Andrzej Kapusta

THE SIGNIFICANCE OF STONE MOROKO, PSEUDORASBORA PARVA (TEMMINCK AND SCHLEGEL), IN THE SMALL-SIZED FISH ASSEMBLAGES IN THE LITTORAL ZONE OF THE HEATED LAKE LICHEÑSKIE

The Significance of Stone Moroko, Pseudorasbora Parva (Temminck and Schlegel), in the Small-Sized Fish Assemblages in the Littoral Zone of the Heated Lake Licheńskie The aim of the study was to determine changes in the seasonal abundance of stone moroko, Pseudorasbora parva (Temminck and Schlegel), and to identify the role this alien species plays in the littoral zone of a heated lake. This study also aimed at defining the habitat preferences of this species and describing the relations between the relative abundance of stone moroko and the occurrence of submerged vegetation. A significant dependence was determined of the degree to which the lake bottom is covered with macrophytes and the occurrence of stone moroko. The fish caught belonged to 14 species and 2 families. Stone moroko preferred habitats that were abundantly overgrown with submerged vegetation and avoided areas devoid of macrophytes. Thus, as the bottom cover increased, so did the relative number of this fish. In light of habitat availability and its food preferences, the abundant occurrence of this species poses a serious threat to the endemic ichthyofauna. Znaczenie Czebaczka Amurskiego, Pseudorasbora Parva (Temminck and Schlegel) W Zespole RYB Niewielkich Rozmiarów W Litoralu Podgrzewanego Jeziora Licheńskiego Celem badań było określenie sezonowych zmian liczebności czebaczka amurskiego, Pseudorasbora parva (Temminck and Schlegel) oraz roli tego obcego gatunku w litoralu podgrzewanego jeziora (rys. 1). W pracy podjęto próbę określenia preferencji siedliskowych oraz scharakteryzowano relacje pomiędzy względną liczebnością czebaczka amurskiego a występowaniem roślinności zanurzonej. Analizie poddano łącznie 329 osobników czebaczka amurskiego (tab. 1). Złowiono ryby należące do 14 gatunków i 2 rodzin (tab. 2, rys. 2). Stwierdzono sezonową zmienność występowania czebaczka amurskiego w litoralu jeziora (rys. 3) oraz istotną zależność pomiędzy stopniem pokrycia dna hydrofitami a jego względnym zagęszczeniem (rys. 4). Czebaczek amurski preferował siedliska obficie porośnięte roślinnością zanurzoną, a unikał siedlisk pozbawionych hydrofitów. Wraz ze wzrostem pokrycia dna hydrofitami wzrastała względna liczebność czebaczka amurskiego. Największą średnią długością całkowitą charakteryzowały się osobniki złowione w czerwcu (rys. 5). W kolejnych miesiącach średnia długość całkowita łowionych ryb była niższa, nawet jeśli w odłowach występowały osobniki o maksymalnych rozmiarach ciała większych niż w czerwcu. Zależność pomiędzy długością a masą ciała opisano za pomocą funkcji wielomianowej (rys. 6). Obfite występowanie tego gatunku w powiązaniu z dostępnością siedlisk i preferencjami pokarmowymi wskazują na duże zagrożenie dla rodzimej ichtiofauny.

Migratory Behavior of Young Sturgeon, Acipenser Oxyrinchus Mitchill, in the Oder River Drainage. Preliminary Results of a Radio Telemetric Study in the Drawa River, Poland

