Kombinovanje intenzivne (ras) i ekstezivne (ribnjak) akvakulture za proizvodnju mlađi smuđa (sander lucioperca)

Ovaj prilog daje kratak osvrt na naše rezultate u oblasti gajenja mlađi smuđa. Opisuju se sve faze gajenja, do dostizanja krajnje telesne težine ribe od 75g: 1) gajenje larvi i mlađi u ribnjaku, 2) izlov mlađi iz ribnjaka, 3) privikavanje mlađi na recirkulacioni sistem (RAS), 4) gajenje mlađi u RAS-u u trajanju od 90 dana, 5) nasađivanje mlađi iz RAS-a u ribnjake, 6) gajenje mlađi u jezerima u toku zime i proleća, 7) izlov mlađi iz ribnjaka i privikavanje na uslove RAS-a i 8) gajenje u RAS-u. Svaka faza gajenja je ocenjena istim parametrima proizvodnje: krajnjim TL (mm) i težina W (g), specifičnom stopom rasta (SGRW in %.d-1), stopom preživljavanja (S u %), stopom kanibalizma (C u %) i koeficijentom konverzije hrane (FCR) ukoliko se primenjuje vestačka hrana. Iniciajalno gajenje u ribnjaku je dalo veoma dobre i obećavajuće rezultate kada je reč o specifičnoj stopi rasta (SGRW= 20.3 %.d-1) i prezivljavanja (27.4%). Veoma velika efikasnost kao što je visoka stopa preživljavanja (78.5%) se pokazala kod mlađi koja je posle ribnjaka privikavana na RAS. Kombinacija gajenja u ribnjaku i RAS sistemu obezbeđuje mlađ za stabilno i efikasno gajenje u RAS sistemu. Njega karakteriše visoka stopa preživljavanja (S = 88.7 – 97.5 %) i visoka stopa rasta (SGR = 1.8 - 4.2 %.d-1). Iako je naredna grupa mlađi gajena u uslovima ribnjaka u toku zimske sezone imala nižu stopu preživljavanja (65%), ovaj sistem može da omogući regulisanje proizvodnje mlađi u vremenu. Rezultati ove studije su pokazali da kombinacija gajenja mlađi smuđa u ribnjacima i RAS sistemima može da proizvede visoko kvalitetnu mlađ sa mogućnošcu da se proizvodnja vremenski reguliše

Defatted black soldier fly (Hermetia illucens) in pikeperch (Sander lucioperca) diets: Effects on growth performance, nutrient digestibility, fillet quality, economic and environmental sustainability

The use of insect meal in aquafeed formulations has recently gained attention. Detailed knowledge about the inclusion levels for pikeperch (Sander lucioperca), a promising candidate for intensive aquaculture in Europe remains, however, fragmented. In the present study, 4 isoproteic (45% dry matter) and isoenergetic (21 MJ/kg) diets were formulated, including a control diet (H0) containing 30% fishmeal (FM) on an as-fed basis and the other 3 diets in which FM protein was replaced by defatted black soldier fly (Hemetia illucens) meal (HIM) at 25%, 50%, and 100% (diet abbreviation H9, H18 and H36, corresponding to an inclusion level of 9%, 18% and 36%, respectively). The feeding trial was performed in triplicate groups of 50 juvenile pikeperch (mean weight, 68.7 g) fed with experimental diets for 84 d during which the growth performance, nutrient digestibility, fillet quality and economic and environmental sustainability of rearing pikeperch were evaluated. Our findings indicated that pikeperch in H0, H9, and H18 groups displayed better results regarding growth performance indices, except for survival rate where no significant difference among groups was recorded (P = 0.642). A significantly lower organ-somatic index, including hepatosomatic, viscerosomatic and perivisceral fat index, was found in fish in H18 groups than other groups (P  0.05) but did reduce total n-3 fatty acids (P = 0.001) and increased total n-6 (P  0.05). The addition of HIM at a level as low as 9% elicited a similar carbon footprint to that of the control diet. The economic conversion ratio and economic profit index were negatively affected at increased insect meal inclusion levels. This study has shown that the incorporation of HIM in feed formulations for pikeperch is feasible at inclusion levels of 18% without adverse effects on growth performance parameters. The feasibility also highlighted the environmental benefits associated with land use and marine resources required to produce farmed fish

Pikeperch (Sander lucioperca) larval rearing optimization: utilization of lactic acid bacteria for improving microbiome diversity and digestive enzyme activity

Lactic acid bacteria (LAB) probiotics were evaluated for their impact on the microbiota and development of pikeperch (Sander lucioperca) larvae during their initial feeding stage (first 21 days). Pikeperch larvae were exposed to LAB probiotics in two ways: (1) via the live-feed only (Treatment 1, live-feed) or (2) via the live-feed and the larval culture water (Treatment 2, probiotic) in comparison to a control group without LAB supplementation. Total length (TL), myomere height (MH), and survival rate were significantly increased in the probiotic compared the Control group. The administration of probiotics significantly positively influenced the microbiome’s diversity. Specifically, the relative abundance of Cytophagales decreased and that of several other taxa increased in both probiotic treatments although differences between treatments became statistically insignificant by day 21. Furthermore, the different treatments had distinct and significant impacts on digestive enzyme development such as protease and lipase, with the most prominent differences occurring at seven days post-hatching (dph). Taken together, these results indicate that the use of LAB in both the live-feed and rearing water has a positive impact on the larvae microbiota and digestive enzyme development in turn positively impacting their development and viability under intensive rearing conditions

