EFFECTIVENESS OF FISHING IN SHALLOW LAKES USING DIFFERENT METHODS

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1 ActaSci.Pol.,Piscaria5(2)2006,59 68 EFFECTIVENESS OF FISHING IN SHALLOW LAKES USING DIFFERENT METHODS Jacek Rechulicz University of Agriculture in Lublin Abstract. The effectiveness of fish catching using three different methods, in six shallow lakes of Łęczyńsko-Włodawskie Lakeland was compared. The lakes concerned were: Kleszczów, Rotcze, Długie, Sumin, Głębokie Uścimowskie and Syczyńskie and the methods were as follows: electrical fishing, and fyke net. The most fish species and their biggest biomass were reported while using fishing. When fishing on the open waters the best effects were obtainedusingnetsofgillnetnordenstype,whilefykenets,whichwereputinlittoral,were found to be the least effective method and of greatest selectiveness of species. For fish sampling in shallow lakes, it is best to use several methods, for example, fishing in the littoral zone butnetfishingontheopenwaters. Key words: fish, fishing methods, Łęczyńsko-Włodawskie Lakeland, shallow lakes INTRODUCTION Thefish,asthebasicelementofthewaterecosystemofinlandreservoirs,areoftenthe subject of research. Several papers analyze their significance in the water ecosystem and try to determine their influence on the overall performance of that system[jeppesen et al. 1990, Scheffer et al. 1993, Starmach 1994, Bnińska 2000]. The best way to evaluate how manyfishthereareinthereservoiristomakecommercialfishcatches.however,itisnot always possible as the reservoir is properly used or proper fishing methods cannot be applied.thatiswhyoneofthewaystoestimatelakes fishcompositionistoconduct a controlled fishing[lagler 1978]. Specifying lakes ichthyofauna by the method of fish sampling is usually conducted by usingoneor,morerarely,acoupleoffishcatchingmethods.thebasicandmostoften used methods while conducting a biological research of a lake are fishing as well as fishing using electrical fish catching tools[hickley 1990, Zalewski and Cowx 1990]. Furthermore, pond tools such as fyke nets can be employed. The possibility of applyingallthosemethodsinlakeresearchisratherlimited.theuseofnordens gill net type is possible only in open water zone while fishing brings satisfactory results only in coastal littoral zone[bohlin et al. 1990, Bachmann et al. 1996]. Corresponding autor Adres do korespondencji: Dr inŝ. Jacek Rechulicz, Departament Hydrobiology and Ichthyobiology, University of Agriculture in Lublin, Akademicka 13, Lublin, Poland, jacek.rechulicz@ar.lublin.pl

2 60 J. Rechulicz The ichthyofauna research in Łęczyńsko-Włodawskie Lakeland is limited to specifying fish species composition in chosen reservoirs[radwan et al. 1995]. These lakes, because of their shallowness as well as good recognition of physical and chemical characteristics[kornijów et al. 2002, Radwan 2002], with no information on different methodsoffishcatching,enableustotestthosemethodsandifneeded,tousethemfor fish stocktaking. The aim of this research was to compare the effectiveness of different techniques of fishing in shallow lakes, methods such as fishing, Norden S multimesh s and fyke nets. METHODS The area of research covered the lakes in south-east Poland, in Łęczyńsko-Włodawskie Lakeland(Kleszczów, Rotcze, Długie, Sumin, Głębokie Uścimowskie and Syczyńskie). Thoselakesareofrathersmallaveragedepth(from1.2to2.7m)andtheirmaximumdepth is7m.thesurfaceareaofthosereservoirsiswithin5.6to91.5ha(table1).thelakesare classified as the reservoirs of diverse trophy, from mesotrophic through eutrotrophic to hyperthropic[radwan and Kornijów 1997, Michalczyk 1998, Kornijów et al. 2002]. Table 1. Characteristics of the lakes studied[after Furtak et al. 1998, changed, Kornijów et al. 2002] Tabela 1. Charakterystyka badanych jezior[za Furtak i in. 1998, zmienione, Kornijów i in. 2002] Lake Jezioro Kleszczów Rotcze Długie Sumin Głębokie Uścimowskie Syczyńskie Area, ha Powierzchnia, ha Max. depth, m Maks. głębokość, m Mean depth, m Średnia głębokość, m Transparency, m Widzialność, m Conductivity, μs x dm 3 Przewodnictwo, μs x dm Total P, μg x dm 3 Fosfor og., μs x dm Total N mg x dm 3 Azot og., mg x dm Three methods of fish catching were used: fishing using Honda 2.5 kw, Norden S-REV multimeshgillnets(10;60;30;6.25;43;22;50;33;12.5;25;8;38;75;16.5mm), andfykenets(each3mlong,0.5mindiameter,meshsize10mm)weresetupinpairs beingconnectedbyastripofnetting(4mlong,0.5mhigh,meshsize12mm). Electrofishingonallofthelakeswasconductedinautumn2000fromtheboat,along theshorelineinthelittoralzoneaswellasontheopenwater[penczak1967,lagler1978, Hickley 1990, Novotny 1990]. The fish sampling with nets(s and ) was conductedinautumn2001.fourgillnetswereputineachlakeasfollows:twonetsparallel andtwonetsperpendiculartotheshoreline.fykenetswereputparalleltotheshoreline inthelittoralzoneofthelakes.thetimeofexposureinthecaseofthenetsaswellasfyke netswas12hours.tocompareallthemethodsoffishcatchingandthetoolsusedtheresults werecalculatedpercpue(catchperuniteffort=ind. h 1 tool 1 org h 1 tool 1 ; where:ind. individuals,g biomassingram). Acta Sci. Pol.

