|Migratory behaviour and habitat use by American eels Anguilla rostrata as revealed by otolith microchemistry|
Jessop, B.M.; Shiao, J.-C.; Iizuka, Y.; Tzeng, W.-N. (2002). Migratory behaviour and habitat use by American eels Anguilla rostrata as revealed by otolith microchemistry. Mar. Ecol. Prog. Ser. 233: 217-229
In: Marine Ecology Progress Series. Inter-Research: Oldendorf/Luhe. ISSN 0171-8630, more
|Authors|| || Top |
- Jessop, B.M.
- Shiao, J.-C.
- Iizuka, Y.
- Tzeng, W.-N.
The environmental history of American eels Anguilla rostrata from the East River, Nova Scotia, was investigated by electron microprobe analysis of the Sr:Ca ratio along transects of the eel otolith. The mean (±SD) Sr:Ca ratio in the otoliths of juvenile American eels was 5.42 ×10 -3 ± 1.22 × 10-3 at the elver check and decreased to 2.38 ×10-3 ± 0.99 ×10-3 at the first annulus for eels that migrated directly into the river but increased to 7.28 ×10-3 ± 1.09 ×10-3 for eels that had remained in the estuary for 1 yr or more before entering the river. At the otolith edge, Sr:Ca ratios of 4.0 ×10-3 or less indicated freshwater residence and ratios of 5.0 ×10-3 or more indicated estuarine residence. Four distinct but interrelated behavioural groups were identified by the temporal changes in Sr:Ca ratios in their otoliths: (1) entrance into freshwater as an elver, (2) coastal or estuarine residence for 1 yr or more before entering freshwater, and, after entering freshwater, (3) continuous freshwater residence until the silver eel stage and (4) freshwater residence for 1 yr or more before engaging in periodic, seasonal movements between estuary and freshwater until the silver eel stage. Small (< 70 mm total length), highly pigmented elvers that arrived early in the elver run were confirmed as slow growing age-1 juvenile eels. Juvenile eels that remained 1 yr or more in the estuary before entering the river contributed to the production of silver eels to a relatively greater extent than did elvers that entered the river during the year of continental arrival.