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"O‘OCQDIlv.( 1 ..\0h ’..J- u . “A‘_‘ u..;»* LIBRARY “AWigEQISCam' .. U' ‘ry ABSTRACT THE DISTRIBUTION AND GROWTH OF THE FISH POPULATIONS ALONG THE WESTERN SHORE OF LAKE ERIE AT MONROE, MICHIGAN DURING 1970 By Benjamin R. Parkhurst The fish papulations along the western shore of Lake Erie at Monroe, Michigan were sampled from May, 1970 to November, 1970 to study the distribution of species, the growth rates of the more abundant species and the use of the area by young fish. This information will be used as a baseline in determining if any detrimental effects will occur from the forthcoming thermal discharge of a new steam electric plant being constructed on the lake shore. Fish were collected by replicated trawling at two week in- tervals at five index stations and by seining along several shallow beach areas. Analysis of variance and Duncan's Multiple Range Test were used to analyze for differences in the species composition, numbers of species, numbers of individuals and the biomass of fish collected. Significant differences were found between the stations and were related to the great extremes in the oxygen concentra- tions, to the relative protection from severe wave action and to differences in productivity at the stations. Nine species comprised 97.5% of the numbers and 90.3% of the biomass of fish. These species could be divided into three categories on the basis of their habitat preferences: yellow Benjamin R. Parkhurst perch, white bass, emerald shiners, spottail shiners and alewifes were found in highest numbers in the open lake areas; carp, gold- fish and sheepshead preferred areas sheltered from wave action; gizzard shad displayed the widest habitat preference being abundant at some time of the year in all the areas sampled. Yellow perch growth in general was slightly less than that reported for other Great Lakes areas but this may be an artifact of the many different sampling methods used in other studies. The coefficient of condition (K) as calculated for the yellow perch followed a seasonal trend reaching a peak in August and then declining in the fall. This decline was caused by a continua— tion of growth in length after weight increases had ceased. Age 0 carp exhibited abnormal growth, growing less in length during their first year of life than during their second. Carp growth in general was average when compared to other studies conducted in the northern United States. The seasonal growth and abundance of young of the year in- dicated that this area was an important nursery for the young of five species. THE DISTRIBUTION AND GROWTH OF THE FISH POPULATIONS ALONG THE WESTERN SHORE OF LAKE ERIE AT MONROE, MICHIGAN DURING 1970 By Benjamin Rf’Rarkhurst A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and Wildlife 1971 ACKNOWLEDGMENTS I wish to express my sincere thanks to Dr. Howard Johnson and Dr. Richard A. Cole for help in the initiation of this study and for their guidance in the development of results and preparation of this manuscript. Financial assistance from the Detroit Edison Company and the Institute of Water Research is most appreciated. ii INTRODUCTION . TABLE DESCRIPTION OF THE STUDY AREA . METHODS AND MATERIALS . RESULTS . . . . OF CONTENTS Species Composition and Distribution . Age and Growth . Yellow Perch Carp Young of the Year . DISCUSSION . . Species Composition and Distribution . Age and Growth . Yellow Perch Carp Young of the Year . SOME PROBABLE EFFECTS OF THE HEATED EFFLUENT ON THE STUDY ARM 0 O O O 0 LITERATURE CITED iii Page 12 15 15 41 41 48 52 58 58 61 61 63 66 68 69 'Table LIST OF TABLES Page Concentrations (mg/l) of suspended solids, chloride, total organic carbon, total phosphorus, and total nitrogen in the near shore area of western Lake Erie, 1970 . . . . . . . . . . . . . . . . . . . . . . . . . . 8 The total numbers and biomass of fish species captured along the western shore of Lake Erie from June to November, 1970 . . . . . . . . . . . . l6 Duncan's Multiple Range Test on the numbers of species, specimens and the biomass of fish caught at five trawling stations located in the near shore areas of western Lake Erie during 1970 . . . . . . . . . . . . . . . . . . . . . . l8 Duncan's Multiple Range Test on the nine most abundant species of fish caught at the five trawling stations in the near shore areas of western Lake Erie during 1970 . . . . . . . . . . . . . 38 Calculated lengths to each annulus for yellow perch from the near shore area of western Lake Erie during 1970 . . . . . . . . . . . . . . . . . 43 Calculated lengths to each annulus for carp from the near shore areas of western Lake Erie during 1970 O O O O O O O O O O O O O O O O O O O O 51 iv Figure LIST OF FIGURES A map of the sampling area located along the near shore area of western Lake Erie at Monroe, Michigan. The locations of the power plant and five trawling stations are shown . . . . . . . . . . . . . . . . . . . . The temperature and concentrations of oxygen in the River Raisin, discharge canal and near shore areas of western Lake Erie during 1970. Squares indicate temperature and circles indicate oxygen. Solids lines indicate surface values and broken lines in- dicate bottom values . . . . . . . . . . . . Mean numbers and biomass of yellow perch caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled . . . . . . . . . . Mean numbers and biomass of white bass caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled . . . . . . . . . . Mean numbers and biomass of emerald shiners caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled . . . Mean numbers and biomass of spottail shiners caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk.were not sampled . Page 21 23 25 27 Figure 10. ll. 12. 13. 14. Page Mean numbers and biomass of alewifes caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled . . . . . . . . . . . 29 Mean numbers and biomass of carp caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled . . . . . . . . . . . 31 Mean numbers and biomass of goldfish caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled . . . . . . . . . . . 33 Mean numbers and biomass of sheepshead caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled . . . . . . . . . . . 35 Mean numbers and biomass of gizzard shad caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled . . . . . . . . . . . 37 Seasonal growth in length (mean + one standard error) for age classes O-IV of yellow perch from the near shore areas of western Lake Erie during 1970 . . . . . . . . . . . . . . . 45 Seasonal growth in weight (mean + one standard error) for age classes O-IV of yellow perch from the near shore areas of western Lake Erie during 1970 . . . . . . . . . . . . . . . 47 The seasonal trend in the coefficient of condition (K) for age classes I-IV of yellow perch from the near shore area of western Lake Erie during 1970 . . . . . . . . . . . . . . . . . . . . . 50 vi Figure 15. 16. 17. Page Seasonal trend in the coefficient of condition, K (mean + one standard error), for carp from the near shore area of western Lake Erie during 1970. A11 age classes are combined . . . . . . . . . . . . . . . . . . . . 54 Seasonal growth in length (mean + one standard error) of young of the year gizzard shad, white bass, sheepshead, alewife and spottail shiners from the near shore area of western Lake Erie during 1970 . . . . . . . . . . . . . 56 Calculated growth of carp from several areas of the United States. Clear Lake, Iowa (English, 1952); Lake Monona, Wisconsin (Frey, 1940); Des Moines River (Rehder, 1959); Cedar Bluff Res., Kansas (Stuckey and Klaassen, 1971); Bear Lake, Utah (Shields, 1958) . . . . . . . . . . . . . 