The effect of feeding method on body weight gains, concentrations of selected components in the blood, and peroxidation processes of carp, Cyprinus carpio L

Background. Fish are the principal source of n-3 and n-6 fatty acids for humans. Traditionally, these fatty acids have been supplied in the form of captured marine and freshwater fishes. Recently, freshwater cultured species have been increasing their share in the fish volume on the market. Therefore it is crucial for fish farmers to rear fish under proper condition and with proper feeding in order to receive good quality fish flesh at harvest. The presently reported study was aimed at determining the effect of diet with the increased level of lipids or carbohydrates on selected blood indices, reduced glutathione content, lipid peroxidation products concentration in the liver, and body weight gains in carp fingerlings reared in post-cooling waters. Materials and methods. The experiment was carried out in spring (2004) on 300 carp divided into two feeding groups. Group I was fed high-fat feed, whereas group II high-carbohydrate feed. After 7 weeks, fish blood and livers were collected for further analyses. Results. Significantly higher body weight gains were found in the fish fed high-fat feed as well as significant increase of haemoglobin (Hb) concentration in the blood of both feeding groups, which was accompanied by the increase of haematocrit (Ht) index. Furthermore, an increase in the concentration of lipid peroxidation products was observed as well as significantly lower content of reduced glutathione (GSH) in the livers of fish examined. Conclusion. The observed MDA values and reduced glutathione (GSH) concentration in the fish liver may indicate enhanced peroxidation processes in the organisms of the fish from both experimental groups, caused by their intensive feeding with extruded feeds. The peroxidation processes were more intensive in fish fed high-fat feeds

Impact of high cortisol level-observed in the blood of two-year-old carp (Cyprinus carpio L.) and caused by different colour of their aquaria-on the electrolyte content and osmolarity

It was determined in the present study that a 14-day stay of carp in blue, yellow, and red aquaria caused significant increase of cortisol levels compared to its initial state and to that of fish kept in aquaria of a natural colour. This in turn caused a decrease in the levels of sodium and chloride ions and statistically significant decrease in potassium ion content

Effect of diet composition on the levels of glucose, lipids, and lipoproteins of the blood and on the chemical composition of two-year-old carp (Cyprinus carpio L.) reared in cooling waters

The present study was conducted on two-year-old carp, reared in the production-scale conditions. The fish were kept for 62 days in cooling water and fed feeds differing in the fat content (35.9% of the energetic value of the diet) and carbohydrate content (35.6% of the energetic value of the diet). The experiment resulted in statistically significant differences in the levels of glucose, lipids, and blood lipoproteins as well as in the body composition of the fish in relation to the pre-experiment values and in relation to the other nutritional groups

Effect of starvation on nutritive value of carp (Cyprinus carpio L.) and selected biochemical components of its blood

The experiment, carried out in the aquarium room of the Faculty of Marine Fisheries and Food Technology, involved 72 carp juveniles. The fish were kept in 6 aquaria for 12 weeks without food. Levels of crude protein, AspAT and AlAT activities, levels of glucose, triacylglycerols, cholesterol and its fractions as well as body weight reduction and body composition were analysed. Starvation was found to significantly affect the crude protein level and AspAT activity as well as the blood levels of glucose, triacylglycerols, cholesterol and its fraction and the body chemical composition. The significant changes occurred both in relation to the initial status of the fish and between successive stages of the experiment

Effects of intensive culture and feeding isoprotein diets with different fat and carbohydrate contents on cortisol, total protein and protein fractions contents, aspat and alat activities, and on body composition and weight increments in carp (Cyprinus carpio L.) fingerlings

The experiment was run on carp individuals in their second year of life. The fish were randomly divided into two groups fed two different isoprotein diets, one with increased fat level (Group I) and the other with increased carbohydrate level (Group II). Cortisol, total protein and protein fraction contents, AspAT and AlAT activities, and body composition and weight increments were monitored. Statistically significant differences between the two experimental groups were found in cortisol content, albumin level, blood AspAT and AlAT activities as well as in dry weight, total protein, and fat contents of the fish body

