PART IV. BABY FISH OF DEEPWATER SPECIES IN LAKES AND PONDS

Dispersive movements of certain baby fish display a unique sequence of movements or pattern of migration into the offshore limnetic region. As an example, our common pumpkinseed sunfish (Lepomis gibbosus) displays such a sequence. This early life strategy is illustrated in Figure 1 (below). Males dig nests in shallow water and keep them clean for incubating fertilized eggs. Pumpkinseed eggs hatch in about two or three days; their light coloured or transparent babies remain on the nest for an additional three or four days. After their yolks are absorbed, they depart their nests and disperse into deeper limnetic waters. They are about 5 mm long at this time. Live pumpkinseed babies are transparent and virtually invisible except for their black eyes. Even their blood is transparent. Gradually, individuals begin to associate together and develop schooling behaviour. Baby pumpkinseeds remain offshore in deep limnetic regions for a period of two to four weeks, depending upon the temperature regime, hydrographic features of the lake, and probably other factors. At a length of about 20 to 35 mm, all return to shallow weedy region's where they live in schools. As juveniles, at a length of about 50 to 75 mm, they live individually or in loose associations with other pumpkinseeds in shallow weedy areas.
Figure IV-1. Overview of the early life strategy of the pumpkinseed sunfish. An adult male protects eggs in a nest (inset, lower left). Transparent larvae leave the nest and swim in deep areas in loose aggregations (right, above). A closer look at the larval pumpkinseed sunfish is given (centre, below). Illustration by Sally Gadd.
Table IV-1 lists the deep water species described and illustrated here. They are arranged alphabetically by family. Both English and French common names are included with their scientific names. These deepwater larval fishes are the most difficult to capture and study because they are almost completely transparent.

Table IV-1. List of Deepwater Larval Fishes Described

Family
Species                                                        Common Names (English; French), Figure

Atherinidae
Labidesthes sicculus (Cope)                         Brook Silverside; Crayon d'argent,* Fig. IV-2.

Centrarchidae
Lepomis gibbosus (L)                                  Pumpkinseed; Crapet-soleil, Fig. IV-3.
Pomoxis nigromaculatus (Le Sueur)           Black Crappie; Marigane noire,* Fig. IV-4.

Gadidae
Lota lota (L)                                                Burbot; Lotte, Fig. IV-5.

Osmeridae
Osmerus mordax (Mitchell)                        Rainbow Smelt; Eperlan arc-en-ciel, Fig. IV-6.

Percidae
Etheostoma exile (Girard)                           Iowa Darter; Dard a ventre jaune,* Fig. IV-7.
Perca flavescens (Mitchell)                         Yellow Perch; Perchaude, Fig. IV-8.
Stizostedion vitreum (Mitchell)                   Walleye; Doré jaune, Fig. IV-9.

Salmonidae
Coregonus clupeaformis (Mitchell)            Lake Whitefish; Grand corégone, Fig. IV-10.
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* Commonly found in both deep water and shallow water habitats.

Following are descriptions of baby fish that have little pigmentation and normally live in deep water out beyond weedy areas, i.e. they live limnetically or pelagically over deep water.

