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[{"key": "dc.contributor.advisor", "value": "Marjom\u00e4ki, Timo", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.advisor", "value": "Tarvainen, Marjo", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.author", "value": "Forsman, Tero", "language": null, "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2015-09-27T16:58:14Z", "language": null, "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2015-09-27T16:58:14Z", "language": null, "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2015", "language": null, "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.other", "value": "oai:jykdok.linneanet.fi:1496467", "language": null, "element": "identifier", "qualifier": "other", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/47203", "language": null, "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Siika (Coregonus lavaretus) on S\u00e4kyl\u00e4n Pyh\u00e4j\u00e4rvell\u00e4 haluttu ammatti- ja virkistyskalastuksen kohde. T\u00e4m\u00e4 tutkimus keskittyy Pyh\u00e4j\u00e4rven siian kasvun ja kutukannan sek\u00e4 kuturys\u00e4saaliin rakenteen ja siivil\u00e4hammasjakauman kuvaamiseen. Lis\u00e4ksi tutkittiin lokki- (Diphyllobothrium dendriticum) ja sukeltajasorsien lapamadon (D. ditremum) esiintyvyytt\u00e4 siiassa. Aineisto ker\u00e4ttiin kutupyynnin yhteydess\u00e4 syksyll\u00e4 2013. N\u00e4ytteit\u00e4 otettiin 346 siiasta, joista m\u00e4\u00e4ritettiin maturiteetti, ik\u00e4, kasvu, silm\u00e4n myki\u00f6n muoto, siivil\u00e4hampaiden lukum\u00e4\u00e4r\u00e4, massa, pituus ja sukupuoli. Lis\u00e4ksi kolme viimeksi mainittua muuttajaa m\u00e4\u00e4ritettiin l02 siiasta. Loisten (D. dendriticum & D. ditremun) esiintyvyys tutkittiin 174 siiasta, joista 93 % oli infektoitunut v\u00e4hint\u00e4\u00e4n toisella lajeista. Siivil\u00e4hammaslaskentojen tulosten ja aiempien tutkimusten havaintojen perusteella Pyh\u00e4j\u00e4rven siiat ovat j\u00e4rvisiikoja. Tutkituissa n\u00e4ytteiss\u00e4 siivil\u00e4hampaiden lukum\u00e4\u00e4r\u00e4n keskiarvo ja moodi olivat 39 vaihteluv\u00e4lin ollessa 28\u201353 kpl. Siivil\u00e4hammasm\u00e4\u00e4ri\u00e4 verrattiin nelj\u00e4n vuosikymmenen aikana Pyh\u00e4j\u00e4rvelt\u00e4 ker\u00e4ttyihin siika-aineistoihin ja erot jakaumien v\u00e4lill\u00e4 j\u00e4iv\u00e4t pieniksi, keskim\u00e4\u00e4r\u00e4isen siivil\u00e4hammasm\u00e4\u00e4r\u00e4n vaihteluv\u00e4lin ollessa 39\u201341 kpl. Ik\u00e4ryhm\u00e4kohtaisen keskipituuden perusteella siian kasvu Pyh\u00e4j\u00e4rvess\u00e4 on kohtalaisen nopeaa suomalaisissa j\u00e4rviss\u00e4 havaittuun siikojen kasvuun verrattuna, eik\u00e4 merkitt\u00e4v\u00e4sti 1990- ja 2000-luvun tutkimuksista poikkeavaa. Runsain ik\u00e4ryhm\u00e4 siikasaaliissa oli 4+. 2-vuotiaiden kalojen m\u00e4\u00e4r\u00e4 n\u00e4ytteiss\u00e4 sen sijaan oli melko v\u00e4h\u00e4inen. Pyh\u00e4j\u00e4rven siikasaaliit ovat heikentyneet merkitt\u00e4v\u00e4sti 1990-luvun lopun vuosista ja ovat nykyisin en\u00e4\u00e4 viidennes noista ajoista. T\u00e4ss\u00e4 tutkimuksessa siikakannan heikentymist\u00e4 l\u00e4hestyttiin tarkastelemalla ei-sukukypsien siikojen osuutta siika- ja muikkurys\u00e4n\u00e4ytteiss\u00e4. Ei-sukukypsien kalojen osuuden selvitt\u00e4misen tarkoituksena oli hahmottaa, kuinka paljon kalastus pyyt\u00e4\u00e4 sellaisia kaloja, jotka eiv\u00e4t ehdi lis\u00e4\u00e4ntym\u00e4\u00e4n kertaakaan ennen pyyntiin rekrytoitumista. Ei-sukukypsien kalojen osuus siian kuturys\u00e4n\u00e4ytteiss\u00e4 oli melko v\u00e4h\u00e4inen (7 %). Muikkurys\u00e4n\u00e4ytteiss\u00e4 ei-sukukypsien kalojen osuus oli selv\u00e4sti suurempi (31 %). Kalastusmenetelmien vaikutusta siikakantaan arvioitiin Y/R-mallinnuksella, jonka perusteella 0+-ik\u00e4ryhm\u00e4n siikojen saaliiksi ottamisen v\u00e4ltt\u00e4minen kasvattaisi teoriassa vuosittaista siikasaalista (per 1000 kg rekryyttej\u00e4) 20 % verrattuna vuoden 2013 kaltaiseen pyyntiin. Pyh\u00e4j\u00e4rvest\u00e4 tavataan siian ja muikun (C. albula) risteymi\u00e4. N\u00e4ytekalojen joukossa olevien hybridien osuutta pyrittiin karkeasti arvioimaan tarkastelemalla kalan yl\u00e4- ja alaleuan pituutta suhteessa toisiinsa ja silm\u00e4n myki\u00f6n muotoa. Tasaleukaisten kalojen osuus n\u00e4ytekaloista oli 5 % ja py\u00f6re\u00e4myki\u00f6isten 2 %. On kuitenkin huomioitava, ett\u00e4 leukojen erotukseen ja myki\u00f6n muotoon perustuva erottelu tunnistaa vain ulkon\u00e4\u00f6llisesti tyypillisest\u00e4 siiasta eroavat kalat. Menetelm\u00e4n tehokkuutta voitaisiin parantaa esimerkiksi selvitt\u00e4m\u00e4ll\u00e4 kuinka suuri osa risteymist\u00e4 menetelm\u00e4n avulla voidaan l\u00f6yt\u00e4\u00e4.