- Published on Saturday, 19 April 2014 17:02
"Protection of the autochthonic population of migratory lavaret (Coregonus lavaretus f. lavaretus) of Łebsko Lake" - stage I
Protection measures in the Słowiński National Park’s ichthyofauna are aimed at restoration of communities of fish typical for a given water reservoir and restoration of population of engendered species. One of the programmes implemented recently (2000-2004) in this scope is the programme of protection of the autochthonic population of migratory lavaret. The tasks of the project were included in the Park’s preservation and protection activity plan, approved by the Minister of Environment.
Below one described the major spheres of activities of the SNP workers prepared together with the expert team from the Koszalin University of Technology, and the University of Warmia and Mazury in Olsztyn and undertaken due to financial support of the EkoFundusz [EcoFund] of the Voivodeship Fund of Environmental Protection and Water Management in Gdańsk.
1. Qualitative and quantitative assessment of lavaret population in Łebsko Lake and project merit assumption preparation.
Academic staff of the Koszalin University of Technology under the supervision of Prof. Tomasz Heese prepared the programme of protection of the autochthonic population in the Łebsko Lake. The research assumptions and results were introduced in the migratory fish restoration programme in Poland.
2. Preparation of the base for keeping spawning fish and catching equipment.
During this stage one prepared fishing base for keeping spawning lavarets, fishnets for alive catches, and equipment for induced spawning, which allowed for obtaining spawning fish and lavaret roe since 2000/2001.
3. Catching and keeping spawning fish
Then, the Słowiński National Park carried out catches of spawning fish to obtain roe, inevitable for further rearing. Spawning fish were caught in November, December, and January. Fish were transported to the centre where in controlled conditions one obtained roe, investigated later in genetic and morphometrical tests at the Warmia and Mazury in Olsztyn.
4. Roe incubation, fry rearing up to 2-5 cm
Roe obtained in subsequent years from spawning lavarets from Łebsko Lake was transported to a breeding ground ensuring proper quality and temperature of water during incubation. In the first and second year of the project fish were incubated in a pool with return water circuit and controlled temperature. Later roe was transported to ground ponds. Lavaret was bred in polyculture with tench and carp. One introduced rearing in a net to reach 2-5 cm long fish. Due to undertaken actions in 2001 one could introduce to the lake 720 units of autumn fry, 71075 units of summer fry, and 20011 units of autumn fry in 2002, 11450 units of fry in 2004, and 240000 units of advanced fry, and 5192 units of autumn fry in 2005.
5. Genotype control
68 spawning lavarets were subject to genetic research. Research on enzymatic protein polymorphism provided results describing stocks (type and level) of gene pool changes in the investigated population. Due to descriptions in publications one could conduct comparative estimation of stocks of lavaret gene population and determine its genetic relatedness with other populations. Comparative tests covered lavarets from Pomerania Bay and Lake Constance. Genetic distance indicators (D) between populations reflect expected positive correlation between small geographical distance and genetic distance. One should noted clear genetic relatedness between lavaret population from the Łebsko Lake and Pomeranian Bay (D=0,007), and genetic distance between lavarets from the Łebsko Lake and Lake Constance (D=0,0221). Moreover, Prof. M. Łuczyński carried out a pilot study on mtDNA polymorphism (sequencing of the section covering a fragment 1 NHi1 of subunit of mitochondrial NADH dehydrogenase). The study results will be used for further comparative analyses with other lavaret populations and preparation of protection strategy.
6. Stocking effect monitoring
Throughout the programme between 28th February 2001 and 15th November 2004 the researchers from the University of Warmia and Mazury in Olsztyn under the supervision of Prof. Andrzej Martyniak conducted the stocking effect monitoring. According to the project assumptions, lavarets were marked before release to Łebsko Lake in the following way:
- mounting ring on otolith by thermal shock – summer fry,
- alcian blue injection under skin – autumn fry.
The monitoring results allows for answering numerous questions posed in the programme projecting stage. According to experts, research began at a last moment. The population was dramatically low, and possibilities of natural spawning were extremely limited.
7. Project monitoring effect publication and lavaret protection strategy preparation.
In this stage one prepared final report summarising all stages of the project covering the assessment of subsequent tasks, stocking effect and ecological effect assessment, complete analysis and guidelines on lavaret protection in the Łebsko Lake, included in the protection plan. The project co-ordinator, Prof. Tomasz Heese, confirmed methodological correctness of undertaken activities underlying their large level of complexity. He also pointed out that 3 years were not enough to carry out such works, in particular as far as the better understanding of lavaret behaviour was concerned.