Wyniki wyszukiwania - Biblioteka Nauki

1

Age, growth rate, and otolith growth of polar cod (Boreogadus saida) in two fjords of Svalbard, Kongsfjorden and Rijpfjorden

100%

Fey D. P. , Węsławski J. M.

Oceanologia

|

2017

|

tom No. 59 (4)

576--584

EN

This work presents biological information for polar cod (Boreogadus saida) collected with a Campelen 1800 shrimp bottom trawl in Kongsfjorden (two stations located in the inner part of the fjord adjacent to the glacier) and Rijpfjorden (one station at the entrance to the fjord) in September and October 2013. The otolith-based ages of polar cod collected in Kongsfjorden (6.1–24 cm total length TL; n = 813) ranged from 0 to 4 years. The growth rate was relatively constant at approximately 4.7 cm year−1 between years 1 and 4, which indicates that growth was fast in the glacier area. The ages of polar cod collected in Rijpfjorden (8.6–15.9 cm TL; n = 64) ranged from 2 to 3 years. The fish from Rijpfjorden were smaller at age than those from Kongsfjorden, and their growth rate between years 2 and 3 (no other age classes were available) was approximately 3.3 cm year−1. In both fjords, males and females were of the same size-at-age and the same weight-at-TL. The small sampling area means that the results on growth rate are not representative of the entire fjords. Instead, the results can be discussed as presenting the possible growth rates of some populations. A strong relationship was identified between otolith size (length and weight) and fish size (TL and TW), with no differences between males and females or the fjords. A significant, strong relationship was also noted between fish and otolith growth rates.

2

Effects of different duration of feeding on results of carp [Cyprinus carpio] fry cage culture in cooling water

63%

Sadowski J. , Filipiak J. , Trzebiatowski R.

|

nr 1

EN

The Safir trout feed (Aller Aqua) was offered to carp (Cyprinus carpio) fry of 21 + 5 g/ind. initial weight, stocked at a density of 300 ind./m3 in cages placed in cooling water. Identical rations (5 4.0% metabolic weight) were offered for 6, 12, and 18 h per day. The data obtained showed the best results (as indicated by SGR and FCR) of culturing carp of up to about 75 g individual weight were obtained when the feeding took 18 h, 12 18 h being the best duration of feeding for the carp weighing 75 130 g. No effect of duration of feeding was observed in the carp weighing more than 130 g.

3

Age structure, condition and length increase of the topmouth gudgeon (Pseudorasbora parva Schlegel 1842) in non-native populations of small rivers of Poland

51%

Czerniejewski P. , Zatoń K. , Kasowska N. , Brysiewicz A.

Journal of Water and Land Development

|

2019

|

tom no. 40

113--118

EN

Monitoring studies of ichthyofauna, in particular non-indigenous species, are an important element of research on aquatic ecosystems. This information is essential for modelling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Actually, the most compelling fish invasion in Polish freshwaters is arguably the accidental introduction of the topmouth gudgeon (Pseudorasbora parva). Age and lengths structure, condition factor and growth rate of the invasive populations of the topmouth gudgeon from small Polish rivers was examined. The samples were collected from the rivers: Molnica (n = 41), Myśla (n = 21) and Wardynka (n = 101) soon after the invasion was recorded (2017). Estimated ages of topmouth gudgeon ranged from 1+ to 3+ for the Myśla River, from 1+ do 4+ for the Molnica River, and from 1+ to 5+ for the Wardynka River. The fish from the Molnica River was characterised by the lowest total and standard length (TL, SL), weight, and highest condition. The results of back-calculations and the parameters of von Bertalanffy’s growth equation revealed distinct disproportions in the standard length (mm) in individual age groups (Molnica River: Lt = 54.94 [1 – e–0.68885 (1 – 0.003404)], Myśla River: Lt = 55.39 [1 – e–0.74921 (1 – 0.030962)], Wardynka River: Lt = 66.33 [1 – e–0.69348 (1 – 0.369505)]). The introduction of the topmouth gudgeon occurred in the upper and medium sectors of small rivers, but in subsequent years the species migrated to new sites further downstream and this may have affected the native ichthyofauna.

