Daniel Żarski

Artificial reproduction of two different spawn-forms of the chub.

The aim of this study was to compare, under controlled conditions, reproduction results of cultured and wild stock of the chub. Wild fish spawned only once a season whereas the cultured stock spawned at least two times. In the multiple-spawn stock, fewer fish spawned and the weight of produced oocytes was reduced compared to the single-spawn stock. Larvae obtained from the multi-spawn forms were smaller than those of the single-spawn stock. The occurrence of one species with two forms of spawning performance in the same area makes it difficult to develop an efficient method for controlling the reproduction.

Artificial spawning of common tench Tinca tinca (Linnaeus, 1758), obtained from wild and domestic stocks

The study encompasses three reproduction seasons. Tench spawners caught during the spawning season originated from carp ponds (domestic stock) and a lake (wild stock). Fish were reproduced under controlled conditions after hormonal stimulation with GnRHa-containing pellets combined with metoclopramide (Ovopel) or carp pituitary homogenate (CPH). As a result of hormonal stimulation, eggs were obtained from a larger number of females originating from the lake (71.7%) than those originating from the pond (58.3%), although no other statistical differences were found. A similar relationship was recorded for the spermatozoa motilities (range from 72 to 76%). The obtained results indicate that both investigated reservoirs are suitable for tench broodstock management due to the fact that synchronization of ovulation among different stocks is easy to achieve. For this purpose, among the tested spawning agents, Ovopel could be recommended as being slightly more effective.

ECONOMIC ASPECTS OF REARING LARVAL ASP, ASPIUS ASPIUS (L.), AND IDE, LEUCISCUS IDUS (L.), IN CLOSED RECIRCULATING SYSTEMS

Economic Aspects of Rearing Larval ASP, Aspius Aspius (L.), and IDE, Leuciscus Idus (L.), In Closed Recirculating Systems The profitability of rearing the rheophilic cyprinid fish species asp, Aspius aspius (L.), and ide, Leuciscus idus (L.), in two independent closed recirculating systems was evaluated. The fish were fed live Artemia nauplii exclusively. The rearing of both species was profitable and the financial risk was relatively low. From the point of view of profitability, the purchase price of stocking material was the most significant factor. The price of juvenile asp was 2.5 times higher than that of ide. Rearing larval asp was the most profitable venture. Ekonomiczne Aspekty Podchowu Larw Bolenia, Aspius Aspius (L.), I Jazia, Leuciscus Idus (L.) W Systemie O Zamkniętym Przepływie Wody Oceniono opłacalności podchowu larw dwóch gatunków należących do grupy karpiowatych ryb reofilnych, tj. bolenia Aspius aspius (L.) i jazia Leuciscus idus (L.) w dwóch niezależnych systemach 18 akwariów o zamkniętym systemie obiegu wody i łącznej pojemności 36 dm3. Ryby karmiono wyłącznie świeżo wyklutymi naupliusami solowca. Wykazano, że podchowy obu gatunków były opłacalne i cechowały się względnie niskim ryzykiem finansowym. Z punktu widzenia opłacalności najistotniejszym czynnikiem okazała się cena zbytu materiału zarybieniowego. W przypadku bolenia była ona o 2,5-krotnie wyższa od ceny jazia. Podchów larw bolenia cechował się najwyższą opłacalnością i najlepszymi wskaźnikami określającymi warunki tej opłacalności. Dochód z tytułu produkcji tego gatunku był przeszło cztery razy wyższy niż w przypadku jazia.

