. The Canadian field-naturalist. 100- 17 18 19 20 OCTOBER Figuri 5. Capture ol alosines by turbine tailrace plankton nets in relation to daylight and dark fishing penod. 17-20 Octobei 1985. Figure 6. Catch of alosines by turbine tailrace plankton nets during 1985 in relation to selected environmental parameters. Note: maximum fish catch is not shown. declined from high levels in late summer and early fall but few were encountered at the seaward terminus of the estuary until October. Since catches of YOY alosines are known to vary dramatically due to schooling (O'Leary and Kynard 1986), the vir
. The Canadian field-naturalist. 100- 17 18 19 20 OCTOBER Figuri 5. Capture ol alosines by turbine tailrace plankton nets in relation to daylight and dark fishing penod. 17-20 Octobei 1985. Figure 6. Catch of alosines by turbine tailrace plankton nets during 1985 in relation to selected environmental parameters. Note: maximum fish catch is not shown. declined from high levels in late summer and early fall but few were encountered at the seaward terminus of the estuary until October. Since catches of YOY alosines are known to vary dramatically due to schooling (O'Leary and Kynard 1986), the virtual absence of alosines from the inshore regions of the Annapolis estuary for almost a month before a final seaward migration suggests they school offshore in the estuary until the correct migration stimulus occurs. Seaward migration during 1986 was two weeks earlier than during 1985 but both peak emigration events occurred during new to quarter moon periods (dark nights). Coincident with the dark nights was a sharp decline in water temperature below 12°C. River input to the estuary during 1986 was almost twice the 1985 levels but appeared to play little role in stimulating seaward â ALOSIDS â ©âPRECIPITATION (mm) o RIVERFLOW(m) TEMPERATURE (c). £;ki;?JtoJ, 6 1121 9 18 ,; 25 2 * 7 K Id 1721 222f-2H3() I AUGUST SEPTEMBER OCTOBER FlGl Rl 7. Catch of alosines by turbine tailrace nets during 1986 in relation to selected environmental Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists' Club. Ottawa, Ottawa Field-Naturalists' Club
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