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.

Fecundity and Gonad Observations of the American Eel, Anguilla rostrata, Migrating from Chesapeake Bay, Virginia

1974 ◽  
Vol 31 (8) ◽  
pp. 1387-1391 ◽  
Author(s):  
Charles A. Wenner ◽  
J. A. Musick
Keyword(s):  
Chesapeake Bay ◽  
Anguilla Anguilla ◽  
Total Weight ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Total Length ◽  
American Eels ◽  
The Relationship ◽  
Sexually Mature ◽  
Gonadal Condition

Fecundity of the American eel, Anguilla rostrata, was estimated from 21 specimens migrating from Chesapeake Bay during November 1970. The relationship between total length and fecundity is log y = −4.29514 + 3.74418 log x where y is fecundity and x is total length (mm) and between total weight and fecundity is log y = 3.22990 + 1.1157 log x where y is fecundity and x is total weight (g). Gonadal condition was described statistically and histologically. Specimens migrating from Chesapeake Bay are more sexually mature than either American eels migrating from Canadian waters or European eels, Anguilla anguilla, migrating from Europe. The significance of these findings with regard to Tucker's hypothesis of European eels being more sexually advanced at the onset of the spawning migration is discussed.

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.

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.

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

2015 ◽  
Vol 73 (1) ◽  
pp. 14-21 ◽  
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.

Total Mercury and Methylmercury Content of the American Eel (Anguilla rostrata)

1973 ◽  
Vol 30 (3) ◽  
pp. 454-456 ◽  
Author(s):  
H. C. Freeman ◽  
D. A. Horne
Keyword(s):  
Nova Scotia ◽  
Total Mercury ◽  
Mercury Content ◽  
Human Consumption ◽  
Anguilla Rostrata ◽  
American Eel ◽  
The Mean ◽  
American Eels

In American eels (Anguilla rostrata) caught in Nova Scotia, the total mercury content was found to be 0.72 ± 0.05 ppm and the methylmercury content was 0.40 ± 0.06 ppm (mean ± SE for 23 fish). Since the mean total mercury content was less than 1 ppm and the toxic methylmercury content was 50% of this, or less than the 0.5 ppm guideline, such eels may be acceptable for human consumption.

Occurrence of American Eels, Anguilla rostrata, in Waters Overlying the Eastern North American Continental Shelf

1973 ◽  
Vol 30 (11) ◽  
pp. 1752-1755 ◽  
Author(s):  
Charles A. Wenner
Keyword(s):  
Continental Shelf ◽  
Chesapeake Bay ◽  
North American ◽  
Cape Cod ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Morphometrical Analysis ◽  
Assateague Island ◽  
American Eels

Eleven reproductively maturing specimens of the American eel, Anguilla rostrata, were collected during three independent off-shore trawling operations. Three females were taken on December 5, 1967 southeast of the mouth of Chesapeake Bay in 10–13 fathoms, one male and one female on November 5, 1969 southeast of Cape Cod in 35–45 fathoms, and six females east of Assateague Island on December 22, 1971 in 5 fathoms. Morphometrical analysis showed that the specimens were within the range of "silver" phase of Anguilla rostrata. Gonadal observations were made on all specimens.

Age and growth of the American eel (Anguilla rostrata (LeSueur)) in Newfoundland waters

1971 ◽  
Vol 49 (1) ◽  
pp. 121-128 ◽  
Author(s):  
R. W. Gray ◽  
C. W. Andrews
Keyword(s):  
Age Groups ◽  
Anguilla Anguilla ◽  
Age And Growth ◽  
Anguilla Rostrata ◽  
European Eel ◽  
Silver Eel ◽  
American Eel ◽  
Brackish Waters ◽  
American Eels ◽  
Freshwater Eels

The age (otolith readings) and growth of American eels (Anguilla rostrata (LeSueur)) from fresh and brackish waters in Newfoundland were studied. The eels in Burnt Berry Brook grew faster than eels in the other areas. The growth of young eels in brackish water was slow. Although the growth of these eels increased in subsequent age groups, freshwater eels were consistently larger at each age.The silver eel migrates after spending 12 to 13 years in Newfoundland waters. The American eel in Newfoundland is generally larger than the European eel (Anguilla anguilla L.) at the onset of migration; however, its appearance and state of maturity parallel the condition described in the European eel.

scholarly journals Calcitropic actions of prolactin in freshwater North American eel (Anguilla rostrata LeSueur)

1989 ◽  
Vol 257 (1) ◽  
pp. R74-R79 ◽  
Author(s):  
G. Flik ◽  
J. C. Fenwick ◽  
S. E. Wendelaar Bonga
Keyword(s):  
Maximum Velocity ◽  
Membrane Vesicles ◽  
Anguilla Rostrata ◽  
Plasma Membrane Vesicles ◽  
Prolactin Cells ◽  
American Eel ◽  
Stimulatory Action ◽  
Ovine Prolactin ◽  
Branchial Epithelium ◽  
American Eels

In freshwater-acclimated American eels (Anguilla rostrata LeSueur), ovine prolactin and grafts of the part of the pituitary gland containing the prolactin cells induced hypercalcemia. The hypercalcemia was associated with increased uptake of calcium from the water (resulting from increased influx and decreased efflux) and with enhanced high-affinity Ca2+-adenosinetriphosphatase (ATPase) activity in the gills, the putative biochemical correlate of the branchial Ca2+ pump. Kinetic analyses of ATPase-mediated Ca2+ transport in plasma membrane vesicles of branchial epithelium provided evidence that prolactin enhanced the maximum velocity of the Ca2+ pump. Prolactin treatments raised plasma cortisol levels slightly but significantly in eels. However, cortisol per se was not hypercalcemic in eels and did not stimulate the branchial Ca2+ pump. We conclude that the hypercalcemic potency of prolactin in fish relates to its stimulatory action on active Ca2+ transport in the gills.

Laboratory Experiments on the Orientation of the Adult American Eel, Anguilla rostrata

1968 ◽  
Vol 25 (10) ◽  
pp. 2143-2155 ◽  
Author(s):  
S. G. Miles
Keyword(s):  
Laboratory Experiments ◽  
Time Lapse ◽  
Physical Basis ◽  
Spawning Migration ◽  
Anguilla Rostrata ◽  
Sargasso Sea ◽  
Breeding Area ◽  
American Eel ◽  
American Eels

Adult American eels, Anguilla rostrata, caught on their spawning migration downriver, were filmed while in a circular tank, and the orientation of the eels was analysed by determining the direction of alignment of each eel in each frame of the time-lapse film. When allowed a view only of the sky, the eels oriented southward, in the direction of their supposed breeding area in the region of the Sargasso Sea. This southward orientation continued even if the eels were denied a view of the sky, provided they were subject to the diel rhythm of light–dark. Thus the eel seems capable of noncelestial orientation; the physical basis of this is not known.

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