ALBERT

Description: Continuously intensifying aquaculture demands reductions in pathogen infections without increased therapeutics use. A potential solution is the use of prebiotic feed additives like β-glucan and mannan oligosaccharides (MOS). This study focusses (1) on the effect of prebiotics glucan/MOS on growth and fitness of Starry flounder and (2) on the viability of Starry flounder as an aquaculture candidate (as it is considered in South Korea). Over 56- days, juvenile Starry flounder were fed with glucan/MOS enhanced diet and a control diet. Feeding behavior, growth rate, morphological and blood physiological parameters were monitored. Fish fed glucan/MOS enriched diets exhibited significantly increased growth over the experimental period (GLM, p〈0.01). Concentrations of cholesterol (P=0.043) and albumin (P=0.016) were significantly increased in the blood plasma of fish fed glucan/MOS. Whole body proximate analysis revealed significantly elevated crude protein (P=〈0.001) and lipid (P=〈0.005) in fish fed glucan/MOS compared to the control. Significant improvements in growth, numerous fitness factors and product quality parameters can be achieved through glucan/MOS supplementation to P. stellatus. The observed growth performance and the feed conversion ratio, especially at low water temperatures, suggest Starry flounder is indeed a promising candidate for aquaculture in temperate regions. More detailed investigation, highlighting the economic and market perspective, is needed before introduction to commercial production.

Description: Thermal requirements of larval weatherfish Misgurnus fossilis were investigated in terms of growth, survival and aerobic performance. Growth and survival of M. fossilis larvae acclimated to five temperatures (11, 15, 19, 23 and 27° C) were measured over 25 days. In the upper temperature treatments (19, 23 and 27° C), survival of larvae was stable throughout the entire rearing period (〉75%), whereas 11 and 15° C resulted in severe declines in survival (to 〈10%). Growth of larvae (expressed as dry mass and total length) was highest at 19 and 23° C, but significantly decreased at 27° C. Routine metabolic rate of 3 days post-hatch larvae was estimated as oxygen consumption rate (ṀO2) during acute exposure (30 min to 1 h) to seven temperatures (11, 15, 19, 23, 27, 31 and 35° C). Larval oxygen uptake increased with each consecutive temperature step from 11 to 27° C, until a plateau was reached at temperatures 〉27° C. All larvae of the 35° C regime, however, died within the ṀO2 measurement period. M. fossilis larvae show greater than expected tolerance of high temperatures. On the other hand, low temperatures that are within the range of likely habitat conditions are critical because they might lead to high mortality rates when larvae are exposed over periods 〉10 days. These findings help to improve rearing conditions and to identify suitable waters for stocking and thus support the management of re-introduction activities for endangered M. fossilis.

Description: The continuing growth in dietary sourcing for aquaculture organisms means that 70% of all fish meal and 75-90% of fish oils is now consumed by the aquaculture sector, despite research to replace fished resources with plant alternatives (soy bean, canola, and wheat) in aquaculture diets (Jacquet et al.. 2010; FAO 2014). Lupines have considerable potential to replace fish meal in diets for carnivorous fish. Despite the presence of anti-nutritive phytases and non-starch-polysaccharides, lupines can offer good nutritional value, and are sustainable nitrogen-fixing plants suited to cultivation in temperate regions including Europe. While previously studied in formulated diets for salmonids, there is a dearth of knowledge about the effects of lupines at high inclusion levels on other carnivorous fish like European sea bass (Dicentrarchus labrax). This study determined the effects of high inclusion levels of fermented (reduced content of anti-nutritional substances) and untreated lupine kernel meal on growth of commercially important European sea bass. European sea bass (57.5 ± 0.4g) were fed ten isonitrogenous and isocaloric diets containing 65% fishmeal (control diet), 15% soybean meal + 50% fishmeal (commercial control diet), untreated lupine kernel meal and fermented lupine kernel meal at 15, 30, 50 and 65% inclusion (+ 50, 35, 15 and 0% fishmeal respectively) in triplicate tanks. Enzymatic fermentation was carried out in an attempt to reduce content of phytases and non-starch-polysaccharides. Fifty fish per tank were fed for 91 days ad libitum and growth was monitored as total body weight measured at experiment onset and termination. Final mean body weight ranged from 127.9 ± 1.6g to 140.3 ± 4.4g in the groups with 0 to up to 50% lupine kernel meal inclusion, but was significantly lower in the LM65 and FLM65 groups (90.1 ± 3.6, 89.2 ± 10.5g, p 〈 0.001). No significant differences were observed between fermented and unfermented lupine kernel meal. The same pattern was reflected in the weight gain, specific growth rate and daily feed intake with significantly lower growth and feed intake in both groups including 65% lupine kernel meal. Fish fed diets containing 50% and 65% untreated and fermented lupine meal showed a significantly lower hepato-somatic index (p 〈 0.001) compared to the group containing less than 30% lupine meal. The final growth parameters mean body weight, weight gain and specific growth rate clearly indicate that lupine can be successfully included at high levels of 50% to the feed without negative effects on growth (thereby replacing 75% of the fishmeal). A complete replacement of fishmeal by lupine led to a reduction of growth by half, which can be only partly explained by a lower feed intake. In Rainbow trout high inclusion level of 50% inclusion level of lupine kernel meal growth was significantly reduced. In the current study, the hepato-somatic index results may indicate negative effects on organ health of the fish at inclusion levels of 50% or higher. Whereas the inclusion level affects growth and health of European sea bass the fermentation of the lupine had no effect and can be eliminated, further reducing production and treatment costs for lupine. Dehulling of the lupine seeds seem to be sufficient to reduce anti-nutritive substances in lupine kernel meal. Given the much lower cost of lupine kernel meal in comparison to fishmeal (ca. 30% of fishmeal cost by weight), significant economic savings can be made. In conclusion, lupines and lupine kernel meal have great potential as a sustainable, locally produced replacement for fishmeal in diets for the carnivorous European sea bass with no negative effects on growth.

