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.

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.

Rheotaxis of Elvers of the American Eel (Anguilla rostrata) in the Laboratory to Water from Different Streams in Nova Scotia

1968 ◽  
Vol 25 (8) ◽  
pp. 1591-1602 ◽  
Author(s):  
S. G. Miles
Keyword(s):  
Organic Matter ◽  
Nova Scotia ◽  
Fresh Water ◽  
Stream Water ◽  
Salt Water ◽  
The Other ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Heat Stable ◽  
Experimental Apparatus

In an experimental apparatus, elvers of the American eel (Anguilla rostrata) showed a stronger positive rheotaxis to fresh water than to salt water. The attractiveness of the fresh water was due to dissolved and particulate organic matter; these components were bio-degradable, heat stable, and nonvolatile. Four streams near Halifax, Nova Scotia, were tested, and were found to differ greatly in their attraction of elvers. Elvers were collected from each of three of these streams, and were not found to be attracted to their own stream water; elvers from one stream gave a greater rheotactic response than elvers from the other streams. The presence of adult eels in the water rendered it more attractive, whereas the presence of elvers made it less so.

Les métaux lourds comme indicateurs d'origine géographique de l'anguille d'Amérique (Anguilla rostrata)

1982 ◽  
Vol 39 (7) ◽  
pp. 1004-1011 ◽  
Author(s):  
Guy Moreau ◽  
Claude Barbeau
Keyword(s):  
Heavy Metal ◽  
Drainage System ◽  
Mercury Content ◽  
Specific Pattern ◽  
Anguilla Rostrata ◽  
Metal Concentrations ◽  
Principal Coordinates ◽  
Saguenay River ◽  
American Eels ◽  
Different Origins

American eels (Anguilla rostrata) were sampled from the St. Lawrence River and many of its tributaries. Heavy metal concentrations (Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn) in muscles were analyzed in relation to collection site, age, length, and weight of the specimens. Among the essential heavy metals, zinc, copper, and especially manganese can be used to distinguish the samples by their origin. In the Saguenay River, which is contaminated by mercury wastes, it is possible to distinguish two types of eels according to their mercury content, weight, and length leading to the hypothesis that these two types lived in different parts of the drainage system. The metal concentrations in the eels seem to depend on the availability of these metals in the bottom sediments. Analysis by flexible grouping and principal coordinates yields groups that are not sufficiently homogeneous and distinct to conclude to a specific pattern of heavy metal contents for all the different origins.

Effects of species, sex, length and locality on the mercury content of school shark Galeorhinus australis (Macleay) and gummy shark Mustelus antarcticus Guenther from south-eastern Australian waters

1976 ◽  
Vol 27 (4) ◽  
pp. 603 ◽  
Author(s):  
TI Walker
Keyword(s):  
Total Mercury ◽  
Mercury Content ◽  
South Eastern ◽  
Muscle Tissues ◽  
Wet Weight ◽  
The Mean

The mercury levels detected in the muscle tissues of sharks ranged from 0.01 to 2.7 pprn wet weight for school shark Galeorhinus australis (Macleay) and from 0.07 to 3.0 ppm for gummy shark Mustelus antarcticus Guenther. Estimates of the mean mercury levels for the 1971 Victorian landed commercial shark catch were found to be 0.90 ppm for the school shark and 0.37 ppm for the gummy shark. The analyses for total mercury determinations were carried out by five independent laboratories. Preliminary analyses carried out by one indicatcd that most of the mercury in school sharks and about two-thirds of the mercury in gummy sharks was present as methylmercury. The mercury concentrations varied exponentially with shark length. School sharks had statistically significantly higher mercury levels than gummy sharks of the same length and for both the medium- sized and large individuals of each species males had significantly higher levels than females. Levels in male gummy sharks were found to be affected by locality.

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.

Glucose and lactate kinetics in American eel Anguilla rostrata

1985 ◽  
Vol 249 (1) ◽  
pp. R67-R72 ◽  
Author(s):  
I. Cornish ◽  
T. W. Moon
Keyword(s):  
Food Deprivation ◽  
Turnover Rate ◽  
Glucose Production ◽  
Glucose Turnover ◽  
Anguilla Rostrata ◽  
Replacement Rate ◽  
The Mean ◽  
Total Glucose ◽  
A Minor ◽  
American Eels

Simultaneous infusion of [6-3H]glucose and [U-14C]lactate was used to calculate the turnover rate of glucose, the irreversible replacement rate of lactate, and the rates of the exchange of carbon atoms between glucose and lactate in free-swimming American eels (Anguilla rostrata) fed or food deprived for 6, 15, and 36 (maturing) mo. The mean turnover rate of glucose in fed animals averaged 1.0 mg X min-1 X 100 g-1, while the lactate irreversible replacement rate was approximately 4.0 micrograms X min-1 X 100 g-1. The conversion of 35% of lactate carbon to glucose implied a substantial Cori cycle activity, but this amounted to less than 1% of total glucose production. Food deprivation for 6 mo altered few kinetic patterns, except for an increased lactate irreversible replacement rate and a minor increase in gluconeogenesis from lactate. After a 15-mo fast, glucose turnover decreased to 0.09 +/- 0.02 mg X min-1 X 100 g-1. Plasma lactate concentrations and production rates continuously increased during the experiment. Maturing eels that had been food deprived for 36 mo maintained glucose and lactate concentrations and kinetics similar to values in animals food deprived for only 6 mo. This study stresses the importance of carbohydrate in the metabolism of this species under fed and food-deprived conditions and further supports the tolerance of Anguillid species to food deprivation.

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.

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