Wybrane cechy morfometryczne, kondycja oraz skład chemiczny ciała okoni (Perca fluviatilis L.) z jeziora Miedwie, Polska

The study material comprised perch obtained from commercial catches conducted in May and November 2009 in Lake Miedwie. Catches were made using gill nets with a mesh size ranging from 40 to 45 mm. Fifty perch (25 from each of the catches) were obtained for the study. The fish were weighed [g], and then total length [mm] and maximum body height [mm] were measured. The dependencies between total length and weight, total length and body height, and weight and body height were calculated. The condition of the perch was determined with Fulton’s condition coefficient (KF). Twelve fish were chosen at random from among the study material collected in spring and autumn to determine body chemical composition. The mean weight of these individuals was 220.51 š 18.68 g and mean length was 264.33 š 6.86 mm in spring and 91.08 š 17.20 g and 189.17 š 7.52 mm in autumn, respectively. The stomachs were excised from the fish and their contents were identified. Gutted and deheaded fish were homogenized, and the percentage share of the following were determined according to Polish norms: protein, lipids, dry matter, and ash. Qualitative analysis of the fatty acid content of the fish was performed with the PN-EN ISO 5509: 2001 chromotagraphic method. The results of the analyses indicate that the perch caught in May 2009 have greater body weights, lengths, and heights and higher quantities of lipid in comparison with the perch caught in autumn of 2009. The values of these parameters for spring and autumn, respectively, are as follows: body weight – 156.86 š 15.98 and 86.46 š 8.98 g; total length – 233.68 š 7.37 and 189.08 š 4.49 mm; body height – 52.66 š 1.97 and 44.39 š 1.59 mm; body lipid content – 1.32 š 0.03 and 0.24 š 0.01 %. However, the fish caught in November 2009 had higher KF, and contained more EPA and DHA fatty acids in comparison with fish caught in spring 2009, as follows (for spring and autumn, respectively): KF – 1.128 š 0.02 and 1.203 š 0.02; EPA content – 7.025 š 0.005 and 8.725 š 0.015 %; DHA content – 16.890 š 0.030 and 18.575 š 0.005 %.Materiał do badań stanowiły okonie pochodzące z połowów gospodarczych prowadzonych wiosną (05.2009) oraz jesienią (11.2009) w jeziorze Miedwie. Połowy ryb prowadzone były wontonami o rozmiarach oczka od 40 do 45 mm. Do badań pozyskano 50 okoni, po 25 sztuk z każdego połowu. Ryby ważono [g], a następnie mierzono ich długość całkowitą l.t. [mm] oraz maksymalną wysokość ciała [mm]. Ponadto obliczono relację długości całkowitej do masy badanych ryb. Obliczono także relację długości całkowitej do wysokości badanych ryb oraz masy badanych ryb do ich wysokości. Kondycję okoni określano za pomocą współczynnika kondycji Fultona (KF). Ponadto spośród złowionych ryb, zarówno wiosną jak i jesienią, wybrano losowo po 12 sztuk o średniej masie 218 š 74 g i długość l.t. 218 š 74 mm w celu oznaczenia składu chemicznego ich ciała. Od ryb pobrano żołądki i oznaczono ich zawartość. Wypatroszone i odgłowione ryby zhomogenizowano i w tak uzyskanej próbie oznaczono wg Polskiej Normy procentową zawartość białka, tłuszczu, suchej masy i popiołu. Przeprowadzona została także analiza jakościowa tłuszczu zawartego w ciele ryb metodą chromatografii PN-EN ISO 5509: 2001. Na podstawie przeprowadzonych badań można stwierdzić, że okonie odłowione w maju charakteryzowały się większą masą, długością oraz wysokością ciała, a także większą zawartością tłuszczu w ciele w porównaniu do ryb odłowionych jesienią 2009 r.; odpowiednio wiosną i jesienią: masa ciała - 156,86 š 15,98 i 86,46 š 8,98 g; długość całkowita - 233,68 š 7,37 i 189,08 š 4,49 mm; wysokość ciała - 52,66 š 1,97 i 44,39 š 1,59 mm; ilość tłuszczu w ciele - 1,32 š 0,03 i 0,24 š 0,01%. Natomiast okonie odłowione w listopadzie charakteryzowały się większą wartością współczynnika kondycji (KF) oraz większą zawartością kwasów tłuszczowych EPA i DHA w ciele w porównaniu do ryb odłowionych wiosną 2009 r.; odpowiednio wiosną i jesienią: współczynnik kondycji (KF) - 1,128 š 0,02 i 1,203 š 0,02; zawartość EPA - 7,025 š 0,005 i 8,725 š 0,015 %; zawartość DHA - 16,890 š 0,030 i 18,575 š 0,005 %