3 Effectiveness of fishing in shallow lakes using different methods 61 Foreachlake,thenumberofindividualspeciesoffishthatwerecaughtandtheirbiomass were measured. The results of the fishing using different methods and their effectiveness in eachlakewerecomparedbynon-parametricaltestx 2 (doubleclassification lakes,fishing tools tablec r=6 3)[Parker1978,Oktaba1987,Łomnicki1995,Mizerski2004]. ItwasassumedasH 0 thatthenumberoffishcaughtinallthelakesusingthethree methodsrespectively fishing:nets:fykenets,willbefixedin112:2.6:1ratio, whilethegeneralmassofthefishin57.3:4.4:1ratio.theproportionsweretheresultof adding up all the caught specimens, using all the methods and under the assumption that all the methods were equally effective regardless of the lake where the fishing took place. As the alternative hypothesis, it was assumed that the effectiveness of the methods used depends on the given reservoir. The value of Pearson variance coefficient in statistical analysis was calculated from the following formula: where: S V= 10; x V coefficient of variation, S variance, x mean. RESULTS Sixteen species of fish were found in the lakes under research. The greatest number of species was noted in the lakes Sumin and Głębokie Uścimowskie(11), while the smallest numberofspeciesindługielake 6(Table2). Significant diversity regarding the number of species, number of fish and fish biomass was observed depending on the method of fishing used. Generally, the greatest number of species was caught using electrical fishing: 6 species in Długie Lake and 10 species in SuminLake.InthecaseofSuminLake,theresultsofelectricalfishingandnetfishing were very similar as far as the number of species was concerned. Additionally, in Głębokie Uścimowskie Lake, more species were caught by net fishing(10). Using the same method intherestofthelakes,from2(długielake)to8(suminlake)specieswerecaught. Thesmallestnumberofspeciesinallofthelakeswascaughtusingthepondtools fyke nets. That method, however, proved to be the most effective in Głębokie Uścimowskie and Syczyńskie lakes(table 2). Thefishingmethodwaseffectivein12outof16foundfishspecies,onlyone specieswasnotcaughtusingthismethod.thefishcaughtbynetbelongedto6species, while 4 species were not caught at all: goldfish(carassius carassius), spined loach (Cobitis taenia), sunbleak(leucaspius delineatus) and tench(tinca tinca). Using fyke nets, in most cases, only one species was caught brown bullhead(ictalurus nebulosus), and this method proved completely ineffective for 8 species. The number of individual speciescaughtusingdifferentmethods(ind. h 1 tool 1 )isshownintable2,while Fig. 1 presents total biomass of fish caught by different methods. Piscaria 5(2) 2006

