During the summer of 1964, pumpkinseeds (Lepomis gibbosus), bluegills (Lepomis macrochirus) and green sunfish (Lepomis cyanellus) were taken by shocking in certain areas of Clear Lake, Iowa, marked with numbered jawtags, and displaced to other neighboring areas. Recaptures indicate that separate populations live in various parts of the lake. Recapture rates for pumpkinseeds and bluegills replaced in their home areas were higher than for those displaced to other areas. No correlation was shown between homing and distance displaced, but distances did not exceed 2200 feet. The larger fish showed a greater homing tendency. Home ranges are apparently maintained only for relatively short periods by these fish. Direct observation of homing indicated that green sunfish have a higher precision in orienting themselves and returning to the area of original capture than do the other two species

Kudrna, Joel J.

English

University of Northern Iowa

Proceedings of the Iowa Academy of ScienceVolume 72 | Annual Issue Article 401965Movement and Homing of Sunfishes in Clear LakeJoel J. KudrnaIowa State UniversityCopyright © Copyright 1965 by the Iowa Academy of Science, Inc.Follow this and additional works at: http://scholarworks.uni.edu/piasThis Research is brought to you for free and open access by UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academyof Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu.Recommended CitationKudrna, Joel J. (1965) "Movement and Homing of Sunfishes in Clear Lake," Proceedings of the Iowa Academy of Science: Vol. 72: No. 1 ,Article 40.Available at: http://scholarworks.uni.edu/pias/vol72/iss1/40Movement and Homing of Sunfishes in Clear Lake1 JOEL J. KUDRNA2 Abstract: During the summer of 1964, pumpkinseeds (Le-pomis gibbosus), bluegills ( Lepomis macrochirus) and green su~sh ( Lepomis cyanellus) were taken by shocking in cer-tam areas of Clear Lake, Iowa, marked with numbered jaw ~ag~, and displaced to other neighboring areas. Recaptures md1cate that separate populations live in various parts of the lake. Recapture rates for pumpkinseeds and bluegills replaced in their home areas were higher than for those displaced to other areas. No correlation was shown between homing and distance displaced, but distances did not exceed 2200 feet. The larger fish showed a greater homing tendency. Home ranges are apparently maintained only for relatively short periods by these fish. Direct observation of homing indicated that green sunfish have a higher precision in orienting them-selves and returning to the area of original capture than do the other two species. lNTRODUCI'ION Investigaticms of fish populations were initiated in Clear Lake, Iowa, in 1941, and, with the exception of 1944 to 1946, have continued to the present. The study here reported dleals with the movement of displaced pumpkinseeds, bluegills and green sunfish. Sampling with gill nets, fyke nets and seines from 1947 to 1954 produced 1,215 bluegills and 336 pumpkinseeds (Di Costa1t1zo, 1957). Sampling with an electric shocker and gill nets in 1963 and 1964 produced 147 bluegill and 431 pumpkinseeds. This suggests a change in species composition, although gear selectivity may have had some effect on the relative numbers of fish caught. DESCRIPTION OF AREA Clear Lake is a shallow, eutrophic lake loca:ted in Cerro Gordo County, nmth-central Iowa. At outlet level, it covers an area of approximately 3,643 acres, with a maximum depth of about 20 feet (Pearcy, 1953). The bottom in the littoral zone is composed mainly of sand and gravel, while bottom areas in deeper water are silt (Bailey and Harrison, 1945). The giant i Journal Paper No. J-5081 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa. Project No. 1374, of the Iowa Cooperative Fishery Research Unit, sponsored by the Iowa State Conservation Commission and Iowa State University .. of Science and Technology. :! Graduate Assistant, Iowa State University, Ames. 263 1Kudrna: Movement and Homing of Sunfishes in Clear LakePublished by UNI ScholarWorks, 1965264 IOWA ACADEMY OF SCIENCE [Vol. 72 bulrush ( Scirpus