Piscicides and Invertebrates: After 70 Years, Does Anyone Really Know?

Abstract

The piscicides rotenone and antimycin have been used for more than 70 years to manage fish populations by eliminating undesirable fish species. The effects of piscicides on aquatic invertebrate assemblages are considered negligible by some and significant by others. This difference of opinion has created contentious situations and delayed native fish restoration projects. We review the scientific evidence and report that short-term (< 3 months) impacts of piscicides to invertebrate assemblages varied from minor to substantial and long-term (> 1 year) impacts are largely unknown. Recovery of invertebrate assemblages following treatments ranged from a few months for abundances of common taxa to several years for rarer taxa. Variation in reported effects was primarily due to natural variation among species and habitats and a lack of adequate pre-and post-treatment sampling which prevents determining the true impacts to invertebrate assemblages. The factors most likely to influence impacts and recovery of aquatic invertebrate assemblages following piscicide treatments are: (1) concentration, duration, and breadth of the piscicide treatment; (2) invertebrate morphology and life history characteristics, including surface area to volume ratios, type of respiration organs, generation time, and propensity to disperse; (3) refugia presence; and (4) distance from colonization sources.

Reintroduction of a native galaxiid (Galaxias fasciatus) following piscicide treatment in two streams: response and recovery of the fish population

“…; Vinson et al. ). A key tool in international fisheries management, restoration and research is the piscicide rotenone (Dean‐Speirs ; Vinson et al.…”

“…; Vinson et al. ). The reintroduction of native fish to a food‐depleted system after rotenone treatment could have negative impacts on the condition and behaviour of fish (Keeley ; David & Stoffels ; Hansen & Closs , ), potentially compromising the aims of native fish restoration.…”

“…A key tool in international fisheries management, restoration and research is the piscicide rotenone (Dean‐Speirs ; Vinson et al. ). Rotenone treatment causes large scale mortality of fish and invertebrates, and can be classified as a ‘pulse’ disturbance because of its clearly defined temporal boundaries (i.e., length of dosing), and its rapid breakdown in the environment once dosing has ceased (Ling ).…”

“…Although the actual activity of rotenone dosing in lakes, rivers or streams may be short term from a few hours to 1 day (Ling ), treatment results in not only severe immediate effects, but potentially longer term effects, which are not well understood (Vinson et al. ). Although it is generally accepted that fish can be rapidly released into rotenone‐treated habitats once toxicity has diminished, the wider impacts of the disturbance caused by rotenone, such as the loss of aquatic invertebrates, are of concern due to their fundamental role in ecosystem processes and as prey for fish (Hamilton et al.…”

The effectiveness of non-native fish eradication techniques in freshwater ecosystems: a systematic review protocol

“…They can include chemicals, harvest regimes, physical removal, or biological control [25]. The effectiveness of chemical eradication (e.g., rotenone, Fintrol) depends on environmental conditions (e.g., water temperature, depth, pH, discharge, target fish species, hydrology, substrate composition, areas of groundwater recharge; [26]); there are also concerns of collateral damage when non-target species are affected by chemical treatments [27]. Harvest regimes can include intentional over-fishing (e.g., gill netting, angling) of target species [28][29][30] or modification of angling regulations (e.g., favour overharvest of target species).…”