Gajenje slatkovodnih riba u centralnoj i istočnoj Evropi: potrebe za istraživanjem i razvojem

Gajenje slatkovodinih riba ima veoma važnu ulogu za stabilizaciju biodiversiteta, resursa podzemnih voda, klime regiona kao i za snabdevenost hranom u Centralnoj i Istočnoj Evropi. Velika konkurencija cena ribe na međunarodnom tržištu i promene u navikama ishrane ljudi pojačavaju pritisak na mala i srednja preduzeća u Centralnoj i Istočnoj Evropi koja se bave gajenjem ribe i mogu da ugroze predeo oko uzgojnih jezera. Da bi povećali vrednost svih karika u lancu proizvodnje slatkovodnih riba, naučnici i proizvođači su identifikovali uobičajene i potencijalne izazove. Da bi se procenile potrebe sektora akvakulture u centralnoj i istočnoj Evropi, sprovedeni su polu strukturirani intervjui sa proizvođačima i prerađivačima ribe i udruženjima u Poljskoj i Češkoj, u okviru projekta SIAD i FP7 EU projekta TRAFOON. Takođe su održane radionice sa istraživačima u sektoru akvakulture duž svake karike lanca proizvodnje riba u Centralnoj i Istočnoj Evropi. Različite interesne strane su identifikovale nekoliko izazova koji ometaju razvoj slatkovodne akvakulture u Centralnoj i Istočnoj Evropi. Razvoj akvakulture zahteva postojanje harmonizovanog regulativnog/pravnog okvira. Razmena znanja bi imala pozitivan uticaj na razvoj uniformnih standarda za održivost, i pomogla bi stvaranju pravnih procedura za izdavanje dozvola i licenci. Potrebno je izvršiti ekonomsku procenu usluga koje ekosistem ribnjaka pruža. Poboljšana tehnoligija koja je povoljna po životnu sredinu i sistemi za upravljanje kvalitetom u proizvodnji i preradi su neophodni da bi se obezbedila ustaljenija ponuda proizvoda od ribe viskog kvaliteta. Potrošači treba da budu bolje informisani o funkciji koju slatkovodna akvakultura i njeni proizvodi imaju za životnu sredinu. Da bi došlo do održivog razvoja sektora akvakulture i da bi se izgradilo poverenje javnosti, veoma je važno podstaći društvene inovacije koje su primenljive na pojedinačni sektor ili pojedinačnu teritoriju. Da bi došlo do održivog razvoja sektora slatkovodne akvakulture potrebno je razviti strategije makro regionalnog razvoja koje su prilagođene određenim tržištima, uslovima životne sredine, ponašanju potrošača, kulturi i tradiciji i koje nude potencijal za razvoj izvan granica jedne zemlje. Razvoj i adaptacija ključnih tehnologija potrebni su da bi se stabilizovala konkurentna i održiva proizvodnja i prerada ribe u čijoj su proizvodnji resursi efikasno iskorišćeni

Ultrastructural feature of spermatogenic cells and spermatozoon in cultured burbot Lota lota

Testis development and ultrastructure of spermatogenic cells and spermatozoa of burbot Lota Iota, a commercially important cold freshwater fish, were studied by light and transmission electron microscopy. Spermatogonia, spermatocytes, spermatids, and spermatozoa are distributed along the seminiferous tubules. Electron-dense bodies appear in germ cells from primary spermatogonia to secondary spermatocytes. We identified three distinct stages of spermatid cell differentiation based on chromatin condensation, development of the flagellum, formation of a nuclear fossa, and elimination of excess cytoplasm. Spermatozoa were anacrosomal and characterized by location of the centrioles outside the nuclear fossa and incomplete perpendicular arrangement of the centrioles. The sperm flagellum displayed an axoneme with nine doublets of peripheral microtubules and two central microtubules. These results provide valuable information for burbot taxonomy and may clarify the process of spermatogenesis for this species.</p

A contribution on the morphometrics of the thick-clawed crayfish Pontastacus pachypus (Rathke, 1837) (Decapoda, Astacoidea, Astacidae)