validus) constitutes the major form of emergent vegetation, while Potamogeton spp. are the main submerged plants (Pearcy, 1953). AREAS OF COLLECTION The areas of Clear Lake at which fish were tagged are shown by the abbreviations on the map of Clear Lake (Fig. 1). A gen-eral description of the areas follows: l -IMIL.E-Fig. 1. Map of Clear Lake, Iowa, showing areas of tagging and/o~ displacing pump-kinseeds, bluegills and green sunfish during the summer of 1963 and 1964. Area 2A extended 675 feet, area 2B extended 1,400 feet and area 3 extended 900 feet along the north shoreline. These three areas contained Carex, Scirpus, Myriophyllum and Pota-mogeton, but the vegetation was less dense in area 3 than in 2A or 2B. Mcintosh Point ( M.P.) is north of Lone Tree Point and has densely distributed patches of Potamogeton, Scirpus and Carex. Lone Tree Cove ( L.T.C.) is an area extending 1,600 feet along the shoreline, containing dense patches of Potamogeton, Ceratophyllum and Myrophyllum. Farmers Beach Cove ( F.B.C.) is an area extending 2,000 feet along the shoreline, containing sparsely distributed patches of Potemogeton, Ceratophyllum, Vallisneria, and some Myriophyl-lum. Farmers Beach ( F.B. ) is an area extending 2,500 feet along the shoreline, containing a 200 foot-wide patch of Scirpus and Ceratophyllum, which starts 300 feet from the shore itself. Dodge Point ( D.P.) is a quite shallow and very rocky area with no aquatic vegetation. 2Proceedings of the Iowa Academy of Science, Vol. 72 [1965], No. 1, Art. 40http://scholarworks.uni.edu/pias/vol72/iss1/401965] SUNFISH MOVEMENT 265 Island East ( Is. E. ) is an area along the east side of the Island, which is rock-free and deep, and contains no vegetation. Island West (Is. W.) is an area along the west side of the Island, which is somewhat rocky and shallow, and contains no vegetation. South Bay Dock ( S.B.D.) is a dock located about 500 feet from the center of South Bay, but is lacking in vegetation. South Bay ( S.B.) is an area about the size of a football field, which is patchily distributed with Potamogeton and Scirpus. Venetian Village is an area along the north shoreline which contains many privately owned boat docks. No tagging was done in this area. West End includes the entire bay located at the west end of the lake. This area has much submerged vegetartion. No tagging was done in this area. METHODS AND MATERIALS During the summer of 1964, sunfish were tagged on the lower jaw with size 1, number 4 Monel metal self-piercing tags. These individually numbered tags, purchased from the National Band and Tag Company, were one-quarter inch long when clamped shut. The fishes were captured by means of an electric shocker which generated approximately 160 volts A.C. The current was transmitted into the water through two 5-foot copper electrodes spaced 8 feet apart. Since the areas in which the shocking was done were shallow, the boat was moved by pushing it manually. ABUNDANCE IN v ARIOUS AREAS Sunfishes differed in abundance in the various areas selected for study (Tables 1 .and 2). Area 2 had higher catches that area 3 in both years, perhaps the result of less abundance and di-versity of submerged vegetation in axea 3. Area 2A had moire bluegills than pumpkinseeds, but the reverse was true in all other areas. The two areas with highest catch per effort for pumpkinseeds in 1964 were Lone Tree and Farmers Beach Coves. Tagging studies indicated movements of fish between areas 2 and 3, between Lone Tree Cove and Lone Tree Point, between Farmers Beach and Farmers Beach Cove and between the two sides of the Island, but no movement between these various 3Kudrna: Movement and Homing of Sunfishes in Clear LakePublished by UNI ScholarWorks, 1965266 IOWA ACADEMY OF SCIENCE [Vol. 72 Table 1. Number of sunfish caught per hour of shocking in Clear Lake, 1963. Hours Number caught per hour Shocking Green Area effort Pumpkinseeds Bluegills sunfish 2A and B 21 3.86 1.05 .05 3 11 .36 .27 0 L.T.P. and L.T.C. 27 2.00 .26 0 Island 12 1.25 0 0 South Bay 3 0 0 0 West End 10 2.40 .20 0 M.P. 4 1.00 0 0 Venetian Village 