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Showing papers in "Aquaculture Research in 2007"


Journal ArticleDOI
TL;DR: This document reviews various plant feedstuis, which currently are or potentially may be incorporated into aquafeeds to support the sustainable production of various ¢sh species in aquaculture and strategies and techniques to optimize the nutritional composition and limit potentially adverse eiects of bioactive compounds are described.
Abstract: Continued growth and intensi¢cation of aquaculture production depends upon the development of sustainable protein sources to replace ¢sh meal in aquafeeds. This document reviews various plant feedstuis, which currently are or potentially may be incorporated into aquafeeds to support the sustainable production of various ¢sh species in aquaculture. The plant feedstuis considered include oilseeds, legumes and cereal grains, which traditionally have been used as protein or energy concentrates as well as novel products developed through various processing technologies. The nutritional composition of these various feedstuis are considered along with the presence of any bioactive compounds that may positively or negatively aiect the target organism. Lipid composition of these feedstuis is not speci¢cally considered although it is recognized that incorporating lipid supplements in aquafeeds to achieve proper fatty acid pro¢les to meet the metabolic requirements of ¢sh and maximize human health bene¢ts are important aspects. Speci¢c strategies and techniques to optimize the nutritional composition of plant feedstuis and limit potentially adverse eiects of bioactive compounds are also described. Such information will provide a foundation for developing strategic research plans for increasing the use of plant feedstuis in aquaculture to reduce dependence of animal feedstuis and thereby enhance the sustainability of aquaculture.

1,910 citations


Journal ArticleDOI
TL;DR: Results from the present study point out to HSD as a stressful rearing condition and suggest that crowding stress may affect amino acid requirements.
Abstract: Fish held at high stocking densities are generally exposed to chronic stress situations that impose severe energy demands and may predispose the fish to infection. Senegalese sole Solea senegalensis (Kaup) juveniles (78.8±18.9 g body weight) were maintained at low (LSD; 4 kg m−2 at the end of the experiment), medium (MSD; 9 kg m−2) and high (HSD; 14 kg m−2) stocking densities during a period of 63 days. Although disease outbreaks were observed in fish reared at HSD, growth and food consumption did not vary among different treatments. Results from plasma cortisol and free amino acids (FAAs) showed significant differences among different rearing densities pointing to HSD as stressful rearing condition. However, higher plasma glucose and osmolality levels indicated that fish held at MSD may also be under stress. The higher usage of FAAs from the HSD group may be due to the higher demand for energy production in order to cope with stressful rearing conditions, higher rate of protein synthesis or due to synthesis of other important metabolites related to stress response. Therefore, results from the present study point out to HSD as a stressful rearing condition and suggest that crowding stress may affect amino acid requirements.

165 citations


Journal ArticleDOI
TL;DR: This work describes the current knowledge on the status, transmission, pathology, isolation, control and genomic characteristics of WSSV, a highly lethal, stress-dependent virus which infects a wide range of aquatic crustaceans by vertical and horizontal transmission, with different mortality results.
Abstract: Shrimp is one of the main aquaculture species in the world. Different viruses affect them, which causes serious mortality to economically important species, such as Penaeus monodon, Litopenaeus vannamei and L. stylirostris, among others. White spot syndrome virus or WSSV is a highly lethal, stress-dependent virus, which belongs to the family Nimaviridae, genus Whispovirus. Three WSSV virus isolates were first detected in 1992 in Thailand, Taiwan and China. Later, a fourth isolate of the virus was detected in the Americas in 1999. This virus has a large circular double-stranded DNA genome with different sizes (292.9-307.2 kb), where the diverse isolates show differences in virulence. This virus infects a wide range of aquatic crustaceans by vertical and horizontal transmission, with different mortality results. The spread of infection between regions may be due to infected shrimp and carriers such as other crustaceans, seabirds, aquatic arthropods or other vectors. The aim of this work is to describe the current knowledge on the status, transmission, pathology, isolation, control and genomic characteristics of WSSV.

