Glass-Eel-Stage American Eels Respond to Conspecific Odor as a Function of Concentration

Seasonal and diel patterns of stream invasion by American eels (Anguilla rostrata) were monitored in a small stream located on the north shore of the Gulf of St. Lawrence from 1981 to 1985. Glass eels and elvers migrated from the sea in late June and July. Glass eels made up only a small percentage of the migrants. Pigmentation progressed quickly in the estuary, but elvers grew very slowly. Migration from the estuary and through the lower reaches of the stream was slow; no glass eels or elvers occurred at a station located only 4 km from saltwater. Juvenile eels reached that station in their second summer of stream residence. Juvenile eels migrated in July and August. They ranged from 70 to 250 mm in length and included more than one age-class. Those less than 100 mm in length were most numerous. Relative abundance of glass eels and elvers decreased in the estuary from 1981 to 1985. This coincided with a decrease in the proportion of smaller sized eels in the stream migration over the same period. Juvenile eels migrated progressively later in summer as the proportion of smaller sized eels decreased. Stream migration was nocturnal. Movements mainly occurred between 21:00 and 23:00. The relationship between glass eel and elver abundance in the estuary and juvenile eel abundance in the stream 1 and 2 years later was not clear.

Download Full-text

River-Specific Gene Expression Patterns Associated with Habitat Selection for Key Hormone-Coding Genes in Glass Eel-Stage American Eels

Transactions of the American Fisheries Society ◽

10.1002/tafs.10065 ◽

2018 ◽

Vol 147 (5) ◽

pp. 855-868

Author(s):

Mélanie Gaillard ◽

Scott A. Pavey ◽

Louis Bernatchez ◽

Céline Audet

Keyword(s):

Gene Expression ◽

Habitat Selection ◽

Expression Patterns ◽

Gene Expression Patterns ◽

Specific Gene ◽

Glass Eel ◽

Specific Gene Expression ◽

Selection For ◽

American Eels

Download Full-text

Increasing Coastal and Continental Shelf Water Temperatures Influence the Start of the Glass Eel Fishery and Recruitment Abundance for American Eels in Atlantic Coastal Nova Scotia

Marine and Coastal Fisheries ◽

10.1002/mcf2.10179 ◽

2021 ◽

Vol 13 (5) ◽

pp. 520-528

Author(s):

B. M. Jessop

Keyword(s):

Nova Scotia ◽

Continental Shelf ◽

Shelf Water ◽

Glass Eel ◽

Continental Shelf Water ◽

American Eels ◽

Atlantic Coastal

Download Full-text

Infection of newly recruited American eels (Anguilla rostrata) by the invasive swimbladder parasite Anguillicoloides crassus in a US Atlantic tidal creek

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv097 ◽

2015 ◽

Vol 73 (1) ◽

pp. 14-21 ◽

Cited By ~ 5

Author(s):

Jennifer L. Hein ◽

Isaure de Buron ◽

William A. Roumillat ◽

William C. Post ◽

Allan P. Hazel ◽

...

Keyword(s):

Tidal Creek ◽

Parasite Prevalence ◽

Anguilla Rostrata ◽

American Eel ◽

Glass Eel ◽

The Usa ◽

Advanced Stages ◽

Glass Eels ◽

American Eels ◽

Anguillicoloides Crassus

Abstract Little is known about the infection status of glass eel and elver stages of the American eel Anguilla rostrata by the invasive swimbladder parasite Anguillicoloides crassus. This study examined infection by adult and larval A. crassus in glass eels (n = 274) and elvers (n = 199) collected during March–December 2013 from an eel ladder at a dammed creek near Charleston, SC, USA. Among all the eels examined [total lengths (TLs), 34–156 mm], the prevalence (±SE), mean abundance, and mean intensity of A. crassus worms was 29.4 ± 2.1%, 0.88 ± 0.12, and 2.98 ± 0.34, respectively. Infection by A. crassus was not detected in the earliest glass eel development stages (pigment stages 1–3), but it was detected in more advanced stages (pigment stages 4–7) and fully pigmented elvers. From March to July, parasite prevalence increased significantly with eel TL, and all eels 125 mm or longer (n = 13) were infected. From August–December, when fewer eels were caught, parasite prevalence was generally lower and less dependent on the eel TL. Our study demonstrates the potential risk of spreading A. crassus to new areas by transporting live glass eels and elvers. This is of particular relevance because our study site was located in the Cooper River drainage, one of the few locations in the USA that permits a glass eel harvest.

Download Full-text

Deep Learning for Automated Detection and Identification of Migrating American Eel Anguilla rostrata from Imaging Sonar Data

Remote Sensing ◽

10.3390/rs13142671 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2671

Author(s):

Xiaoqin Zang ◽

Tianzhixi Yin ◽

Zhangshuan Hou ◽

Robert P. Mueller ◽

Zhiqun Daniel Deng ◽

...

Keyword(s):

Deep Learning ◽

Fish Passage ◽

Automated Detection ◽

Anguilla Rostrata ◽

Automated Method ◽

Detection And Identification ◽

And Migration ◽

Imaging Sonar ◽

American Eels ◽

Deep Learning Model

Adult American eels (Anguilla rostrata) are vulnerable to hydropower turbine mortality during outmigration from growth habitat in inland waters to the ocean where they spawn. Imaging sonar is a reliable and proven technology for monitoring of fish passage and migration; however, there is no efficient automated method for eel detection. We designed a deep learning model for automated detection of adult American eels from sonar data. The method employs convolution neural network (CNN) to distinguish between 14 images of eels and non-eel objects. Prior to image classification with CNN, background subtraction and wavelet denoising were applied to enhance sonar images. The CNN model was first trained and tested on data obtained from a laboratory experiment, which yielded overall accuracies of >98% for image-based classification. Then, the model was trained and tested on field data that were obtained near the Iroquois Dam located on the St. Lawrence River; the accuracy achieved was commensurate with that of human experts.

Download Full-text

Challenges to quantifying glass eel abundance from large and dynamic estuaries

ICES Journal of Marine Science ◽

10.1093/icesjms/fsx182 ◽

2017 ◽

Vol 75 (2) ◽

pp. 727-737 ◽

Cited By ~ 1

Author(s):

Sarah Walmsley ◽

Julie Bremner ◽

Alan Walker ◽

Jon Barry ◽

David Maxwell

Keyword(s):

Large Scale ◽

Anguilla Anguilla ◽

Commercial Fishing ◽

European Eel ◽

Estuarine System ◽

Glass Eel ◽

The North ◽

Adequate Sampling ◽

South Shore ◽

Glass Eels

Abstract European eel Anguilla anguilla recruitment into the rivers of the northeastern Atlantic has declined substantially since the 1980s. Monitoring of recruiting juveniles, or glass eels, is usually undertaken in small estuaries and rivers. Sampling of large-scale estuaries is rare, due to the size of the sampling area and the resources needed to provide adequate sampling levels. Here we describe surveys for glass eels in the UK’s largest estuarine system, the Severn Estuary/Bristol Channel. We sampled across a 20 km-wide stretch of the estuary in 2012 and 2013, using a small-meshed net deployed from a commercial fishing trawler, and the surveys yielded over 2500 glass eels. Eels were more abundant in the surface layer (0–1.4 m depth) than at depth (down to 8.4 m depth), were more abundant close to the south shore than along the north shore or middle of the estuary, and were more abundant in lower salinity water. Numbers were higher in the second year than in the first and eels were more abundant in February than April. The difficulties and logistics of sampling in such a large estuary are discussed, along with the level of resources required to provide robust estimates of glass eel abundance.

Download Full-text