Relative weight (Wr) of yellow perch (Perca flavescens) was evaluated for fish collected from the Indiana waters of Lake Michigan in June, July and August of 1976 and 1984-1991. Computation of Wr was completed for individual fish in 20 mm intervals over the size range from 100-219 mm using Wr = (W/Ws) 100 where W=weight of a fish in grams and Ws=standard weight for a fish of the same length. Length was highly correlated with weight in all years for males, females and sexes combined (r=0.97-0.99). Distributions of predicted weights for fish at 130 mm and 250 mm were at or near modes of the populations used to construct the Ws equation for yellow perch. Relative weights consistently decreased with increasing size in all years for males, females and sexes combined. Using 1976 length-weight data when the yellow perch population was sparse and fast growing as a standard (100%) for comparison, relative condition factors (Q) increased with increasing size in some years and decreased with increasing size in others for males females and sexes combined and it did not appear to be length dependent. When comparing Wr at 100 mm and 200 mm by sex and month, f hales had higher Wr than males at 100 mm in seven of nine years in June, six of nine years in July and only four of nine years in August. Female fish also had higher Wr than males at 200 mm in eight of nine years in June and July and six of nine years in August. There appeared to be no consistent pattern or trend of Wr increasing or decreasing by month for males, females or sexes combined. When Kn was evaluated for 100 mm and 200 mm fish by sex and year, male fish had higher Kn than females at 100 mm in all eight years. Male and female fish at 200 mm were more similar; male fish had higher Kn in three years, lower Kn in three years and equal Kn in two years. No relationships were found at 200 mm comparing Wr or Kn and CPE (quality/ h) for males (r=0.43; r=0.42), females (r=0.12; r=0.13) or sexes combined (r=0.28; r=0.22). Simple linear correlations of proportional stock density (PSD) with Wr and Kn revealed relative weights increased with PSD for 100 mm (r=0.51) and 200 mm (r=0.72) fish. Relative condition factors also increased with PSD for 100 mm fish, however the relationship was weak (r=0.30) but a strong correlation was found between Kn and PSD (r=0.81) for 200 mm fish. Based on these results, it appears that either Kn or Wr may be used inassessing the condition of yellow perch from the Indiana waters of Lake Michigan. / Department of Biology

AbstractPlankton samples were collected from June through October, 1970, at 5, 10, 15, and 18 m stations on transects extending into Indiana waters of Lake Michigan from Michigan City, Burns Ditch, and Gary.Bosmina longirostris, Daphnia retrocurva, and Cyclops bicuspidatus thomasi were the three dominant crustacean zooplankters in Indiana waters of Lake Michigan. Each species made up more than 10% of the total crustacean zooplankton community.The rotifer community was dominated by Polyarthra vulgaris. Other numerous rotifers included Keratella cochlearis, Synchaeta sp., and Kellicotia lonqispina.There were few consistent differences between the three transects, but, as station depth increased to 18 m, the population dynamics on the three transects tended to become more similar.In general the zooplankton community structure was made up of small microfiltrators with few macrofiltrators or predacious zooplankton present.The dominance of the microfiltrators, small size of Daphnia retrocurva sampled, seasonally late appearance of larger zooplankters, skewed sex ratios of Diaptomus, and increased numbers of zooplankton in general may all be the result of heavy alewife predation on large zooplankton forms.The dominance of less effective microfilter feeding zooplankton and the continued increase of nutrient levels in southern Lake Michigan may be combining to effect an increase in the eutrophication rate in the shallow Indiana waters of Lake Michigan.Ball State UniversityMuncie, IN 47306

