Swimming Depth of Adult American Eels (Anguilla rostrata) in a Saltwater Bay as Determined by Ultrasonic Tracking

1974 ◽  
Vol 31 (6) ◽  
pp. 1148-1150 ◽  
Author(s):  
A. B. Stasko ◽  
S. A. Rommel Jr.
Keyword(s):  
New Brunswick ◽  
Anguilla Rostrata ◽  
Depth Range ◽  
Pressure Sensing ◽  
Intermediate Depth ◽  
Swimming Depth ◽  
Passamaquoddy Bay ◽  
Ultrasonic Tracking ◽  
American Eels ◽  
Ultrasonic Transmitters

Pressure-sensing ultrasonic transmitters in the gut were used to determine the swimming depth of five American eels (Anguilla rostrata) in Passamaquoddy Bay, New Brunswick, in autumn. The eels made frequent dives from surface to bottom, in places diving at least 45 m deep, at vertical speeds to 76 cm/s. About one quarter of the time was spent near the surface; very little time was spent near the bottom or at any constant intermediate depth range.

The migration of stocked, trapped and transported, and wild female American silver eels through the Gulf of St. Lawrence

2018 ◽  
Vol 75 (11) ◽  
pp. 2024-2037 ◽  
Author(s):  
Mélanie Béguer-Pon ◽  
Guy Verreault ◽  
David Stanley ◽  
Martin Castonguay ◽  
Julian J. Dodson
Keyword(s):  
Detection Efficiency ◽  
Anguilla Rostrata ◽  
Migration Speed ◽  
Hydroelectric Dams ◽  
Wild Female ◽  
Swimming Depth ◽  
Silver Eels ◽  
Diel Vertical Migrations ◽  
American Eels ◽  
St Lawrence River

The stocking of juvenile eels and trap and transport programs of large yellow (American) eels (Anguilla rostrata) were initiated in Ontario to mitigate mortalities observed at hydroelectric dams and to increase escapement from the upper St. Lawrence River and Lake Ontario (Canada). A total of 380 migrating female silver eels (stocked, trapped and transported, and wild) were tagged with acoustic transmitters between 2011 and 2014. Their migration and escapement at the exit of the Gulf of St. Lawrence, the Cabot Strait, were recorded using acoustic receivers. Escapement rates varied between 8.9% and 20.0% annually (mean = 11.4%). A high proportion of stocked eels were detected (N = 27 of 43 detected at Cabot Strait), demonstrating their ability to escape the Gulf. No differences in migration speed or crossing locations at Cabot Strait were found among the three categories. Eels crossing Cabot Strait did not display diel and tidal patterns, but their estimated swimming depth indicated diel vertical migrations. The low escapement rates observed may be related to predation events and (or) the low and variable detection efficiency of the acoustic receivers’ line.

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

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.

Herring Fishery in Southern New Brunswick

1960 ◽  
Vol 17 (2) ◽  
pp. 133-168
Author(s):  
R. A. McKenzie ◽  
S. N. Tibbo
Keyword(s):  
New Brunswick ◽  
Tidal Power ◽  
Annual Variations ◽  
Significant Relationships ◽  
Passamaquoddy Bay

Most of the herring taken in the Passamaquoddy area of southern New Brunswick are caught in stationary weirs built close to shore. Analyses of weir catches show no significant relationships between average catches inside Passamaquoddy Bay and catches in outside areas for the same year. Weirs inside Passamaquoddy Bay are more efficient and catch about twice as many herring per weir as those outside the Bay.Seasonal and annual variations both in individual weir catches and in total catches in the various statistical districts of Charlotte County are far greater now than any changes that can be forecast as resulting from the installation of the proposed Passamaquoddy tidal power dams.

Artificial maturation, fertilization, and early development of the American eel (Anguilla rostrata)

2010 ◽  
Vol 88 (11) ◽  
pp. 1121-1128 ◽  
Author(s):  
K. Oliveira ◽  
W. E. Hable
Keyword(s):  
Early Development ◽  
Anguilla Rostrata ◽  
Sargasso Sea ◽  
American Eel ◽  
Important Species ◽  
Vitro Fertilization ◽  
Commercially Important ◽  
Elusive Species ◽  
American Eels

Spawning for the American eel ( Anguilla rostrata (Le Sueur, 1817)) takes place in secretive locations within the Sargasso Sea, which has thus far prevented investigations of gametogenesis and early development in this ecologically and commercially important species. Attempts to induce maturation and reproduction in this species have been few and have produced limited results, with a single report of the production of gastrula-stage embryos. Here we report the successful maturation of female American eels. Maturation occurred within 13 weeks and ovulation was induced with a single injection of 17α,20β-dihydroxy-4-pregnen-3-one (DHP). Following in vitro fertilization, embryogenesis through hatching was observed and larvae were maintained for up to 6 days. We show that a crucial factor for successful fertilization is the stage of the oocyte at the time of induced ovulation. Oocytes that had not reached the migratory nucleus stage, or had passed this stage, were not successfully fertilized. These findings demonstrate that American eel can reproduce in the laboratory and previously untestable hypotheses pertaining to the developmental biology of this elusive species can now be explored.