65 vii INTRODUCTION Lake Erie has gained the reputation of being a dead lake while continuing to maintain a high abundance of fish and other aquatic life. However, the increasing demand upon the use of Lake Erie water by industrial and dense urban centers poses a continuing threat to the quality of the lake and its ability to support a fishery. The near shore areas which are most accessible to sport and commercial fishermen are also those areas which are most threatened by the undesirable side effects of man's activities. One of the major environmental concerns is the potential effects of thermal discharges from steam-electric stations. It is generally unknown if waste heat from these installations will cause significant changes in the aquatic environment of Lake Erie. The present study was undertaken to provide information specifically of value in determining the effects of a large fossil fuel power plant being constructed in Monroe, Michigan located on western Lake Erie at the mouth of the River Raisin. This study, completed before the plant began operating, will be followed by at least two years of study after operation begins. The purpose of this study was to describe the general characteristics of the fish pOpulations along the western shore of Lake Erie and to detect the more subtle variations in the distributions of species as they relate to some of the physical, chemical and biological characteristics of the lake. The specific 1 2 parameters that were sampled included the numbers of species and individuals, the biomass of fish that inhabited the different sampling areas and how these factors changed with time. Yellow perch (Perca flavescens) and carp (Cyprinus carpio) because of their abundance were more intensively studied to provide information on growth rates, condition and year class strengths. The distribution, abundance and growth of juvenile fish were examined to determine the use of the area as a rearing ground. DESCRIPTION OF THE STUDY AREA The study area (Figure 1) included a variety of environmental conditions and a number of habitats that may potentially be affected by the heated effluents from the new Monroe power plant. The plant is being constructed immediately south of the mouth of the River Raisin at Monroe, Michigan. The plant will use river and lake water to cool its condensers and then release the heated effluent into a canal which empties into western Lake Erie 24 km south of the River Raisin's mouth. The River Raisin has been reported to have a detrimental effect on this area (Carr and Hiltunen, 1965) because it carries municipal and industrial wastes into western Lake Erie. These wastes consist of effluents from several paper companies, an automobile manufacturing plant and a primary sewage treatment plant. The chemical characteristics of the study area (Figure 2, Table l) are typical of a lake undergoing rapid eutrOphication. Beeton (1961) reported evidence of environmental changes in western Lake Erie that suggest accelerated eutrophication; Hexagenia sp. the dominant benthic organism have been replaced by chironomids and oligochaetes; during periods of thermal stratification severe oxygen depletions occur; and the concentrations of nitrogen and phosphorus have increased significantly. Drastic changes in the fish fauna have occurred but overfishing is thought to be at least partially responsible (Van Osten, 1948). Figure 1. A map of the sampling area located along the near shore area of western Lake Erie at Monroe, Michigan. The locations of the power plant and five trawling stations are shown. North I take Station 4m ~Y::‘~~-- Plant Plum Creek Dischor 0 (Cam: I! Shoal Station g4? Lake Erie 1.0 Kilometers p————-——-—-‘ South Lake 111 Stofion Figure 2. The temperature and concentrations of oxygen in the River Raisin, discharge canal and near shore areas of western Lake Erie during 1970. Squares indicate temperature and circles indicate oxygen. Solid lines indicate surface values and broken lines indicate bottom values. ‘ Oxygen (mg! I) Lake Eric 12 12- A“; .—K /-/ \ / / \I— \ \ \V..._0___ __._______. /"~-e, // \ \k \i I w... /._"""——'-—--—-_. \. // \kw ~24 2. o liver Ralsln Calendar Date 1970 0 Temperature C Table l. 8 Concentrations (mg/1) of suspended solids, chloride, total organic carbon, total phosphorus, and total nitrogen in the near shore area of western Lake Erie, 1970. Total Suspended Total Organic Total Total Solids Chloride Carbon Phosphorus Nitrogen Low High Low High Low High Low High Low High May River 26.0 52.0 27.3 30.6 38.0 52.0 .15 .25 - 1.0 1.7 Canal 52.0 94.0 22.0 34.0 37.0 94.0 .08 .16 .6 1.2 Lake 28.0 76.0 17.0 25.0 27.0 39.0 .05 .21 .l 1.2 June River 24.0 54.0 19.8 33.3 44.0 54.0 .11 .24 1.2 1.8 Canal 26.0 54.0 17.2 34.6 30.0 39.0 .09 .10 .9 1.8 Lake 22.0 42.0 18.0 21.5 25.0 32.0 .04 .09 .4 .8 July River 34.0 74.0 22.9 34.2 40.0 48.0 .22 .25 1.1 1.8 Canal 42.0 70.0 17.2 32.6 39.0 50.0 .12 .15 1.1 1.7 Lake 18.0 34.0 18.2 20.8 29.0 36.0 .06 .10 .4 ‘ .8 August River 52.0 80.0 34.1 37.6 40.0 47.0 .23 .30 1.0 1.3 Canal 46.0 62.0 29.4 33.9 38.0 44.0 .11 .14 1.0 1.5 Lake 26.0 34.0 26.5 31.4 23.0 26.0 .06 .14 .6 .7 September River 32.0 56.0 30.1 41.0 40.0 53.0 .29 .36 .8 1.5 Canal 18.0 46.0 27.1 30.8 38.0 50.0 .07 .23 . 1.3 Lake 16.0 34.0 20.5 26.7 22.0 31.0 .05 .14 .6 October River 32.0 40.0 24.1 41.0 41.0 56.0 .19 .30 1.0 1.5 Canal 16.0 28.0 17.5 29.8 42.0 47.0 .07 .14 .9 1.6 Lake 14.0 28.0 16.4 21.2 30.0 38.0 .06 .15 .3 .8 November River 26.0 36.0 27.1 31.9 17.0 56.0 .25 .35 1.0 1.5 Canal 24.0 42.0 15.4 24.5 40.0 49.0 .06 .11 .7 1.2 Lake 8.0 14.0 21.6 43.8 29.0 37.0 .08 .27 .4 .1 9 The study area included the off shore area of Lake Erie that extends 5 km north and 6.5 km south of the power plant discharge canal. Also included was the recently excavated discharge canal plus the last 1 km of the River Raisin. The lake bottom has a gentle slope to a miximum depth of 7 m in the study area. The River Raisin and the discharge canal are steep sided ditches maintained by periodic dredging. Maximum depth in both is 8 m. Dredging of the discharge canal was com- pleted in July, 1970. The dredging resulted in highly turbid water in the canal and neareby areas of the lake until after its completion. Western Lake Erie is normally quite turbid because this shallow basin (maximum depth about 12 m) is continuously roiled by wind and high con- centrations of plankton occur during the growing season. The prevailing winds are from the west though easterly winds are not uncommon in the spring and fall. Turbidity and wave action probably inhibit the growth of macrophytes which occurred only in shallows along the shore that were protected from rough water. Commercial fishing was once very intensive in this area. The elimination of the high value species such as the cisco (Coregonus artedii) and whitefish (Coregonus clupeaformis), the decline of the walleye (Stizostedion vitreum) plus the recent discovery of high levels of mercury in Lake Erie fish had all but eliminated commercial fishing in this area by the summer of 1970. Sport fishing primarily for yellow perch and carp occurs in the study area, though the number of fishermen encountered throughout the sampling period was small. Trawling was used as the primary method for monitoring the fish populations. Five stations were selected, each to include different environmental conditions in the area, both in relationship to the lake and to the forthcoming thermal discharge from the power plant. 10 Station I (north lake station) was located 2 km north of the discharge canal, and 100 m off Sterling State Park. The water depth ranged from 2 to 3 m over a muck and sand bottom. The bottom had a gentle slope with a slight dropoff 50 m from shore. The station was affected only by winds out of the east to northeast which could cause the area to become quite rough and roiled. Station 11 (shoal station) was located 1.6 km out on the large sandy shoal which extended into the lake off of the power plant. water depth was 1.5 to 2 m over a sandy bottom which had very little slope. This area was easily roiled by winds from the north, east and south quadrants. As a result, the sandy bottom was almost continuously disturbed. Station IV (discharge canal station) was located in the last kilometer of the power plant discharge canal. The water depth ranged from 3 to 8 m over a peatydmuck bottOm. A small stream (Plum Creek) entered the canal midway on its western side. Even though the canal was completely protected from rough wave action, the turbidity of the canal was as great as in the lake prOper. This was caused by frequent fluctuations in the lake level (seiches) which results in lake water moving in and out of the canal. Erosion from the recent