Effect of Rainbow Trout Size on Response to Rotenone and Antimycin

Abstract

The piscicides rotenone and antimycin are commonly used to eradicate unwanted fish populations. However, the relationships (if present) between their toxicities and fish sizes are unknown and could be especially important when bioassay fish are used to detect piscicide presence and effectiveness. Size-mediated toxicity could lead to either excessive or inadequate piscicide applications if bioassay fish are larger or smaller than the fish being eradicated. The relationships between time to death and weight of rainbow trout Oncorhynchus mykiss (0.7-574.0 g) at an antimycin concentration of 7.5 µg/L and a rotenone concentration of 12.5 µg/L were determined. Antimycin took significantly longer than rotenone to kill rainbow trout at concentrations typically used in eradication projects. Significant positive relationships existed between fish size and time to death for rotenone and antimycin exposures and were probably caused by size-mediated differences in metabolic rate; however, these relationships accounted for less than 21% of the variation in time to death. Smaller fish appeared to be affected by the chemicals more quickly, but their deaths did not consistently occur before the deaths of larger fish.

Determining the minimum effective dose of rotenone for eradication of alien smallmouth bassMicropterus dolomieufrom a South African river

“…Similar results were reported for several fish species, including largemouth bass Micropterus salmoides and spotted bass Micropterus punctulatus during both laboratory and field exposures (Hester 1959, Rowe-Rowe 1971, Chadderton et al 2003. Brown et al (2011) found a significant but weak correlation between rainbow trout size and time to death for rotenone exposures. Smaller fish appeared to be affected more quickly, but they did not consistently die before the large fish, and less than 21% of the observed variation could be explained by body size.…”

A Review of Grass Carp and Related Species Literature on Diet, Behavior, Toxicology, and Physiology Focused on Informing Development of Controls for Invasive Grass Carp Populations in North America

“…Antimycin A is more toxic to bighead and silver carp when delivered as microparticles of a size similar to those targeted by those species during feeding [561] than to native fish species, including bluegill and largemouth bass [561], with toxicity being greater in warmer water [596]. Rainbow trout (Oncorhynchus mykiss), a salmonid fish species with invasive populations outside its native range in western North America, required longer exposure to kill using antimycin A compared to rotenone when exposed to concentrations typically used for eradication [597]. A significant positive relationship was found between rainbow trout size and time of death for both compounds; however, this relationship was limited in its ability to predict death based on size.…”