THE EFFECT OF STOCKING DENSITY ON THE GROWTH AND SURVIVAL OF LARVAL ASP, ASPIUS ASPIUS (L.), AND EUROPEAN CHUB, LEUCISCUS CEPHALUS (L.), DURING REARING UNDER CONTROLLED CONDITIONS

The Effect of Stocking Density on the Growth and Survival of Larval ASP, Aspius Aspius (L.), and European Chub, Leuciscus Cephalus (L.), During Rearing Under Controlled Conditions The aim of the study was to determine the effect of increased stocking density on the growth and survival of larval asp, Aspius aspius (L.), and European chub, Leuciscus cephalus (L.), during mass rearing under controlled conditions. Fish larvae were obtained during artificial spawning at a hatchery. The larvae were reared for 21 days in a semi-closed recirculating system at a water temperature of 25°C. They were stocked at four densities (50, 100, 150, and 200 indiv. dm-3) and were fed freshly hatched Artemia sp. nauplii. The fastest growth rate for both species was obtained at the smallest stocking density (ITL = 0.67 and 0.58 mm d-1 for asp and chub, respectively). The highest mortality of larval asp was recorded at the density of 200 indiv. dm-3 (11.68%), and for chub at the density of 50 indiv. dm-3 (40.4%). The results obtained indicated that the stocking densities applied do not have an impact on larval growth or survival in the first week of rearing. Wpływ Zagęszczenia Obsady NA Wzrost I Przeżywalność Larw Bolenia Aspius Aspius (L.) I Klenia Leuciscus Cephalus (L.) W Trakcie Podchowu W Warunkach Kontrolowanych Celem pracy było określenie wpływu zagęszczenia na wzrost oraz przeżywalność larw bolenia Aspius aspius (L.) i klenia Leuciscus cephalus (L.) w masowym podchowie w warunkach kontrolowanych. Materiał do badań (larwy) pozyskano w trakcie kontrolowanego rozrodu w warunkach wylęgarniczych. Podchów prowadzono przez 21 dni w półzamkniętym obiegu wody o temperaturze 25°C. Larwy karmiono świeżo wyklutymi stadiami nauplialnymi solowca (Artemia sp.). Larwy przetrzymywano w czterech zagęszczenia (50, 100, 150 i 200 osobn. dm-3). Podchów prowadzono w zbiornikach o pojemności 50 dm3 każdy. Najszybsze tempo wzrostu larw obu gatunków uzyskano w najmniejszym zagęszczeniu obsad (ITL = 0,67 i 0,58 mm d-1 odpowiednio dla bolenia i klenia). Największa śmiertelność larw bolenia stwierdzono w grupie o zagęszczeniu 200 osobn. dm-3 (11,68%), a klenia w zagęszczeniu 50 osobn. dm-3 (40,4%). Uzyskane wyniki, z uwagi na brak różnic w tempie wzrostu larw obu gatunków w pierwszym tygodniu podchowu, wskazują na możliwość obniżenia kosztów produkcji poprzez stosowanie większych zagęszczeń w tym okresie.

A new classification of a preovulatory oocyte maturation stage suitable for the synchronization of ovulation in controlled reproduction of Eurasian perch, Perca fluviatilis L

To improve controlled reproduction of Eurasian perch Perca fluviatilis, the criteria for the evaluation of final oocyte maturation stages were revised. The new classification covers six preovulatory maturational stages (I -VI) from the end of vitellogenesis to germinal vesicle breakdown (GVBD) and was based on macroscopic changes of preovulatory oocytes (position of the germinal vesicle, GVBD, oil droplets coalescence). The observation was performed during out-of-season artificial reproduction with the use of a single hCG injection (500 IU/kg). The classification was subsequently verified with the controlled reproduction of wild female perch with the use of hormonal stimulation (500 IU hCG/kg of body weight at 12°C). The females were at different maturational stages and constituted respective experimental groups (I-VI). During the experiment, ovulation appeared to be considerably synchronized within particular groups. Statistical differences in latency time (time between hormonal treatment and ovulation) were found between experimental groups (mean latency time: 110, 92, 68, 49, 29 and 18 h in groups representing VI, V, IV, III, II and I stage of the proposed classification, respectively). The proposed classification and the results presented in the study allowed for effective synchronisation of ovulation. The use of our new oocyte maturation classification may positively influence the effectiveness of Eurasian perch production.

