Sławomir Krejszeff

Reproductive parameters of common carp (Cyprinus carpio L) spawners during natural season and out-of-season spawning

Common carp spawning characteristics were compared between season and out-of-season periods. There were no differences in the percentage of ovulation, spermatozoa motility and embryo survival to the eyed-egg-stage between the spawning periods. Fish spawned during the season produced oocytes of higher total weight than those spawned out-of-season. On the day exogenous feeding began, larvae obtained in out-of-season spawning were shorter than those obtained during the spawning season. However, the out-of-season larvae started feeding two days earlier than in-season larvae. As a result, seven days after fertilization, larvae obtained during out-of-season had the same length as larvae obtained during season. It appears to be possible to obtain common carp larvae half a year before the natural spawning period without decreasing the quality of gametes and larvae.

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.

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%).

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.

Early development and allometric growth in Nannacara anomala Regan, 1905 (Perciformes: Cichlidae) under laboratory conditions

were studied from hatching tothe loss of larval characters and beginning of squamation (18 days post-hatching) at 26°C. The mean total length (TL) of larvaeand juveniles increased from 3.74 mm at hatching to 9.60 mm at metamorphosis. Morphogenesis and differentiation were mostintense during the first week of development. During this period (TL interval = 3.74 - 4.84 mm) there was an evident priority t oenhance the feeding and swimming capabilities by promoting accelerated growth in the head and tail regions. Following thisperiod, there was a major decrease in growth coefficients, indicating a change in growth priorities. Observations on the earlydevelopment of

Method of evaluation of wild common tench, Tinca tinca (L.), female suitability for artificial reproduction during the spawning season

The aim of this study was to evaluate the suitability of females for artificial reproduction of common tench based on an analysis of the size and percentage share of oocytes sampled in vivo. The females were collected from natural waters (lakes) during the spawning season, After catching, the selected fish were transported to the hatchery, where the fish were kept under controlled conditions and oocytes were collected from all females. It was found that sampled oocytes were different in size and developmental stages. Oocytes were classified into 3 groups: small, medium and large. The diameter intervals for each group were 0.18–0.22 mm, 0.48–0.57 mm and 0.95–1.01 mm, respectively. Analysis of the percentage of the largest oocytes showed that their numbers decreased in time from over 40% on Day 1 to slightly over 10% on Day 10. A positive correlation was found between the percentage of the largest oocytes in the cathetered egg sample and the weight of the stripped eggs during artificial reproduction. The percentage of the largest oocytes (diameter 0.95–1.01 mm) might be used as an indicator of the possibility of reproducing wild tench. No statistical differences were observed in latency time and embryo survival of females showing different quantities of the largest oocytes.

Influence of age of wild ide Leuciscus idus (L.) female on spawning effectiveness under controlled conditions

The aim of this study was to determine the effect of age of female ide on spawning success under controlled conditions. All ide breeders were collected from one wild population. Data concerning reproductive parameters were collected during induced spawning under hatchery conditions. The age of mature females ranged from 4 (average weight 504 g) to 9 years (average weight 2540 g) and the youngest collected females (3+) (average weight 330 g) were immature. The females from group 4+ produced smaller oocytes (1.28 mm diameter after hydration) than older fish (1.44–1.57). There were no differences in oocyte sizes in females 6+ and older. The highest relative fecundity (mean 44,621 eggs kg−1) was noted for fish aged from 5 to 7. Eggs obtained from the oldest females had the lowest biological quality: the highest percentage of dead embryos during incubation (49.9) and the highest percentage of morphological abnormalities in hatched larvae (5.6%). In addition, in the group of the oldest females, only 67% of fish produced eggs.