Donor life stage influences juvenile American eel Anguilla rostrata attraction to conspecific chemical cues

Abstract

The present study investigated the potential role of conspecific chemical cues in inland juvenile American eel Anguilla rostrata migrations by assessing glass eel and 1 year old elver affinities to elver washings, and elver affinity to adult yellow eel washings. In two-choice maze assays, glass eels were attracted to elver washings, but elvers were neither attracted to nor repulsed by multiple concentrations of elver washings or to yellow eel washings. These results suggest that A. rostrata responses to chemical cues may be life-stage dependent and that glass eels moving inland may use the odour of the previous year class as information to guide migration. The role of chemical cues and olfaction in eel migrations warrants further investigation as a potential restoration tool.

American eels produce and release bile acid profiles that vary across life stage

“…To prepare elver washings (prepared by Galbraith et al . ()), 450 elvers (1350 g total), 90 L of well water (at 15°C), and a 25 min holding time wash were used. The concentration of the washing was 2.08 eels (6.24 g) L −1 h −1 .…”

“…Studies with European eels indicated that yellow eel odour was attractive to some juvenile stages (Briand et al, 2002;Pesaro et al, 1981;Saglio, 1982). Conversely, American eel elvers were not attracted to elver or yellow eel washings in Galbraith et al (2017), but were mildly attracted in Sorensen (1986). Therefore, these findings cannot be used to implicate attractive washing components at the present time.…”

“…() and attractive elver washings used in Galbraith et al . (), their presence could be potentially responsible for the washing attractiveness. Therefore, the potential role of bile acid as chemical messengers in the American eel cannot be discounted.…”

“…Conspecific washings (eel holding waters) were prepared at NARL for nontarget full‐scan analysis by ultraperformance liquid chromatography/high‐resolution mass spectrometry (UPLC‐HRMS). Many of the washings evaluated in this study were prepared by Galbraith et al ., and Schmucker et al . (, ) and frozen following preparation for storage until use in this study.…”

“…Studies have shown that glass eels are attracted to odours emitted by other glass eels in a dose-dependent relationship (Briand et al, 2002;Pesaro et al, 1981;Schmucker et al, 2016). Glass eels are also attracted to elver odour and natural river water collected from waterbodies with established anguillid populations (Creutzberg, 1961;Galbraith et al, 2017Hain, 1975. Conversely, there is mixed evidence for elver attraction to conspecific odour, indicating that responses to chemical cues may be concentration or life-stage dependent Miles, 1968;Sorensen, 1986).…”