Daily and seasonal movements of adult alewives, Alosa pseudoharengus, were studied at depths of 5 to 18 m in Indiana waters of Lake Michigan near Michigan City. Collections were made June to October, 1971, with gill nets and a bottom trawl and June to September, 1972, with gill nets.There was no significant difference (P > 0.05) between trawl and gill net catch rates in 1971 regardless of time of day. Significantly more fish were caught during early summer than late summer. Noon gill net catches did not differ significantly between stations. At 10 m, midnight gill net catches were larger than noon catches and bottom gill net catches were greater than surface catches.In 1972, June and July gill net catches were greater than August and September catches. Spawning was essentially completed by August, and inshore populations of spawning adults returned to deeper offshore areas.Midnight catches were greater than noon catches at all depths. During the day, alewives were farther offshore than the 15 m station, but at night they moved inshore. Crowding of alewives inshore at night resulted in significantly larger catches at the 5 m than at the 15 m station.Food habit studies in 1971 and 1972 revealed zooplankton comprised the major portion of the alewife diet. The copepod Cyclops bicuspidatus was the main zooplankter consumed. Bosmina longirostris and Eurycercus lamellatus were major cladoceran food items. Major non-zooplankton food items were Cryptochironomous, Chironomous, and larval alewives.Zooplankton and cladoceran percent volume in stomachs increased to maxima in July of each year followed by a general decline. Copepods were the dominant food in June. Chironomid larvae were a major component of the diet in May, 1972, and August of both years. The largest percent volume of alewife larvae in stomachs occurred in September.A comparison of daily movements and food habits by percent composition of food items in alewives collected July, 1971, revealed the dominant zooplankton species in alewife stomachs were Bosmina longirostris, Chydorus sphaericus, Alona affinis, Eurycercus lamellatus, Polyphemus pediculus, Cyclops,bicuspidatus, and Limnocalanus macrurus. B. longirostris and P. pediculus, which accumulate at the surface at night, were consumed by alewives in greatest quantity at midnight and sunset when the alewife is near the surface. The benthic species C. sphaericus, A. affinis, and E. lamellatus were consumed in greatest quantity at sunrise when the alewife is near the bottom.Ball State UniversityMuncie, IN 47306

Lake trout (Salvelinus namaycush), chinook salmon (Oncorhynchus tschawytscha), coho salmon (Oncorhynchus kisutch), steelhead trout (Salmo gairdneri), and brown trout (Salmo trutta were collected from April 30 to November 18, 1970 with gill nets at selected sites in Lake Michigan near Gary, Burns Ditch, and Michigan City, Indiana. Catch-per-uniteffort was law and most catches occurred when nets were set in water temperatures in the 50 F (10.0 C) range or lower. Sea lamprey (Petrcnyzon marinas) scars and wounds were found on 25.4% of 71 lake trout captured and fresh wounds occurred on 6.0% of the fish. Scars and wounds were restricted to lake trout 20.0 in. (50.6 cm) or greater in total length and 32.7% of the 55 fish in this size group carried scars or wounds.Food items in stomachs of 39 lake trout, 34 coho salmon, and 29 chinook salmon were expressed as percent frequency of occurrence, numerical percent, and volumetric percent. The alewife (Alosa pseudoharenp_us) was the predominate food consumed by all three species. The crustaceans, Mysis sp. and Pontoporeia affinis, were consumed only by lake trout less than 19.0 in. (48.1 cm) total length.The age and growth of 69 known age fin clipped lake trout were examined. The body-scale relationship was TL = 6.2001 + 0.1238 Sc. The mean calculated total lengths for the first 5 years of growth were 5.3, 10.7, 16.3, 21.0, and 24.0 in. (13.5, 27.2, 41.4, 53.2, and 60.8 cm). Annual growth is considerably greater than recorded for Lake Michigan lake trout prior to alewife introduction and dominance. The length-weight relationship was log W = -2.5087 + 3.2338 log L which agrees closely with previous length-weight analyses of Lake Michigan lake trout.Ball State UniversityMuncie, IN 47306

