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Larvae Information Summary for
Alosa pseudoharengus
| 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 | 2.5 | ||
| Preanal L. % TL | 79.8 | 4639 |
| Place of development | in close association with substrate | |||
| Larval area | Mid-Atlantic Bight ( Delaware Bay) | |||
| Yolk-sac | ovoid pigmented | Ref: | ||
| Yolk | Oil globules | no oil globule | ||
| Rows on tail | no rows | |||
| Other melanophores on tail | one dorso-ventral cluster or band | |||
| Melanophores on head + trunk | melanophores on head + trunk | |||
| Head deflected at hatching, straight or deflected at 1 day, straight at 2 days; mouth absent, or barely evident at hatching, nonfunctional at 1 day, functional at 2 days with maxillary extending under anterior edge of eye. Yolk initially hemispherical, pale amber, granular; several oil droplets around periphery, or throughout, absent at 1 day; yolk 1/2 absorbed by 1 day about as wide as deep at 3 days. Auditory vesicles triangular at hatching, much enlarged by 2nd day; otoliths visible at hatching. Operculum visible, branchiostegal rays appearing at 1 day. Pectoral fin bud present immediately after hatching, rounded at 3 days. Dorsoventral finfold complete immediately after hatching, extends from second somite, around tail to vent and on to base of yolk sac, reduced at 3 days. Pigmentation: In recently hatched specimens pigmentation pattern of yolk variable, typically with about 10 rows of melanophores across ventral half of yolk. Two chromatophores present below pectoral fin insertion, 3-6 posterior. Row of melanophores along dorsal edge of gut from behind yolk sac to myomere 17-19 and on 3-5 myomeres preceding anus. Series of elongate melanophores on ventral edge of gut from myomere 18-20, to anus. Posterior to vent chromatophores irregularly scattered on body above mid-lateral line, 4-7 chromatophores on caudal fin, usually 2 above notochord, 3-5 below. At 1 day pigment reduced on yolk sac and above mid-lateral line, eye completely pigmented, flecked with gold; melanophores fewer but more pronounced and in more defined rows on upper and lower gut. At 2 days after hatching chromatophores concentrated along posterior and ventral edges of yolk sac; 2 elongate chromatophores below pectoral fin, chromatophores posterior to vent sparse, small. At 3 days after hatching, anterior yolk-sac melanophores form an elongate dash in throat region along ventral surface. Upper gut melanophores often appear as thin extended line. | ||||
Post larvae
| Striking feature | none | |||
| Striking shape lateral | eel-like | dorsal | normal (not striking) | |
| Striking feature | none | |||
| Shape of gut | elongated | |||
| Gas bladder early | visible | late | visible | |
| Spinal armature early | no spines | late | no spines | |
| Pigmentation early | ||||
| Rows on tail | dorsal + ventral row | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on head + trunk | |||
| Pigmentation late | ||||
| Rows on tail | dorsal + ventral row | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on head + trunk | |||
| Peritoneum | with row of melanophores | |||
| Pectorals | normal melanophores at fin base | |||
| Pelvics | normal (i.e. small or absent) without melanophores | |||
| Body long, narrow; head variable, rounded at about 6.0 mm, flattened by 8th day; lower jaw projected beyond upper at 8 days, and at 9.0 mm TL; mouth terminal at 6.0 mm; at 4.5 mm TL maxillary reaches anterior 1/3 of eye, lower jaw with small teeth at 16.5 mm. Gut straight at 9.0 mm TL, striated at 10.4-15 mm. At 4.3-11.9 mm TL anus at beginning of posterior 1/5 of total body length; gas bladder visible at 15.0 mm TL and probably earlier. Caudal and pectorals with or without incipient rays up to 5.4 mm; preanal finfold retained to 16.5 mm. Pigmentation: At 6.0 mm, melanophores in a row on dorsal surface of anterior half of intestine and on dorsal and ventral midline of tail near developing caudal fin. At 8 days, about 12 melanophores along dorsal surface of anterior half of gut, 22-24 on ventral surface of posterior half of gut; scattered melanophores on lateral body wall and in area behind eye. At 9.0 mm TL melanophores on upper gut more expanded, caudal melanophores more stellate, 1 large melanophore dorsal to pectoral fin insertion. At 10.4 mm TL melanophores along ventral surface between pectoral fins forming unjoined V. At 12.1 mm, pigmentation increasing along upper and lower gut with small chromatophores reappearing above lateral line. By 19.0 mm, pigment increased, particularly in area of gills, otic region and caudal fin; dorsolateral row of chromatophores appearing above lateral line. | ||||
| 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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