ARTIFICIAL REPRODUCTION OF WILD AND CULTURED BARBEL (BARBUS BARBUS, CYPRINIDAE) UNDER CONTROLLED CONDITIONS

The aim of this work was to compare the effects of controlled reproduction of cultured and wild common barbel, Barbus barbus (L.). Preparations containing different GnRH analogues and dopamine receptor antagonists (Ovopel, Ovaprim) as well as human chorionic gonadotropin (hCG) (in the case of cultured fish) were applied and their influence on ovulation, spermiation and quality of gametes obtained was determined. No differences in the qualitative or quantitative parameters of semen were found between fish stimulated with different hormonal preparations and those not receiving hormonal stimulation. The high suitability of Ovaprim for ovulation induction in (cultured and wild) barbel was confirmed. The highest synchronisation of ovulation was obtained after the application of Ovopel (18 ± 3 h), but the best results of controlled reproduction (expressed as the percentage of ovulations and survival of embryos) were obtained by applying Ovaprim (83.2 ± 4.1). A significantly higher percentage of ovulation was obtained in cultured fish (80-90%) than in wild fish (< 25%).

ECONOMIC ASPECTS OF THE EXPERIMENTAL REARING OF ASP, ASPIUS ASPIUS (L.), IDE, LEUCISCUS IDUS (L.), AND DACE, LEUCISCUS LEUCISCUS (L.), UNDER CONTROLLED CONDITIONS

Economic Aspects of the Experimental Rearing of ASP, Aspius Aspius (L.), Ide, Leuciscus Idus (L.), and Dace, Leuciscus Leuciscus (L.), Under Controlled Conditions The profitability of rearing larval asp, Aspius aspius (L.), ide, Leuciscus idus (L.), and dace, Leuciscus leuciscus (L.), was assessed in a system of 12 aquaria with a combined volume of 600 dm3. Two feeding variants were used: a) natural feed exclusively; b) natural feed plus formulated feed after seven days of rearing. All rearing variants were profitable and posed relatively low financial risks. The variant in which only natural feed was used was the most profitable. The savings incurred by the addition of formulated feed did not offset the profit lost from lower larval stock survival rates. In light of profitability, the most important aspect of larval rearing was the price of the stocking material, which was 250% higher for asp than for ide or dace. In both feeding variants, asp rearing was the most profitable and the values of the indices used to describe profitability were the best. Ekonomiczne Aspekty Wychowu Eksperymentalnego Larw Bolenia, Aspius Aspius (L.), Jazia, Leuciscus Idus (L.), I Jelca, Leuciscus Leuciscus (L.) W Warunkach Kontrolowanych Oceniono opłacalności podchowu larw bolenia Aspius aspius (L.), jazia Leuciscus idus (L.) i jelca Leuciscus leuciscus (L.) w systemie 12 akwariów, o łącznej pojemności 600 dm3. Stosowano dwa warianty żywieniowe: a) wyłącznie z pokarmem naturalnym oraz b) z pokarmem naturalnym i z paszą zadawaną w późniejszym okresie podchowu. Wszystkie warianty podchowu były opłacalne i cechowały się względnie niskim ryzykiem finansowym. Największe dochody osiągnięto w wariantach, w których stosowano wyłącznie pokarm naturalny. Oszczędności w kosztach żywienia związane z dodatkiem pasz były mniejsze od spadku przychodów związanych z niższą przeżywalnością obsad w tych wariantach podchowu. Z punktu widzenia opłacalności podchowu najistotniejszym czynnikiem okazała się cena zbytu materiału zarybieniowego, która w przypadku bolenia była o 250% wyższa od cen jazia oraz jelca. W obu wariantach żywieniowych podchów larw bolenia cechował się najwyższą opłacalnością i najlepszymi wskaźnikami określającymi warunki tej opłacalności. W wariancie z karmieniem pokarmem naturalnym oraz z dodatkiem pasz dochód z tytułu podchowu larw bolenia kształtował się odpowiednio na poziomie 1435 zł oraz 1308 zł i był o ponad 65% wyższy od analogicznego podchowu larw dwóch pozostałych gatunków ryb.

Comparison of two different methods in the cryopreservation of Eurasian perch (Perca fluviatilis) sperm.

