Pigmentation, size, and migration of elvers (Anguilla rostrata (Lesueur)) in a coastal Rhode Island stream

1988 ◽  
Vol 66 (11) ◽  
pp. 2528-2533 ◽  
Author(s):  
Alexander J. Haro ◽  
William H. Krueger
Keyword(s):  
Rhode Island ◽  
Water Depth ◽  
Stream Temperature ◽  
Anguilla Rostrata ◽  
Tidal Zone ◽  
Tidal Influence ◽  
Total Length ◽  
Spawning Area ◽  
And Migration ◽  
Range Of Variation

Progressive pigmentation of Anguilla rostrata elvers was very similar to that described for A. anguilla. Pigmentation increased rapidly with the advancing season, while total length decreased. The increase in pigmentation was independent of the decrease in length and may have been influenced by increased contact with the substrate. Mean lengths showed significant differences within seasons and between years, and the range of variation was greater than that described by V. D. Vladykov (1966. Verh. Int. Ver. Theor. Angew. Limnol. 16: 1007–1017) for elvers collected from Maryland to Quebec. We substantiate Vladykov's finding that elver size tends to increase with increasing distance from the spawning area, but reject his size/sex hypothesis. The main migration occurred in April and May and was related to decreasing water depth and rising stream temperature. Elvers took about 4 weeks to ascend 180 m above the tidal zone, probably because of a high stream gradient and the absence of tidal influence.

Pigmentation, otolith rings, and upstream migration of juvenile American eels (Anguilla rostrata) in a coastal Rhode Island stream

1991 ◽  
Vol 69 (3) ◽  
pp. 812-814 ◽  
Author(s):  
Alexander J. Haro ◽  
William H. Krueger
Keyword(s):  
Phase Transition ◽  
Fresh Water ◽  
Rhode Island ◽  
Late Summer ◽  
Anguilla Rostrata ◽  
Upstream Migration ◽  
Total Length ◽  
Winter Temperatures ◽  
American Eels ◽  
Yellow Eels

American eels of <250 mm total length were collected in late summer and fall from three stations on the coastal Annaquatucket River. All eels possessed the yellow–green pigmentation characteristic of the yellow phase. Transition of partially pigmented elvers to fully pigmented yellow eels occurred during the summer months following the spring entry into fresh water and was accompanied by significant growth. Mean total length and mean number of annulus-like otolith rings increased significantly with distance upstream, suggesting that elvers migrate a limited distance in the 1st year, but continue on for at least several years thereafter as yellow eels. Upstream progress of eels in this system may be impeded by low winter temperatures, high stream gradient, dams, and impoundments.

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.

A radioautographic study of the development of the somite in the chick embryo

Development ◽  
1968 ◽  
Vol 19 (2) ◽  
pp. 217-226
Author(s):  
Jan Langman ◽  
George R. Nelson
Keyword(s):  
Chick Embryo ◽  
Controversial Issue ◽  
Lateral Direction ◽  
Total Length ◽  
Difference Of Opinion ◽  
And Migration

Considerable difference of opinion exists about the origin of the various components of the somite. According to Williams (1910), Hamilton (1952) and Boyd (1960), the cells of the myotome originate in the dorso-medial angle of the somite wall and migrate beneath the dermatome in ventro-lateral direction. A group of older investigators (Remak, 1855; His, 1888; Bardeen, 1900) state, however, that the myotome cells originate not only in the dorso-medial angle but also along the total length of the dorsal somite wall, formed by the dermatome. Similarly, in birds whether the myotome extends in ventro-lateral direction by growth and migration of existing cells (Engert, 1900; Williams, 1910) or by differentiation of locally found mesoderm cells into myoblasts (Straus & Rawles, 1953) remains even at present a controversial issue.

scholarly journals New clues on the Atlantic eels spawning behavior and area: the Mid-Atlantic Ridge hypothesis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yu-Lin K. Chang ◽  
Eric Feunteun ◽  
Yasumasa Miyazawa ◽  
Katsumi Tsukamoto
Keyword(s):  
Ocean Circulation ◽  
Specific Area ◽  
Migration Behavior ◽  
Sargasso Sea ◽  
Distribution Fitting ◽  
Particle Tracking Method ◽  
Spawning Area ◽  
Mid Atlantic Ridge ◽  
And Migration ◽  
Atlantic Eels

Abstract The Sargasso Sea has long been considered as the only spawning area for Atlantic eels, despite the absence of direct observations. The present study raises a novel scenario, deviating from Schmidt’s dogma, begins with a review of historical and recent observations that were combined to build up a global theory on spawning ecology and migration behavior of Atlantic eels. From this, it is argued that a favorable spawning area could be located eastward of Sargasso Sea at the intersection between the Mid-Atlantic Ridge and the oceanic fronts. Ocean circulation models combined with 3D particle-tracking method confirmed that spawning at this specific area would result in larval distribution fitting the field observation. This study explores the hypothesis that leptocephali are able to swim and orientate to reach their specific growth areas. It proposes a novel framework about spawning ecology, based on orientation, navigation and meeting cues of silver eels to the spawning area. Together this framework may serve as a stepping-stone for solving the long-lasting mystery of eel reproduction which first came out 2,400 years ago and promotes the understanding of oceanic migration and reproduction of marine organisms.

Life history characteristics and strategies of the American eel, Anguilla rostrata

1999 ◽  
Vol 56 (5) ◽  
pp. 795-802 ◽  
Author(s):  
Kenneth Oliveira
Keyword(s):  
Life History ◽  
Rhode Island ◽  
Life History Traits ◽  
Life History Strategies ◽  
Anguilla Rostrata ◽  
Female Size ◽  
Silver Eel ◽  
Male Size ◽  
American Eel ◽  
Female Age

Several life history hypotheses for the American eel, Anguilla rostrata, were examined using seaward-migrating silver-phase eels collected in the Annaquatucket River, Rhode Island, U.S.A. Female eels were significantly larger and older than males. Female eels also had a significantly higher mean growth rate. The addition of life history data from Annaquatucket River eels to published silver eel data from locations throughout the eels' range shows that female size at migration is positively correlated with latitude (r = 0.56, p = 0.05) but male size is not (r = 0.54, p = 0.17). Female age was not related to latitude (r = 0.57, p = 0.27) but male age showed a positive relationship (r = 0.87, p = 0.05). Growth rates for females and males were inversely related to latitude (r = -0.98, p = 0.02 and r = -0.95, p = 0.05, respectively). Differences between the latitudinal relationships and life history traits of the sexes may be due to differences in life history strategies.

Macrophthalmia in the American Eel (Anguilla rostrata)

1973 ◽  
Vol 30 (5) ◽  
pp. 689-693 ◽  
Author(s):  
Vadim D. Vladykov
Keyword(s):  
Lake Michigan ◽  
Anguilla Rostrata ◽  
University Of Michigan ◽  
Same Sex ◽  
American Eel ◽  
The Third ◽  
Total Length ◽  
Horizontal Diameter ◽  
American Eels

Three American eels (Anguilla rostrata) with unusually large eyes, obtained from the collections of the Museum of Zoology, University of Michigan (UMMZ 80616), are described. Two are males, 495 and 521 mm in total length, and the third, probably of the same sex, had an estimated length of 752 mm. The horizontal diameter of the eye was equal to the inter-orbital width in the smallest specimen, while in the two others it was greater. These fish, captured in 1926, came from a sample of elvers liberated into Sherman Lake, Michigan, about 35–40 years earlier.

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