Fish were collected at 1 and 5 m stations along three transects in Lake Michigan near Michigan City, Indiana. The five major species captured by trawling and/or seining between June and October, 1973 included: yellow perch, Perca flavescens; rainbow smelt, Osmerus mordax; alewife, Alosa pseudoharengus; spottail shiner, Notropis hudsonius; and trout-perch, Percopsis omiscomaycus.The alewife and spottail shiner were major species collected by seining, comprising 94.5% and 4.9% of the catch, respectively. The majority of individuals captured were young-of-the-year (yoy), especially alewives taken predominantly during the daytime.The bottom trawl captured a greater number of species than the seine. Catch-per-unit-effort (cpe) of most species was greatest in night trawling.The yellow perch comprised 16% of the total trawl catch. Spawning adults predominated in June and July with a deep water migration of this species beginning in August. The yoy first appeared in the catch in August.Rainbow smelt represented 24% of the total trawl catch. Adults were present in June catches and yoy were first captured in July. Off-shore movement was underway by October.Alewives comprised 13% of the total trawl catch. Spawning adults were taken in greatest numbers during June and July with a slight off-shore movement beginning in August. Young fish were first captured in the trawl in August.The most abundant species captured with the trawl was the spottail shiner comprising 27% of the total catch. Larger fish were well represented in the catch from June through August with a strong off-shore movement in October. Young fish were first captured in August.Trout-perch represented 16% of the total trawl catch. Catches were restricted to adults and no yoy were captured except in September at one sample site. Off-shore migration of trout-perch had begun by October.There were significant similarities in cpe and size distribution of fish captured at Dunes and Kintzele Ditch transects. In general, catches at the Michigan City transect were lower and size distribution was less consistent compared to the other transect catches.Ball State UniversityMuncie, IN 47306

Age, growth, and abundance data were collected on yellow perch, Perca fla vescen, in Indiana waters of Lake Michigan in 1987 and 1988. The data collected were compared to data on yellow perch in Indiana waters of Lake Michigan dating back to 1975.Changes in growth, mortality, and abundance between 1975 and 1988 were clearly illustrated by the data. Growth has decreased; back-calculation indicates that "quality" (> 200 mm) perch in 1975 were about age II, however, "quality" perch in 1988 were over age V. Annual mortality values produced from following a cohort or comparing age classes indicate that mortality has decreased since 1981, most sharply in 1987 and 1988. Changes in growth and mortality are likely resultant of large changes in abundance. Indices of abundance (biomass and catch-per-uniteffort) reveal that the yellow perch population has become much more dense in the late 1980's than the 1970's and early 1980's. The percentage of quality perch has decreased, however, the abundance of quality perch has increased and peaked in 1988. / Department of Biology

Excess phosphorus is often identified as a major factor in the eutrophication of wetlands and lakes. Often attributed to agricultural practices, the specific source of a large part of this excess has been difficult to determine. The term "nonpoint" source is often used to broadly describe the inflow along waterways of significant amounts of this essential plant nutrient and other pollution. This research was intended to determine the effectiveness of using cattails (Typha), a common plant along waterways, as indicators of plant available phosphorus in the soil along these waterways. Two sites in the southern part of Michigan's lower peninsula (45°N,84°W) where cattails grew were systematically examined for phosphorus and certain cattail characteristics. Plant and soil data were gathered in a grid-like pattern to determine both the relationship of paired data and their spatial distribution across each site. One set of data was shown to be significant. At one site, the density of cattails is weakly correlated with Phosphorus concentrations. Of particular importance, the spatial distribution of both variables is also noticeably similar at the site. No significant correlation between other data was shown. There is also no apparent similarity in spatial distribution. Though weakly correlated, we were able to support a hypothesis that a reasonable correlation exists between cattail density and plant available phosphorus at one site. The spatial distribution of these traits are also similar suggesting that cattails may, in some cases, be useful as indicators of excess phosphorus, perhaps better defining its source than “nonprint”. / Department of Biology