Migratory Behavior of Young Sturgeon, Acipenser Oxyrinchus Mitchill, in the Oder River Drainage. Preliminary Results of a Radio Telemetric Study in the Drawa River, Poland The movements of individual juvenile sturgeon, Acipenser oxyrinchus Mitchill, during their first stage of downstream migration were observed in the Drawa River, Poland. Two groups of 10 sturgeon each (9 months old, reared in closed recirculation systems) were tagged with internal radio-transmitters. The first group of sturgeon (119-184 g) were tagged with Holohill BD-2N transmitters (weight 0.43 g, operational life 14d) and released on May 7. Fish from the second group (143-206 g) were tagged with BD-2 (weight 1.2 g, operational life 56d) and were released on May 24. The releases took place in the Drawa River below Kamienna Dam, 33 km upstream from the rivers confluence with the Noteć River. All of the fish moved downstream, but migration speeds differed. Seven sturgeon from the first group reached the confluence with the Noteć River, approximately 30 km downstream from the release site, during the first 18 days, which indicated there had been staging intervals in pools. Within four days, six fish from the second group had moved downstream the Drawa River and were located 20 km downstream from the confluence with the Noteć River. The downstream migration speed of the fish correlated with fish size and increased with water temperature. Behawior Juwenalnych Jesiotrów, Acipenser Oxyrinchus Mitchill W Czasie Wędrówki W Zlewni Odry. Wstępne Wyniki Badań Radiotelemetrycznych W Drawie, Polska Obserwowano przemieszczanie się juwenalnych jesiotrów Acipenser oxyrinchus Mitchill w ciągu ich pierwszego etapu migracji w dół rzeki Drawy. Dwie grupy po 10 jesiotrów (9-miesięczne ryby podchowywane w zamkniętym obiegu wody) zaopatrzono w wewnętrzne nadajniki radiotelemetryczne. Jesiotry pierwszej grupy (masa ciała od 119 do 184 g) z nadajnikami BD-2N (Holohill, Kanada) (waga 0,43 g, przeciętny czas działania 14 dni) wypuszczono do rzeki 7 maja. Ryby z drugiej grupy (143-206 g) z nadajnikami BD-2 (waga 1,2 g, przeciętny czas działania 56 dni) wpuszczono do Drawy 24 maja poniżej Elektrowni Kamienna. W trakcie migracji w Drawie ryby lokalizowano ręcznie raz dziennie, natomiast w Noteci raz w tygodniu. Wszystkie ryby przemieszczały się z nurtem w dół rzeki, a tempo migracji poszczególnych osobników było zróżnicowane. Ogólnie dystans 30 km, od miejsca wpuszczenia ryb do ujścia Drawy do Noteci, siedem jesiotrów z pierwszej grupy pokonało w ciągu 18 dni. Sześć ryb z drugiej grupy w ciągu 4 dni od zarybienia spłynęło z Drawy i przemieściło się 20 km od jej ujścia do Noteci. Tempo migracji było dodatnio skorelowane z wielkością ryb i temperaturą wody.

SPATIAL AND TEMPORAL VARIATION IN SMALL FISH OCCURRENCE IN SHALLOW HABITATS OF THE VISTULA LAGOON (SOUTHERN BALTIC SEA)

The aim of the study was to determine the composition and structure of small fish assemblages inhabiting coastal areas of the brackish Baltic Lagoon. Spatial and temporal variations in ichthyofauna were analysed as part of the work. Additionally, the data obtained falsified the hypothesis that the share of marine species in fish assemblages grows along with salinity. A total of 19 species belonging to eight families were recorded in shallow habitats of the Vistula Lagoon. These belonged to four ecological guilds among which freshwater species were represented most numerously. Marine species dominated quantitatively. Marine opportunist species constituted the largest part of catches although they made up just 10.5% of the 19 species recorded in the course of the four-year study. A significant variation was recorded in the fish assemblage structure in regions of the lagoon with differing water salinity. Significance of marine species in the quantitative structure of small fish assemblages increased along wi...

Past and present of and perspectives for the Danube huchen, Hucho hucho (L.), in the Danube basin

Abstract Huchen, Hucho hucho (L.), also known as Danube salmon, is an iconic, endemic species inhabiting the Danube basin of Central Europe. Historically, the Danube huchen inhabited a significant portion of the Danube drainage basin stretching to the Iron Gate and the majority of large and medium-sized tributaries. Larger populations in the natural zoogeographical distribution of Danube huchen were once found in Austria, Bavaria, the former Yugoslavia, Slovakia, and western Ukraine. Currently, the species is severely fragmented within the Danube drainage, where most populations exclusively depend on stocking and natural reproduction is very limited due to habitat alterations and flow regime changes. In the Czech Republic and Poland, Danube huchen occurrence is the result of introducing the species to several rivers in the Baltic Sea and North Sea drainage basins. Danube huchen is a threatened species throughout is range of occurrence, and, according to IUCN criteria, it is classified as endangered (EN). Habitat degradation is the most serious negative factor impacting huchen populations. Dam construction, pollution, and river regulation have led to loss and degradation of spawning sites. Detailed research on population abundance and structure is greatly needed to help identify the populations which are most threatened and to help to develop the best protection systems.

