Abstract from -
https://cdnsciencepub.com/doi/10.1139/f76-243 on observed results from collecting eggs from free range Spotfin Shiners.
In 1975 experiments were conducted in the Susquehanna River, near Berwick, Pennsylvania, to investigate spawning-site selection of the spotfin shiner (Notropis spilopterus), a crevice spawner.
Results of experiment A revealed that visual cues and water currents were important in spawning-site selection.
Spotfins deposited
43.638 eggs on black discs and only 2 eggs on clear discs;
87% of the eggs were in horizontal crevices and the remainder in vertical crevices paralleling (7%) and perpendicular (6%) to the current.
Fish spawned over the entire disc in slow currents but avoided strong currents (0.57 m/s) by spawning on the downstream side of the discs. Nearly
90% of the eggs were deposited in crevices 1.5 and 3.0 mm wide, the two smallest sizes. In angular crevices 15–90° from horizontal, fish deposited 74% of 8,358 eggs in the 15° crevice and 24% in the 30° crevice.
In experiment B, a stack of black acrylic plates was placed near the river surface, at midwater, and near the bottom;
in July fish deposited 91% of 13.088 eggs in the bottom stack. By mid-August stack usage had changed and 80% of 11,456 eggs were in the surface stack; the others were in the midwater stack. Rate of egg deposition on acrylic plates between July 10 and August 20 peaked in early August.In experiment C,
95% of 46,328 eggs were placed in crevices between blue (55%) and black (40%) plates; other colors were green (4%), red (1%), and white, yellow, and orange (< 1%). Fish usually spawned on the plates between 0600 and 1000; spawning did not occur at night.
The spotfin has potential as a bioassay organism because of its wide distribution, the ease with which large numbers of its eggs can be collected, its extended breeding season, and the simplicity of rearing the young.
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Stressless Note: There's not enough money to pay me to count thru 46,000 and change pin head eggs!!
So I'm building stacked sets of rigid black or dark blue plates with crevices 1.5 - 3.0 mm wide that will be put in the eddy areas of the local creeks/rivers that have Spotfins, using
FISHMAP(click here) to find those, setting the stacked crevices horizontal at the bottom of the water column and moving them up in the column as the month slides from Late June thru Aug in Ohio.
