scholarly journals Evaluation of Modular and Scalable Downstream Passage Systems for Silver American Eels

2021 ◽  
Author(s):  
Stephen Amaral ◽  
Jenna Rackovan ◽  
Kimberly Capone ◽  
Brian McMahon ◽  
Kimbal Hall ◽  
...  
Keyword(s):  
American Eels

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.

Intracellular pH-temperature interactions of hepatocytes from American eels

1983 ◽  
Vol 245 (1) ◽  
pp. R32-R37
Author(s):  
P. J. Walsh ◽  
T. W. Moon
Keyword(s):  
Intracellular Ph ◽  
Acclimation Temperature ◽  
C Cells ◽  
Medium Ph ◽  
American Eel ◽  
Temperature Changes ◽  
American Eels ◽  
Temperature Interactions

The effects of acclimation temperature and acute temperature changes on the intracellular pH (pHi) of hepatocytes isolated from the American eel, Anguilla rostrata, were studied by the measurement of the distribution ratio of dimethyloxizolidinedione (DMO). Varying the concentration of DMO (10(-7) to 10(-4) M) did not affect estimates of pHi, indicating that DMO acts as an ideal pHi probe in eel hepatocytes. In vitro studies yielded values of liver cell pHi identical to those previously measured in vivo (in vitro pHi = 7.556 +/- 0.010; in vivo pHi = 7.570 +/- 0.049 at 20 degrees C); hepatocyte pHi varied inversely with acclimation temperature (5-20 degrees C) in a manner consistent with alphastat regulation (delta pH/delta T = -0.0182 +/- 0.021). During acute temperature increases (5-20 degrees C) and decreases (20-5 degrees C) hepatocytes regulated pHi to the appropriate (acclimated) value within 30-45 min posttransfer under conditions of constant medium pH (pHe). The effects of medium pH were also studied, and although patterns of pHi regulation differed between 5 and 20 degrees C cells, a pHi difference consistent with alphastat regulation was maintained between 5 and 20 degrees C cells over the pHe range 7.8-8.3.

scholarly journals Characterizing Downstream Migration Timing of American Eels Using Commercial Catch Data in the Penobscot and Delaware Rivers

2021 ◽  
Vol 13 (5) ◽  
pp. 545-558
Author(s):  
Daniel M. Weaver ◽  
Douglas B. Sigourney ◽  
Mari‐Beth Delucia ◽  
Joseph D. Zydlewski
Keyword(s):  
Downstream Migration ◽  
Commercial Catch ◽  
Migration Timing ◽  
Catch Data ◽  
American Eels

scholarly journals Direct observations of American eels migrating across the continental shelf to the Sargasso Sea

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Mélanie Béguer-Pon ◽  
Martin Castonguay ◽  
Shiliang Shan ◽  
José Benchetrit ◽  
Julian J. Dodson
Keyword(s):  
Continental Shelf ◽  
Sargasso Sea ◽  
Direct Observations ◽  
American Eels

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):  
Water Temperature ◽  
Stream Flow ◽  
River System ◽  
Lunar Phase ◽  
Upstream Migration ◽  
Potomac River ◽  
River Drainage ◽  
Thermal Refuge ◽  
American Eels ◽  
Atlantic Coastal

<em>Abstract.—</em>Yellow-phase American eels <em>Anguilla rostrata </em>migrate upstream extensively in Atlantic coastal river systems. However, few studies have focused on movements of large yellow American eels near dams in upper watersheds of Atlantic coastal rivers. We examined relationships between environmental variables (stream flow, water temperature, and lunar phase) and movements of radio-tagged yellow American eels (518–810 mm TL) near Millville hydroelectric dam in the lower Shenandoah River drainage of the upper watershed of the Potomac River system, West Virginia. Movements of yellow American eels differed seasonally. Water temperature and stream flow were associated with upstream migration during spring. Downstream movements during fall coincided with decreasing water temperatures and darker nights near the new moon. Eels overwintered in thermal refuge areas near tributary mouths. Localized irregular upstream and downstream movements during summer occurred near dusk and dawn and possibly reflected crepuscular foraging. Our study in the Potomac River drainage suggests the need for upstream eel passage at hydroelectric facilities when spring water temperatures exceed 15°C.

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.

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