142 citations


Journal ArticleDOI
TL;DR: It is suggested that enzyme supplementation can significantly improve growth performance and feed utilization in juvenile hybrid tilapia.
Abstract: A 12-week feeding trial was conducted to investigate the effects of supplemental exogenous enzyme on growth performance in juvenile hybrid tilapia Oreochromis niloticus×O. aureus (18 g, average initial weight). A commercial enzyme complex (neutral protease, β-glucanase and xylanase) was included at the level of 0.0 (control group), 1.0 and 1.5 g kg−1 diet in three test diets. Each diet was fed to triplicate tanks of the juvenile three times a day at 4–6% of wet body weight, and each tank was stocked with 50 fish. The results showed that specific growth rate and feed efficiency ratio significantly increased (P 0.05). However, the ADC of dry matter in fish fed high supplementation (1.5 g kg−1) was significantly higher than the control and low supplementation (P<0.05). There were no significant differences in condition factor, whole body moisture, protein, lipid and ash among dietary treatments. Viscera ratio, hepatosomatic index and the liver lipid decreased significantly with increasing enzyme (P<0.05). Both protease and amylase activities in the intestine and the hepatopancreas of juvenile hybrid tilapia significantly increased (P<0.05) with increasing dietary enzyme levels. The results suggested that enzyme supplementation can significantly improve growth performance and feed utilization in juvenile hybrid tilapia.

134 citations


Journal ArticleDOI
TL;DR: The study revealed that satisfactory growth and feed utilization responses could be achieved through the replacement of FM by PBM, SBM and MBM in the diet of African catfish.
Abstract: A 12-week feeding trial was carried out in concrete tanks to examine complete and partial replacement (75%) of fish meal (FM) with poultry by-product meal (PBM), meat and bone meal (MBM) and soybean meal (SBM) in practical feeds for African catfish Clarias gariepinus. Triplicate groups of fish (initial body weight ranged from 90.33 to 93.93 g fish−1) were fed seven isonitrogenous and isocaloric diets of 20% digestible protein and 300 kcal 100 g−1 of digestible energy. The control contained 25% herring meal, whereas in the other six diets, PBM, MBM and SBM replaced 75% or 100% of the FM. Final body weight (FBW) and specific growth rate (SGR) of the fish fed diets containing PBM (75% and 100%), SBM (75% and 100%) and MBM (75%) were all higher, but not significantly different than those for fish fed the control diet. Replacing 100% of the FM by MBM significantly lowered FBW and SGR. Concerning whole body composition, there were no significant differences in ash and gross energy content of whole-body among fish; fish fed diets containing PBM-100% recorded significantly lower protein content compared with the control diet, while fish fed diet SBM-100% recorded significantly lower moisture content compared with the control diet. Also fish fed diets SBM-100% and PBM-75% recorded higher lipid and gross energy contents compared with the control diet. The study revealed that satisfactory growth and feed utilization responses could be achieved through the replacement of FM by PBM, SBM and MBM in the diet of African catfish.

131 citations


Journal ArticleDOI
TL;DR: It was shown that female livebearers benefited from inclusion of probiotics in diet during their reproductive stages and the use of higher concentration of probiotic cells in diet did not always lead to signi¢ cantly improved reproductive performance of the spawners.
Abstract: A probiotic bacterial strain, Bacillus subtilis, isolated from the intestine of Cirrhinus mrigala (Hamilton), was incorporated in ¢sh feed at four diierent concentrations (5 � 108 cells g�2, 5� 107 cells g�2, 5 � 106cells g�1 and 5 � 105 cells g�1) and fed to four species of livebearing ornamental ¢sh, Poecilia reticulata (Peters), Poecilia sphenops (Valenciennes), Xiphophorus helleri (Heckel) and Xiphophorus maculatus (Gunther) for one year duration to observe the effect of dietary probiotic supplementation on their reproductive performance. Sixty virgin females of each species were stocked separately in circular FRP tanks (350 L) and fed diets with varying levels of probiotic cells and control feed. Broodstock performance was evaluated based on gonadosomatic index (GSI), fecundity and fry production of female broodstock. The results showed that supplementation of feed with probiotics increased signi¢cantly (Po0.05) the GSI, fecundity and fry production of spawning females and length and weight of fry in all the four species of ¢sh. The number of dead and deformed fry were also signi¢cantly lower (Po0.05) in ¢sh fed with the probiotic feeds.The use of higher concentration of the probiont in diet did not always lead to signi¢ cantly improved reproductive performance of the spawners. Collectively, this study showed that female livebearers bene¢t from inclusion of probiotics in diet during their reproductive stages.