The thick–clawed crayfish Pontastacus pachypus (Rathke, 1837) is an endangered, and the least known, crayfish species in Europe. Currently, detailed information regarding the morphology, ecology and reproduction of thick–clawed crayfish is outdated. This study presents, for the first time, detailed photographs of the thick-clawed crayfish, and updated information on distinctive morphological characters and morphometric analysis. New specifications of the carapace and appendage morphological characteristics were established as: 1) the rostrum is long, sharply pointed and has three pairs of distinctive sub-apical lateral spines, 2) two well–developed pairs of post–orbital ridge on the carapace are ended by prominent spine; 3) each finger of chelae ends with a black sharp tip. Among the 18 morphometric indices, carapace width to the total length (CPW/TL), abdomen width to the total length (ABW/TL) and claw height to the claw width (CLH/CLW) clearly differentiate P. pachypus from the other representatives of Astacus genus (A. colchicus and A. astacus) and P. leptodactylus (P<0.05). Comparison of individual indices between P. pachypus and P. leptodactylus revealed that almost all indices differed significantly except head length to the total length (HEL/TL) and rostrum length to the total length (ROL/TL). This study contributes to the identification of the thick–clawed crayfish for the purpose of conservation and protection of its localities

Use of Lactic Acid Bacteria During Pikeperch (Sander lucioperca) Larval Rearing

This trial tested the use of lactic acid bacteria (LAB) on pikeperch (Sander lucioperca) larvae during their first feeding. The trial included the use of two probiotic treatments and one control (no probiotics). Pikeperch larvae were exposed to LAB as follows: (1) the live feed (Treatment 1, live feed) or (2) via the live feed and the larval rearing water (Treatment 2, probiotic). Significant differences were found between the treatments in terms of total length (TL), myomere height (MH), overall survival, and the tolerance to a high salinity challenge. Larvae exposed to LAB via both the live feed and the rearing water had a significantly higher overall survival rate (85%) than the other two treatments at 21 dph. When both treatments were subjected to high salinity rates (18 parts per thousand (ppt)), both treatments exposed to LAB demonstrated higher survival rates than the control treatment (28% and 40% survival rate at 180 min for the live feed and probiotic treatments, respectively, as compared with a 100% mortality rate at 150 min for the control). At the same time, larvae exposed to the probiotic treatment had a significantly higher TL as compared to the control after 12 and 21 days post hatch (dph) (probiotic 7.13 &plusmn; 0.21 and 11.71 &plusmn; 1.1 mm, control 5.86 and 10.79 mm at 12 and 21 dph, respectively). The results suggest that the use of LAB in both the live feed and the rearing water has a positive effect on pikeperch larval quality by strengthening their resilience to stress conditions, as well as improving the growth and survival rates

Effects of temperature on sperm motility of burbot Lota lota: spontaneous activation and calcium dependency

Several factors regulating activation of spermatozoon motility in Eurasian burbot, Lota lota, including osmolality, calcium (Ca2+) ions, and temperature were investigated. Spermatozoon motility in Eurasian burbot, Lota lota was assessed at 4 and 30 degrees C in seminal fluid, isotonic media (with and without Ca2+) and hypotonic media (with and without Ca2+). Spermatozoa were spontaneously activated in seminal fluid at 20 degrees C and the maximum motility was recorded at 30 degrees C, which is out of the spawning temperature range, indicating that no risk of activation occurs during routine semen handling in artificial insemination. Initiation of spermatozoon motility in L. lota is mediated by Ca2+ and sensitivity to Ca2+ is dependent on temperature.</p

Changes of sperm morphology, volume, density and motility and seminal plasma composition in

Eighteen spermiating males were randomly selected from a hatchery-reared stock and electronically tagged to record changes in their sperm quality parameters (spermatozoa morphology, ultrastructure and motility, ionic composition and osmolality of the seminal plasma, and sperm volume and density) during the spawning season. Stripping was performed at the beginning of March, April and May. The Barbus barbus spermatozoon has a head without acrosome, a midpiece with 4–6 mitochondria and proximal and distal centrioles, and a flagellum with the typical 9+2 pairs of microtubules. Apart from posterior width of the midpiece, morphological and ultrastructural parameters changed significantly during the reproductive season; generally by decreasing toward the end of reproductive season. Sperm volume also decreased from 0.42 in March to 0.15 ml in May, and density from 18.81 in March to 12.45 × 109 spz ml−1 in May. Osmolality (mOsmol kg−1) was 268 ± 4, 276 ± 2 and 268 ± 2 in March, April and May respectively. Chloride, sodium, calcium and potassium ion concentrations (mM) did not show significant differences between March and April (Cl−: 125.3 vs. 120.5, Na+: 75.7 vs. 69.7, Ca2+: 0.4 vs. 0.3 and K+: 84.7 vs. 84.0). The percentage of motile spermatozoa at 15 s post activation did not show a significant difference between dates, but the highest spermatozoa velocity at 15 s post activation was observed in April (91.4 ± 3.2 µm s−1) and then decreased significantly towards the end of the reproductive season (80.6 µm s−1 in May). However, lowest spermatozoa velocity was measured in March (70.4 ± 1.9 µm s−1). This study supports the hypothesis that longer spermatozoa swim faster. Within one stripping, velocity and percentage motility decreased significantly with time post activation. In conclusion, changes observed in B. barbus sperm parameters during the reproductive season, suggest there is association between such changes and spermatozoa aging processes

The possible involvement of oxidative stress in the oocyte ageing process in goldfish Carassius auratus (Linnaeus, 1758)

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