Fred P. Binkowski

Dynamics of Consumption and Food Conversion by Lake Michigan Alewives: An Energetics-Modeling Synthesis

Abstract We developed an energetics model for the alewife Alosa pseudoharengus to evaluate consumption and conversion efficiency processes. We estimated alewife standard metabolism (R) as a function of wet body weight (W, g) and water temperature (T, °C): R (g˙g−1˙d−1) = 0.0073 W−0.215e0.0548T. We estimated maximum daily ration for 15-g, yearling alewives at 20°C to be as much as 37% of their body weight in experiments of 24 h. Modeling simulations based on observed growth in Lake Michigan indicated that yearling alewives may attain close to 70% of their estimated maximum consumption rate during September and October. Simulation results indicated wide seasonal variations in consumption rates; almost 50% of the yearly consumption by an individual adult alewife (age ≥ II) occurs in September and October, suggesting abundant food and possibly relaxed competition during that season. In contrast, adult alewives lose weight during the summer when stratification of Lake Michigan would permit orientation to water...

Evaluating Otolith Analysis for Bloater Coregonus hoyi: Do Otoliths Ring True?

Abstract Laboratory experiments with known-age bloater larvae raised under constant photoperiod (12 h light: 12 h darkness) showed that deposition of otolith rings began at first feeding and occurred daily at all but the lowest growth rates. Based on ring counts, the age of individual bloaters could be estimated within ±6 d over the first 5 months of life. Otoliths of larvae fed high rations interrupted by 5-d periods of starvation or low rations contained obvious bands of abnormally low-contrast rings corresponding to these stress periods. The relationship between fish length and otolith diameter varied among experiments, independent of growth rate. Therefore, back-calculation of length at age will require an estimate of this relationship for each field application.

Foraging behaviors and the interaction of alewife, Alosa pseudoharengus, and bloater, Coregonus hoyi

SynopsisAlewife, Alosa pseudoharengus, and bloater, Coregonus hoyi, are common planktivores in Lake Michigan. Both alewife and bloater use a variety of feeding modes. Alewives can filter, gulp and particulate feed; bloaters can only gulp and particulate feed. We examined handling time per prey and probability of capture for alewife and bloater particulate feeding on Mysis relicta. Using these estimates and available data for filtering alewives, cost curves were derived for alewife and bloater particulate feeding and for alewife using all three modes of feeding. Alewives filter small prey relative to their own body size and particulate feed on larger prey. Feeding mode appears to be dependent on prey size and density and shifts in feeding mode are apparently based on maximizing biomass eaten per time. The ability to filter confers a competitive advantage on alewife when small prey are abundant as they were in the mid 1960s in Lake Michigan. If the zooplankton are large, bloater young-of-year do not suffer this relative disadvantage. In fact, large bloaters can consume prey on the bottom not available to alewife. This shifting competitive balance may explain, in part, the observed dynamics of alewife and bloater.

Size-Dependent Effects of Continuous and Intermittent Feeding on Starvation Time and Mass Loss in Starving Yellow Perch Larvae and Juveniles

Abstract Starvation rates of fish larvae living in patchy prey environments can have an important impact on cohort survival and recruitment. Despite this, little is known about how fluctuations in feeding experience influence starvation resistance and how this changes with ontogeny. Fish previously exposed to fluctuating food densities may not respond to long periods without food in the same way as fish previously exposed to a constant prey density. In a series of laboratory experiments with larvae and juveniles of yellow perch Perca flavescens, we tested the effects of continuous and intermittent feeding on times to starvation and on mass loss up to death from starvation for fish with initial total lengths of 10, 15, and 20 mm. Results indicated that proportional mass loss up to starvation was independent of fish mass, but that it did depend on feeding history. Fish that fed continuously before starvation all died after losing the same proportion of body mass (55%), but intermittent feeders died when the...

Maximum Daily Ration of Great Lakes Bloater

Abstract Maximum daily consumption rates of bloater Coregonus hoyi from Lake Michigan were measured in the laboratory for 1-, 5-, 10-, 25-, 50-, 100-, and 200-g fish at 4, 8, 12, and 16°C. These represent most of the ranges in bloater size and temperature likely to be encountered in Lake Michigan. Bloaters were raised from eggs in the laboratory and acclimated to test temperatures for 22–23 d prior to the experiments. Maximum daily consumption rates were determined by feeding the fish surplus amounts of brine shrimp Artemia sp. at4-h intervals for 24 h. Specific daily ration increased with temperature up to 16°C for all size-groups. At 12 and 16°C, the maximum daily ration of small bloaters (about 1 g) exceeded 120% of body weight per day (based on wet weight; equivalent to 79%/d based on dry weight); the maximum daily ration of large bloaters (over 100 g) ranged between 5 and 12%/d (2–7%/d based on dry weight). As percentage of maximum consumption at 16°C, consumption rates averaged 82% at 12°C, 45% at 8...

Examination of Sampling Bias for Larval Yellow Perch in Southern Lake Michigan

ABSTRACT Evidence suggests larval yellow perch, Perca flavescens, utilize nearshore and offshore habitat during the 30–40 day period between hatch and transition from pelagic to demersal habitat. In a large, open system like Lake Michigan this represents a significant increase in available habitat and it is important to understand how this increase may impact our ability to sample larval yellow perch in an unbiased manner. We measured the vertical distribution of larval yellow perch in southern Lake Michigan as a function of size, age, and diel period. Larval yellow perch were collected from two zones (surface and epilimnion) from 1 to 32 km from shore in 2001 during the day; on four dates surface samples were also collected at night. Results indicate larval perch are more abundant at the surface at night than during the day. Larval yellow perch < 15 mm total length (TL) and younger than 18 days post hatch were found in both surface and epilimnion habitat during the day, but larvae > 15 mm TL were captured only in the epilimnion and farther than 5 km from shore, which suggests a different spatial distribution for larger, older larvae. Diel differences in larval abundance and size at the surface suggest more and larger larvae will be caught for a similar effort at night as compared to daytime sampling. Observed differences in larval distribution with size and age also suggest that sampling concentrated nearshore and/or at the surface has the potential to under-sample larger/older yellow perch larvae in Lake Michigan.

Identification of Gender in Yellow Perch by External Morphology: Validation in Four Geographic Strains and Effects of Estradiol

Abstract External morphological criteria that enable the rapid determination of gender have been developed for Yellow Perch Perca flavescens. Criteria are based upon (1) shape of the urogenital papilla (UGP), (2) size of the UGP relative to the anal (AN) opening, and (3) coloration of the UGP. In females, the UGP appeared (1) rounded at the anterior margin, (2) pointed at the posterior margin and had a V or U shape (crescent shaped in mature animals), (3) generally lacked reddish coloration, and (4) narrower relative to the AN. In males, the UGP (1) appeared circular or oval around the entire margin, (2) typically displayed reddish coloration, and (3) was generally wider relative to the AN. To verify accuracy of these criteria, gender was verified internally in perch of various sizes, sex, and maturity from four domesticated geographic strains (n = 1,389). For all perch tested, accuracy was 97.3% for both sexes, 98.8% for females, and 95.9% for males. To experimentally verify accuracy of these criteria, j...