12 2.00 .17 0 Table 2. Number of sunfish caught per hour of shocking in Clear Lake, 1964 Hours Number caught per hour Shocking Green Area effort Pumpkinseeds Bluegills sunfish 2A 31 .84 2.13 .06 2B 25 1.88 .88 .08 3 22 .27 .27 0 L.T.C. 16 5.62 1.94 .25 L.T.P. 9 1.22 1.00 0 F.B. 18 1.66 .89 .06 F.B.C. 22 3.23 .23 .09 Is. E. 11 1.73 0 0 Is. W. 18 1.78 .22 .56 S.B. 10 2.10 .60 0 D.P. 10 3.20 .10 0 major areas. The populations in these general areas may be in-dependent of each other. MOVEMENT AND HOMING Movement and homing of sunfish were studied by removing the fish from the area of capture and releasing them elsewhere. Several factors, such as habitat preference, distance of displace-ment, size of fish and time at large were investigated as vari-ables which would affect movement and homing. The homing behavior of sunfish was· studied by observing the movement of the fish. Some of the fish were not displaced, but were replaced in the area of initial capture. Recapture Rates. A total of 368 pumpkinseeds, 166 bluegills and 23 green sunfish were diisplaced from one area of the lake and transported to another area. Of the displaced pumpkinseeds 44% ( 163) were recaptured; of the bluegills 44% ( 73) were recaptured; of the green sunfish 7 4% ( 17) were recaptured. Per-haps the green sunfish are hardier fish and are more able to withstand the physical effects of handling and tagging. Since none of the fish used in this study were caught more than twice, 4Proceedings of the Iowa Academy of Science, Vol. 72 [1965], No. 1, Art. 40http://scholarworks.uni.edu/pias/vol72/iss1/401965] SUNFISH MOVEMENT 267 there is a possibility that fish suffer mortality when subjected to hyperactivity. Homing Percentages. The percentages of homing are based on the total number of the recaptured fish which homed, compared to the total number of fish displaced and recaptured (per cent h . Number homed Ollllng -~~~~~~~~~~~~~~~~~~ Number recaptured after displacement. Of the recaptured pumpkinseeds 64% homed; of the recaptured bluegills 60% homed; and of the recaptured green sunfish 76% homed. Pumpkinseeds and bluegills appear to home with about the same percentage, while green sunfish appear to home more after displacement than do the pumpkinseeds and bluegills. Homing and Habitat Preference. Movements of sun£sh in areas 2A, 2B and 3 (Table 3) show that pumpkinseeds prefer the habitat of area 2A and 2B o¥er area 3. Pumpkinseeds shocked in area 2A and displaced to area 3 mostly returned to area 2A, but some went to area 2B. Pumpkinseeds captured in area 2B and taken to area 3 mostly returned to 2B, but some want to airea 2A. Conversely, pumpkinseeds shocked in area 3 and displaced to area 2A or 2B stayed in area 2A and 2B. Bluegills prefer the habitat of area 2A over those of areas 2B m 3 (Table 3). Bluegills shocked in either area1 2B or 3 and transported to area 2A stayed in area 2A. Bluegills shocked in area 2A and transported to either area 2B or 3 tended to return to area 2A. Pumpkinseeds shocked in Lone Tree Cove and transported to Lone Tree Point and later recaptured had a high percentage of homing (92%), as did pumpkinseeds shocked in Farmers Beach Cove and transported to Farmers Beach ( 70%). On the other hand, there was no homing of sunlish shocked at Lone Tree Point ,and released at Lone Tree Cove and a low percentage of homing of pumpkinseeds shocked at Farmers Beach and re-leased at Farmers Beach Cove. Homing and Distance Displaced. Most investigators of homing behavior show that the homing percentages decrease as the distamce the fish are displaced increases. Data from this study (Table 3) show little effect of distance displaced upon homing percentages. The distances the fish were displaced were less than 220 feet and possibly were not great enough to have an effect on homing percentages. Pumpkinseeds captured at Dodges Point were transported various distances out into the lake in con-b"ast to the other displacements along shore. Homing and Size of Fish. It is commonly held that larger fish will return more often than smaller ones to the same ter-5Kudrna: Movement and Homing of Sunfishes in Clear LakePublished by UNI ScholarWorks, 1965268 IOWA ACADEMY OF SCIENCE [Vol. 72 Table 3. Percentages of sunfish which were recaptured and percentages of these which homed after being tagged in one area and displaced to another area in Clear Lake during the summer of 1964 ._, "'O <J.) Cl) Cl) .... ..... ~ bl) .