) were exposed to different concentrations (1, 5, 10, 15, 20, 25, 30, 35 ppt) of MOC aqueous extract with a control at different exposure periods. The LC50 values are 19.109 ppt for 24 h, 16.052 ppt for 48 h, 11.827 ppt for 72 h, and 7.631 ppt for 96 h. The high LC50 values indicate less sensitivity of this crab to the MOC extract than other aquatic animals. MOC extract has toxic effect on the mouthparts activity, whirling motion of water current producing activity, froth releasing activity, aggregation, balance and coordination actions, medium escaping behavior, locomotor activity, and fecal matter excretion of this crab in different exposure periods. Behavioral responses such as froth releasing activity, aggregation, and medium escaping behavior can be used as biomarkers of MOC pollution in aquatic environment.

A 96 h static toxicity bioassay was carried out to examine fish responses and to determine the median lethal concentration (LC50) of Balanites aegyptiaca stem bark extract on adults of Brycinus nurse, Labeobarbus bynni and Labeobarbus intermedius. Experimental fish were exposed to piscicide plant extract of 0.0 (control), 15.0, 17.5, 20.0, 22.5, and 25.0 mgL-1. Fish exposed to these extracts except the control showed symptoms of toxicity including darting, agitated swimming, air gulping, loss of sensitivity and knockdown before death. These responses were much frequent and faster in L. bynni and L. intermedius. The 96 h LC50 values for the different test fishes were 18.99, 20.72 and 20.72 mg L-1 for L. bynni, L. intermedius and B. nurse, respectively. Based on the present investigation, we can conclude that the application of B. aegyptiaca extract causes lethal toxic effects on different fishes even at low concentrations and hence, indiscriminate use of the plant for fishing should be discouraged and regulated in order to protect fish biodiversity lose in the Alitash National Park area. Key words: Alitash National Park (ALNP), Balanites aegyptiaca, floodplain rivers, piscicide, toxicity, LC50.

In 1992, a sampling crew from a multiagency group discovered a population of Bull Trout Salvelinus confluentus estimated at approximately 50 individuals in Threemile Creek, Oregon threatened with competition and hybridization with nonnative Brook Trout Salvelinus fontinalis. The group implemented Brook Trout and Bull Trout × Brook Trout hybrid removal using multiple techniques to conserve this population of Bull Trout in the Klamath River basin. From 1996 to 2000, backpack electrofishing and night snorkel spearing were used upstream of a culvert barrier to eradicate Brook Trout and hybrid trout from a 3.59-km section of Threemile Creek over 101 total days of effort (274 person-days of effort). Night snorkel spearing removed a lower percentage (7%) of target fish relative to electrofishing (93%), although this technique eliminated the risk of electrofishing injury to Bull Trout. Concurrent with the reduction and subsequent removal of Brook Trout, Bull Trout observations increased over 15-fold from 19 in 1996 to 299 in 2012 and Bull Trout distribution more than doubled, from 1.48 to 3.43 km during that same time. Immediately downstream in a separate 2.3-km section, the group eradicated Brook Trout using backpack electrofishing and rotenone application upstream of two man-made barriers from 2004 to 2010 over 43 total days of effort (150 person-days of effort). By 2016, Bull Trout had expanded their distribution throughout the upper 3.59-km section of Threemile Creek. Effort expended to eradicate Brook Trout was similar to successful eradication in other streams with comparable habitat characteristics and similar treatment length (< 3.0 km). However, similar removal attempts have not been successful in streams with comparable habitat characteristics that had longer treatment length (> 7.0 km). Application of piscicide may be more cost effective than manual techniques to remove Brook Trout when there is no risk to native fish of conservation concern, where target species are allopatric, and when piscicide use is publicly accepted. Brook Trout eradication proved valuable in providing Bull Trout the opportunity for range expansion and increased abundance necessary for recovery in the Klamath River basin.