construction of the canal also contributed to the turbidity. The discharge canal will empty into the sandy shoal where station II was located. Station III (south lake station) was located 6 km south of the discharge canal, 1.6 km off shore. The water depth ranged from 2 to 4 m over a muck bottom with a gentle lepe. Due to its proximity to the south shore of the lake, this area was only subject to rough wave action when winds were out of the east. The south lake station 11 is expected to be virtually unaffected by the thermal discharge and will thus serve as a control station in the subsequent years of sampling. Station V (River Raisin station) was located in the last 1 km of the River Raisin. The water depth ranged from 6 to 8 m over a bottom composed of a pudding-like mixture of paper fiber and fine sediment. The river in addition to its heavy load of pollutants was markedly different from the other stations in that it was subject to severe oxygen depletion during the warmer months (Figure 2). At that time of the year, hydrogen sulfide gas continuously bubbles to the surface. Rafts of paper mill wastes drift down the river, break up and settle to the bottom. The river also differed from the other areas in the higher concentrations of organic carbon, nitrogen, phosphorus and suspended solids. METHODS AND MATERIALS To provide an index of change in the fish populations throughout the year, the trawling stations were sampled from May, 1970 to November, 1970 at two week intervals. Two hauls were made at each station on each sampling date to provide information on the variability of the trawl hauls. It was established through trial runs that a five minute haul at 1500 rpm provided an adequate sample. Longer hauls would at times completely fill the cod end thus allowing many fish to escape through the wings. The gear was a 5 meter otter trawl with 2.5 cm stretch mesh netting in the wings and 6 mm stretch mesh netting in the cod end. During a 5 minute tow the trawl moved over an area of bottom 5 m wide and approximately 1 km in length, or about 0.5 hectare. An unknown portion of the fish present were captured in the trawl, but in these shallow waters it was assumed that most fish remain near the bottom and were susceptible to the sampling technique. In addition to the trawl, a 30 m seine with 1 inch (2.5 cm) stretch mesh was used to collect additional fish from the shallow areas of the lake between the mouth of the discharge canal and the mouth of the river. Data collected by seining was primarily used in the age and growth studies. When samples were brought aboard the vessel the larger (greater than 1 kg) carp and goldfish (Crassius auratus) were immediately processed. All other fish were preserved for later analysis. No 12 13 effort was made to distinguish between preserved and unpreserved samples in the analysis. All fish were measured and weighed and in addition scale samples were taken from carp and yellow perch. During the first four months of the study all the perch and carp captured were tagged with dart tags and released in an attempt to study the movement of these species. Tagged fish were never rec6vered and the perch and carp caught in subsequent sample periods were sexed. Impressions of the scale samples were made on cellulose acetate (Smith, 1954) and age and growth were determined by measuring the distance from the origin of the scale to each annulus and to the margin. Annulus formation was assumed to occur on January 1 with all fish collected after January 1 and before the time of actual annulus formation being credited with an annulus. Length frequencies checked by random scale samples were used to determine the age and numbers of young of the year for species other than perch and carp. The length-weight relationships, body-scale relationships, calculated lengths and calculated weights for perch and carp were determined using a computer program designed by Hogman, (1970). The program computed back-calculated lengths to each annulus using the Lee-Lea method: L1 = a + Sl/5 (L-a) where L1 is the total length of the fish at the time of annulus formation; a is the y intercept of the body-scale relationship; S1 is the length of the scale radius at each annulus; S is the length of the fish at capture. Calculated weights at each annulus were computed by fitting the calculated lengths at each annulus to the length-weight relationship. i ‘4 '.‘Il 1| I ll ll.- 14 The coefficient of condition (K), an index of the relative "plumpness" of a fish, was computed for the perch and carp according to the relationship: K: W x 10 L3 where W is the weight in grams and L is the total length at capture (Carlander, 1969). Analysis of variance using a randomized block design was used to test for differences in numbers of fish and biomass of fish caught at the different trawling stations. Tests were run on each of the nine most abundant species and also on the total number of species caught, the total numbers of individuals of all species caught, and the total biomass of fish of all species caught. Duncan's Multiple Range Test (Steel and Torrie, 1960) was used to test for specific differences when significance was found with the analysis of variance. To meet certain of the assumptions of analysis of variance the data were transformed. The numbers of fish and numbers of species data were transformed using square roots while biomass data were transformed using common logarithms. RESULTS Species Composition and Distribution A total of 8661 individual fish comprising 22 species (Table 2) were captured by trawling at the five sampling stations from May 24, 1970 to November 8, 1970. It was found that there was no significant difference (p>.05) in the numbers of fish caught in the two replicate sets of hauls made during each sampling period. There were definite descernible differences between the stations in the numbers of species, types of species, number of individuals and biomaSs of fish caught. The first two sampling dates were excluded from the analysis because sampling had not included all five trawling stations. The results (Table 3) showed the River Raisin to have signifi- cantly lower values for all the parameters tested. Fish were caught at the river station on only three of the sampling dates. On one of these (July 7) the catch consisted of two yellow bullheads caught in only one of the two replicate hauls. The catches from the river on the last two sampling dates (October 25 and November 8) included eight species with 170 specimens and was comparable in composition to the catch at the other stations on those dates. The north lake station had the highest mean numbers of species but was not significantly different from the discharge canal and south lake stations in this respect. The shoal station, while having significantly fewer species than the north lake station, did not differ 15 l6 II: III H.v A III: lllll H.v 0 iiiiiiiiii Anuuma woav movoumau mafiouam «.0 NH llllllllll H.v m H.v q H.0 m Auamamv xmvuoa maumamo III In: H.v H H.v N N.0 m H.v H Anaso uo>aawv mamfiuwuoum mammonhr In: In: H.v H m.0 w H.0 N q.H o Awkwaamsv abouuH> aOHvaumouHum III III N.m 0H null lllll N.H m Avmmnaaan BOHHmhv mHHauma mauaamuuH III III m.H NH m.H m III: lllll u.m m Aanwumo HmaamnoV mauauuaam maHaHmuOH H.V H m.o NH H.v N H.v H ~.o SH HmHaaon OOHHOV mHumHBEm mHaonm --- -u- o.m o m.H N o.s m w.mH AN eHuaaa amHHwHom aumu --- --- m.Hs as w.mH NH 0.0 om w.ao ow Haumuv OHAAHO maaHumHu In: In: m.m an m.m Nu N.0 m q.~ on Ammonmamosmv mamfiaaauw mauoafiwowmd --- -u- H.o H a.o Hm S.o mm m.~ mHN HOHHsmHHV mmwwmumaoesmwm,mm0Ha III In: n.00 NHm N.o HH m.o «N «.5N mm Anmfimcaowv maumuaa mawmwmmm. H.v q «.0 ca 0.0 QHH m.o «ma 0.0 00m Ahmafinm HHmuuoamv mawaomvan mwmouuoz H.v q H.v m m.H qu 0.H mom ~.0 mm Auoafism pamumam0 mopwoumfimnum mfimouuoz H.0 e 0.0 no 0.H mam m.H mum o.e wwm Amman Oqusv madmauno mauuom m.~ qu o.wH cemH o.q mHN m.~ wow m.H mm Amman pumNNHmv aaaaavmamo Naomouon N.o N o.m HOH s.HH HHS.H a.~ no m.Hm MHw Hauuma 3oHHmb mcmumo>mHH «upon as: as: 35 3: 33 . O3 . oz . O3 . oz . O3 .02 . O3 . oz . H2 . oz aoHumum COHumum COHumum GOHumum aHmHmm Hmamo mama coaumum mama HO>HM mwumnomfio nusom Hmonm nuuoz onaH .umnao>oz ou mash aouw wwum axmq mo muozm auwumma ozu maon vauaummo mmHomam swam mo mamaown 0am mumnaba Hmuou any .N maan l7 m.m mNH 0.qu mmq.