Euroopa angerja (Anguilla Anguilla) potentsiaal vähi võõrliikide tõrjes
Laen...
Kuupäev
2023
Kättesaadavus
01.09.2023
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Jõevähkide (Astacus astacus) populatsioonid on vähenemas üle maailma, sealhulgas ka
Eestis. Üheks põhjuseks on invasiivsete vähiliikide negatiivne mõju põlisvähkide
asurkondadele, näiteks ohtliku vähikatku levitamine, kiirematempolisem levila
laiendamine kui jõevähkidel ning suurem viljakus ja tolerantsus elutingimuste suhtes.
Sellest tulenevalt on käesoleva uurimistöö eesmärgiks hinnata kasvanduse päritolu
kunstlikul söödal olnud euroopa angerja (Anguilla anguilla) potentsiaali vähi võõrliikide
bioloogilises tõrjes. Eesmärgi saavutamiseks viidi läbi kuu aega kestnud söötmiskatse 30
angerja ning kahe invasiivse vähiliigiga. Kolme ühe kuupmeetrilisse basseini paigutati
lisaks kaladele eksperimendi jooksul 30 signaalvähki (Pacifastacus leniusculus) ning 23
marmorvähki (Procambarus virginalis). Andmete kogumiseks teostati pidevalt
visuaalseid vaatlusi angerjate söömuste jälgimiseks ja dokumenteeriti veeparameetrid.
Katse lõppes kalade seedekulgla analüüsimisega. Saadud tulemused näitasid, et kõige
rohkem langesid saagiks mõõtude poolest väiksemad vähid, eriti marmorvähid, kelle kadu
moodustas kolme basseini peale 91,3%. Lisaks täheldati angerja rünnakut marmorvähi
vastu, mida kinnitasid ka angerja seedekulgla analüüsid, kus esines marmorvähi säilmeid
kolmel angerjal. Signaalvähkide vastu oli kaladel huvi aga tunduvalt väiksem, sest
täheldati vaid 33,3%-list vähkide kadu. Väiksem signaalvähkide kadu võis tuleneda
angerjate liiga väikesest aklimatiseerumise perioodist ja signaalvähkide suuremast
suurusest. Tulemused näitavad, et ~400-grammiste kasvanduse päritolu angerjate
asustamisel on potentsiaali alla 70 mm pikkuste invasiivsete vähiliikide tõrjes ning võib
soovitada nende asustamist kinniste süsteemidega vähi võõrliigi veekogudesse.
The noble crayfish (Astacus astacus) populations are declining worldwide, including in Estonia. One reason for that is the negative impact of invasive crayfish species on native crayfish populations, such as the spread of dangerous crayfish plague, faster range expansion than the noble crayfish, greater fecundity and tolerance to worse environmental conditions. Consequently, the aim of this research is to evaluate the potential of the European eel (Anguilla anguilla) fed on fish farm artificial feed in the biological control of non-indigenous crayfish species. To achieve the results, a month-long feeding experiment was conducted with 30 eels and two invasive crayfish species. In addition to the fish, 30 signal crayfish (Pacifastacus leniusculus) and 23 marbled crayfish (Procambarus virginalis) were placed in three one cubic meter pools during the experiment. In order to collect data, visual observations were made continuously to monitor eel feeding, water parameters were also documented. The experiment ended with the analysis of the fishes digestive tract. The obtained results showed that smaller crayfish were the most preyed upon, especially marbled crayfish, whose loss was 91.3% over the tree pools. In addition, attack on a marbled crayfish by an eel was observed, which was also confirmed by analyzes of the eel's digestive tract, where remains of marbled crayfish were present in three eels. However, the interest of the fish in the signal crayfish was much lower, making up 33,3% mortality. The smaller loss of signal crayfish may have resulted from the too short acclimatization period of the eels and the larger size of signal crayfish. The results show that the stocking of ~400-gram farmed eels has the potential to control invasive crayfish species that are less than 70 mm in length and can be recommended for their stocking in closed systems in non-indigenous crayfish water bodies.
The noble crayfish (Astacus astacus) populations are declining worldwide, including in Estonia. One reason for that is the negative impact of invasive crayfish species on native crayfish populations, such as the spread of dangerous crayfish plague, faster range expansion than the noble crayfish, greater fecundity and tolerance to worse environmental conditions. Consequently, the aim of this research is to evaluate the potential of the European eel (Anguilla anguilla) fed on fish farm artificial feed in the biological control of non-indigenous crayfish species. To achieve the results, a month-long feeding experiment was conducted with 30 eels and two invasive crayfish species. In addition to the fish, 30 signal crayfish (Pacifastacus leniusculus) and 23 marbled crayfish (Procambarus virginalis) were placed in three one cubic meter pools during the experiment. In order to collect data, visual observations were made continuously to monitor eel feeding, water parameters were also documented. The experiment ended with the analysis of the fishes digestive tract. The obtained results showed that smaller crayfish were the most preyed upon, especially marbled crayfish, whose loss was 91.3% over the tree pools. In addition, attack on a marbled crayfish by an eel was observed, which was also confirmed by analyzes of the eel's digestive tract, where remains of marbled crayfish were present in three eels. However, the interest of the fish in the signal crayfish was much lower, making up 33,3% mortality. The smaller loss of signal crayfish may have resulted from the too short acclimatization period of the eels and the larger size of signal crayfish. The results show that the stocking of ~400-gram farmed eels has the potential to control invasive crayfish species that are less than 70 mm in length and can be recommended for their stocking in closed systems in non-indigenous crayfish water bodies.
Kirjeldus
Bakalaureusetöö
Kalanduse ja rakendusökoloogia õppekaval
Märksõnad
bakalaureusetööd, euroopa angerjas, signaalvähk, marmorvähk, jõevähk, bioloogiline tõrje, Roheline Ülikool (töö toetab EMÜ Rohelise Ülikooli põhimõtteid), elurikkus, pärandkooslused, pärandmaastikud, maastikukaitse