Feeding Ecology and Vertical Migration of Adult Alewives (Alosa pseudoharengus) in Lake Michigan

1980 ◽  
Vol 37 (2) ◽  
pp. 177-184 ◽  
Author(s):  
John Janssen ◽  
Stephen B. Brandt

Vertical distributions of adult alewife (135–216 mm long) and Mysis relicta were measured acoustically on a 24 h basis during July, September, and October 1975 and June 1976 at a station 8 km northeast of Milwaukee, Wisconsin in 50 m of water. Both Mysis and adult alewife concentrated on the bottom during day and migrated upwards to the base of the thermocline at night. Extent and timing of vertical migrations of Mysis and alewife coincided. During bright moonlight Mysis concentrated at depths well below the thermocline and larger adult alewives concentrated within this Mysis layer while smaller adult alewives migrated to the base of the thermocline. An examination of stomach contents indicated that vertical migrations were mechanistically linked to feeding behavior. Adult alewives fed extensively on Mysis at night. Total lengths of Mysis in alewife stomachs were significantly longer than total lengths of Mysis captured in vertical plankton tows. Pontoporeia hoyi occurred in alewife stomachs in late afternoon (September) and early evening (June, October). Microcrustacean zooplankton were eaten mostly during day (June) or early morning (October). As Mysis was the most important food, the vertical migration of alewives is interpreted as an adaptation for feeding on vertically migrating Mysis.Key words: alewives, Lake Michigan, Mysis, Pontoporeia hoyi, vertical migration, feeding ecology, light

1990 ◽  
Vol 47 (5) ◽  
pp. 977-983 ◽  
Author(s):  
John T. Lehman ◽  
James A. Bowers ◽  
Robert W. Gensemer ◽  
Glenn J. Warren ◽  
Donn K. Branstrator

Mysis relicta were sampled at a 100-m reference staton in southeastern Lake Michigan (43°N 86°40′W) from 1985 to 1989, to quantify nighttime water column abundances and to compare vertical distributions with those of Daphnia. Diel vertical migration produced maximum concentrations in the thermocline at night of 1 to 10 mysids∙m−3. Variation among replicates averaged 28% with a 3-net Tucker trawl and 19% with Puget Sound vertical closing nets. Mean areal abundances over 5 yr averaged 110 mysids∙m−2 (SE = 20; n = 30; range = 25 to 645) based on nighttime vertical and oblique net tows at 1–3-wk intervals during summers at the reference station. Synoptic cruises from 43°N to 45°N during August indicated that densities were considerably greater offshore than inshore, and greater in the north than in the south. Hypothesized long-term changes in mysid abundances were not detected. Although Mysis is potentially an important predator on Daphnia, differences in nighttime vertical distributions reduce encounters between Mysis and Daphnia during summer in Lake Michigan, such that Mysis exert mortality rates on Daphnia of < 1.5% per day; the latter are in general less than 10% of the birth rates of Daphnia populations, estimated from fecundities.


1978 ◽  
Vol 35 (2) ◽  
pp. 249-253 ◽  
Author(s):  
John Janssen

Particulate feeding, where fish orient to and take prey one at a time, is shown by the alewife, Alosa pseudoharengus, and the ciscoes Coregonus hoyi and C. artedii. Specialized particulate feeding is found in ciscoes and alewives for capturing strongly swimming prey such as Mysis relicta and calanoid copepods. This involves simultaneous darting and sucking. Alewives filter feed by swimming with the mouth fully agape for 0.5–2 s while driving hard with the tail. Ciscoes do not filter feed, but they and alewives display gulping behavior where fish open and close the mouth 2–3 times/s, do not drive hard with the tail, and may take more than one prey per gulp. The alewife has difficulty feeding near or on the bottom. The ciscoes feed easily on or near the bottom and will also take buried prey. Key words: Alosa pseudoharengus, Coregonus hoyi, C. artedii, feeding behavior, Great Lakes, Lake Michigan


1995 ◽  
Vol 52 (2) ◽  
pp. 358-363 ◽  
Author(s):  
John Janssen ◽  
Warren R. Jones ◽  
Audrey Whang ◽  
Philip E. Oshel

The alewife (Alosa pseudoharengus) is an obligate planktivore which uses a variety of methods for capturing zooplankton. Alewife eat Mysis relicta, especially larger individuals, at night during a vertical migration by both predator and prey. We proposed and tested the hypothesis that alewife use the lateral line to sense prey and feed particulately (single prey at a time) in the dark. We used Daphnia magna and Artemia salina adults as prey. Prey densities were such that they did not elicit filter feeding. Observations using infrared video showed that alewife captured individual prey and bit at a vibrating inert bead. We concluded that under appropriate conditions, alewife were size selective and that streptomycin (which blocks the lateral line sensory cells) eliminated this feeding behavior.


Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 610
Author(s):  
Yu Shi ◽  
Lei Liu ◽  
Fei Hu ◽  
Guangqiang Fan ◽  
Juntao Huo

To investigate the evolution of the nocturnal boundary layer (NBL) and its impacts on the vertical distributions of pollutant particulates, a combination of in situ observations from a large tethered balloon, remote sensing instruments (aerosol lidar and Doppler wind lidar) and an atmospheric environment-monitoring vehicle were utilized. The observation site was approximately 100 km southwest of Beijing, the capital of China. Results show that a considerable proportion of pollutant particulates were still suspended in the residual layer (RL) (e.g., the nitrate concentration reached 30 μg m−3) after sunset. The NBL height calculated by the aerosol lidar was closer to the top of the RL before midnight because of the pollutants stored aloft in the RL and the shallow surface inversion layer; after midnight, the NBL height was more consistent with the top of the surface inversion layer. As the convective mixing layer gradually became established after sunrise the following day, the pollutants stored in the nocturnal RL of the preceding night were entrained downward into the mixing layer. The early morning PM2.5 concentration near 700 m in the RL on 20 December decreased by 83% compared with the concentration at 13:34 on 20 December at the same height. The nitrate concentration also decreased significantly in the RL, and the mixing down of nitrate from the RL could contribute about 37% to the nitrate in the mixing layer. Turbulence activities still existed in the RL with the bulk Richardson number (Rb) below the threshold value. The corresponding increase in PM2.5 was likely to be correlated with the weak turbulence in the RL in the early morning.


1993 ◽  
Vol 50 (10) ◽  
pp. 2119-2128 ◽  
Author(s):  
Michael D. Riehle ◽  
J. S. Griffith

We assessed changes in density, distribution, and microhabitat of age-0 rainbow trout (Oncorhynchus mykiss) in Silver Creek, a partially spring-fed stream, by periodic snorkeling in August 1987 through January 1988. We examined trout stomach contents and invertebrate drift samples in diel collections in August, September, October, and January to test if the period of feeding shifted from daytime to nighttime, concurrent with a transition to day concealment. In late September, fish aggregated briefly during the day and then began to conceal themselves in macrophyte beds, undercut banks, and submerged sedges and grasses along streambanks as temperature dropped below 8 °C in early October. Fish emerged from concealment at night, and numbers of trout visible were greatest 30–60 min after sunset and about 30 min before sunrise. Periods of peak feeding changed from afternoon and evening in August and September, when fish were day active, to mainly at night in October after the initiation of day concealment. Trout did not feed upon abundant chironomids in the daytime drift in October. In January, fish fed at 1–4 °C on mayflies, and stomachs were fullest in the early morning. Observations suggest that Silver Creek trout experienced a metabolic deficit that began in September.


2015 ◽  
Vol 41 (2) ◽  
pp. 436-447 ◽  
Author(s):  
Michael J. Weber ◽  
Blake C. Ruebush ◽  
Sara M. Creque ◽  
Rebecca A. Redman ◽  
Sergiusz J. Czesny ◽  
...  

Author(s):  
J.R. Ellis ◽  
M.G. Pawson ◽  
S.E. Shackley

The stomach contents of ten species of elasmobranch from the north-eastern Atlantic indicate that most are generalist predators, eating a variety of polychaetes, molluscs, crustaceans and teleosts. Two species, Mustelus asterias and Squatina scjuatina were found to be specialist feeders, consuming portunid crabs and pleuronectids, respectively. Measures for both dietary breadth and dietary overlap are given and the implications of elasmobranch predation on the prey communities and on commercial species are discussed.


1983 ◽  
Vol 40 (6) ◽  
pp. 681-698 ◽  
Author(s):  
Donald J. Stewart ◽  
David Weininger ◽  
Donald V. Rottiers ◽  
Thomas A. Edsall

An energetics model is implemented for lake trout, Salvelinus namaycush, and applied to the Lake Michigan population. It includes an egestion function allowing any proportional mix of fish and invertebrates in the diet, a growth model accounting for both ontogenetic and seasonal changes in energy-density of predator and prey, a model for typical in situ swimming speed, and reproductive energy losses due to gametes shed. Gross conversion efficiency of energy by lake trout over their life (21.8%) is about twice the efficiency of converting biomass to growth because they store large amounts of high-energy fats. Highest conversion efficiencies are obtained by relatively fast-growing individuals, and over half the annual energy assimilated by older age-classes may be shed as gametes. Sensitivity analysis indicates a general robustness of the model, especially for estimating consumption by fitting a known growth curve. Largest sensitivities were for the intercept and weight dependence coefficients of metabolism. Population biomass and associated predatory impact of a given cohort increase steadily for about 3.5 yr then decline steadily after fishing mortality becomes important in the fourth year in the lake. This slow response time precludes manipulation of lake trout stocking densities as a means to control short-term prey fluctuations. Predation by lake trout on alewife, Alosa pseudoharengus, has been increasing steadily since 1965 to about 8 400 t∙yr−1, and is projected to rise to almost 12 000 t∙yr−1 by 1990.


1983 ◽  
Vol 40 (4) ◽  
pp. 542-547 ◽  
Author(s):  
James S. Maki ◽  
Michael E. Sierszen ◽  
Charles C. Remsen

Comparisons of two methods of separating dissolved adenosine triphosphate (dATP) were made, both in the laboratory and in vertical profiles in Lake Michigan. Laboratory work indicated that filtration through a 0.2-μm pore filter or centrifugation of samples gave similar concentrations of dATP. In Lake Michigan, however, the filtration method gave significantly higher dATP concentrations suggesting some adverse filtration effect. Therefore, centrifugation was chosen as the method to determine dATP. Resulting particulate ATP (pATP) concentrations indicated the highest levels of microbial biomass were located below the epilimnion. Feeding by Mysis relicta appeared to decrease pATP but not release much dATP.


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