~ «.mm moo.~ w.w~ omH.H 0.00H omm.m H4909 III III H.0 H IIII IIIII IIII llllllllll IIIII HummzHHan caounv msmOHanmc mausHmuOH III III uuuuu IIIII H.0 H Amman xoouv mHuummaau mwuHHadHna< III III IIIIIIIIII IIII IIIII H.v H H.0 0 Azoumauaouuv mauhmaoomHBo mHmQOOHOm m.0 H H.V H IIII lllll IIII IIIII 0.0 m Ammuonpmuv .am maoumoxoz III III N.0 o IIII IIIII IIII IIIII H.v H ASmHmaam mommaHxaaaav mammonnwwanaommH III III H.0 m IIII IIIII m.H H 0.~ m Auwxoamaumo xumnHHHavv maaHumxw wwwofimwmo A90 H30 H30 30 A30 .u3 .02 .us .02 .u3 .oz .u3 .oz .u3 .oz aoHumum GOHumum aOHuaum :OHumum aHmHmm Hmaao ome COHumum ame um>Hm mwumnomHo nuaom Hmosm nuuoz H.u.aoOV N mHnaH 18 Table 3. Duncans Multiple Range Test on the numbers of species, specimens and the biomass of fish caught at five trawling stations located in the near shore areas of western Lake Erie during 1970. Numbers of Species Stations1 V 2 II III IV I Means/date 0.95 ' 5.70 6.15 6.65 7.30 Numbers Stations V II IV I III Means/date 8.5 50.6 121.1 134.6 138.6 Biomass (gm) Stations V II III IV I Means/date 193.0 1390.3 2709.1 7108.1 7415.6 11 = north lake station; 11 = shoal station; III = south lake station; IV = discharge canal station; V = River Raisin station 2Means not underlined by the same line are significantly different (p>.05) 19 appreciably from the discharge canal or the south lake stations. The highest number of specimens was caught at the south lake station though this station did not differ significantly from the north lake or discharge canal stations. The river and shoal stations had significantly fewer specimens than the other three stations. In terms of the total biomass of fish caught the north lake station had the highest catch while the discharge canal had a slightly smaller but similar catch. The south lake and shoal stations had similar catches and both were significantly lower than the discharge canal and north lake stations. The nine most abundant species comprised 97.5% of the total numbers of specimens and 90.3% of the total biomass of fish collected. The biweekly abundance of each of these nine species and the proportion of young of the year is presented in Figures 3 through 11. These species can be divided into three categories on the basis of their habitat preferences within the study area as indicated by the Duncan's Multiple Range test (Table 4). The first category included yellow perch, white bass, emerald shiners, spottail shiners and alewifes. These five species showed a definite preference for the lake stations and tended to avoid the river and discharge canal. Yellow perch were most abundant at the south lake station though the catch consisted largely of young of the year caught during August. The north lake station had more consistent numbers and a greater biomass of yellow perch and young of the year were present almost continuously after June 24. Low but fairly consistent numbers of yellow perch were caught in the discharge canal and shoal stations. White bass catches were quite variable at all three lake stations. 20 Figure 3. Mean numbers and biomass of yellow perch caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled. 21 ———-I / K - __ .,-__., ____.‘ .—__.1 9-2 94¢ 9.28 IO-I2 10-25 ”-8 Date I970 -L .__H1 1. l ._J.. l .HHHL- _ . H I“ T. .n H .7 H. , H7 , K H , Ix, I H m _ Rm A H H .6 / H H H2 _ H a a H NH 4 H H 6 . H _ H “ 3 .- a. . _ a... H .H H. H . FL P p p P P — H b _ U n b h r p P H I P P mmoo mmmmmoo mmmmmmommmnmaommmmaommm H33; .02 I 35..) 62 I H83? 62 I 35..) .02 I 35..) 02 I 9.0.. £52 .093 3.3 faom _ocoU 00.0335 calm Calendar Figure 4. 22 Mean numbers and biomass of white bass caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled. Discharge Canal South Lake Shoal North Lake River No. WI.(Kg) No. Wt.(Kg) No. Wt.(l(g) No Wt.(Kg) wI.(Kg) No. 23 lO' Ioot .HHI--.HI_--__L_-HI ..-I___-1 H I LHHJ _ Hl-__l _ . ..H .1. l - - 5'23 6'12 6-24 7-7 7-22 8'5 9-2 9-l6 9-2810-l2l0-251l-8 Calendar Date 19 70 24 Figure 5. Mean numbers and biomass of emerald shiners caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled. 25 8.3 £32 IH . H H H . H . H H H _ M . H H H H I. H H H m _ H . I. H H H . H H H H H H. H H _ H H . . H H H m m H . . H a . *H H H H H . _ H _ H H H I IIILll I -I... H FL H .— lr Pb b F H L O .l. 0 O O 0 l O 0 0 .l. 0 .I m l. 0 l m .3...) .oz .3: .;> .02 .095 3.0.. £30m _0caU 00.0535 33¢ --I 9'2 9'16 9'28 l0'l2 l0'25 ”'8 7'7 7'22 8'5 5'23 6'l2 6'24 Calendar Date 1970 Figure 6. 26 Mean numbers and biomass of spottail shiners caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked with an asterisk were not sampled. 27 33 £32 .093 .1 H H H . - H \ - H . H - H H H H H . H H H H . H H - H H H H . _ _ H H _ - _ _ H H H H H H - H _._ H . _ - H H H H H H H H H H H H . - / A A. H» r . r. r A _ r r .w L _ r W _ FIHH mmommmmommmaommmaomm .3: .3 .oz .3: a? 62 .3: .3 .oz .3: is 62 8.0.. {new .0c0U 00.9.3.0 HHt - HH -H__H-- -HH HL -1- 9'2 9'l6 9'28 l0'l2 l0'25 "'8 Date I970 7'7 7'22 8'5 ._-.l..--L-.- __l__..l .. -1.-- .L. .. 5'23 6-l2 6'24 —J—_-J.- I. O . IL.-- L m m .3: ..>> .033 O 10 Z 100- Calendar Figure 7. 28 Mean numbers and biomass of alewives caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled. 29 .1 ¥ k l l. r r r PLH‘. _ _ . . . r . . . b p . . _ maommmmmommmaommmaommmaomm .8:.;> .oz .323 .oz .3...) 6: 3:..3 .oz .05..) .oz 3.0.. £52 .095 9.0.. foam .0c0U @9335 .35. 9'2 9'16 9-28 IO"? IO'25 "-8 5-23 6-‘2 6-24 7-7 7-22 8-5 Calendar Date 1970 Figure 8. 30 Mean numbers and biomass of carp caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote propor- tion of young of the year in the catch. Dates marked by an asterisk were not sampled. Discharge Canal Sauth Lake Shoal North lake River 10.0 .0 Wt. (Kg) 0 No. 3 100 l0.0 1.0 0.l Wt. (Kg) 10 N0. 100 l0.0 1.0 0.l Wt. (Kgl l0 N0. lOO 10.0 1.0 0.l Wt. (Kg) N0. 31 C a lendar Date 1970 r- \/\/\\ /'/\. / - ‘\“\/ N A“ L. \/ b / \/ H: L. l- r H ‘H p \/ r- v“\ l- \ D i l- * p. 1 l L L 1 1 H I 1 H H 1 1 5'23 642 6'24 7'7 7'22 8'5 9'2 9'l6 9'2810'l2l0'25 Il- Figure 9. 32 Mean numbers and biomass of goldfish caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled. 33 j..,,,.,il.H , H H H _ - H H H H m . . m- - H H H H . . H .1. _ H H _ w H H H - H _ . H ., H- H H. H H , H H H m /H H_ H. H H/ H H H H H H H \ H H P P H — F? P WI w m m o m mm m o. o .3.- ..>> 62 .3: a? u.q-::oz _oo.m .OZ zl--l.ilH.ll!a -- I l - 9'2 9'16 9'28 10-12 10-25 ”'8 fl H / _ 7 H H , _ /. . H e H H - x H H H H H .- H H H .- HH - . H H . \ H H .H - . H H H _ .H H H _ H H .H i I i H * * I. b b L _ p p p _ b 1?: P P m m o m mm m m o w mm m o. o w m .3: .3 .oz .3: .3 .oz .3: .3 .oz 8.0.. £00m .0:0U 0903030 .3:. 5'23 6'12 6'24 7'7 7'22 8'5 Calendar Date 1970 Figure 10. 34 Mean numbers and biomass of sheepshead caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled. 35 . . H 4 H H _ H H H H H H H H _, H H H H H H H H H . . . . H H .1 .1 .1 I i H . b b _ — P P p r p _ b _ b P p b _ p p mmommmaommmaowmmaommmmomm .8...) 6: .3:..3 .oz .3:.) .oz .8...) .oz ..ox...>> .oz 3.0.. 5.02 .09...." 3.0.. foam .acou o9af».0 .95. 9-2 9-16 9-28 10-1210-2511-8 5-23 642 6-24 7-7 7-22 8-5 Date 1970 Calendar Figure 11. 36 Mean numbers and biomass of gizzard shad caught at the five trawling stations in the near shore areas of western Lake Erie during 1970. Shaded areas denote proportion of young of the year in the catch. Dates marked by an asterisk were not sampled. 37 H _ . H .l. .I i. J .I i L F p _ _ _ p h _ 0. 00+» _ F _ _ p L _ LF. _ p _ mmQowmmwoowwmmmoowmmwwaowmmmmmowmm 30...; .oz .. .3:; .oz .. .3...) .oz .. .3:; .oz .. .3:; z .. 3.0.. 5.02 .00..» 8.0.. £00m .0:0U 09053.0 ..o>.~. 