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "The aim of this study is to represent growth, structure of spawning stock, structure of fyke net catch used in spawning areas and number of gill rakers of whitefish (Coregonus lavaretus) in Lake Pyh\u00e4j\u00e4rvi (South West Finland). In addition, prevalence of some parasites in whitefish was also studied. Material for the research was gathered during autumn 2013 from 346 whitefish individuals. Also 102 fish were measured by mass, length, and sex. From first mentioned fish also maturity, age, growth, shape of eye lens and gill raker number were investigated. Prevalence of parasites (D. dendriticum & D. ditremun) was studied from 174 fish of which 93 % was infected by at least either of mentioned species. The annual yield of whitefish in the Lake Pyh\u00e4j\u00e4rvi has recently decreased to 1/5 of the yield in the late 1990s. In this study one of the aims was to investigate proportion of immature whitefish in the fyke net catch and to assess the effect of fishing on the whitefish stock. Intensive harvesting of immature whitefish may reduce the abundance of spawning stock and consequently also recruitment. However it was found that the proportion of immatures in fyke nets targeting spawning whitefish was insignificant (7 %). Conversely fyke nets targeting vendace caught more significant percentage of immatures (31 %). According to gill raker count and earlier studies, whitefish of the lake Pyh\u00e4j\u00e4rvi belong to typical lake dwelling whitefish form. The average and mode gill raker count was 39 and the number of gill rakers ranged between 28 and 53. Gill raker counts were compared to earlier samples from the same lake and the differences in distributions during the period of 40 years were quite insignificant, while range in mean distributions was between 39\u201341 pieces. Growth of whitefish is fairly quick compared to observations done in other finnish lakes and not significantly different from observations done 1990s and 2000s. Most abundant age group in the whitefish fyke nets was 4+. Proportion of 2+ aged whitefish was quite small. Impact of fishing methods on whitefish stock was modelled by Y/R-modelling. Avoiding of fishing of 0+ aged whitefish would in theory increase 20 % annual whitefish catch (per 1000 kg recruits) compared to fishing carried out in the year 2013. Some proportion of coregonids in the Lake Pyh\u00e4j\u00e4rvi are hybrids of whitefish and vendace (C. albula). In this study the proportion of hybrids was roughly assessed by investigating the ratio of the length of upper and lower jaw and the form of eye lens. 5 % of sampled fish were found to have equally long upper and lower jaws. The proportion of sampled fish with round shaped eye lens was 2 %. However the weakness of the method is that it might not reveal those hybrids which are morphologically similar to whitefish. The efficiency of the method could be improved by investigating proportion of hybrids found from samples by this method.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted using Plone Publishing form by Tero Forsman (tejufors) on 2015-09-27 16:58:09.473586. Form: Pro gradu -lomake (https://kirjasto.jyu.fi/julkaisut/julkaisulomakkeet/pro-gradu-lomake). JyX data: [jyx_publishing-allowed (fi) =True]", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by jyx lomake-julkaisija (jyx-julkaisija.group@korppi.jyu.fi) on 2015-09-27T16:58:14Z\nNo. of bitstreams: 2\nURN:NBN:fi:jyu-201509273267.pdf: 1586606 bytes, checksum: 9efaae4fe3e7a80be128da249614a7d6 (MD5)\nlicense.html: 4864 bytes, checksum: 5550e0ada9fac3b8392296d686911310 (MD5)", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2015-09-27T16:58:14Z (GMT). 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"dc.subject.other", "value": "i\u00e4nm\u00e4\u00e4ritys", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "kalastus", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "kalastuksen s\u00e4\u00e4tely", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "kutupyynti", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "lis\u00e4\u00e4ntyminen", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "rys\u00e4", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "siivil\u00e4hampaat", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": 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