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  • Author: Mirosław Szczepkowski x
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Impact of Feed Rations on Growth, Selected Body Parameters and Maturation of Vendace, Coregonus Albula L., Reared in RAS

Abstract

Vendace, Coregonus albula L., was reared to commercial size in a recirculating system. Three different feed rations were applied during the ten-month-long experiment. The feed rations impacted fish growth rates, and fish in the different groups achieved body weights of 26.6 g to 57.5 g. The final survival in all groups was similar from 44.3% among the fish fed the smallest feed ration to 53.2% in the group receiving the largest feed ration. No differences were noted in the share of viscera, peritoneal fat, or in the hepatosomatic indexes, but there were differences in the gonadosomatic indexes. After thermal stimulation, only males achieved sexual maturity. The number of mature fish was similar in all groups and ranged from 17.8 to 21.3% of all fish. The results of the present study indicated that vendace can achieve commercial size in an intensive rearing period of ten months in RAS.

Open access
Assessment of the impact of the timing of first feeding with live and formulated feeds on the survival and growth of larvae Atlantic sturgeon (Acipenser oxyrinchus Mitchill) in recirculating systems

Abstract

The aim of the study was to determine the optimum timing of the first feeding of live and formulated feeds and its impact on the survival and growth of larval Atlantic sturgeon, Acipenser oxyrinchus Mitchill, reared in recirculating systems. The first experiment compared the rearing effects on larvae that were provided live feed (Artemia sp.) at first feeding on 6, 9, and 12 days post hatch (DPH). The timing of the first feeding with live feed had an impact on the specific growth rate, the final body weight, and the coefficient of body weight variation. The most advantageous rearing parameter values were noted in the group given their first feeding 9 DPH (P < 0.05). The second experiment compared the results of rearing larvae that were first given formulated feed on days 20, 25, and 30 post hatch. The highest specific growth rate and final body weight were obtained by the group of fish given their first feeding of formulated feed on day 20 post hatch (P < 0.05). The timing of the first feeding did not impact fish survival, which was above 76% (P > 0.05) in all groups. The results of the experiment indicate that the optimum timing of Atlantic sturgeon first feeding on live feed was nine DPH, and on formulated feed it was 20 DPH.

Open access
Polyculture of juvenile pikeperch (Sander lucioperca (L.)) and sterlet (Acipenser ruthenus L.) in a recirculating system

Abstract

The experiment examined the possibility of rearing juvenile pikeperch, Sander lucioperca (L.) in polyculture with sterlet Acipenser ruthenus L. in a recirculating system. Three variants of pikeperch rearing were tested: monoculture (group S), with the addition of sterlet at 10% (group S10) and 20% (group S20) of the initial pikeperch biomass. After 56 days of rearing, no differences in the growth rates or survival of the pikeperch were noted. The value of the feed conversion ratio in the monoculture group was 1.19 and was significantly statistically higher than in the polyculture groups, the values of which were 0.84 (S10) and 0.74 (S20). The mean oxygen consumption and ammonia excretion values did not differ significantly statistically among the studied groups. Including the sterlet stock with the pikeperch permitted obtaining the additional value of the sterlet biomass using the same quantity of feed. Additionally, the inclusion of sterlet decreased the labor intensity of pikeperch rearing since the tanks did not need cleaning as frequently.

Open access
Impact of sex and diet on hematological and blood plasma biochemical profiles and liver histology of pikeperch (Sander lucioperca (L.))

Abstract

The aim of the study was to determine the impact of diet and sex on the hematological and blood plasma biochemical profiles and the liver histology of pikeperch, Sander lucioperca (L.) reared in recirculating aquaculture systems (RAS) (initial mean body weight (BW) 1.35 kg). The proximate composition of the two commercial feeds used were (protein/lipid/nitrogen-free extracts) (P/L/NFE)) P505/L118/NFE294 g kg−1 (group I) and P471/L141/NFE290 g kg−1 (group II). Neither diet nor sex had a significant impact on final fish body weight (≈ 2.0 kg). Sex was noted to significantly impact glucose content (Glu – higher in males) and cholesterol (Chol – higher in females) in the blood plasma. Diet was confirmed to have a significant impact on levels of hematocrit (Ht), hemoglobin (Hb), and mean corpuscular hemoglobin (MCH), and the values of these indicators were higher in group I. Sex had a significant impact on Ht, Hb, MCH, and mean corpuscular hemoglobin concentration (MCHC), with higher values in male pikeperch. Diet and sex had significant impacts on the values of the pikeperch hepatosomatic index (HSI), hepatocyte size and that of their nuclei, and the values of the nucleocytoplasmic index (NCI).

