. The Canadian field-naturalist. 2004 Leslie and Timmins: Age-0 Round Goby in Ontario 321. Figure 3. Neogobius melanostomus at 25 mm. Length bar = 2 mm. respective modal values of mm and mm (range: mm and mm). Eggs are oblong with rounded base and blunt apex, with a fibre-like basal pedestal or stalk mm long. Yolk is light orange and occupies nearly 75% of the capsule. These eggs incubated in situ in turbid, almost lentic water at 28- 30°C. Similarly, egg clusters were found in early June 2000 at 14°C in the St. Clair River beneath limestone rocks and human arte
. The Canadian field-naturalist. 2004 Leslie and Timmins: Age-0 Round Goby in Ontario 321. Figure 3. Neogobius melanostomus at 25 mm. Length bar = 2 mm. respective modal values of mm and mm (range: mm and mm). Eggs are oblong with rounded base and blunt apex, with a fibre-like basal pedestal or stalk mm long. Yolk is light orange and occupies nearly 75% of the capsule. These eggs incubated in situ in turbid, almost lentic water at 28- 30°C. Similarly, egg clusters were found in early June 2000 at 14°C in the St. Clair River beneath limestone rocks and human artefacts. A cluster of approximately 300 eggs formed an oval patch (estimated area = 40 cm-) under a rock at a depth of m in slow flowing water. Eggs (n = 78) were mm long and mm wide (modal values, nrni and mm). Morphology Yolk, which is usually retained in the gut of fish to mm long, may persist to 11 mm. At 5-8 mm, minute teeth are present on the jaws. Origin of Dl is at the fourth myomere or fifth vertebra, whereas D2 originates at the seventh or eighth myomere (elev- enth or twelfth vertebra). Scales first appear on mid- caudal peduncle at approximately 8-9 mm and body scalation may be complete at 12-15 mm. The upper lip is protractile and jaw articulation is below the anterior margin of the pupil. The anterior tubular nostril protrudes, whilst the minute posterior nostril is flush. At about 13 mm the cranium is de- pressed, cheeks begin to enlarge, and sub-orbital canals and papillae are barely visible. At all sizes, the head is bluntly arrow-shaped in ventral profile (Figure 2). All spines and fin rays are formed, although principal rays are incomplete in the caudal fin. Pectoral fin rays are joined distally by membrane. A small genital papilla is first obvious at about 23 mm. Origin of D2 is on a vertical line with the anus and separated from Dl by a flap of tissue. FuU complement of branched caudal rays is attained at about 20 mm. At 22-2
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