120 citations


Journal ArticleDOI
TL;DR: Results showed that the growth-promoting effect was higher in groups fed a sub-optimum protein (25%) diet containing both 3% citric acid and 500 U kg−1 of microbial phytase than those fed 35% CP diets, which suggests that microbialphytase andcitric acid in sub- optimum CP diet had a synergistic effect on nutrient digestibility and growth performance of L. rohita juveniles.
Abstract: A 2 × 2 × 2 factorial experiment was designed to study the main effect of dietary microbial phytase, citric acid, crude protein (CP) level and their interactions on growth performance, nutrient digestibility and body composition of Labeo rohita juveniles. Two basal diets were formulated using plant-based ingredients containing either sub-optimum (25%) or normal (35%) CP levels. Both the diets were supplemented with microbial phytase (U kg−1) and citric acid (%) at the level of 0, 0; 500, 0; 0, 3; and 500, 3 respectively. One hundred and twenty L. rohita juveniles (average weight 12.61–13.72 g) were randomly distributed in eight treatments, each with three replicates. Dietary microbial phytase alone had no significant effect on whole-body ash content but addition of citric acid (3%) in the diet activated the phytase as evidenced by their significant interaction. A significant interaction between citric acid and microbial phytase was also found on weight gain%, specific growth rate, protein efficiency ratio. Increasing the dietary CP level from 25% to 35% significantly (P<0.01) decreased phosphorus and dry matter digestibility. Thus, these results showed that the growth-promoting effect was higher in groups fed a sub-optimum protein (25%) diet containing both 3% citric acid and 500 U kg−1 of microbial phytase than those fed 35% CP diets. This suggests that microbial phytase and citric acid in sub-optimum CP diet had a synergistic effect on nutrient digestibility and growth performance of L. rohita juveniles.

119 citations


Journal ArticleDOI
TL;DR: It is concluded that storing of lupin kernel under a suitable condition may have partially hidden the positive effects of exogenous enzymes through activating the endogenous enzymes.
Abstract: High inclusion levels of dehulled lupin (Lupinus angustifolius) in salmonid diets significantly decrease growth rates. This may be caused by the high concentrations of non-starch polysaccharides including oligosaccharide (OS) in lupin. The antinutritive effects of OS have not yet been fully investigated in fish. The objective of this study was to determine the effect of enzyme supplementation of dehulled lupin-based diets on the fish performance. There were two control diets: a fish meal-based diet with no plant protein (FM) and a diet that contained 50% dehulled lupin (L). Four experimental diets based on diet L and containing four different exogenous enzyme supplements were used: diet L(E) (Energex™); diet L(B) (Bio-Feed™ Pro); diet L(α) (Alpha galactosidase™); and diet L(Mix), which contained all the enzymes. Fish were randomly stocked into tanks in duplicate groups of 38 fish, 16.58±0.169 (SE) g, and were fed twice a day for 6 weeks. The supplemented enzymes did not improve weight gain in fish fed lupin-based diets. However, mixed enzyme significantly improved Protein Efficiency Ratio (PER). Apparent digestibility of DM, CP and GE significantly improved in fish-fed L(E) diet. None of the supplemented enzymes affected digestive tract indices or carcass composition. Surprisingly, weight gain was significantly higher in fish-fed L(α), L(E) and L(Mix) diets as compared with FM diet. Feed intake was significantly higher in fish-fed L, L(α) and L(E) diets compared with the FM diet. It is concluded that storing of lupin kernel under a suitable condition may have partially hidden the positive effects of exogenous enzymes through activating the endogenous enzymes

102 citations


Journal ArticleDOI
TL;DR: Based on the second-degree polynomial regression analysis of the live weight gain, FCR, PER and PPV data, the optimum dietary level of threonine for fingerling L. rohita was found to be in the range of 1.51-1.70 g per 100 g of the dry diet.
Abstract: A 6-week growth trial was conducted to assess the dietary histidine requirement of fingerling Indian major carp, Labeo rohita (3.50±0.04 cm; 0.40±0.02 g) by using amino acid test diets (40% crude protein; 4.28 kcal/g) containing casein, gelatin, and L-crystalline amino acids. Diets with graded levels of histidine (0.25, 0.50, 0.75, 1.00, 1.25, and 1.50% of the diet) were fed to triplicate groups of fingerlings at 5% of their body weight divided into two feedings (07:00 and 17:30). Live weight gain, specific growth rate, protein efficiency ratio, and feed conversion ratio were significantly (p<0.05) affected by dietary histidine concentration. Weight gain and conversion efficiencies were best at 0.75% dietary histidine. Whole body protein content was highest and moisture and fat were lowest in the 0.75% dietary histidine treatment while whole body ash was the same at all treatment levels. Second-degree polynomial regression analysis of the live weight gain and feed conversion ratio resulted in more accurate histidine requirement estimates of 0.90 and 0.82% of the dry diet, respectively, corresponding to 2.25 and 2.05% of the dietary protein. It is recommended that dietary histidine be included at a level of 0.82% of the feed, corresponding to 2.05% of the dietary protein, for optimal growth in L. rohita fingerlings.