Two different cryopreservation methods were compared and an optimal dilution ratio for the use of controlled-rate freezer (CRF) was established for Eurasian perch (Perca fluviatilis) sperm. Progressive motility (72 ± 15%) and curvilinear velocity (VCL, 146 ± 11 μm/s) of sperm cryopreserved with CRF did not reduce significantly compared to fresh sperm [progressive motility (90 ± 4%), VCL (173 ± 24 μm/s)]. On the other hand, progressive motility (62 ± 15%) and VCL (120 ± 21 μm/s) of sperm cryopreserved with the conventional floating frame technique were significantly lower when compared to the fresh control. Sperm in both cryopreserved groups showed significantly higher straightness [STR, CRF (84 ± 4%), frame (84 ± 2%)] than in the fresh control group (68 ± 4%). Perch sperm cryopreserved with CRF at a dilution ratio of 1:20 showed significantly higher progressive motility (49 ± 6%) than at a ratio of 1:5 (39 ± 6%) and showed significantly higher VCL (129 ± 11 μm/s) than at dilution ratios of 1:10 (112 ± 17 μm/s) and 1:5 (115 ± 9 μm/s).

Reproduction of Nase, Chondrostoma Nasus (L.), Under Controlled Conditions

Reproduction of Nase, Chondrostoma Nasus (L.), Under Controlled Conditions The aim of this work was to compare the effectiveness of the application of two hormonal preparations (Ovopel and Ovaprim) in the controlled reproduction of nase, Chondrostoma nasus (L.). The experiment was conducted under natural thermal and light conditions. Positive effects of hormonal stimulation were obtained in both experimental groups. No oocytes were obtained from any of the females in the control group. The most highly synchronized ovulation was noted in females that had received Ovaprim. The results of this study confirm reports that female nase must be stimulated hormonally during artificial reproduction in captivity. The results also indicate that Ovaprim is a more effective preparation than is Ovopel. Rozród Świnki, Chondrostoma Nasus (L.) W Warunkach Kontrolowanych Celem pracy było porównanie efektywności działania dwóch środków hormonalnych: Ovopelu i Ovaprimu, w kontrolowanym rozrodzie świnki, Chondrostoma nasus (L.). Tarlaki złowiono poza naturalnym sezonem rozrodczym i do momentu zabiegu sztucznego rozrodu przetrzymywano w stawie. Eksperyment przeprowadzono w naturalnych warunkach termicznych i świetlnych. Przeprowadzono tylko jedną iniekcję hormonalną. W obu doświadczalnych grupach uzyskano pozytywny efekt stymulacji. W grupie kontrolnej nie pozyskano oocytów od żadnej samicy, a po zastosowaniu Ovaprimu uzyskano największą synchronizację owulacji samic. Uzyskane wyniki potwierdzają dotychczasowe doniesienia o konieczności stymulacji samic świnki w niewoli, w trakcie kontrolowanego rozrodu, przy użyciu analogu GnRH wraz z antagonistą dopaminy. Najbardziej do tego celu przydatny okazał się Ovaprim.

Cortical reaction as an egg quality indicator in artificial reproduction of pikeperch, Sander lucioperca

The aim of this study was to investigate the process of the cortical reaction in eggs of pikeperch, Sander lucioperca (L.), as well as the application of microscopic assessment of this process in egg quality evaluation. The analysis was carried out with eggs obtained from 10 females by artificial reproduction, in which hormonal stimulation with hCG was applied. Subsequently, each sample of eggs (separately from each female fish) was analysed. The analysis included observation of the cortical reaction and the process of egg swelling, and determination of the effect of temperature (12, 14 and 16°C) and the presence of spermatozoa on the cortical reaction. The results indicate that the cortical reaction in pikeperch eggs is quite violent, resulting in visible deformation of eggs between 3 and 5 min after activation. No effect of temperature or the presence of spermatozoa on the cortical reaction was observed. A strong correlation was recorded for the percentage of egg deformations observed and embryo survival rate. The described method of determination of pikeperch egg quality (based on egg deformation rate between 3 and 5 min after activation) may be highly useful, both in scientific research (where high-quality eggs are required) and in hatchery practice.