A commercial diet for rainbow trout (Oncorhynchus mykiss) was supplemented with 0 (control), 8.5%, or 15.0% (w/w) of flaxseed oil (FO). Trouts were harvested on days 0, 30, 60, 90, and 120. Boneless skinless trout fillets were recovered from fish and analyzed for fatty acid profile (FAP) and total fat. While the total fat levels of fillets were not (P > 0.05) affected by FO supplementation, the FAP was. The lowest (P < 0.05) proportion of saturated fatty acids was obtained from 15%, followed by 8.5% FO group, and the control group. The opposite results were observed for the unsaturated fatty acids. The highest (P < 0.05) content of omega-3 fatty acids (ω-3 FA) in fillets was determined in the 15.0%, followed by the 8.5% FO group, and the control group. While the 15.0% and 8.5% of FO supplementation increased (P < 0.05) concentration of linolenic acid (ALA, 18:3n3) in fillets, the eicosapentaenoic (EPA, 20:5n3) and docosahexaenoic acids (DHA, 22:6n3) contents decreased (P < 0.05). At the same time, higher (P < 0.05) concentration of linoleic (L, 18:2n6) and lower (P < 0.05) concentration of arachidonic acids (AN, 20:4n6) in fillets were obtained in the 15.0% FO group compared with the control group. The ω-3/ω-6 FA ratio was also improved (P < 0.05) by supplementing basal diet with 15.0% FO. Our results suggest that trout fillets with enhanced content of ω-3 FA can be developed from trout raised in aquaculture systems fed diets supplemented with 15.0% FO. These fillets could be a basis to develop novel functional aquatic foods for some niche markets.

No abstract

Two species from the families Acipenseridae and Polyodontidae, Russian sturgeon (Acipenser gueldenstaedtii, Brandt and Ratzeberg, 1833; functional tetraploid) and American paddlefish (Polyodon spathula, Walbaum 1792, functional diploid) were hybridized. The hybridization was repeated using eggs from three sturgeon and sperm from four paddlefish individuals. Survival in all hybrid family groups ranged from 62% to 74% 30 days after hatching. This was the first successful hybridization between these two species and between members of the family Acipenseridae and Polyodontidae. Flow cytometry and chromosome analysis revealed two ploidy levels in hybrids. The chromosome numbers of the hybrids ranged between 156–184 and 300–310, in “functional” triploids and “functional” pentaploids, respectively. The hybrid origin and the ploidy levels were also confirmed by microsatellite analyses. In hybrids, the size and the number of dorsal and ventral scutes correlated with the ploidy levels as well as with the calculated ratio of the maternal and paternal chromosome sets. An extra haploid cell lineage was found in three hybrid individuals irrespective of the ploidy level, suggesting polyspermy. Although the growth performance showed high variance in hybrids (mean: 1.2 kg, SD: 0.55), many individuals reached a size of approximately 1 kg by the age of one year under intensive rearing conditions.

No abstract

This study examined the establishment and growth performance of 34 food crops grown in a cool, low nutrient aquaponic system. Process water from a spring-fed flow-through trout raceway, with an average fish biomass of 3630 kg, was used as the water and nutrient source for the plant growing operation. Process water temperature entering the plant growing channels was 13 °C with average concentrations of 0.35, 0.34 and 0.19 mg•L-1 for ammonium, nitrate, and phosphate, respectively. Crop types included lettuce, Asian greens, mustards, other greens, vegetables and herbs. Stand establishment (percent filled cells) and harvest and individual biomass were evaluated under three treatments; low flow (18.9 L/min), high flow (75.7 L/min) and an amended high flow treatment. The amended high flow treatment consisted of vermiculite planting media amended with composted fish waste and was placed in a channel receiving high flow. These treatments represented a gradient of nutrient availability with low flow receiving the fewest and the amended high flow treatment receiving the most nutrients. Due to space constraints cultivars were sown in two sets. Cultivars in set two were sown as space was made available when cultivars from set one were harvested. Stand establishment was greater than 80% for most cultivars under all treatments. However, the herbs sage, garlic chive, and lovage had poor stand establishment as did the vegetables Swiss chard and beets, which were sown late in the study. For most cultivars, stand establishment was not significantly different among treatments. The majority of cultivars attained the lowest biomass on the low flow treatment. Notable exceptions were cilantro, parsley, and minutina. Eight cultivars, including kohlrabi and the bibb lettuce 'Rex', grew best on the high flow treatment. The remaining 21 cultivars realized the greatest biomass on the amended treatment although in many cases the increase in biomass was minor. Additionally, for some cultivars, significant increases in stand establishment offset decreases in growth. Minimal improvements in water quality were observed, probably as a result of nutrient mobilization from accumulated solids within the aquaponic channels.