9-2 9-16 9-28 10-12 10-25 11-8 Calendar Date 1970 5-23 6-12 6-24 7-7 7-22 8'5 38 Table 4. Duncan's Multiple Range test on the nine most abundant species of fish caught at five trawling stations in the near shore areas of western Lake Erie during 1970. Species Numbers Biomass (gm) Yellow Perch Station V II IV I 2 III V II IV III I Mean/date 0.1 3.0 4.1 32.2 73.8 9.1 133.2 179.9 868.1 1595.8 Carp Station V II III I IV V II III IV I Mean/date 0.0 3.0 0.6 2.4 4.7 0.0 297.8 789.3 2073.0 3390.8 Goldfish Station V II III I IV V II III I IV Mean/date 0.0 0.7 0.9 3.3 15.6 0.0 308.1 326.7 1369.1 3334.0 Gizzard shad Station I III II V IV I III II V IV Mean/date 4.2 7.2 10.4 10.7 85.3 67.3 116.0 143.8 229.0 930.8 Alewifes Station V IV II III I V IV II III I Mean/date 0.0 0.1 2.6 2.7 10.0 0.0 4.5 33.4 44.6 146.1 Emerald shiners Station V IV I II III V IV I II III Mean/date 0.1 0.3 1.9 8.8 23.8 0.3 2.1 8.3 48.5 96.5 Spottail shiners Station V IV III II I V IV III I II Mean/date 0.2 3.6 5.8 6.5 14.6 1.2 18.1 30.0 39.4 44.3 White Bass Station V IV III II I V IV III II .I Mean/date 0.2 3.4 10.5 16.1 29.4 2.5 29.3 51.9 94.4 230.7 Sheepshead Station V II III IV I V II IV I III Mean/date 0.0 0.2 3.6 3.7 3.8 0.0 11.4 115.1 121.2 125.5 11 = north lake station; II = shoal station; III = south lake station; IV = discharge canal station; V a River Raisin station. Means not underlined by the same line are significantly different (p>.05). 39 They were most abundant at the north lake station and were moderately abundant at the south lake and shoal stations especially in August and early September. The majority (95%) of bass collected after July 22 were young of the year. Only at the north lake station were older white bass caught after that date. Emerald shiners were most abundant at the south lake station while spottail shiners had a greater preference for the north lake station. There was no appreciable difference in the biomass of spottail shiners at the three lake stations. Similar numbers of both species were found at the shoal station. The emerald shiners showed much more variability in the catch than did the spottail shiners. Young of the year emerald shiners were only common in the catch during October and November while young of the year spottail shiners were common throughout most of the sampling period. The alewifes showed two peak periods of abundance, one in May when they were found at the north lake, shoal and discharge canal stations and the other coming after September 2 at all three lake stations. The first peak consisted of all adult alewifes while the second peak was all young of the year. Alewifes were caught in greatest numbers at the north lake station but were found more commonly during the sampling period at the shoal station. They were collected in fairly high numbers at the south lake station in the late summer and fall but were virtually absent from the discharge canal and completely absent from the river. The second category of fish consisted of carp, goldfish, carp— goldfish hybrids and sheepshead, three species which showed a preference for the discharge canal and north lake stations though sheepshead were also found in quite large numbers at the south lake station. These three species were never collected in the river station and only 40 occasionally were caught at the south lake and shoal stations. Carp were caught at the north lake and discharge canal stations in all months except September and the first sampling date in October. They dominated the biomass of the catch in the period before September 2. Goldfish were very abundant in the discharge canal, especially towards the end of the sampling period. Fairly consistent numbers of goldfish were caught at the north lake station but only occasionally were they found at the south lake and shoal stations. They became dominant in the biomass of the catch in the period after September 2. Only a few carp and goldfish young of the year were caught. Carp-goldfish hybrids were fairly common in the catch for the discharge canal and north lake station and seemed to have the same habitat preference as the carp and goldfish, thus the hybrids could also be included in the second category of fish. Sheepshead followed similar trends in abundance at all the stations where they were caught. There was no significant difference in the numbers of sheepshead at the north lake, discharge canal and south lake stations. Their abundance at the south lake stations showed a more diversified habitat preference than the carp and goldfish. Young of the year sheepshead numbers followed the same trends as the adults. The third category included only one species, the gizzard shad. The gizzard shad showed the widest habitat preference of all the species being found at some time of the year in at least moderate abundance at all five stations. No gizzard shad were collected within the study area until July 22, when they were caught at the north lake and shoal stations. During the next sampling period they were found at the south lake and discharge canal but were not caught in the river until October 25. Gizzard shad indicated a tendency to rapidly colonize new habitats 41 such as the freshly dug discharge canal and the river after tolerable oxygen concentrations returned in the fall. All the gizzard shad collected during the entire sampling period were young of the year. Of the thirteen less abundant species collected, six contributed moderate numbers to the catch at certain times of the year. Channel catfish and yellow bullheads were commonly found in the discharge canal, north lake and south lake stations. Young of the year channel catfish were common in the discharge canal in the fall. White crappies were fairly common in the catch after July 7 and were most abundant in the discharge canal and north lake stations. Seventeen walleyes, fifteen of which were young of the year, were caught primarily from July through September at the north lake and south lake stations. Twelve adult smelt were caught in the river station on the last two sampling dates. A few young of the year smelt were caught at the lake stations during August. Age and Growth Yellow Perch Annuli were complete on 72 per cent of the perch taken on the first sampling date, May 23, 1970. By June 12, 1970 annulus formation was complete in all perch samples. Of the 2,453 perch collected during the entire sampling period, 51 per cent were age 0, 7 per cent age I, 30 per cent age II, 6 per cent age III, 4 per cent age IV and 2 per cent age V. A body-scale relationship was computed using a random subsample of 747 perch ranging in length from 30 to 250 millimeters and representing age groups 0 through VI. The body-scale relationship for the sexes 42 combined was found to be linear with a correlation coefficient of 0.93. The equation was defined as: L = 23.48 + 1.73518 where L is the total length in millimeters at capture and S is the scale radius (32x) in millimeters. The length-weight relationship for the fish used in the body-scale relationship is defined as: w = 5.35 x 10"5L2"6823 where W is the weight in grams and L is the total length in millimeters. Table 5 presents the back-calculated lengths and weights for yellow perch collected in the study area. These Lake Erie perch grew most rapidly in length, 32.4% during their first year of life. Sixty per cent (134 mm) of their total length was attained during the second year, 79.5% (172 mm) the third year, 89.5% (194 mm) the fourth year and 94.5% (201 mm) the fifth year. The largest perch captured during the study period was an age VI fish 230 millimeters long, weighing 144 grams which had a calculated length at the end of five years of 212 millimeters. A significant difference (p>.05) was found between the back-calculated lengths of male and female perch. Male perch averaged 192 millimeters by age V while female perch were 204 milli- meters. Because sex determinations were made on only 195 perch captured after September 2, 1970, no sexual distinctions were made in the analysis of the overall results. Observed seasonal growth for the individual age groups of perch (Figure 12 and 13) indicate greater growth rates than the calculated growth rates. By November, 1970 age 0 perch were an average of 105 mm (9 grams), age I were 146 mm (31 grams), age II were 184 mm (70 grams), age III were 200 mm (90 grams) and age IV were 213 mm (120 grams). 