Kvalitet jaja morskih riba u akvakulturi, pregled tehnika i rezultata

Background: Despite most of marine teleosts can produce large quantities of viable eggs in captivity, the quantity and quality of the larvae are low and variable, being the initial quality of the eggs one of the main causes of the variability. Considering that commercial hatcheries rely on good larval quality, the establishment of a series of criteria for egg quality is of paramount importance. Objectives: This review presents an overview on some of recent researches carried out in IRTA and University of Salzburg (2004‒2010) to address this bottleneck through correlating egg biochemical contents (BC) to embryo/larva success in a marine teleost considered as new species for Mediterranean aquaculture. Target species: Besides production cost reduction and market enlargement, species diversification is one of the main strategies to ensure future expansion of aquaculture industry. A series of biological and commercial characteristics make the common dentex, Dentex dentex, a highly suitable species to enter mariculture systems as a new species to supplement the intensive sparids production and to increase diversification. Applied methodologies: (i) Viable eggs were obtained from natural spawning of broodfish in captivity. (ii) Egg biometrical parameters (i.e., wet mass, dry mass, and water content) were recorded. (iii) Embryo/larva viability parameters (VPs, i.e., floating rate, hatching rate, and survival rate) were determined. (iv) Egg biochemical parameters (i.e., carbohydrate metabolites/enzymes, vitellogenin-derived proteins [VDP], non-Vtg-derived protein [non-VDP], free amino acid [FAA], proteinic amino acids [PAA], lipid classes [LC], fatty acids [FA], and morphological characteristics of lipid vesicle [LV]) were characterized and quantified. (v) A variety of statistical analyses were used to define the relationships existing between the egg BCs (as egg quality indicators) and the VPs (as criteria for embryo/larva success) that are currently used in mariculture systems. Results: Although a combination of statistical methods were used to correlate the egg BCs to embryo/larva success in common dentex, the current review was prepared based on the results of regression models. Carbohydrate (CH) metabolite contents and enzyme activity of the egg together with VDP, non-VDP, FAA, PAA, LC , and FA contents for one side and lipid vesicle (LV) morphological characteristics on the other were significantly and strongly correlated to embryo/larva success through almost 350 simple regression model (11 [r2=0.184‒0.490] for CHs and enzymes, 16 [r2=0.095‒0.634] for VDPs, 55 [r2=0.079–0.637] for non-VDPs, 49 [r2=0.605–0.875] for FAAs, 19 [r2=0.919−0.991] for PAAs, 5 [r2=0.459–0.739] for LCs, 201 [r2=0.640–0.948] for FAs, and 10 [r2=0.293–0.480] for LV). Conclusions: (i) Under a biological/physiological perspective the significant relationships found between egg BCs and embryo/larva success in common dentex highlight the importance of egg composition during the initial events of embryonic/larval development. The results obtained present a series of new relationships (either in agreement or against previous findings) that deserve further investigation to define their physiological ground. (ii) Under a more applied perspective these relationships indicate a potential use of egg BCs, as bio-markers, to predict egg quality in aquaculture. These markers can also be used as molecular probes to assess the improvements in broodstock management