94 citations


Journal ArticleDOI
TL;DR: This study provides further evidence that growth rates of trout fed ¢sh meal-free diets, using conventional and concentrated plant protein ingredients, are good but some limitation to growth exists in the¢sh mealfree diets.
Abstract: The eiects of protein source and nutrient density on growth e⁄ciency, nutrient digestibility and plasma amino acid concentrations of rainbow trout were evaluated. A 3 by 2 factorial treatment design with three protein sources, ¢sh meal^barley (F^B), plant concentrates (PC) and plant meals (PM), and two nutrient densities were used. A commercial reference diet was also fed. Triplicate tanks of 30 ¢sh (initial wt. 28 g) were fed each diet, and the ¢nal weight averaged 240 g ¢sh � 1 . Protein source and nutrient density aiected feed intake, weight g ain and feed conversion ratio. Weight gain of trout fed the PC and PM diets was approximately 10% less than ¢sh fed the F^B diets. Protein retention was aiected by protein source, but not nutrient density, and was the highest for the ¢sh fed diets containing ¢sh meal and the lowest for the ¢sh fed PM diets. Apparent digestibility coe⁄cients and apparent amino acid availabilities of the diets corresponded with diierences in weight gain. This study provides further evidence that growth rates of trout fed ¢sh meal-free diets, using conventional and concentrated plant protein ingredients, are good but some limitation to growth exists in the ¢sh mealfree diets.

91 citations


Journal ArticleDOI
TL;DR: Temperature, salinity and their interaction also significantly affected larval development and a different trend of salinity effects was shown for megalopae as their duration consistently increased with an increase in salinity from 20 to 35 g L−1.
Abstract: The combined effects of temperature and salinity on larval survival and development of the mud crab, Scylla serrata, were investigated in the laboratory. Newly hatched larvae were reared under 20 °C temperature and salinity combinations (i.e. combinations of four temperatures 25, 28, 31, 34 °C with five salinities 15, 20, 25, 30, 35 g L−1). The results showed that temperature and salinity as well as the interaction of the two parameters significantly affected the survival of zoeal larvae. Salinity at 15 g L−1 resulted in no larval survival to the first crab stage, suggesting that the lower salinity tolerance limit for mud crab larvae lies somewhere between salinity 15 and 20 g L−1. However, within the salinity range of 20–35 g L−1, no significant effects on survival of zoeal larvae were detected (P>0.05). The combined effects of temperature and salinity on larval survival were also evident as at low salinities, both high and low temperature led to mass mortality of newly hatched larvae (e.g. 34 °C/15 g L−1, 34 °C/20 g L−1 and 25 °C/15 g L−1 combinations). In contrast, the low temperature and high salinity combination of 25 °C/35 g L−1 resulted in one of the highest survival to the megalopal stage. It was also shown that at optimal 28 °C, larvae could withstand broader salinity conditions. Temperature, salinity and their interaction also significantly affected larval development. At 34 °C, the mean larval development time to megalopa under different salinity conditions ranged from 13.5 to 18.5 days. It increased to between 20.6 and 22.6 days at 25 °C. The effects of salinity on larval development were demonstrated by the fact that for all the temperatures tested, the fastest mean development to megalopa was always recorded at the salinity of 25 g L−1. However, a different trend of salinity effects was shown for megalopae as their duration consistently increased with an increase in salinity from 20 to 35 g L−1. In summary, S. serrata larvae tolerate a broad range of salinity and temperature conditions. Rearing temperature 25–30 °C and salinity 20–35 g L−1 generally result in reasonable survival. However, from an aquaculture point of view, a higher temperature range of 28–30 °C and a salinity range of 20–30 g L−1 are recommended as it shortens the culture cycle.

Journal ArticleDOI
TL;DR: The results suggest that the nutritional quality of LS crabs is better than that of PR crabs, and the nutritionalquality of males is poorer than those of females.
Abstract: The morphological characteristics, tissue indices, proximate and fatty acid compositions of hepatopancreas, gonad and muscle of pond-reared (PR) and lake-stocked (LS) Eriocheir sinensis broodstock were compared. Lake-stocked crabs are characterized by a blue carapace, white abdomen, golden legs and yellow setae while PR crabs have a brown carapace, grey abdomen, black legs and similar yellow setae. The carapace length and width of PR crabs were significantly less than those of LS crabs of the same wet weight (WW). The results showed that the hepatosomatic index (HSI) of PR males was significantly higher, but the gonadosomatic index (GSI) was significantly lower for PR females when compared with LS individuals of the same sex. Regardless of their origin, the muscular index (MI) of males was higher than that of females. The hepatopancreas of LS crabs had higher protein levels and lower lipid levels compared with PR crabs. The results of proximate analysis of male gonads from two different sources were similar, while the protein level in the ovary of LS females was higher than that of PR females. The tissues of males had higher water content but lower lipid and protein levels compared with females regardless of their source. The LS crabs had higher highly unsaturated fatty acid (HUFA) levels than PR crabs in their gonad and hepatopancreas. In conclusion, our results suggest that the nutritional quality of LS crabs is better than that of PR crabs, the nutritional quality of males is poorer than that of females. The reproductive performance and larval quality of crabs from these two rearing systems should be further verified.