PL

Badania monitoringowe ichtiofauny, w szczególności gatunków nierodzimych, są ważnym elementem badań nad ekosystemami wodnymi. Informacje te są niezbędne do modelowania wzrostu populacji i przewidywania tempa ekspansji, ilościowego określania skutków ekologicznych i oceny skuteczności strategii eliminacji tych ryb z wód rodzimych oraz ich kontroli. Jednym z najbardziej interesujących gatunków inwazyjnych w świecie ryb w polskich słodkowodnych wodach jest prawdopodobnie przypadkowe wprowadzenie czebaczka amurskiego (Pseudorasbora parva). W pracy analizowano strukturę wieku i długości, współczynnik kondycji i tempo wzrostu inwazyjnych populacji czebaczków amurskich z małych cieków w Polsce. Ryby złowiono w 2017 r. z rzek: Molnica (n = 41), Myśla (n = 21) i Wardynka (n = 101). Szacowany wiek czebaczków amurskich wynosił od 1+ do 3+ (Myśla), od 1+ do 4+ (Molnica) i od 1+ do 5+ (Wardynka). Ryby z Molnicy cechowały się najmniejszą długością całkowitą i długością ciała (TL, SL) oraz masą osobniczą. Odczyty wsteczne i parametry równania wzrostu von Bertalanffy’ego ujawniły wyraźne dysproporcje w długości całkowitej w poszczególnych grupach wiekowych (rzeka Molnica: Lt = 54,94 [1 – e–0,68885 (1 – 0,003404)], rzeka Myśla: Lt = 55,39 [1 – e–0,74921 (1 – 0,030962)], rzeka Wardynka: Lt = 66,33 [1 – e–0,69348 (1 – 0,369505)]). Wprowadzenie czebaczka amurskiego miało miejsce w górnej i środkowej strefie małych cieków, ale w kolejnych latach gatunek ten może migrować do nowych miejsc zlokalizowanych w dolnych odcinkach rzek i może wpływać na rodzimą ichtiofaunę.

4

The influence of littoral zone type and presence of YOY pike [Esox lucius L.] on growth and behaviour of YOY pikeperch, Stizostedion lucioperca [L.] - consequences for water quality in lowland reservoirs

51%

Lapinska M. , Frankiewicz P. , Dabrowski K. , Zalewski M.

International Journal of Ecohydrology and Hydrobiology

|

2001

|

tom 01

|

nr 3

EN

The influence of littoral type at presence and absence of young of the year (YOY) pike (Esox lucius L.) on growth and diurnal behaviour of YOY pikeperch Stizostedion lucioperca (L.) was investigated in triplicate (7.5 m2) field enclosures. Three types of littoral zone were applied: with homogeneous macrophytes (HOM), with heterogeneous macrophytes (HEM) and with woody debris (WD), together with control enclosure–without any structure (C). The type of littoral zone influenced the growth rate and behaviour of YOY pikeperch. The growth rates of small (<60mm) pikeperch were significantly higher in HOM than in controls, HEM and WD types of littoral. Similar but weaker relationships were found for larger pikeperch (>60mm) with their growth rates higher in HOM than in HEM and WD littoral types. At the presence of pike, the highest pikeperch growth rate was still noted in HOM, compared to WD enclosures. The results of pikeperch diurnal behaviour showed high littoral use at absence of pike (on average: 38% for C, 62% for HOM, 55% for WD, and 30% for HEM enclosures). Pikeperch utilised littoral habitat much less at presence of pike (15% for C, 8% for HOM, 3% for WD, 6% for HEM enclosures). On the basis of experiments it can be concluded that pikeperch growth rate and behaviour may be strongly affected by diversified littoral zones and by the presence of pike competition. Observed relationships may be applied for water quality control in reservoir. As a strong pikeperch population, achieved by enhancement of its growth through creation of most preferred nursery habitat (HEM), may enable to reduce zooplanktivorous fish community even in the presence of pike competition.