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.

Invasion and upstream migration by glass-eels of Anguilla australis australis Richardson and A. reinhardtii Steindachner in Tasmanian Freshwater Streams

1984 ◽  
Vol 35 (1) ◽  
pp. 47 ◽  
Author(s):  
RD Sloane
Keyword(s):  
Fresh Water ◽  
River Flow ◽  
Condition Factor ◽  
Late Summer ◽  
Upstream Migration ◽  
Larval Life ◽  
Freshwater Streams ◽  
Anguilla Australis ◽  
Glass Eels ◽  
High River Flow

The recruitment of glass-eels into fresh water was investigated by hand-netting and electrofishing at the lowest permanent freshwater riffle on several streams in eastern Tasmania. Measurements of the forward extent of the dorsal fin distinguished the short-finned eel, A. a. australis, from the long-finned eel, A. reinhardtii; this separation was verified by vertebral counts and A. a, australis glass-eels were found to be larger than A. reinhardtii. A. a. australis glass-eels were collected at the first riffle during all seasons of the year except mid-summer. Numbers in the catch declined during mid-winter, probably as a result of an effective seaward movement of the freshwater-estuarine interface during periods of high river flow; A. a. australis glass-eels were still found to be abundant near estuary mouths at such times. A. reinhardtii glass-eels exhibited a more restricted movement into fresh water during late summer and autumn with no collections recorded after mid-winter. For both species, the stage of pigmentation was found to advance as the season progressed, and length, weight and condition factor declined with advancing pigmentation. The otoliths of invading glass-eels of both species appeared similar with a single summer ring, suggesting a larval life of 1-1½ years. The restricted invasion period of A. reinhardtii and the similar size throughout the species range suggests a short and precise larval life. The length of larval life of A. a. australis is probably quite variable, resulting in a more substantial and prolonged influx of glass-eels into Tasmanian waters.

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.

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.

Distribution and growth of juvenile mulloway, Argyrosomus hololepidotus (Pisces: Sciaenidae), in the Hawkesbury River, south-eastern Australia

1993 ◽  
Vol 44 (3) ◽  
pp. 401 ◽  
Author(s):  
CA Gray ◽  
VC McDonall
Keyword(s):  
Fresh Water ◽  
Relative Abundance ◽  
Salinity Gradient ◽  
Late Summer ◽  
River Otter ◽  
South Eastern ◽  
Total Length ◽  
Eastern Australia ◽  
South Eastern Australia

The distribution, recruitment, relative abundance and growth of juvenile mulloway, Argyrosomus hololepidotus Lacepede, was investigated in the Hawkesbury River. Otter trawling was used monthly between July 1986 and March 1988 at 12 sites along a salinity gradient over 85 km of the estuary. The greatest numbers of juveniles were caught at sites in the mid section of the estuary (20-40 km from the mouth) where salinities were greatly reduced. No A. hololepidotus were caught at sites that were permanently fresh water and few were caught at the marine-dominated sites closest to the mouth of the estuary. The greatest numbers of juveniles were caught between March and September (autumn-winter) and the fewest between October and January (spring-summer). Juveniles with an estimated age of 2-6 months were caught between February and July (late summer-winter) each year at a size of 30-150 mm total length. Juveniles increased in length by 80-100 mm between March and October.

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.

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