The piscicide CFT Legumine is applied to freshwater systems around the world to control invasive fish species. Rotenone, a potent inhibitor of mitochondrial cellular respiration, is the active ingredient of the piscicide; however, other rotenoids of unknown persistence and toxicity account for an equivalent amount by weight. This work identified six distinct rotenoids in CFT Legumine using liquid chromatography coupled with high-resolution orbitrap mass spectrometry and optimized a rapid surface water sampling procedure for their analysis. The rotenoids were identified as rotenone and its isomer deguelin, their 12α-hydroxylated products rotenolone and tephrosin, as well as 6α,12α-dehydrorotenone and 6α,12α-dehydrodeguelin. The optimized procedure, extraction with Spin-X nylon membrane microcentrifuge filters followed by elution with acetonitrile, achieved recoveries ranging from 101 to 107% and 97 to 145% for all six rotenoids at high (125 nM, ~ 50 ppb) and low (25 nM, ~ 10 ppb) concentrations of CFT Legumine, respectively. Overall, this method provides a rapid sampling procedure necessary for monitoring rotenoid persistence in surface water to ensure safe and efficacious application of the pesticide.

The direct and indirect photochemical degradation of rotenone (ROT) and deguelin (DEG), the primary reduced nicotinamide adenine dinucleotide-inhibiting rotenoid components of the piscicide CFT Legumine, were investigated under simulated sunlight conditions relevant to their dissipation from high-latitude surface waters. Photochemical degradation dominated the elimination of ROT and DEG from surface waters with half-lives ranging from 1.17 to 2.32 and 4.18 to 20.12 h for DEG and ROT, respectively, when the rotenoids were applied in the formulation CFT Legumine. We assessed enhanced degradation processes using argon-purged and cesium chloride-amended water, which demonstrated the rotenoids to rapidly decompose from excited triplet states. We further assessed the influence of reactive oxygen species by hydroxyl radical quenching and thermal generation of singlet oxygen. The studied reactive oxygen species did not significantly contribute; however, alcohols such as isopropanol may inhibit degradation by quenching ROT excited states or preventing intersystem crossing. Finally, we compared photochemical degradation in water collected from Hope Lake, Alaska, to a solution of Suwanee River fulvic acids, which demonstrated that dissolved organic matter (DOM) quality is a major factor that modulates ROT attenuation through a combination of shielding (light attenuation) and excited-state quenching mechanisms and is temperature-dependent. Molecular-level characterizations of DOM may help account for the site-specific degradation of these rotenoids in the environment.

Mahua oil cake (MOC), a derivative of the seeds from Bassia latifolia is used as a piscicide in pre-stocking pond preparation for composite fish culture. However, for its nutritional potency MOC is used as a protein substitute in the formulated diets for fish, poultry and cattle. In present experiment piscicidal potency of Acacia pericarp preparation (APP) has been evaluated to get a substitute of MOC. LC-ESI-MS analysis of the methanolic extract of Acacia auriculiformis pericarp revealed seven triterpenoid saponins (acaciasides), twenty two flavonoids, eight tannins and a phenolic rich fraction- gallyl glucose. In the present experiment Minimum lethal concentration, LC50 and LC100 of APP were worked out through static bioassay and subsequent probit analyses putting trial upon nine potential predator fishes viz. Channa punctatus (Bloch), Channa gachua (Hamilton), Channa striata (Bloch), Clarias batrachus (Lin), Clarias gariepinus (Burchell), Heteropneustes fossilis (Bloch), Anabas testudineus (Bloch), Notopterus notopterus (Pallas) and Wallago attu (Bloch & Schneider). Among the native species C. striata exhibited its toxicological response with higher Minimum lethal concentration (70 ppm), LC50 (78.7 ppm) and LC100 (90 ppm). Toxicological response of the exotic species C. gariepinus however, were found to be with highest LC50 (98.4 ppm) and LC100 (130 ppm). On the basis of toxicological response of different predator species the piscicidal application concentration of APP has been recommended in reference to LC100 of C. striatus. However, if the exotic species C. gariepinus is present in the system, APP application should be made with reference to LC100 to this species. Kaplan-Meier analysis on survivality of fish under exposure was performed to justify the results of the bioassay experiments. APP has the least effect on non-target invertebrate organisms of the aquatic body. Application of APP results in improving soil nutrients such as NPK and organic carbon. The result of the study revealed that Acacia pericarp could be a better substitute of MOC as a piscicide.