Eels at the Edge: Science, Status, and Conservation Concerns

2009 ◽  
Keyword(s):  
North America ◽  
Anguilla Japonica ◽  
Japanese Eel ◽  
Southern United States ◽  
Anguilla Rostrata ◽  
Annual Growth Rate ◽  
Spawning Site ◽  
One Year ◽  
American Eels ◽  
Delayed Spawning

<em>Abstract.</em>—In Taiwan, there has been a shortage of local Japanese eel <em>Anguilla japonica </em>elvers for culture, so culturists have imported American eel <em>Anguilla rostrata </em>(Le Sueur) elvers from North America to meet their needs. From 1999 to 2001, six exotic adult American eels were found in the estuary of the Kaoping River of Taiwan that had escaped from aquaculture ponds as young eels and stayed in the river until silvering. This study compares growth performance and migratory behavior, using otolith strontium (Sr)/calcium (Ca) ratios of those six American eels with cohabitating Japanese eels and American eels in North America. Regardless of sex, mean age at maturity of the exotic American eels was greater and mean annual growth rate was less than that of Japanese eels in Taiwan and similar to that of American eels in the southern United States. Sr/Ca ratios at the otolith edge of the six exotic American eels, which recorded their salinity history, increased significantly. Furthermore, four of the six exotic American eels spent more than one year in the high-salinity estuary. Their extended residence in the estuary may be due to a delayed spawning migration resulting from a failure to orientate and migrate properly to their native spawning site.

Life history of Mysis stenolepis Smith (Crustacea, Mysidacea)

1975 ◽  
Vol 53 (7) ◽  
pp. 942-952 ◽  
Author(s):  
T. Amaratunga ◽  
S. Corey
Keyword(s):  
Young Adults ◽  
Life History ◽  
New Brunswick ◽  
Shallow Water ◽  
Field Study ◽  
Sexual Maturity ◽  
Developmental Stages ◽  
Shallow Waters ◽  
Passamaquoddy Bay ◽  
History Of

A 17-month field study showed that Mysis stenolepis in Passamaquoddy Bay, New Brunswick lives for about 1 year. Young are released in shallow water early in spring and grow rapidly during the summer. In the fall, young adults migrate to deeper water where they reach sexual maturity. Transfer of sperm lakes place during winter in deeper regions of the Bay. soon after which the males die. Females survive and in spring migrate to shallow waters to release young after which they die. Females breed once and carry an average of 157 young per brood. Developmental stages of the postmarsupial young are described and discussed.

scholarly journals Terrestrial Locomotion in American Eels (Anguilla rostrata): How Substrate and Incline Affect Movement Patterns

2020 ◽  
Vol 60 (1) ◽  
pp. 180-189
Author(s):  
Erica Redmann ◽  
Alina Sheikh ◽  
Areej Alqahtani ◽  
Mica McCarty-Glenn ◽  
Shazrah Syed ◽  
...  
Keyword(s):  
Wave Amplitude ◽  
Body Position ◽  
The Body ◽  
Complex Life Cycle ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Distance Ratio ◽  
Terrestrial Environment ◽  
Terrestrial Locomotion ◽  
American Eels

Synopsis Fishes overcome a variety of challenges in order to invade the terrestrial environment. Terrestrial invasions by fish occur over a variety of environmental contexts. In order to advance their bodies on land, fishes capable of terrestrial excursions tend to use one of three different types of locomotor modes: axial-based, appendage-based, or axial-appendage-based. Elongate species with reduced appendages, such as the American eel, Anguilla rostrata, rely on axial based locomotion in water and on land. When eels move from water to land as part of their complex life cycle, they inevitably encounter a variety of substrates and must traverse variable degrees of incline. The aim of this study was to determine the effect of substrate and incline on the terrestrial locomotion of the American eel. In order to do this, eels were filmed from a dorsal view on three substrates and four inclines: sand, loose pebbles, and fixed (glued) pebbles at 0°, 5°, 10°, and 15°. We digitized 20 evenly spaced points along the body to examine the following characteristics of locomotion: velocity, distance ratio (DR), and wave parameters such as wave amplitude, frequency, and length and assessed whether substrate, incline, or body position affected these parameters. DR, our metric of movement efficiency, was highest on the flat sand condition and lowest on 15° pebble conditions. Efficiency also varied across the body. Velocity followed a similar pattern being highest on sand at 0° and lowest at the steepest inclines. Wave amplitude generally increased toward the tail but was similar across substrates and inclines. Wave frequency was relatively consistent across the body on both pebble substrates, but on sand, frequency was higher toward the head but decreased toward the tail. Wavelengths on sand were the longest at 0° near the head and shorter wavelengths were observed on steeper inclines. Both pebble substrates elicited lower wavelengths that were more similar across the body. Overall, A. rostrata were more effective in navigating compliant substrates but struggled at steeper inclines. Our findings provide insight into locomotor challenges that American eels may encounter as they move from and between bodies of water.

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