Feeding of hatchery-reared juvenile Atlantic sturgeon, Acipenser oxyrinchus Mitchill, released into the Drwęca River

Feeding of hatchery-reared juvenile Atlantic sturgeon, Acipenser oxyrinchus Mitchill, released into the Drwęca River Atlantic sturgeon, Acipenser oxyrinchus Mitchill was once one of the largest European freshwater fish, and it was common in the Vistula River drainage. Since 2006, juvenile Atlantic sturgeon obtained by artificially reproducing wild spawners caught in the St. John River in Canada have been stocked into several rivers in Poland. The current study to assess the feeding of Atlantic sturgeon in the Drwęca River in Poland is part of a larger project to restore the species to this region. Hatchery-reared eleven-month-old Atlantic sturgeon were recaptured 2 to 10 days after their release into the river. This study provides the first data on the diet of A. oxyrinchus in the fresh waters of Europe. In June 2008, the stomach contents of the juvenile Atlantic sturgeon that had been recaptured were collected using gastric lavage. Of the 70 sturgeon the Drwęca River which were subjected to gastric lavage, 67% of them had empty stomachs. The diet of juvenile Atlantic sturgeon consisted of nine taxa of prey. Primarily, sturgeon eat small, soft-bodied larval Oligochaetae and Chironomidae. Pokarm wyhodowanych w wylęgarni juwenalnych jesiotrów ostronosych Acipenser oxyrinchus Mitchill w trakcie początkowej migracji w rzece Skład diety i odżywianie się Acipenser oxyrinchus Mitchill w warunkach naturalnych są słabo poznane. Juwenalne jesiotry wyhodowane w Zakładzie Hodowli Ryb Jesiotrowatych w Pieczarkach zostały wpuszczone do Drwęcy. Łącznie wypuszczono 378 jedenastomiesięcznych jesiotrów (długość całkowita 423mm ± 40,8 SD, masa ciała 239,8 g ± 74,7 SD), a odłowiono 150 osobników. Ryby odłowiono w okresie od 2 do 10 dni po zarybieniu. Skład pokarmu pobranego za pomocą płukania żołądków określono u 70 osobników. Większość złowionych jesiotrów (67%) miała puste żołądki. U pozosta łych osobników odnotowano występowanie 9 taksonów bezkręgowców. Podstawą diety juwenalnych jesiotrów były Oligochaeta i larwy Chironomidae. Wskaźnik względnej ważności dla tych składników pokarmu wynosił odpowiednio 66,2 i 26,4%.

Atlantic sturgeon, Acipenser oxyrinchus Mitchill, infected by the parasitic leech, Caspiobdella fadejewi (Epshtein) (Hirudinea; Piscicolidae), in the Drwêca River

Atlantic sturgeon, Acipenser oxyrinchus Mitchill, infected by the parasitic leech, Caspiobdella fadejewi (Epshtein) (Hirudinea; Piscicolidae), in the Drwęca River This study presents the parasitic relationship between the leech, Caspiobdella fadejewi, and the juvenile Atlantic sturgeon, Acipenser oxyrinchus. The aim was to determine leech invasion intensity and extensity and describe parasite feeding location preferences on the ventral side of the snout and gill cavities. The prevalence of C. fadejewi occurrence was 37.3%, at an intensity of one to eight leeches. It was confirmed that the intensity of leech occurrence was positively correlated with sturgeon total length (r=0.545, P<0.05, N=15). The host-searching mechanism is most probably based on positive phototaxis. This is the first record of C. fadajewi from A. oxyrinchus. The leech was first observed during routine examinations of sturgeon collected in June 2008. The leeches were usually attached to the inside lower portion of opercula near the isthmus. Zarażenie jesiotra Acipenser oxyrinchus Mitchill pasożytniczą pijawką Caspiobdella fadejewi (Epstein) (Hirudinea; Piscicolidae) w Drwęcy Słodkowodne gatunki pijawek pasożytujące na rybach (Piscicolidae) jako monofiletyczna rodzina, z nielicznymi wyjątkami, zamieszkują wody kontynentalne Holarktyki. W pracy scharakteryzowano występowanie pasożytniczej pijawki Caspiobdella fadejewi u juwenalnych jesiotrów Acipenser oxyrinchus Mitchill. Określono ekstensywność oraz intensywność zarażenia jesiotrów wpuszczonych do Drwęcy. Ekstensywność występowania C. fadejewi wynosiła 37,3%, a intensywność od 1 do 8 pijawek. Stwierdzono, że intensywność występowania pijawek była dodatnio skorelowana z długością całkowitą jesiotrów (r=0,545, P<0,05, N=15). Pijawki najczęściej były zlokalizowane na płetwach parzystych lub rostrum, rzadziej na bokach ciała, płetwach odbytowej lub ogonowej. Prawdopodobnie odszukiwanie żywiciela związane jest z pozytywną fototaksją. Pijawki wykorzystują w odszukiwaniu żywiciela jego cień, który powoduje spadek natężenia światła odbierany przez plamki oczopodobne znajdujące się na przyssawce tylnej.