Plants and plant products are constituent parts of the inventory of drugs since time immemorial. Millettia pachycarpa (Family: Fabaceae) is widely seen in India, Bangladesh, Bhutan, Myanmar, China, Taiwan, and Japan. The plant is used as anticancer, agricultural pesticide, blood tonics, anti-infertility, anthelmintic, piscicide, and kidney disorder and also to manage fish nursery. Anthelmintic and piscicidal properties of root peel, insecticidal potential of the seed, and antifeedant properties of the leaf of the plant have been established. Phytochemicals recovered from M. pachycarpa reveal to be millepachine; daidzein; genistein; wighteone; alpinumisoflavone; pomiferin; warangalone; auriculasin; 6,8-diprenylorobol; furowanin A; isoerysenegalensein E; erysenegalensein E; 17β-estradiol; 4-hydroxytamoxifen; 4-hydroxylonchocarpin; barbigerone; 13-homo-13-Oxa-6a, 12a-dehydrodeguelin; tephrosin; deguelin; 4′,5′-dimethoxy-6,6-dimethylpyranoisoflavone; 6a,12a-dehydrodeguelin; phenylated isoflavone; dihydroflavonol; lupinifolol; cis-12a-hydroxyrotenone; rot-2′-enonic acid; cis-12′-enonic acid; 5,7,4′-tetrahydroxy-6,8-diphrnyl isoflavones; 5,7,3′,4′-tetrahydroxyl-6,8-diphenylisoflavone; phenylated chalcone; 6″-dimethyl-ranoisoflavone; millewanin G; millewanin H; furowanin B; 4-methoxylonchocarpin; isobavachromene; and dorspoinsettifolin. Anticancer, antifungal, antibacterial, anthelmintic, anti-inflammatory, anti-diabetic, antiestrogenic, as well as estrogenic activities of some of these isolated compounds of the plant have already been established. This article reviews the pharmacological properties of crude extract and 12 major phytochemicals recovered from M. pachycarpa.

Restoration of fisheries often requires removal of invasive fishes. Although piscicides such as antimycin a and rotenone are reliable and cost‐effective tools for such removals, they may reduce the abundance of nontarget species directly via toxicity‐induced mortality (toxic effect) or indirectly via loss of prey (trophic effect). Toxic effects are well documented in some taxa, especially in benthic macroinvertebrates (BMIs). Yet, the corresponding trophic effects on nonpiscine, aquatic, and riparian species remain unstudied. I tested for a trophic effect of piscicides using a population of American Dippers (Cinclus mexicanus), songbirds that feed extensively on BMIs. I caught breeding birds and estimated body condition before, during, and after treatment of the stream with antimycin a or rotenone. Birds exhibited poorer body condition (3.0–3.7% lower body mass) during treatment than before or after treatment. These differences suggested that treatment reduced prey availability enough to impact birds at least 9 months after application. Therefore, continued use of piscicides for fish restoration would benefit from (1) site‐specific comparison of benefits of invasive fish removal to costs of potential or documented toxic and trophic effects of piscicides on nontarget organisms; (2) continued adherence to best practices for recovery of the BMI community after piscicide treatment; and (3) experimental study of piscicide impacts.