Fig. IV-2. Diagnosis: Brook silverside babies hatch from adhesive, demersal eggs at lengths of 4-5 mm in July. They occur in rivers and lakes. Brook silverside babies are identifiable by their small size, short intestine, line of melanophores or myomeres along the notochord, and lines of melanphores on both dorsal and ventral body.
Fig. IV-3. Diagnosis: Pumpkinseed babies hatch in nests from adhesive, demersal eggs at a length of 2.5-3.5 mm during June, July and August. They live in open water just beyond the littoral beds of aquatic weeds. Pumpkinseed babies are identifiable by their small size, short intestine and parallel series of melanophores along the mid lateral and ventral body.
Fig. IV-4. Diagnosis: Black crappie larvae hatch in nests from adhesive, demersal eggs at lengths of 4 5 mm in late May and June. They live in rivers and lakes. Black Crappie larvae are identifiable by their short intestine, air bladder with dorsal concentration of melanophores, and late development of body pigment.
Fig. IV-5. Diagnosis: Burbot babies hatch from non-adhesive eggs at lengths of 3-4 mm in early spring. They live in open water in deep lakes. Burbot babies are identifiable by their small size, short intestine and linear series of melanophores along both dorsal and ventral body.
Fig. IV-6. Diagnosis: Rainbow smelt babies hatch from adhesive eggs, which attach to the substrate by a slender stalk formed from the outer coating of the egg. They hatch mainly in small runoff creeks in early spring at lengths of 4-5 mm. Rainbow Smelt babies are identifiable by their slender shape, long intestine, absence of pigmentation along the dorsal body and a linear series of melanophores along the ventral body.
Fig. IV-7. Diagnosis: Iowa darter babies hatch from adhesive, demersal eggs at lengths of 3-4 mm in June, July and August. They live in rivers, streams and lakes. Iowa Darter babies are identifiable by their short body length, intermediate length of intestine, short vertical pigment line at the base of each pectoral fin, and parallel series of melanophore maculae lying between myomeres from the anus to the caudal peduncle.

Fig. IV-8. Diagnosis: Yellow perch babies hatch from eggs contained in gelatinous egg masses which are shaped like accordion-folded strands about 4 cm thick. They hatch in shallow lakes and rivers during May and in deeper lakes
during June. They live in open water areas of both shallow and deep lakes. Yellow Perch babies are identifiable by their length of intestine, presence of air bladder, and parallel series of chevron-shaped melanophores along the mid-lateral body.

Fig. IV-9. Diagnosis: Walleye babies hatch from non-adhesive eggs at lengths of 7-8 mm. They live in open water in rivers and lakes. Walleye babies are identifiable by their intestine, the presence of canine teeth, and the irregular series of melanophores along the mid-lateral body.

Fig. IV-10. Diagnosis: Lake whitefish babies hatch from 10.5-11.5 mm during the month following ice-breakup (April or May). They live in the top metre of water in deep lakes along shores. Lake Whitefish babies are identifiable by their long intestine and linear series of melanophores along the dorsal, ventral and mid-lateral body.

Literature Cited

Amundrud, J.R., D.J. Faber and A. Keast. 1974. Seasonal succession of freeswimming perciform larvae in Lake Opinicon, Ontario. Journal of Fisheries Research Board of Canada 31:1661-1665.

Auer, N.A. 1982. Family Salmonidae, trouts. Pp. 80-145. In: N.A. Auer, ed. Identification of larval fishes of the Great Lakes basin with emphasis on the Lake Michigan drainage. Great Lakes Fishery Commission, Ann Arbor, MI 48105. Special Publication 82-3: 1-744.

Faber, D.J. 1967. Limnetic larval fish in northern Wisconsin lakes. Journal of Fisheries Research Board of Canada 24: 927-937.

Faber, D.J. 1968. A net for catching limnetic fry. Transactions of the American Fisheries Society 97(1): 61 63.

Faber, D.J. and S. Gadd. 1983. Several drawing techniques to illustrate larval fishes. Transactions of the American Fisheries Society 112: 349-353.

Fish, M.P. 1932. Contributions to the early life of sixty two species of fishes from Lake Erie and its tributary waters. United States Bureau of Fisheries, Bulletin 47(10): 293-398.

Storck, T.W., D.W. Dufford and R.T. Clement. 1978. The distribution of limnetic fish larvae in a flood control reservoir in central Illinois. Transactions of the American Fisheries Society 107(3): 419-424.

Werner, R.G. 1969. Ecology of limnetic bluegill (Lepomis macrochirus) fry in Crane Lake, Indiana. American Midland Naturalist 81(1): 164-181.
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