43 Table 5. Calculated lengths to each annulus for yellow perch from the near shore area of western Lake Erie during 1970. Length (millimeters) at end of year Length at Age Number Capture 1 2 3 4 5 6 I 97 129 80 II 367 169 77 136 III 84 198 67 135 172 IV 50 209 55 125 174 198 V 13 214 48 116 171 187 201 VI 1 230 77 90 153 190 202 212 weighted Means Length at Age Capture 2.3 172 73 134 172 194 201 212 Increment 73 62 44 22 14 10 Percent of Growth 32 28 20 10 6 4 Calculated weights (gm) 5 27 52 73 80 92 44 Figure 12. Seasonal growth in length (mean + one standard error) for age classes 0 - IV of yellow perch from the near shore areas of western Lake Erie during 1970. Length (mm) 45 220 200 — 180 r- 160 >- 5 O 1 $ 80— 60- 40'- 20l I H] l I I I l I I I I 5’23 6-12 6-24 7-7 7-22 8-5 9-2 9-16 94810421015 "-8 Calendar Date 19 7O 46 Figure 13. Seasonal growth in weight (mean + one standard error) for age classes 0 - IV of yellow perch from the near shore areas of western Lake Erie during 1970. 47 140 130 120 110 100 90 80 7O 60 50 40 Weight (gm) 30 2O 10 °o L I 1 1 I l L 1 L I l J 5'23 6'12 6‘24 7-7 7-22 8-5 Calendar Date 1970 9-2 9-16 9-2810-1210-25 11-8 48 The coefficient of condition (K) computed for age classes I through IV (Figure 14) changed seasonally. There was no significant difference (p<.05) between the age groups over the entire sampling period. The mean K for all age groups was 1.04 on May 23, 1970. The mean K reached a high of 1.44 in August and then declined to 1.15 in September and to 1.08 by November. The season's growth in weight was completed by August and September while the growth in length was not completed until October. The continuation of growth in length without a corresponding increase in weight caused the perch to become longer for a given weight and reduced the K value. Carp Annulus formation for all age I carp collected within the study area was completed by May 23, 1970. In older fish annulus formation was not completed until July 22, 1970. The total collection of 298 carp ranged in size from 110 to 670 millimeters and represented age groups 0 through XI and XIII. Age 0 carp comprised 1.3% of the total catch, age I and II fish comprised 18.4%, ages III and IV comprised 58.1%, ages VII and VIII comprised 15.8% and fish older than age VIII comprised 6.4%. The two oldest carp collected were thirteen years old and had an average weight of 4208 grams. A linear body- scale relationship was computed from the data and was defined as: L = 18.96 + 1.92185 and had a correlation coefficient of 0.937. The length-weight relationship for these carp was defined by the equation: ' w = 1.44 + 10'5-L3"0042 The calculated length and weights (Table 6) show slow growth (118 mm and 24 grams) during the first year of life. Growth in the second 49 Figure 14. The seasonal trend in the coefficient of condition (K) for age classes I-IV of yellow perch from the near shore area of western Lake Erie during 1970. 50 1.5 1.4- . . \'. 1.3- [4 \'. \ 1.2- I ‘ -. \\ I \' ,7 \ Mean K ( > I.. , 0. . ”1111f / j l - -' I \. 1.0— V l .9 1 l 1 1 1 5'23 6"12 6-24 7-7 7-22 8'5 1 l l l I 1 9-2 9-16 9-28 10-12 10-2511-8 Calendar Date 1970 51 wmoq «New omnm comm meow moqm ooam moma weed moaa moo HmN «a Aawv munwfimz vouaaaoaau nuaouo m ma ma NH NH 0H ON mm mm mm mm oma wHH mo unmouam uaoamuoaH mmo omo Hmo Nae mum own mmm was «we mus wmm mom mHH o.m~q w.q annuamu um sumama mw< mama: wounwfioz mmo one nmo mam com awn «mm «cm mas «as mos «mm mNH New N HHHx mwo mac mwm mom mmm mmm who omq was mum RNA wmo N Hx oHo mom mum oom Hmm «om use Hue HNm HqH mac 0 x Nmn New mam com mus mme mom mom mNH nmm Ha xH New mmm mom one mmq mmm mmm 50H new «N HHH> mom wmq seq one mwm Haw HNH cam mm HH> qu ooq mmq wnm mum mHH Hme no H> Hmc was «on mum oNH «no we > «00 «mm «cw Boa 0H0 so >H mam mmN HHH 0mm He HHH mmN mm Hon ow HH mNH mam mm H ma NH H. 0H s w a s m s m N H «saunas umsasz mm< um Samoan .ONmH wafiuao afium axwu auaumaz mo madam muonm mama anu Baum ammo Mom maaaaam £000 on anuwama mauaaaoaau .s magma 52 year was much accelerated with the carp reaching 268 mm and 281 gms, an increase of 226% and 833% respectively. After the second year the growth in length was progressively slower through the next four years and thereafter remained fairly constant. The numbers of carp collected within any one individual age group was insufficient to provide an estimation of their seasonal growth. No seasonal trends were evident in the coefficient of condition for carp collected in the study area (Figure 15). However, there was a significant difference (<.05) in K between spawning carp collected by seining on May 23, 1970 and those collected by trawling throughout the rest of the sampling period. The carp collected on May 23 were heavy with eggs and milt and in "ripe" Spawning condition. No signifi— cant differences in K were found between age classes. Young of the Year Sufficient numbers of age 0 fish were collected to establish the first years growth of six species found within the study area (Figures 11 and 16). Young of the year gizzard shad which are spawned during the month of June in Lake Erie (Bodda, 1964) had their greatest rate of growth from May until the beginning of September when a length of 120 mm had been attained. Through the rest of the season little additional growth was made. Young of the year Lake Erie yellow perch which are spawned in May (Jobes, 1952) also had their greatest growth rate during the same period but then continued to grow at a slower rate into the first part of October. Maximum mean length attained by the perch was 105 mm. Young of the year alewifes were not collected until September. Juvenile white bass spawned in June 53 Seasonal trend in the coefficient of condition, K (mean + one standard error), for carp from the near shore area of western Lake Erie during 1970. All age classes are combined. Figure 15. Mean K 1.9 1.7 1.6 1.5 1.4 1.3 54 I 1 _l I J 1 I I I J L I I 5’23 6‘12 6‘24 7-7 7-22 8-5 9-2 946 9-2810-1210-2511-8 Calendar Date 1970 55 Figure 16. Seasonal growth in length (mean + one standard error) of young of the year gizzard shad, white bass, sheepshead, alewife, and spottail shiners from the near shore area of western Lake Erie during 1970. Mean Length (mm) 140 120 100 80 80 60 40 120 5 o O O O O :3 a 6 ‘0 O 70 80 60 4O 56 .. Gizzard shad White has: _ Sheepshead // +— a/ _ Alewife W 0 ‘4 L Spottail shiners L. H... 4+... ’- uff/(A —§ 1- 1 1 1 I I I 1 L L a I n 1 5-23 6-12 6-24 7-7 7-22 8-5 9-2 9-16 9-2810-1210-2511-8 Calendar Date 1970 57 (Van Oosten, 1942) reached 58 mm by August 5. A slower growth rate was continued until the beginning of October when a mean length of 85 mm was attained. Juvenile spottail shiners had their greatest growth rate from July 7 through September 16 when a mean length of 67 mm was attained. No appreciable growth was found after that date. The first young of the year sheepshead (2) were collected on July 7 when they were 60 mm long. The next group of juvenile sheepshead collected on September 2 were 80 mm. No appreciable growth was seen after September 28 when the average length of the juveniles was 106 mm. DISCUSSION Species Composition and Distribution The discharge canal and north lake stations showed a number of similarities in the high abundance of fish and types of fish found. This was quite striking because of the physical differences between the stations; primarily the semi-isolation of the discharge canal from the lake and the discharge canal being a newly created environment. The large sandy shoal which extended out into the lake off the mouth of the discharge canal from the lake after the canal was dug. A period of progressively increased colonization followed completion of the canal in July, 1970. The mean catch rose from 12 fish per haul in June and July to 29 per haul in October and November. The seasonal trend of abundance was almost the opposite at the north lake station where the highest number of fish per haul was caught during the period from June 24 through September 28 (137 fish) while the lowest number per haul was caught from October 12 through November 8 (27 fish). The primary reason for the high abundance and biomass of fish at the north lake and discharge canal stations may have been due to the relative richness of these areas. As shown in Table l the discharge canal had high concentrations of all the nutrients listed resulting in a high level of productivity. The richness of the north lake station is not indicated by Table 1 but the higher productivity may have been stimulated by