4 62 J. Rechulicz Table2.Numberoffishcaughtbydifferentfishingmethod,CPUE(ind.h -1 tool -1 ) Tabela2.LiczebnośćrybzłowionychróŜnymimetodami,CPUE(osob.h -1 narzędziepołowu -1 ) Lake Jezioro Kleszczów Rotcze Długie Sumin Głębokie Uścimowskie Syczyńskie Species Gatunek Methods Metody Perch Okoń n.d Pike Szczupak n.d Pikeperch Sandacz 0.08 n.d. Roach Płoć n.d Break Ukleja n.d Crucian carp Karaś śr n.d Techn. Lin n.d White bream Krąp n.d Bream Leszcz n.d Gudgeon Kiełb n.d Ruffe Jazgarz n.d Sunbleak Słonecznica n.d Brown bulhead Sumik karł n.d Rudd Wzdręga n.d Goldfish Karaś posp n.d Spined loach Koza n.d. Number of species Liczba gatunków n.d. nodata. n.d. brak danych. Acta Sci. Pol.

5 Effectiveness of fishing in shallow lakes using different methods 63 g E N F E N F E N F E N F E N F E N F Kleszcz Rotcze D ugie Sumin G bokie Syczyƒskie Lake Jezioro UÊcimowskie Fig.1.Totalfishbiomass(ing)caughtbydifferentfishingmethod(E fishing,n gillnet,f ) Rys. 1. Ogólnabiomasaryb(wgramach) złowionychróŝnymimetodami(e połowy, N, F Ŝaki) Thegreatestbiomassoffishinallthelakeswasacquiredbyfishinganditranged from0.5toalmost0.8kginkleszczówandrotczelakesandfrom2toover4kginsyczyńskie and Głębokie Uścimowskie Lakes respectively(v = 40.88%)(Fig. 1). Thegreatestdiversityasfarasthebiomassofthecaughtfishisconcernedwasnotedwhile usingfykenets(v=126.24%).however,thebiomassoffishcaughtusinggillnetdidnotexceed 0.5kganditscoefficientofvariationwas56.2%(Fig.1). Afterapplyingthestatisticaltestwithα=0.0005,itturnedoutthattheH 0 hypothesiswas rejected.itcouldbestatedthatinkleszczówirotczelakeslessfishwascaughtusingthe fishing than it could be deduced from the obtained proportion, while much more in the lakes of little transparency. The effectiveness of the tools depended on the reservoirs. In Sumin, Głębokie Uścimowskie and Rotcze Lakes, significantly greater number of fish was caught using netsthandeducedfromtheassumedproportion.atthesametimeinthecaseofthesamelakes, the results of electrical fishing were statistically much lower. In Sumin and Kleszczów Lakes the number of fish biomass caught by nets was significantly higher than deduced from the assumed proportion. On the other hand, in Długie, Sumin and Głębokie Uścimowskie Lakes, the number of fish biomass caught by electrical fishing was much greater than expected(table 3, Fig. 2). Table 3. Effectivness of fishing methods in lakes(α = ) Tabela 3. Skuteczność metod połowu w jeziorach(α = ) Number of fish Liczebność ryb Fish biomass Biomasa ryb Lake Jezioro fishing połów nets fishing połów nets Kleszczów Rotcze Długie 0 + Sumin + + n. d. + + n. d. Głębokie Uścimowskie Syczyńskie has not significant differences in proportions, + above gets out of the proportion, ++ the resoluteness above gets outoftheproportion, lessthangetsoutoftheproportion, theresolutenesslessthangetsoutoftheproportion. n.d. nodata. 0 nie ma istotnych róŝnic w proporcjach, + więcej niŝ wynika z proporcji, ++ zdecydowanie więcej niŝ wynika z proporcji, mniej niŝ wynika z proporcji, zdecydowanie mniej niŝ wynika z proporcji. n.d. brak danych. 4038,7 Piscaria 5(2) 2006