Invasive sea lamprey (Petromyzon marinus) are controlled in the Great Lakes using the lampricide 3-trifluoromethyl-4-nitrophenol (TFM), which is applied to streams infested with larval lamprey. However, lamprey that survive treatments (residuals) remain a challenge because they may subsequently undergo metamorphosis into parasitic juvenile animals that migrate downstream to the Great Lakes, where they feed on important sport and commercial fishes. The goal of this study was to determine if body size and life stage could potentially influence sea lamprey tolerance to TFM by influencing patterns of TFM uptake and elimination. Because mass specific rates of oxygen consumption (M˙O2) are lower in larger compared to smaller lamprey, we predicted that TFM uptake would be negatively correlated to body size, suggesting that large larvae would be more tolerant to TFM exposure. Accordingly, TFM uptake and M˙O2 were measured in larvae ranging in size from 0.2-4.2g using radio-labelled TFM (14C-TFM) and static respirometry. Both were inversely proportional to wet mass (M), and could be described usingthe allometric power relationship: Y=aMb, in which M˙O2=1.86M0.53 and TFM Uptake=7.24M0.34. We also predicted that body size would extend to rates of TFM elimination, which was measured following the administration of 14C-TFM (via intraperitoneal injection). However, there were no differences in the half-lives of elimination of TFM (T 1/2-TFM). There were also no differences in M˙O2 or TFM uptake amongst size-matched larval, metamorphosing (stages 6-7), or post-metamorphic (juvenile) sea lamprey. However, the T1/2-TFM was significantly lower in larval than post-metamorphic lamprey (juvenile), indicating the larval lamprey cleared TFM more efficiently than juvenile lamprey. We conclude that larger larval sea lamprey are more likely to survive TFM treatments suggesting that body size might be an important variable to consider when treating streams with TFM to control these invasive species.

Invasive fish eradication is a key management strategy in aquatic ecosystems, and is often accomplished using piscicides such as rotenone. However, the effects of piscicides on aquatic invertebrate communities are poorly understood, particularly over long time scales. We monitored invertebrate communities in two treatment and two reference streams prior to and for one year following the use of rotenone to eradicate trout in Zealandia wildlife sanctuary, Wellington. Immediately following treatment, invertebrate density and taxonomic richness declined significantly, and community composition diverged markedly relative to reference streams, with pollution sensitive taxa declining greater than more tolerant taxa. Treatment streams recovered to pre-treatment conditions within 4–12 months of rotenone application, indicating minor long-term impacts on invertebrate communities. Speed of recovery of individual taxa appeared to be associated with life history variables, e.g. generation times and dispersal a...

Amphibians may experience collateral effects if exposed to CFT Legumine (5% rotenone), a piscicide that is used to remove invasive fish. A series of 48-h static toxicity tests assessed the acute effects of CFT Legumine on multi-aged tadpoles of the federally listed Chiricahua leopard frog Lithobates chiricahuensis, the widespread northern leopard frog L. pipiens, and the increasingly invasive American bullfrog L. catesbeianus. At the earliest Gosner stages (GS 21–25), Chiricahua leopard frogs were more sensitive to CFT Legumine (median lethal concentration [LC50] = 0.41–0.58 mg/L) than American bullfrogs (LC50 = 0.63–0.69 mg/L) and northern leopard frogs (LC50 = 0.91 and 1.17 mg/L). As tadpoles developed (i.e., increase in GS), their sensitivity to rotenone decreased. In a separate series of 48-h static nonrenewal toxicity tests, tadpoles (GS 21–25 and GS 31–36) of all three species were exposed to piscicidal concentrations of CFT Legumine (0.5, 1.0, and 2.0 mg/L) to assess postexposure effects on...

The sharptooth catfish Clarias gariepinus is an emerging global invader for which control strategies might include the use of piscicides such as rotenone. Experimental exposure demonstrated that C. gariepinus was less susceptible to rotenone than most other fish species, with unexpected survival observed at rotenone concentrations of 87.5 and 100 µg L−1. C. gariepinus were also observed exhibiting avoidance behaviour to rotenone treated water and were found to be capable of recovering from rotenone exposure. As such, effective eradication might not be attainable even at a dose exceeding 100 µg L−1 with exposures of longer than 24 h. This exposure scenario may pose an unacceptable risk to non-target fauna and highlights the difficulty associated with managing current and future invasions.