--:::; .a i::: bl) <J.) Species <J.) .s cd "'O "O ~ § §' s ..... <J.) 4-; <J.) CD .... ......... ......... ,... 4-; (.) (.) <ll i::: ::l i::: ;;-~] 0 (.) i::: 1 <J.) ..... Q) ..,i ...= Oj~ cd (.) p. ~ §' ~ <J.) fil' ~ .... Oj <:§ <.:e <l.l (.) d.l <:.>...<:: 0 z p.... 11:: p.... 11::::: Pumpkinseeds L.T.C. L.T.C. 0 17 65 82 D.P. 200 12 67 88 D.P. 300 10 50 60 D.P. 400 10 60 33 S.B. S.B.D. 500 21 57 66 L.T.C. L.T.P. 800 73 34 92 L.T.P. L.T.C. 800 11 36 0 2A 2B 1000 14 43 50 2B 2A 1000 22 50 82 Is. E. Is. W. 1000 19 42 38 Is. W. Is. E. 1000 32 44 57 3 2B 1200 3 100 0 2B 3 1200 25 40 90 F.B. F.B.C. 2200 30 33 30 F.B.C. F.B. 200 71 42 70 2A 3 200 12 67 62 3 2A 2200 3 33 0 Total displaced 200-2200 368 44 64 Bluegills 2A 2A 0 10 70 88 D.P. 200 1 100 100 S.B. S.B.D. 500 6 17 0 L.T.C. L.T.P. 800 31 32 40 L.T.P. L.T.C. 800 9 44 0 2A 2B 1000 26 46 83 2B 2A 1000 12 67 25 Is. W. Is. E. 1000 4 100 100 3 2B 1200 3 33 0 2B 3 1200 10 70 71 F.B. F.B.C. 2200 16 31 40 F.B.C. F.B. 2200 5 60 33 2A 3 2200 30 47 93 3 2A 2200 3 67 0 Total displaced 200-2200 166 44 60 Green sunfish L.T.C. L.T.P. 800 4 100 50 L.T.P. L.T.C. 800 1 100 100 Is. E. Is.W. 1000 1 0 Is. W. Is. E. 1000 10 80 88 2B 3 1200 2 100 100 F.B. F.B.C. 2200 1 0 F.B.C. F.B. 2200 2 0 2A 3 2200 2 50 100 Total displaced 800-2200 23 74 76 6Proceedings of the Iowa Academy of Science, Vol. 72 [1965], No. 1, Art. 40http://scholarworks.uni.edu/pias/vol72/iss1/401965] SUNFISH MOVEMENT 269 ritory in which they were captured. The pumpkinseeds show this quite clearly (Table 4). Reasons for the low recapture r:ates for pumpkinseeds 4.6 to 5.3 inches long are not known. Bluegills also show a general increase in homing with size. Green sunfish show no indication of this trend, but the sample size is too small to give a valid interpretation of the data. Table 4. Returns to the original site of capture by displaced sunfish ac-cording to size Total length Number Per cent Number Per cent Species in inches tagged recaptured homed homed Green sunfish 3.4-3.7 4 50 2 100 3.8-4.1 4 50 1 50 4.2-4.5 4 75 3 100 4.6-4.9 4 100 3 75 5.0-5.3 5 80 3 75 5.4-5.7 2 50 1 100 Pumpkinseeds 3.4-3.7 37 43 9 56 3.8-4.1 85 52 24 54 4.2-4.5 40 90 17 47 4.6-4.9 87 21 14 73 5.0-5.3 92 12 9 82 5.4-5.7 24 75 17 94 5.8-6.1 15 87 12 92 6.2-6.5 5 60 2 67 Bluegills 3.0-3.3 8 37 1 33 3.4-3.7 9 33 1 33 3.8-4.1 11 45 3 60 4.2-4.5 22 45 7 70 4.6-4.9 42 29 9 75 5.0-5.3 32 34 10 91 5.4-5.7 15 53 4 50 5.8-6.1 12 50 4 67 6.2-6.5 5 20 1 100 6.6-6.9 4 25 1 100 7.0-7.3 8 25 0 0 7.4-7.7 5 20 0 0 7.8-8.1 3 33 0 0 Homing and Days at Large. Parker and Hasler ( 1959) are of the opinion that, the longer fish are kept at large between marking and initial recapture, the better is the percentage of homing. They attribute this increase to the fact that with more searching, the fish are more likely to find their way back home. Parker and Hasler determined their homing percentages by dividing the number of fish tagged into the number of fish returning. Homing percentages in the present study are based onJy on recaptured fish. Data from the present study (Table 5) show that the homing percentages decrease as the time at large increases. This may indicate that fish at large for a longer period of time have a tendency to move around, rather than to 7Kudrna: Movement and Homing of Sunfishes in Clear LakePublished by UNI ScholarWorks, 1965270 IOWA ACADEMY OF SCIENCE [Vol. 72 Table 5. Returns to the original site of capture by displaced sunfish being at large for specified periods subsequent to tagging Number of days between tagging and Number Number Per cent Species initial recapture recaptured homed homed Pumpkinseeds 0-5 31 28 90 6-11 29 23 79 12-17 49 31 63 18-23 13 7 54 Bluegills 24+ 39 15 38 0-5 12 10 83 6-11 14 10 71 12-17 20 11 