6 64 J. Rechulicz DISCUSSION The carried out observations showed that using the same three fishing methods in different shallow lakes situated in proximity, the efficiency of the fishing turned out to be ratherdiverse.so,ifwewanttoobtainthefullfishcomposition,weoughttouseseveral methods of fishing and try to choose and adjust them to different habitats[lagler 1978]. The lack of reference concerning different fishing methods including fish composition and productivity of shallow lakes in Polish publications, allows us to mention a couple of important aspects. Electrofishing in the case of shallow has satisfactory results in the littoral zone with little water transparency which depends directly on the fertility of a reservoir(total P and total N)(Table 1). So, such things as physical and chemical characteristics of lakes, water transparency or conductivity have a direct impact on the efficiency of fishing aswellasnetfishing.itismuchhardertocatchfishbyfishinginthelakesofhigh water transparency(kleszczów, Rotcze, Długie). It is definitely easier to use that method in thelakesoflowwatertransparency.thenumberoffishcaughtismuchbiggerthanandtheir biomassisgreateraswell.theuseofnetsisthemosteffectiveintheopenwaterzoneand the results expressed by means of biomass are significantly better in the case of fertile lakes (hightotalpandn)(table1).accordingtoperrowandjowitt[1996],theproperuseofnets following the use fishing, can slightly improve efficiency of fish stocking. Supposing that the effectiveness of fishing methods in shallow lakes depends on physical and chemical characteristics of the lakes, we can assume higher than expected effectiveness of using nets fyke and nets depends on better water transparency, while the advantage of electrical fishing on lower water transparency and better conductivity. That is why the sequence of lakes regarding the effectiveness of fishing methods(net and fyke nets fishing)asfarasthenumberoffishcaughtisconcerned,goesasfollows: Sumin, Głębokie Uścimowskie, Rotcze, Kleszczów, Syczyńskie, Długie, while when biomass is concerned: Sumin, Rotcze, Kleszczów, Syczyńskie, Głębokie Uścimowskie, Długie(Table 3). It is possible that with different number proportion and biomass proportion in shallow lakes, the effectiveness of fishing methods also depends on the changeability of fish species composition. Hence, it would be worth verifying what is the influence of species diversity or individual size of fish species in such reservoirs on the effectiveness of tools used. AccordingtoRiemannetal.[1990],theindividualsizeoffishspeciesinthecaseof predatory fish can have great influence on trophic relationship between fish. The research conductedbykornijówetal.[2003]onthesamelakesallowedtheconclusionthatthefyke net method of fishing proved to be very selective especially with brown bullhead and turned out to be exceptionally useful for catching this unwanted species. It needs to be mentioned that a very important aspect while conducting any ichthyobiological research and any test fish catching is the time dedicated to the fishing method used. As the discussed observations showed, fishing can supply us with satisfactory qualitative fish composition. It is also connected to the time spend on test fishingwhichinthecaseoffishingisusuallyshorterandmorespecific(1to2hrs), while when nets are used grows considerably longer. Acta Sci. Pol.

7 Effectiveness of fishing in shallow lakes using different methods 65 Kleszczów E N 10 Rotcze E N F B N N F B 4 2 N N N B F N N B F N E B E B D ugie F B E N N N Sumin F B E N N N N B F N N B F N G bokie UÊcimowskie F B E N E B N N Syczyƒskie F B E N E B N N 2 2 N B F N N B F N E B E B E N Numberoffishinfishing Liczebnośćrybwpołowach N N Numberoffishinnets Liczebnośćrybwach F N Numberoffishin LiczebnośćrybwŜakach E B Biomassoffishinfishing Biomasarybwpołowach N B Biomassoffishinnets Biomasarybwach F B Biomassoffishin BiomasarybwŜakach Fig.2.Numberoffishandfishbiomasscaughtbydifferentfishingmethod,in% Rys. 2. Liczebność i biomasa ryb złowionych róŝnymi metodami, w% Piscaria 5(2) 2006

