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Larvae Information Summary for
Alosa mediocris
| 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) | 6.5 | 5.2 | 6.1 | 4639 |
| Preanal L. % TL | 86 | 80 |
| Place of development | ||||
| Larval area | Mid-Atlantic Bight (Delaware Bay) | |||
| Yolk-sac | Ref: | |||
| Yolk | segmented | Oil globules | ||
| Rows on tail | ventral row | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on trunk | |||
| Yolk is large, restricted to 1/4 of body and characterized by granular appearance. Eye large, unpigmented at hatching; hyomandibular, Meckel's cartilage, auditory vesicles present. Mouth open, but lacking esophageal connection; cleithrum and gill clefts formed or forming by 2nd day. Pectoral buds prominent at hatching; leaf-like at 1 day (Ref. 38619). Pigmentation: Initially limited to few chromatophores along gut. 1st day: abdomen with small melanophores; 18-20 elongate melanophores along ventral surface of gut between yolk and anus; few dots on dorsal surface; eye darkly pigmented. 3rd day: single line of 18-25 melanophores on upper surface of intestine, bifurcating at yolk and extending to region below origin of pectoral fin; few melanophores posterior to anus and on caudal finfold. | ||||
Post larvae
| Striking feature | none | |||
| Striking shape lateral | normal (not striking) | 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 | tail partly covered with melanophores | |||
| Melanophores on head + trunk | melanophores on trunk | |||
| Rows on tail | ventral row | |||
| Other melanophores on tail | tail partly covered with melanophores | |||
| Melanophores on head + trunk | melanophores on trunk | |||
| Pectorals | normal | |||
| Pelvics | normal (i.e. small or absent) | |||
| Size range: 6.5-18.0 mm TL. Average preanal myomeres 39 at 6.5-7.0 mm, 38 by end of stage. Body is elongated; anus 4/5 TL from head. Pigmentation: Initially as in yolk-sac larvae; by end of stage, melanophores on ventral part of body from gular region to area above anal fin. Sequence of fin formation: dorsal (9.0 mm), anal (14.0 mm), pelvics (13.0 mm). | ||||
| 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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