Characteristics of the grey seal ( Halichoerus grypus ) diet in the Vistula River mouth (Mewia Łacha Nature Reserve, Southern Baltic Sea), based on the osteological and molecular studies of scat samples

This study reports the propagation dynamics of the Kara Sea surface desalinated layer (SDL) during the summer and autumn seasons. We analysed shipboard measurements data collected in 2013–2018 and MODIS ocean colour data that correlated with the shipboard ones. We formulated a comparatively strict criterion to determine the SDL border based on satellite data. For that, we analyzed the shipboard flow-through measuring system data obtained while crossing the surface desalinated layer border. Further, we used a regional algorithm to process the satellite data and estimate the coloured dissolved organic matter absorption coefficient for the Kara Sea. The results demonstrate a significant effect of the wind regime on the interseasonal and interannual variability of the transformation of the SDL boundaries. The positions of the surface desalinated layer boundaries at different times during 2013–2018 are given. The obtained results are important for calculating the heat balance and analyzing the Kara Sea bio-productivity

Reproduction of cod, Gadus morhua (Actinopterygii: Gadiformes: Gadidae), from the Gdańsk Deep (Baltic Sea) under controlled conditions

Background. The stocks of cod, Gadus morhua Linnaeus, 1758, have been declining within recent decades and the Baltic Sea is one of the most affected areas. The latter body of water with its low salinity, pollution, and vast areas of demersal hypoxia is particularly vulnerable. Areas of natural spawning are scarce and the reproductive output of cod has been irregular and more and more limited. One of the proposed solutions for this problem might be an artificial reproduction.  One of such areas has been the Gdańsk Deep, but the number of potential brood fish is relatively low, which makes the eggs and sperm poorly accessible. The aim of the presently reported study was to conduct spawning and egg incubation under controlled conditions to obtain viable hatchlings and to monitor the embryonic development of cod originating from the area of the Gdańsk Deep. Materials and methods. The parental fish specimens were obtained during commercial trawl catches. The eggs were fertilized artificially at the field laboratory using filtered brackish sea water with salinity of 15‰, and then were incubated at a constant temperature of 8 ± 0.5°C. Eggs and larvae development, and larvae beginning exogenous feeding were observed under a stereo microscope, and photographed regularly to determine the sizes of the eggs and larvae and to document the results of the experiment. Results. The mean percentage of fertilization of eggs was 70%. Hatching began 236 h after fertilization, and the newly hatched larvae comprised 30% of the initial stocking density. The mean length of the larvae was 3.95 mm. The cod larvae began exogenous feeding before the yolk sac was fully absorbed. Conclusion. Artificial reproduction with gametes obtained from cod spawning in the Gdańsk Deep is possible, and the fertilization rates obtained were similar to those achieved with cod from the Bornholm and Gotland basins. Therefore, our results also show that cod spawning in the Gdańsk Deep can be suggested as a model species for further research