55 18-23 12 5 42 Green sunfish 0-5 2 2 100 6-11 4 4 100 12-17 3 3 100 18-23 5 3 60 24+ 2 1 50 horne, and that a home range rnay be retained only a relatively short tirne by these sunfish. Direct Observations of Homing. At various times throughout the summer fish were observed directly after being displaced from an area of capture. These observations were made to determine if any patterns of orientation were being used by the fish. Because of wave action present rnost of the time on the lake it was difficult to find a suitable site for these observations. The southwest side of the Island was finally chosen because all three species of fish were found there, and the area was relatively calm most of the time. The method of conducting this observation was similar to that used by Hasler and Wishy ( 1958). However, a small round balloon, instead of a bobber, w:as attached to the fish by a mono~ filament thread 3-4 feet long, tied to a hook. The hook was then attached to the flesh behind the dorsal fin. Different colored balloons were used to keep the species of fish separate. The time of return to the place of capture was recorded, and the course the fish took was noted by observing the balloon being pulled along the surface. The fish were initially captured close to the shoreline along the west side of the island. They were then transported by boat to a point 1,000 feet from shore. Each fish was released in-dividually so that the lines or balloons would not get tangled up. During all these experiments, the sun was visible to some extent. Green sunfish took less time to home than did the pumpkin-8Proceedings of the Iowa Academy of Science, Vol. 72 [1965], No. 1, Art. 40http://scholarworks.uni.edu/pias/vol72/iss1/401965] SUNFISH MOVEMENT 271 seeds or bluegills. The bluegill and pumpkinseed behavior dif-fered from the green sunfish behavior in two respects. When pumpkinseeds or bluegills were released from the boat, they spent considerable time moving around in circles or even swimming around the boat. This behavior is considered as searching. The green sunfish, on the other hand, started directly toward the Island after being put into the water. When the pumpkinseeds or bluegills reached the Island, they moved along the shoreline and often reversed direction. Green sunfish usually stayed in one spot when they reached the shoreline. Siay-at-home Fish. Some of the fish used in the study were re-placed in the area of initial capture (Kudrna, 1965). Of the fish which were recaptured, the fish which stayed in the area were recaptured within 1 to 2 weeks. The fish which strayed out of the area were recaptured 3 weeks later. The fact that the fish which were recaptured later were away from the area of initial capture indicates that they may not maintain a small home range for a long period of time. Recapture rates for fish which were not displaced are higher than recapture rates for displaced fish. Of the 17 pumpkinseeds which were not displaced, 64% ( 11) were recaptured; of the 10 bluegills which were not displaced 80% ( 8) were recaptured. While these figures are not large, they suggest that displacement reduces the recapture rate. Literature Cited Bailey, R. M. and H. H. Harrison, Jr. 1945. The fishes of Clear Lake, Iowa Iowa State J. Sci. 20:57-77. Di Costanzo, C. J. 1957. Growth of bluegill, Lepomis macrochirus, and pumpkinseed, L. gibbosus, of Clear Lake, Iowa. Iowa State J. Sci. 32:19-34. . Hasler A. D. and W. J. Wishy. 1958. The return of displaced largemouth b~s and green sunfish to a "home" area. Ecology 39':289-293. Kudrna, J. J. 1965. Ecological distribution and relationships of sunfish in Clear Lake, Iowa. Unpublished M.S. thesis. Ames, Iowa, Library, Iowa State University of Science and Technology. Barker, R. A. and A. D. Hasler. 1959. Movements of some displaced centrarchids. Copeia 1959: 11-18. Pearcy, W. G. 19>53. Some limnological features of Clear Lake, Iowa. Iowa State J. Sci. 28:189•207. 9Kudrna: Movement and Homing of Sunfishes in Clear LakePublished by UNI ScholarWorks, 1965

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