Description: The purpose of this study was to investigate whether meat from blue mussels (Mytilus edulis) harvested from offshore structures could be used as an alternative protein source in aquaculture fish feed for turbot (Scophthalmus maximus). Two feeding experiments with turbot were conducted in an initial experiment to test the applicability of mussel meal as a fishmeal replacement and/or supplement in turbot feed. In experiment A, the welfare, acceptance, and digestibility of feedstuff with 100%, 50% and 0% of mussel meal replacement for the fishmeal were tested for 8 weeks. In experiment B that followed, the convenience ratio of mussel meal protein in turbot feed for optimum growth was examined. Feedstuff with 25%, 10% and 0% of mussel meal were also fed for 8 (+6) weeks. Growth rates of fish were measured every 2 weeks and their health condition (liver somatic index) determined at the beginning and end of the experiments. Experiment A revealed that a replacement of fishmeal with either 100% or 50% mussel meal resulted in depressed growth (SGR: 1.31 ± 0.04 with 100% mussel meal; 1.54 ± 0.04 with 50% mussel meal; 1.71 ± 0.07 with 0% mussel meal). Experiment B revealed that a fishmeal replacement with 10% or 25% of mussel meal did not reduce growth nor did it have a negative effect on the health of the tested turbot. The study revealed that mussel meal has a high potential to serve as a supplement or as a fishmeal replacement in feed for turbot raised in aquaculture systems. Thus, its use in commercial aquaculture should be given future consideration.

Description: Many marine gastropods show species-specific behavioral responses to different predators, but less is known about the mechanisms influencing differences or similarities in specific responses. Herein, we examined whether two limpet species, Scurria viridula (Lamarck, 1819) and Fissurella latimarginata (Sowerby, 1835), show species- and size-specific similarities or differences in their reaction to predatory seastars and crabs. Both S. viridula and F. latimarginata reacted to their main seastar predators with escape responses. In contrast, both limpets did not flee from common crab predators, but, instead, fastened to the rock. All tested size classes of both limpet species reacted in a similar way, escaping from seastars, but clamping onto the rock in response to crabs. Limpets could reach velocities sufficient to outrun their specific seastar predators, but they were not fast enough to escape crabs. Experiments with limpets of different shell conditions (with and without shell damage) indicated that F. latimarginata with a damaged shell showed “accommodation movements” (slow movements away from stimulus) in response to predatory crabs. In contrast, intact F. latimarginata and all S. viridula (intact and damaged) clamped the shell down to the substratum. The response details suggest that the keyhole limpet F. latimarginata is more sensitive to predators (faster reaction time, longer escape distances, and higher proportion of reacting individuals) than S. viridula, possibly because the morphology of F. latimarginata (the relationship of its shell size and structure to its total body size) makes this species more vulnerable to predation. Our study suggests that chemically mediated effects of seastar and crab predators result in contrasting behavioral responses of both limpet species, independent of their habitat and morphology. Despite the different characteristics of the limpet species and the identity of predators, the limpets react in comparable ways to similar predator types.

Description: Formulated feeds used for the growing production of carnivorous fish and crustaceans generally have a high protein content still met mostly by fish meal supply. Maintaining the steady and enormous growth of aquaculture production requires practical alternative protein sources. Terrestrial protein sources have been the focus of feed research for more than twenty years. Many studies test legumes like field peas, lupin and faba bean. Several different cultivars of lupin have been tested with different fish species mainly in Australia. The results of these studies are promising for example for salmon and seabass but. Lupin diets with a relevant replacement level for high value crustaceans are tested in the present study. An experimental diet (Basis) with 30% fish meal as main protein source was formulated. Lupinus angustifolius kernel meal was added as 10, 20 and 30 % of the diet, incrementally replacing fishmeal. All diets were balanced to meet the requirements of L. vannamei in the grow out phase, concerning energy content, protein and amino acid profile, lipid and fatty acid composition, vitamins and minerals. These diets were compared with a commercial controlFeeding experiments were conducted over 8 weeks in a RAS device, with 18 separate 50 l tanks. Mean survival rate of the shrimps was 65% across all treatments. Mean biomass of animals fed with high lupine levels (L30) was significantly lower than in control diets (Basis and Commercial control) and L10 after 8 weeks. Metabolic analyses showed malnutrition of animals fed the L30 diet concerning glucose and triglyceride levels, although appropriate protein provision was attained with all experimental feeds. The total haemocyte count showed significantly higher counts in animals fed the L10 diet, which hints at an elevated immune capacity of these animals. This is an intriguing result concerning immunostimulation in cultured animals and needs further investigation. Untreated lupine meal can be used as an alternative protein source at rates of up to 10% (-20%) of the total feed (= 30-40% of animal protein).