The vendace Coregonus albula (Salmonidae) management
in lakes of the North-West Poland
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1
West Pomeranian University of Technology, Poland
The natural reservoir of vendace Coregonus albula (L., 1758) there are numerous lakes situated around the Baltic sea, from Germany and Denmark in the west, through Poland to Estonia, Lithuania, Latvia and Russia in the east. The economic significance of vendace is especially great in cold, clean and rich in oxygen waters of North-West Poland. The aim of this study was to characterise the vendace management (the estimation of catching yield, fishing devices used, the basic data of morphometrical and trophic characteristics of these lakes).
Vendace catching and stocking data, obtained from 72 vendace lakes, situated in the North-West Poland of the overall surface 21685.23 ha, were analysed. The data characterizing these reservoirs have been collected on the basis of questionnaires sent to fishermen and interviews carried out together with the study of lakes’ management and service protocols . For each lake, the arithmetical mean values of catching and yield of vendace the type and rate of restocking material, catching gears used in exploitation of vendace (including the mesh diameter of nets), in the period 2012-2016, were determined.
In lakes of the North -West Poland mainly gillnets (with mesh size of 22-28 mm) and very rarely seine (only in 3 lakes) for catch of vendace were used. In most of lakes, gillnets with the mesh size of 24 mm (the devices relatively selective), the average fish total length (ca. 20.9 cm) and individual weight of fish (about 87.6 g) fluctuated from 17 to 25 cm and 10 – 180 g, respectively. The average fishing yield from 72 vendace lakes was 14.78 kg ha-1 (the range from 0.11 to 26.21 kg ha-1), although the participation of vendace in those reservoirs was on average 14.30%. There are 53 eutrophic (with small population of vendace) and 19 mesotrophic lakes, where catch of this species are usually greater than 5 kg ha-1. Off the 72 lakes analyzed in the present work, 14 were not stocked by any material of vendace, 58 were usually stocked by larvae and sometimes by summer fry or very rarely by the older stages.
In the vendace lakes analyzed here, the high variety in area of water surface was observed (the range from 27.2 to 3572 ha). After the division into classes according to this parameter, the majority of reservoirs were categorized to “small lakes” with the surface of (1) – 100 ha (24 lakes, that is 33.33% of total number of lakes examined). The fewest reservoirs were listed for the class with the area of surface above 1000 ha (four lakes, comprising only 5.56% of all number of lakes). The highest vendace yield (>3.0 kg ha-1) was recorded in the classes with the surface area of lake (1) – 100 ha and 100 – 250 ha, however in “big lakes” (500 – 1000 ha and above 1000 ha) the yield was the lowest. We described the relationship between the area of the reservoirs (Y) and the vendace catch yield (kg ha-1) (X), and there was a high correlation between these parameters following the formula: Y = 12.387 X0.245 (R = 0.748).
The analysis of the depth of vendace lakes showed also significant variety of this reservoirs, both in their maximal depth as well as in their average depth. The highest average yield (kg ha-1 ) was noted in the class of lakes with maximum depth above 40 m, and mean depth above 10 m. Taking into consideration these data, the relation between the maximum and mean depth of the reservoirs and catching yield of vendace, shows the high correlation between these parameters: Y = 0.205 X + 3.388 (R=0.4954), and Y = -0.0053 X2 + 0.3804 X - 0.1574 (R = 0.9213). It was concluded that the vendace yield (in kg/ha) was dependent not only on stocking (the number of vendace larvae), but on some of the morphometrical features of lakes (area and depth).
According to the scale of grades, proposed by the authors, as many as 28 lakes (38.89%) were characterized by low (<2 kg ha-1) yield of vendace (so called “bad lakes”) and only in four lakes (5.55%) the value of this parameter was higher than 10 kg ha-1 (so called “very good lakes”).
Keywords:
Coregonus albula,
Northern Poland,
Management,
yield of vendance,
trophic characteristics of lakes,
Conservation measures
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Poster
Topic:
THREATS AND CONSERVATION
Citation:
Czerniejewski
P,
Więcaszek
B,
Wawrzyniak
W and
Dąbrowski
J
(2019). The vendace Coregonus albula (Salmonidae) management
in lakes of the North-West Poland.
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00144
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Received:
27 May 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Prof. Beata Więcaszek, West Pomeranian University of Technology, Szczecin, West Pomeranian, Poland, beata.wiecaszek@zut.edu.pl