A piscicide, rotenone (RT), is frequently used for clear and management of aquatic systems such as fish pond, and even for illegal fishing throughout the world. The effects of RT on submerged macrophytes remain elusive although the effects of RT on many kinds of animals are well documented. We wanted to determine the effects of RT on the growth and metabolism of three submerged plants (Vallisneria natans, Myriophyllum spicatum, Potamogeton maackianus) and try to find the reasons of these effects. The results showed that the shoot height, shoot dry weight, root dry weight, root:shoot ratios, contents of soluble protein and soluble carbohydrate of the three tested submerged plants were significantly negatively affected by RT and the effects were different among the studied species. Furthermore, pH rised a little and light transmission was greatly reduced in the water with RT treatment. We think that the negative effects of RT on the growth and metabolism of submerged species is partially attributing to the lower light caused by RT application. Accordingly, we highlight that submerged species may be greatly suppressed by RT, and we should apply RT in water ecosystems with great caution.

The distributions of most native trout species in western North America have been severely reduced, and conservation of many of these species will require translocation into vacant habitats following removal of nonnative species. A critical question managers have is “Does it matter which donor sources are used for these translocations?” We present a case study that addressed this question for a large native trout translocation project in Montana. We introduced embryos from five source populations of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi to a large, fishless watershed in Montana following removal of nonnative fish with piscicides. Source populations providing embryos for translocations were three nearby ( 350 km from the translocation site), and a population in captivity for one generation comprised of i...

In December 2009, during a piscicide treatment targeting the invasive Asian carp in the Chicago Sanitary and Ship Canal, Rhodamine WT dye was released to track and document the transport and dispersion of the piscicide. In this study, two modeling approaches are presented to reproduce the advection and dispersion of the dye tracer (and piscicide), a one-dimensional analytical solution and a three-dimensional numerical model. The two approaches were compared with field measurements of concentration and their applicability is discussed. Acoustic Doppler current profiler measurements were used to estimate the longitudinal dispersion coefficients at ten cross sections, which were taken as reference for calibrating the longitudinal dispersion coefficient in the one-dimensional analytical solution. While the analytical solution is fast, relatively simple, and can fairly accurately predict the core of the observed concentration time series at points downstream, it does not capture the tail of the breakthrough curves. These tails are well reproduced by the three-dimensional model, because it accounts for the effects of dead zones and a power plant which withdraws nearly 80 % of the water from the canal for cooling purposes before returning it back to the canal.

Botanical piscicides over the years have been used singly in fishing efforts. This research investigated the joint action of binary mixtures of Carica papaya + Nicotiana tabacum, Anacardium occidentale + Senna occidentalis, and A. occidentale + Luffa cylindrica. Relative toxic units (RTU) estimations and synergistic ratio (SR) models were used in the joint action evaluation. The 96 h LC50 (95% confidence limit [CL]) results revealed that the mixture of C. papaya and N. tabacum showed antagonism (reduction in toxicity) in both predetermined mixture ratio 1:1 and equitoxic mixture ratio 1:2. The RTU value for mixture ratio 1:1 was 0.298, while SR was 0.221. The mixture ratio 1:2 had RTU of 0.421 and SR of 0.384. The mixture of A. occidentale and S. occidentalis also followed the antagonistic model with mixture ratio 1:1, having RTU of 0.927 and SR of 0.577, while the mixture ratio 1:2 had RTU of 0.489 and SR of 0.360. The mixture ratio 1:1 of A. occidentale and L. cylindrica was synergistic with RTU of 2.145 and SR of 1.442. Most of the binary mixtures of the botanical piscicides were antagonistic. Key words: Joint action, binary mixtures, botanical piscicides, Clarias gariepinus.