Open access
Impact of feed ration on the growth and body weight variation in pikeperch (Sander lucioperca L.) at different life stages in a recirculating aquaculture system

Abstract

The aim of the study was to determine the impact of different feed rations (0.5, 0.8, 1.1% fish biomass) on the rearing parameters of pikeperch, Sander lucioperca (L.), reared in a recirculating aquaculture system. The study comprised two experiments. In the first, the material used had been sorted by a mean body weight of 35.5 g, while in the second the pikeperch were divided into three size classes: smallest individuals (class S) with a mean body weight of 59.5 g, medium-sized individuals (class M) with a mean weight of 69.3 g, and largest individuals (class L) with a mean body weight of 84.8 g. The experiments ran for 42 days. At the conclusion of the experiments, the highest body weight and length, daily growth rate, and specific growth rate were attained by the group of fish fed the ration of 1.1% of the fish biomass in both experiments I and II. The feed conversion ratio was also the lowest in this feed ration group, and it differed significantly statistically among the experimental groups (P < 0.05). The feed ration of 0.5% of the fish biomass was only sufficient to maintain vital functions, but it contributed only slightly to growth. The different feed rations did not have a significant impact on the final value of the body weight coefficient of variation of the pikeperch reared in the two experiments. The results of the experiment also indicated that pikeperch is a species with weak stock hierarchy and domination structure.

Open access
Effect of visible implant elastomers (VIE) and coded wire tags (CWT) on the growth, survival, and tag retention of juvenile European whitefish (Coregonus lavaretus)

Abstract

This study examined the effect of visual implant elastomers (VIE) and coded wire tags (CWT) on the growth, survival, and tag retention of juvenile European whitefish, Coregonus lavaretus (L.), (mean body weight 18.7 ± 0.4 g, mean body length 9.7 ± 0.4 cm). The VIE tags were implanted subcutaneously in the anterior head, and the CWTs were implanted intramuscularly under the left gill operculum. The experiment consisted of two stages. The first stage (70 days) examined the effects of tagging on growth and survival, while the second stage (days 71-140) focused on assessing tag retention. Daily and specific growth rates, feed conversion factor, condition factor, coefficient of body weight variation, and survival did not differ significantly between the control fish and those tagged with the VIE tags and CWTs. Tag retention was high in the fish tagged with both VIE tags (100%) and CWTs (93%).

Open access
Slaughter yield and fatty acid profiles of fillets of pike (Esox lucius L.) caught before and after spawning

Abstract

The aim of the study was to determine the impact pike fishing season (before spawning in fall (group A) and after spawning in spring (group B)) had on the slaughter yield and fillet fatty acid profile. The slaughter yield of fillets with skin and skinned fillets from the group B fish was significantly lower (by approximately 7.5% of body weight). The fatty acid profile of the fish meat from the groups examined differed significantly. The fillets of pike caught before spawning were dominated by unsaturated fatty acids (UFA), while those from fish caught after spawning had mainly saturated fatty acids (SFA). The share of polyunsaturated fatty acids (PUFA) in the fillets of fish that had spawned was sixfold lower, and the n-3 PUFA differences were nearly ninefold. The content of eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids in fillets of fish that had spawned was ninefold lower than in those that had not yet done so. Consequently, the ratio of n-3 PUFA/n-6 PUFA in pike from group A was over three times higher than that in the fish that had spawned (2.61 vs 0.82). Fillets from pike that have spawned are a significantly poorer source of valuable fatty acids for consumers.

Open access