A computer simulation model was developed to examine the effects of various levels of alewife densities, harvest, and bycatch rates on yellow perch Perca flavescens relative densities in Indiana waters of Lake Michigan. The model utilized STELLA® Research software to develop the age-structured population model to include measured or predicted biological characteristics of density-dependent growth, recruitment, and mortality.The model was validated by simulating historically documented yellow perch catch per unit effort (CPUE) from 1984 - 1998. A strong linear relationship (R2= 0.70) between the model predicted CPUE values and the actual CPUE values was found. Twenty year model projections were performed using 1998 yellow perch trawl CPUE as starting values. Alewife abundance was established as either constantly high, constantly low, or allowed to fluctuate randomly and forecasts made used the average of 100 runs. Harvest was imposed on the yellow perch population at 20, 40, and 60% rate levels for fish >_ 200 mm coupled with bycatch at20, 40 and 60% rate levels for fish ranging from 165 - 200 mm.Alewife abundance was the major factor determining the relative abundance of the yellow perch population. On average, constantly high alewife abundance with no harvest or bycatch resulted in projected continuing suppression of yellow perch abundance from 1998 levels. The model predicted the population to rebound using constant low and random alewife abundance with no harvest or bycatch to approximately 1,100 fish/h and 700 fish/h, respectively.The model revealed harvest to have a generally negative impact on the yellow perch population. Increasing harvest and bycatch rate levels resulted in the suppression of projected increases in yellow perch relative abundance. Additionally, increasing harvest and bycatch rates resulted in greater predicted declines in yellow perch abundance. / Department of Biology

Food habit analyses of the young-of-the-year alewife in lake Michigan show zooplankton was the primary component of the diet in 1972 and 1973. Cyclops bicuspidatus contributed the largest portion of the diet in both years. The dominant cladocerans consumed in each year were Bosmina longirostris, Daphnia retrocurva, Chydorus sphaericus, Polyphemus pediculus, and Diaphanosoma brachyurum. Diaptomus spp. was the only other copepod of importance. Chironomid larvae and pupae provided minor volumes in both years.Monthly food habits revealed a general decline in cladoceran percent volume from August to October at the Michigan City and Dunes transects. Bosmina longircstris was the predominant cladoceran in August of both years at both stations. Chydorus sphaericus was a major food item in September, 1972 at the Michigan City transect, and August and September, 1972 at the Dunes transect. Daphnia retraocurva was a primary prey species in August of each year and in September, 1973 at Michigan City, and in August and September of both years at the Dunes transect.Polyphemus pediculus percent volume was greatest in August and September, 1973 at both stations. At the Michigan City transect, Cyclops bicuspidatus was the dominant food item, and was more important in September than August in both years. In contrast, C. bicuspidatus contributed a major portion of the alewife diet at the Dunes transect in each year, but was more important in August than September. Diaptomus spp. percent volume was greatest at the Michigan City transect in October of both years. Chironomids were major food items only in August, 1972 at the Dunes transect.Young-of-the-year alewife food habits in relation to fish length indicated that smaller YOY alewives selected smaller cladocerans and copepods, whereas larger alewives preferred larger cladocerans, copepods, and chironomids.Ball State UniversityMuncie, IN 47306

Monthly water temperature profile series were taken in a near-shore harbor area of Lake Michigan near a fossil-fueled electric generating facility at Michigan City, Indiana. Profiles were recorded every 6 hours over 24 hours at monthly intervals from June through September, 1970. Zooplankton and macrobenthos were sampled monthly from stations at 2, 3 and 5 m depths in the heated-water discharge area in the harbor.A thermal plume was present during each sampling series. The extent of the plume varied and was capable of charging directions within short periods of time. Maximum recorded temperature in the plume was 28 C, but the maximum difference in temperature between plume and control area was only 4 C.Zooplankton species diversity was similar between experimental and control areas. Higher zooplankton densities were found in the harbor area but did not appear to be plume related. Benthos populations were lower in the experimental area compared to the control area. Any effect of the heated water in the harbor area was complicated due to the probable but unknown influence of water quality from Trail Creek.Ball State UniversityMuncie, IN 47306