8 66 J. Rechulicz Summingup,wecanstatethatwhileusingonefishingmethodwhentestfishingin shallow lakes, the real quantity structure and ichthyofauna biomass cannot be obtained. Ifpossible,itisbesttousethetwoofthemethodsdiscussedabove,fishingand nets for control fishing(such as for example Norden S). The effectiveness of those methodsdependstoalargedegreeonthetypeofareservoirbutalsoonotherfactorssuch as: species diversity, characteristics of individual species or the individual size of fish. Itisworthtostudytheinfluenceofthosefactorsinanotherresearch. ACKNOWLEDGMENTS ThestudywascarriedoutasapartoftheprojectsfoundedbyEU5thFP-ECOFRAME no EVK , and by Polish State Committee for Scientific Research grant no 2 PO6S Author would like to thank Jacek Malicki for help in the choosing appropriated statistical methods. REFERENCES Bachmann R.W., Jones B.L., Fox D.D., Hoyer M., Bull L.A., Canfield D.E., Jr., Relations between trophic state indicators and fish in Florida(USA) lakes. Can. J. Fish. Aquat. Sci. 53, Bnińska M., Commercial fisheries versus water quality in lakes with special reference to coregonid management. Fish. Manag. and Ecol. 7, Bohlin T., Heggberget T.G., Strange C., 1990.[Electric fishing for sampling and stock assessment (in: Fishing with Electricity Applications in Freshwater Fisheries Management)]. I.G. Cowx, P. Lamarque(Eds.). Oxford, Fishing News Books, Blackwell Scientific Publications, Furtak T., Sobolewski W., Turczyński M., Charakterystyka zlewni jezior(w: Jeziora Łęczyńsko-- Włodawskie)[Characteristics of the catchment areas of the lakes(in: Lakes of the Łęczna-Włodawa region)]. M. Harasimiuk, Z. Michalczyk, M. Turczyński(Eds.). UMCS, Lublin, 73 85[in Polish]. Hickley P., Electric fishing in practice(in: Fishing with Electricity Applications in Freshwater Fisheries Management). I.G. Cowx, P. Lamarque(Eds.). Oxford, Fishing News Books, Blackwell Scientific Publications, Jeppesen E., Søndergaard M., Mortensen E., Kristensen P., Riemann B., Jensen H.J., Mőller J.P., Sortkiær O., Jensen J.P., Christoffersen K., Bosselmann S., Dall E., Fish manipulation as a lake restoration tool in shallow, eutrophic temperate lakes 1: cross analysis of three Danish case studies. Hydrobiologia 200/201, Kornijów R., Pęczuła W., Lorens B., Ligęza S., Rechulicz J., Kowalczyk-Pecka D., Płytkie jeziora Polesia z punktu widzenia teorii stabilnych stanów alternatywnych(w: Środowisko przyrodnicze Polesia: stan aktualny i zmiany)[shallow lakes of Polesie with the point of view of the theory of stable alternative states(in: The natural environment of Polesie: the current state and changes)]. S. Radwan, J. Gliński, M. Geodecki, M. Rozmus(Eds.). Acta Agrophys. Vol. III, 68, 61 72[in Polish]. Acta Sci. Pol.

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10 68 J. Rechulicz Starmach J., Struktura zespołów ryb w zbiornikach zaporowych o róŝnym stopniu eutrofizacji (w: Zintegrowana strategia ochrony i zagospodarowania ekosystemów wodnych)[the structure of fish stocking in dam reservoirs about the different degree of the eutrophication(in: The integrated strategy of the protection and stocking of water ecosystems)]. M. Zalewski[Ed.]. Bibl. Monit. Środ. Łódź, [in Polish]. Zalewski M., Cowx I.G., Factors affecting the efficiency of electric fishing[in: Fishing with Electricity Applications in Freshwater Fisheries Management]. I.G. Cowx, P. Lamarque(Eds.). Oxford, Fishing News Books, Blackwell Scientific Publications, SKUTECZNOŚĆ POŁOWU RYB RÓśNYMI METODAMI W PŁYTKICH JEZIORACH Streszczenie. W sześciu płytkich jeziorach Pojezierza Łęczyńsko-Włodawskiego(Kleszczów, Rotcze, Długie, Sumin, Głębokie Uścimowskie i Syczyńskie) porównano skuteczność połowów ryb trzema metodami: połów, i Ŝaki. Najwięcej gatunków ryb i największą ich biomasę stwierdzono przy połowach. Przy połowach w otwartej wodzie zadowalające efekty dawały połowy ami typu gillnet Norden S, natomiast Ŝaki stawiane w litoralu okazały się narzędziem najmniej skutecznym i o duŝej wybiórczości gatunkowej. Do połowów kontrolnych ryb w płytkich jeziorach najlepiej uŝywać kilku metod połowu np.: połowy w strefie litoralu i połowy ami w strefie otwartej wody. Słowa kluczowe: metody połowu, płytkie jeziora, Pojezierze Łęczyńsko-Włodawskie, ryby Accepted for print Zaakceptowano do druku: Acta Sci. Pol.