Jõevähi (Astacus astacus) söötmiskatsete metoodika väljatöötamine akvaariumitingimustes
Laen...
Kuupäev
2019
Kättesaadav alates
7.09.2019
Autorid
Teorein, Agnes
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Eestis on vähikasvatusega tegeletud juba üle 20 aasta, kuid toodangu mahtusid ei ole
suudetud tõsta. Selle üheks põhjuseks on vähi jaoks sobiva granuleeritud sööda
puudumine. Praegu toimub Eestis vähi söötmine kogemuslikult, silma järgi ja juhuslike
kättesaadavate komponentidega. Koostöös Sannio Ülikooliga Itaalias hakati Eesti
Maaülikoolis välja töötama spetsiaalset sööta jõevähile. Sobiva sööda leidmiseks on vaja
läbi viia mitmeid söötmiskatseid kontrollitavates tingimustes, kuid siiani puudus sobiv
söötmiskatsete läbiviimise metoodika vee korduvkasutussüsteemiga
akvaariumitingimuste jaoks. Antud töö eesmärgiks on jõevähi söötmiskatsete metoodika
väljatöötamine akvaariumitingimustes. Selle jaoks viidi Eesti Maaülikooli vesiviljeluse
õppetoolis läbi söötmiskatse. Katse tulemustes selgus, et 4-5% söödanorm ei ole 3-
aastastele jõevähkidele sobilik. Katse lõppedes oli söödanorm 1,7%, mille juures
minimaalselt söödajääke. Suurimaks probleemiks söötmiskatsel sai suremus (65%). Katse
alguses surid ja põgenesid vähid peamiselt ammoniaagi kontsentratsiooni tõusu tõttu vees.
Vajalik oleks olnud enne vähkide akvaariumitesse asustamist toita biofiltri baktereid
lämmastikuühenditega, et biofilter korralikult tööle hakkaks. Söödajääkide paremaks
kokku kogumiseks ei lisatud põhjale substraati, kuid katse lõppedes osutus see kestumisel
oluliseks. Vähkidel ei olnud kusagile kinnituda ning nad surid kestumisel. Pärast põhjale
kruusa lisamist hakkasid vähid edukalt kestuma. Samuti ei õigustanud ennast
automatiseeritud söötmine. Söötjad olid ebatäpsed ja tundlikud ning suuremate
söödatükkide tõttu kiilusid kinni. Lahenduseks sai käsitsi söötmisele üle minek.
Estonia has been practise grayfish farming for over 20 years but production volumes have not been increased. At present, crayfish is fed in Estonia by experimental, by eye and randomly available components. The purpose of this work is to develop a methodology for noble crayfish feeding experiment under aquarium conditions. In collaboration with the University of Sannio in Italy, a special feed for crayfish was developed. It is necessary to carry out a number of feeding experiments under controlled conditions to find a suitable feed, but so far there was no suitable method for carrying out feeding experiments for aquarium conditions with water reuse system. For this purpose, a feeding experiment was carried out at the Estonian University of Life Sciences in the Chair of Aquaculture. The results of the experiment showed that 4-5% of feed rate is not suitable for 3 year old crayfish. At the end of the experiment, the feed rate was 1,7%, with minimal feed residue. Morbidity (65%) was the biggest problem in the experiment. At the beginning of the experiment, the crayfishes died and escaped mainly due to the water chemistry caused by the increase in ammonia concentration in water. It would have been necessary to feed the biofilter bacteria with nitrogen compounds before populating them into aquariums, so that the biofilter would start working properly. A substrate was not added to the bottom for better collection of feed residues, but at the end of the experiment it proved to be important for crayfish moulting. The crayfishes didn't have anywhere to attach during moulting and they died. After adding gravel to the bottom, the crayfishes began to moult successfully. Also, automated feeding did not justify itself. The feeders were inaccurate and sensitive, and due to larger pieces of granulated feed they were trapped. The solution was manually feeding.
Estonia has been practise grayfish farming for over 20 years but production volumes have not been increased. At present, crayfish is fed in Estonia by experimental, by eye and randomly available components. The purpose of this work is to develop a methodology for noble crayfish feeding experiment under aquarium conditions. In collaboration with the University of Sannio in Italy, a special feed for crayfish was developed. It is necessary to carry out a number of feeding experiments under controlled conditions to find a suitable feed, but so far there was no suitable method for carrying out feeding experiments for aquarium conditions with water reuse system. For this purpose, a feeding experiment was carried out at the Estonian University of Life Sciences in the Chair of Aquaculture. The results of the experiment showed that 4-5% of feed rate is not suitable for 3 year old crayfish. At the end of the experiment, the feed rate was 1,7%, with minimal feed residue. Morbidity (65%) was the biggest problem in the experiment. At the beginning of the experiment, the crayfishes died and escaped mainly due to the water chemistry caused by the increase in ammonia concentration in water. It would have been necessary to feed the biofilter bacteria with nitrogen compounds before populating them into aquariums, so that the biofilter would start working properly. A substrate was not added to the bottom for better collection of feed residues, but at the end of the experiment it proved to be important for crayfish moulting. The crayfishes didn't have anywhere to attach during moulting and they died. After adding gravel to the bottom, the crayfishes began to moult successfully. Also, automated feeding did not justify itself. The feeders were inaccurate and sensitive, and due to larger pieces of granulated feed they were trapped. The solution was manually feeding.
Kirjeldus
Bakalaureusetöö
Kalanduse ja vesiviljeluse õppekaval
Märksõnad
bakalaureusetööd, jõevähk, söötmine, söödanormid