Distribution of Larval Fishes Related to Potential Navigation Impacts on the Upper Mississippi River, Pool 7

Abstract

Ichthyoplankton samples were collected twice monthly during spring and summer 1981 from a variety of habitats in Navigation Pool 7 of the upper Mississippi River. Larval-fish distributions in the pool and variations in those distributions were analyzed relative to potential impacts of increased commercial navigation. Although as many as 66 species of adults have been found in the area (33 considered common), only 17 taxa were identified from our collections. In April and May, most larvae were collected in main-channel and main-channel-border areas next to major expanses of shallow backwaters. White bass Morone chrysops, yellow perch Percaflavescens, and crappies Pomoxis spp. were predominant. Numerous catostomids also were taken. In June and July, most larvae were taken in the lower pool. Freshwater drum Aplodinotus grunniens and gizzard shad Dorosoma cepedianum predominated in these samples, which also included many cyprinids and centrarchids. Diel patterns of abundance varied with species and sampling location. Freshwater drums were more abundant near the surface at midnight than during the day. Coralnon carp Cyprinus carpio were most abundant in collections at dusk, whereas all other cyprinids were most abundant at dusk and dawn. Numbers of gizzard shad also increased slightly at dusk. Total numbers of larvae collected were greatest at dusk in main-channel and mainchannel-border samples; backwater areas produced the greatest catches at midnight and dawn. Seasonal, spatial, diel, and species-specific variations in larval fish abundances significantly influenced the proportion of the community potentially vulnerable to increased boat traffic through Pool 7.

Assessment of Larval Crappie (Pomoxisspp.) Abundance and Lengths in Day and Night Push Net Collections from Coves

“…Larval crappie were 3 16% more abundant in nighttime samples than day samples. Other studies have found similar results regarding larval crappie collections (Lewis and Siler 1980, Holland and Sylvester 1983, Sarnmons and Bettoli 1998. Multiple factors may contribute to the differences between daytime and nighttime collections including larval diel migrations, net avoidance, age of larvae, and changing reservoir conditions.…”

“…The desire to assess crappie year-class strength earlier has led managers to sample larval populations (Taber 1969, Tuberville 1979, Cada et al 1980, Lewis and Siler 1980, Van Den Avyle and Fox 1980, Holland and Sylvester 1983, Thayer et al 1983, Muth and Schrnulbach 1984, Claramunt et al 2005. McDonaugh and Buchanan (1991) documented a high correlation between age-0 and age-1 crappie densities.…”

“…Sampling with surface push nets during the first few weeks after spawn has been used with some success (Stork et al 1978). Some results suggest that night collections capture greater numbers of larval crappie than day collections (Lewis and Siler 1980, Holland and Sylvester 1983, Sammons and Bettoli 1998; however, day sampling is easier to employ in coves with large woody debris. Additionally, information surrounding length distribution comparing these two sampling timeframes has not been published.…”

Distribution of early life history stages of fishes in selected pools of the Upper Mississippi River

“…Protolarvae are common in the drift in spring (Fig. 2) when water temperatures are 14 "C to 16 "C. A strong die1 pattern of drift is evident for this taxa (Holland & Sylvester, 1983). Movement of larvae from backwaters to the main channel peaks at dusk.…”

Structure et typologie ichtyenne de trois bras morts de la Garonne

“…Ce rôle de nurserie est confirmé par l'entrée d'adultes en phase de maturation et formant un troisième groupe au printemps. La remontée d'adultes dans les bras morts durant cette période de hautes eaux printanières assure donc, d'une part, le recrutement qui maintient un peuplement important et diversifié entre le bras mort et la Garonne (Daget in Welcomme 1979, Van Vooren 1981, Holland & Sylvester 1983, Scott & Nielsen 1989 et, d'autre part, le déroulement des processus biologiques de reproduction des poissons (Carrel 1986, Sheaffer & Nickum 1986, Copp 1989.…”