the fertile discharge of the Raisin River. The river water, which had very high levels of most essential nutrients, was 58 59 pushed into the north lake station area whenever there were southern winds. Although the river water had very low concentrations of oxygen, the wave action of the lake would quickly enrich it with oxygen. These two stations were also the least exposed to severe wave action. The discharge canal was protected from all wind action while the north lake station was protected from all but northeasterly winds. Of the major species found at the discharge canal and north lake stations the differences in abundance of gizzard shad and alewifes was most apparent. Gizzard shad were found in their highest abundance in the discharge canal and in least abundance at the north lake station. Alewifes showed just the opposite relative abundance. Both of these species are primarily pelagic planktivores (Dendy, 1946, Odell, 1934), have similar morphologies and would be expected to prefer the same areas. The differences in abundances of these species may be due to a failure of the alewife to colonize the discharge canal or possibly different feeding habitats. The other major species found in the discharge canal were primarily bottom feeders. Gizzard shad do feed extensively on bottom fauna at certain times (Miller, 1960) and may have been able to exploit the discharge canal environment while the alewife could not. The shoal and south lake stations were quite similar in the numbers and types of species found. The only species that had significantly different abundances were yellow perch and sheepshead, which showed a preference for the south lake station, perhaps because of its greater depth. The species collected at these two stations tended to be small planktivoraus fish. There was a conspicuous scarcity of carp and goldfish which seemed to prefer the near shore areas . 60 The characteristics which distinguished the shoal station from the other was its shallow and sandy nature. This was probably responsible for the low numbers of fish caught in this area, as sand is not a very productive or stable substrate and the shallowness of the area made it very turbulent during times of easterly winds. The river station was obviously different in many respects from the other stations. The factor which probably had the greatest affects an prohibiting fish from utilizing the river was the low levels of oxygen present during the warmer months (Figure 2). Oxygen levels were below 4 ppm during the entire summer and were less than 1 ppm during September. These measurements were taken during the day when the concentrations were most likely to be highest. The large numbers of small young fish point to the study area as being an important nursery for yellow perch, white bass, gizzard shad and alewifes. Young of the year of all species comprised 65% of the total number of fish caught. The conspicuous absence of large predators may be an important contributing factor for the large numbers of small fish. Only one large predator, the walleye, was caught and only in small numbers. The walleye is the only high value commercial species remaining in substantial numbers in Lake Erie. They were known to be common in the study area in the early spring and late fall when they were common in the commercial catch (Baldwin and Saalfield, 1962) but were absent, except for young of the year, during the remainder of the year. The only medium quality commercial species common in the catch, white bass and yellow perch, accounted for 42% of the specimens and 12% of the biomass caught. Yellow perch of all ages and sizes were common but 48% of the white bass were young of the year. Adult white 61 bass spawn in this area during the spring and are important in the commercial catch at that time. Two species considered as only low value commercial species, the carp and goldfish, made up 67% of the total biomass caught. The inshore areas, especially the north lake and discharge canal, seem to be very productive habitats for these species. Age and Growth Yellow Perch The age distribution for the yellow perch was very similar to that reported by Baker and Scholl (1970) from their trawling survey in the Ohio waters of western Lake Erie. The age distribution has fluctuated widely in the past, the result of great differences in spawning success from year to year. Baker and Scholl (1970) reported the 1970 population of yearling and adult perch to be the lowest ever recorded and the num- bers of young of the year to be the most abundant since 1965. The calculated growth in length for the yellow perch during their first four years of life are similar to what has been previously re- ported throughout the Great Lakes. Age IV yellow perch from this study average 194 mm.while those from the Ohio waters of western Lake Erie were 203 mm (Baker and Scholl, 1970); Saginaw Bay perch were 241 mm (Hile and Jobes, 1941); Green Bay perch were 201 mm and Lake ‘Michigan perch were 180 mm (Hile and Jobes, 1942). Yellow perch greater than age IV from.these other Great Lakes areas averaged sub- stantially larger than the perch from this study. Different sampling methods probably account for most of this difference in length in the older fish. The other Great Lakes studies relied primarily on commercially caught yellow perch for their analysis which would tend 62 to bias their results toward the larger, faster growing fish. Trap nets, the principle method used for commercial fishing for yellow perch in the Great Lakes have been found to be selective for the larger fish of a size class (Latta, 1959). The growth rates of yellow perch from waters other than the Great Lakes show the same range of variation as those from the Great Lakes (Carlander, 1953). A definite Lee's Phenomenon was seen in the back-calculated lengths of the yellow perch. Lee's Phenomenon is the tendency of back-calculated lengths at a given age to become progressively smaller for older fish. Tesh (1968) gave four possible factors which might cause Lee's Phenomenon; incorrect procedure for back-calculation, non—random sampling of the stock, selective natural mortality, and selective fishing mortality. Among these, selective fishing mortality is probably the primary cause of Lee's Phenomenon in perch from this area but the sampling procedure and selective natural mortality may have contributed effects. Prior to the summer of 1970 commercial fishing with trap nets was quite intensive. These large mesh nets would tend to select for the larger, faster growing fish and allow greater survival of the smaller fish of a given age. The overall mean coefficient of condition for the yellow perch was 1.14 which was as low as the lowest mean K reported for Great Lakes yellow perch (Hile and Jobes, 1942), (Jobes, 1952). The problem with comparing mean K's from these various studies is seen in the marked seasonal trend in K for the fish in the present study. A similar but less pronounced trend was previously reported in Lake Erie perch by Jobes, 1952, who showed for the year 1928 and 1929 that K increased from 1.12 in May to 1.23 in August and decreased to 1.16 in October. 63 If in this study only fish collected in the month of August had been used to calculate the mean K, this value would have been greater than that found in any other previous study on the Great Lakes. Carp A pronounced reversed Lee's Phenomenon is seen in the back— calculated lengths of the carp. A reversed Lee's Phenomenon is thought to be caused by size selective mortality that bears more heavily on the smaller fish of an age group (Tesh, 1968), and favors survival of the faster growing fish. The inhibited first year's growth in carp has also been reported in Utah, (Shields, 1958) and Wisconsin (Frey, 1940). The factors that inhibit growth in western Lake Erie are unknown but may result from high densities of juvenile carp and goldfish in the marshy carp spawning areas that abound along the shores of western Lake Erie. High densities have been found to inhibit carp growth even in areas of high food abundance (Robel, 1962). The competition between these species may be severe as juvenile carp and goldfish have similar feeding habits. This competition could result in a lower survival of smaller carp which would cause the reversed Lee's Phenomenon. The increased growth rate seen in the carp during the second year of growth is probably the result of migration of the carp into the Open areas of the lake where density would be less of a problem. Adult carp feed primarily on bottom fauna (Moen, 1954) while goldfish feed on phyto— plankton (Shimodate 35 El» 1957) thus there is probably less competition between these species as adults. The growth rate of Lake Erie carp was about average when compared to what has been reported from the northern United States (Figure 17). Figure 17. 