History of the Sturgeon in the Baltic Sea and Lake Ladoga

This paper presents a short review of the information on the history regarding Atlantic sturgeon Acipenser oxyrinchus Mitchill in the Baltic Sea and Lake Ladoga. Due to overfishing and habitat alternation, including damming and pollution, the Atlantic sturgeon was extirpated from this area. The history of the fisheries exploitation of the Atlantic sturgeon population dates back to the Neolithic period.

Non-native fish species in heated lakes: Origins and present status

Abstract This paper discusses the problem of the occurrence of non-native fish species in a strongly transformed aquatic ecosystem. The changes in this ecosystem are caused by warm water discharges from two electric power plants. Twelve non-native fish species are confirmed to occur in the system of five heated lakes located in central Poland. In total, 30% of the total number of non-native species confirmed in Polish inland waters were noted. Aquaculture and fisheries are the primary sources of non-native species in these lakes. Among the species identified, most reached the lakes or canals by escaping from farming facilities or through commercial stocking. Four species have established stable populations. Pseudorasbora parva (Temminck & Schlegel), Carassius gibelio (Bloch), and Carassius auratus (L.) are invasive species that occur abundantly in all the lakes, while Cyprinus carpio L. reproduces irregularly and only in the most heated lakes. The remaining species do not reproduce in the heated lakes system, or anywhere else in Poland; still, the threat these species pose must not be underestimated.

Impact of diet and culture conditions on the body shape of crucian carp (Carassius carassius L.)

The ecological consequences of hatchery rearing have been widely studied, whereas there are relatively few investigations of the impact diets and culture conditions have on morphological variation, especially in rare or endangered species. The aim of the current study was to determine the impact of diet and culture conditions on the morphometric features of crucian carp (Carassius carassius), which is a species characterised by a highly variable body shape. In the first experiment, the impact of feed type on crucian carps body shape was tested, while in the second, the impact of culture conditions on the body shape was determined. Feed type and culture conditions significantly impacted the shape and the morphology of crucian carp. Fish-fed larval chironomids exhibited the least variation in biometric characters, while those fed high-energy-formulated feed exhibited the greatest variation. In turn, individuals cultured in ponds exhibited greater variability in measurable characters than did fish cultured in recirculating systems. The body depth index of fish fed different feeds or cultured under controlled conditions did not differ significantly in comparison to wild crucian carp. The phenotypes of the cultured fish from the two experiments were similar to those of individuals inhabiting the natural environment.

Growth and survival in earthen ponds of different sizes of juvenile pike reared in recirculating aquaculture systems

Abstract The aim of the study was to determine the growth and survival of juvenile pike, Esox lucius L., reared in recirculating aquaculture systems (RAS) and then released into earthen ponds. Three different sizes of fish were used in the experimental releases of stocking material with mean body weights of 1.5 g (group S), 7.0 g (group M), and 18.5 g (group L) which were reared in a recirculating aquaculture system and fed formulated feed exclusively. Before the fish were released, they were tagged with visible implant elastomer (VIE) tags. The highest final body weight was attained by the fish in group S, the mean body weight of which was 85.5 g, which was significantly statistically higher than in the other groups (P < 0.001). No differences in survival were noted among the groups. Positive biomass increases were only exhibited in group S (37 kg ha-1), and it was highly statistically significantly greater than it was in the other groups (P < 0.001). The results of the experiment could indicate that the suitability of juvenile pike for stocking depends on its size at release. Extending the rearing period in RAS resulted in poorer stocking results in the ponds.