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Larvae Information Summary for
Alosa aestivalis
| Main Ref: | Jones, P.W., F.D. Martin and J.D. Hardy Jr. 1978 | |||
Yolk-sac larvae
| max | min | mod | Ref. | |
| Length at birth (mm) | 5 | 3.1 | 4.3 | 4639 |
| Preanal L. % TL |
| Place of development | planktonic | |||
| Larval area | Mid-Atlantic Bight (Delaware Bay); fresh and brackish rivers | |||
| Yolk-sac | spherical pigmented | Ref: | ||
| Yolk | Oil globules | more than one oil globule | ||
| Rows on tail | no rows | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on head + trunk | |||
| Body elongate, relatively slender, head moderately deflected at hatching. 1st day: Greatest length less than 1/4 TL, markedly reduced at end of first day. Auditory vesicles poorly developed. 2nd day: Average length 5.1 mm TL; oil droplets absent from yolk mass; auditory vesicles prominent. 3rd day: Average length 5.1 mm TL; lower jaw extends beyond upper. Incipient caudal rays apparently formed at hatching. Pectorals initially absent; conspicuous and possibly rayed at one day, fin enlarged by third day. Origin of dorsal finfold relatively far back on body at hatching; dorsal finfold apparently somewhat more narrow at hatching than at one day; in recently hatched larvae ventral finfold narrow, caudal finfold small, rounded. Pigmentation: At hatching, eye completely pigmented, chromatophores scattered over ventral surface of yolk sac. Series of pigment on dorsal edge of gut from behind yolk sac to anus, occurs as elongate chromatophores to myomere 17-19 followed by irregular widely spaced pigment. Series along ventral gut from myomere 18-20 to anus. At second day, scattered chromatophores more stellate, irregular, row below pectoral fin; melanophores on upper gut enlarged, becoming stellate near vent. | ||||
Post larvae
| Striking feature | none | |||
| Striking shape lateral | eel-like | dorsal | ||
| Striking feature | none | |||
| Shape of gut | tube-like | |||
| Gas bladder early | late | |||
| Spinal armature early | no spines | late | no spines | |
| Pigmentation early | ||||
| Rows on tail | ventral row | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on trunk | |||
| Pigmentation late | ||||
| Rows on tail | ventral row | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on trunk | |||
| Urostyle region early | unpigmented | late | unpigmented | |
| Peritoneum | with row of melanophores | |||
| Pectorals | normal melanophores at fin base | |||
| Pelvics | normal (i.e. small or absent) without melanophores | |||
| 4th day (after hatching): Average length 5.2 mm TL; mouth open, protuberant; auditory vesicles greatly enlarged. Yolk absorbed completely. 5th day: Average length 5.4 mm TL; mouth terminal, upper jaw extends to anterior 1/3 of eye; operculum and otoliths prominent; branchiostegals developing. 6th day: Length 6.0 mm TL; head broader than body. Ventral finfold deep at 2 mm TL; body depth increased by 14 mm TL. Pigmentation: At 5 days after hatching, elongate chromatophores at pectoral bases; melanophores along upper and lower gut in distinct rows. 6th day: Most anterior melanophores on ventral edge of body below pectoral fin typically 4, enlarged; small chromatophores above mid-lateral line. By 10.4 mm TL (and possibly smaller) double line of pigment beginning at pectoral bases, merges gradually so that lines appear to be almost straight. | ||||
Meristic characters
| max | min | mod | Ref. | |
| Total number of myomeres | 53 | 47 | 4639 | |
| Preanal number of myomeres | 45 | 42 | 4639 |
| L 1st feeding | Ref. | Months of presence of larvae | ||||
| max | Jan | Feb | Mar | Apr | ||
| min | May | Jun | Jul | Aug | ||
| mod | Sep | Oct | Nov | Dec | ||
| Water parameters Metric characters |
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