64 Calculated growth of carp from several areas of the United States. Clear Lake, Iowa (English, 1952); Lake Monona, Wisconsin (Frey, 1940); Des Moines River (Rehder, 1959); Cedar Bluff Res., Kansas (Stucky and Klaassen, 1971); Bear Lake, Utah (Shields, 1958). Length (mm) 400 300 200 100 65 Clear Lake, Iowa Lake Monona,W_igc. - es Moines River Bear Lake, Utah Age (years) 66 Within the United States there is little evidence of regional differences in carp growth rates or in their length-weight relationships (Carlander, 1969). Though not enough fish were sexed to determine if there were differences in the growth of the sexes, Carlander, (1969) reported about half the studies in the United States showed no differences while the other half reported faster growth of females. Most investigators reporting coefficient of condition (K) have not considered the many factors affecting this parameter. K may vary with season, sex, maturity, age and various other factors (Carlander, 1969). This has made it impossible to make reliable comparisons of the K calculated for Lake Erie carp with that calculated for other populations. Young of the Year The seasonal growth of the six species of young of the year collected in the study area was near or above that previously reported for these species in Lake Erie and reflects an adequate food supply for young fish in this area. Gizzard shad was the only species to show a much slower growth. Bodola (1964) reported that Lake Erie age 0 gizzard shad grew to 193 mm by October for the year 1952-1955. Bodola (1964) collected his fish from the Bass Islands of Lake Erie using a wide variety of methods, so his results are probably quite representative for those years. Baker and Scholl (1970) reported that an average of 4% of their trawling survey catch over the last ten years from the Ohio waters of Lake Erie was gizzard shad. In the present study, 26% of the catch was gizzard shad and this higher percentage may reflect a higher density of gizzard shad which may have resulted in the lower growth for gizzard shad in this area (125 mm). 67 The growth of age 0 Lake Erie gizzard shad in 1970 was near average when compared to other areas of the United States (Carlander, 1969). Van Oosten (1942) reported a substantially higher seasonal growth for age 0 Lake Erie white bass. His use of fish from commercial trap nets probably biased his results toward the larger, faster growing fish (Latta, 1959). The growth of age 0 white bass reported by Baker and Scholl, 1970 was similar to that for the present study, and has not varied substantially over the last ten years. The seasonal growth of age 0 alewifes and spottail shiner (Baker and Scholl, 1970) were very similar to those from the study area and are near the mean values reported for the United States, (Carlander, 1969). Age 0 sheepshead growth was similar to that reported by Edsall (1967) but was lower than what has been reported throughout most of the United States. He thought that the high abundance of sheepshead now abundant in Lake Erie are responsible for this. Sheepshead have become much more abundant in the lake since the decline of all the major predator species. SOME PROBABLE EFFECTS OF THE HEATED EFFLUENT ON THE STUDY AREA The Monroe power plant may potentially affect the fish papulations within the study area by the direct effects of the heated effluent and the rerouting of the discharge canal. The heating of the river water may cause a long period of severe oxygen depletion in the discharge canal during the warmer months of the year. This may severely limit the use of the discharge canal by most species. The shoal station will become a mixing ground for the heated water. The heated water may attract fish during the colder months (Trembly, 1961) and will probably repulse them during the warmer months. The addition of the river water to this area will provide a richer environment which could result in higher numbers of fish. The rerouting of the river water away from the north lake station may reduce the nutrient input to this area and could conceiveably reduce the carrying capacity for fish. The effects of the heated water may be only minimal at this station except possibly during temporary periods when the plume is pushed up along the share by offshore winds. The river station may be affected by lake water being pulled up the river channel and through the power plant for cooling purposes. The influx of oxygen rich lake water into the river channel would prob- ably result in many lake species moving into and utilizing this area. The south lake station,due to its greater distance from the source of heated waten*will probably be unaffected. 68 LITERATURE CITED LITERATURE CITED Baker, Carl T. and Russel L. Scholl. 1971. Lake Erie fish pOpulation trawling survey. Dingell—Johnson Project F-35-R—9. 30 pp. Baldwin, Norman S. and Robert W. Saalfeld. 1962. Commercial fish production in the Great Lakes - 1867—1960. Great Lakes Fish. Comm., Tech. Rept. No. 3, 166 p. Beeton, Alfred M. 1961. Environmental changes in Lake Erie. Trans. Am. Fish. Soc., 90(2): 153-159. Bodola, Anthony. 1964. Life history of the gizzard shad in western Lake Erie. Fish. Bull. U.S., 65(2): 391-425. Carlander, Kenneth D. 1953. Handbook of freshwater fishery biology with the first supplement. Dubuque, wm. C. Brown Co. 429 p. Carlander, Kenneth D. 1969. Handbook of freshwater fishery biology, Vol. I. Iowa State University Press. Amer, Iowa. 752 pp. Carr, John F. and Jarl K. Hiltunen. 1965. 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Arts, Lett. 27: 241-266. 69 7O Hogman, Walter J. 1970. A computer program for stock.analysis in Fortran IV. Univac 1108. Trans. Am. Fish. Soc. 99(2): 426-427. Jobes, Frank W. 1952. Age, growth and production of yellow perch in Lake Erie. Fish. Bull. U.S. 52: 205-266. Latta, W. C. 1959. Significance of trap-net selectivity in estimating fish papulation statistics. Paps. Mich. Acad. Sci. Arts. Lett. 44: 123-128. Miller, R. R. 1960. Systematics and biology of the gizzard shad (Dorosoma cepedianum) and related fishes. Fish. Bull. U.S. 60(173): 371-92. Moen, T. E. 1954. Food habits of the carp in morthwest Iowa lakes. Proc. Ia. Acad. Sci. 60: 665-86. Odell, T. T. 1934. The life history and ecological relationships of the alewife (Pomolubus pseudoharengus (Wilson)) in Seneca Lake, New York. Trans. Amer. Fish. Soc., 64: 118-24. Rehder, Dudley D. 1959. Some aspects of the life history of the carp, Cyprinus carpio, in the Des Moines River, Boone County, Iowa. Iowa St. College J. Sci. 34(1): 11-27. Robel, R. J. 1962. weight increases of carp in populations of different densities. Trans. Am. Fish. Soc. 91(2): 234-236. Shields, James T. 1958. The ecology and use of carp in Utah. Utah St. University Ag. Exp. Sta. Bull. 405: 1-63. Shimadate, M. K., Nakamura, H. Koyama, T. Ito, and J. Toi. 1957. Effect of fertilization and significance of artificial feeding to fish production in farm pond. Shioda Plain, Nagano Prefecture (Japanese with English summary). Bull. Freshw. Fish. Res. Lab. Tokyo, 7(1): 1-32. Smith, Stanford H. 1954. Method of producing plastic impressions of fish scales without using heat. Prog. Fish-Cult. 16(2): 75-78. Steel, Robert G. D. and James H. Torrie. 1960. Principles and Procedures of Statistics. New York, McGraw-Hill Book Co., Inc. 481 pp. Stucky, Norman P. and Harold E. Klaassen. 1971. Growth and condition of the carp and river carpsucker in an altered environment in western Kansas. Trans. Am. Fish. Soc. 100(2): 276-282. Tesch, F. W. 1968. 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