Journal ArticleDOI
TL;DR: Results show that production cycle in areas traditionally considered suboptimal for aquaculture can be equivalent to the cycle in Areas traditionally considered optimal for mussel aquacculture if mussel Aquaculture is integrated with ¢n¢sh aquac culture.
Abstract: Integrating mussel and ¢n¢sh aquaculture has been recognized as a way to increase pro¢ts and decrease environmental impacts of ¢n¢sh aquaculture, but not enough is known about the eiects of ¢n¢sh aquaculture on mussel growth. Here we present a pilot study aimed at determining how distance from ¢n¢sh aquaculture aiects mussel growth. To this end, we measured growth and condition index of mussel (Mytilus galloprovincialis) at three diierent distances (0, 60 and 700 m) from ¢n¢sh aquaculture in the eastern Adriatic Sea. There was a statistically signi¢cant diierence in growth of tagged mussels with respect to site. Average measured lengths of mussels at sites 1, 2 and 3 after the 10 months of the experiment were 57.60, 62.73 and 58.66 mm. Mussels grew fastest from March to May, and slowest from July to September, regardless of their position. Condition index showed spatial and temporal variations with higher values during fall and winter ( � 23), and lower values during spring and summer ( � 20). Our results show that production cycle in areas traditionally considered suboptimal for aquaculture can be equivalent to the cycle in areas traditionally considered optimal for mussel aquaculture if mussel aquaculture is integrated with ¢n¢sh aquaculture.

Journal ArticleDOI
TL;DR: The global growth results suggest the possibility of feeding sea bream weighing less than 80 g with 30% soybean meal, and for fish weighing more than80 g, a 50% dietary soybean Meal can be used until the fish reach commercial weight, with no negative effects on growth or feed efficiency.
Abstract: The value of defatted soybean meal as a protein source for sea bream fingerlings (15.2±4.4 g on average) growing to market size (300–350 g) was evaluated by feeding extruded isonitrogenous and isoenergetic diets (46% protein and 22 MJ kg−1) containing 20%, 30%, 40% and 50% soybean meal considering two phases. On day 87, the fish weight ranged between 66 and 81 g. The specific growth rate (SGR) of sea bream fed 50% soybean was lower (1.73% day−1) than that of fish fed 20% (1.87% day−1) and 30% (1.93% day−1), but the food conversion ratio (FCR) was not significantly affected, and a quadratic significant trend was observed for the feed intake (FI) in relation to the dietary soybean level. At the end of the second phase on day 309, fish weight was between 303 and 349 g, but SGR and FCR were similar for all diets, and ranged between 0.64 and 0.69% day−1, and 1.95 and 2.10% day−1 respectively. The final biometric parameters were not affected by the diets, although the levels of some free amino acids in the muscle were affected. Sensory differences were detected by panellists in fish fed diet 20% as compared those fed diet 50%, which had a less marine flavour and was less juicy. The global growth results suggest the possibility of feeding sea bream weighing less than 80 g with 30% soybean meal, and for fish weighing more than 80 g, a 50% dietary soybean meal can be used until the fish reach commercial weight, with no negative effects on growth or feed efficiency. Nevertheless, when sensory analysis and economic aspects are considered, the maximum inclusion level of soybean was 20–22%.

Journal ArticleDOI
TL;DR: Feed intake, protein efficiency ratio, body composition and economic profitability were not influenced by the amount of soybean oil in the diets, but muscle fatty acid composition differed with diets.
Abstract: A 309 days feeding experiment was carried out on gilthead sea bream fingerlings (initial weight 14.7±4.4 g) to evaluate effects of substitution of fish oil with soybean oil in diets on growth and sensory characteristics and muscle fatty acid composition. Duplicate groups of fish were hand fed with four isoenergetic and isonitrogenous diets (46% protein, 14% lipid and 22 MJ kg⁻¹) in which 0%, 24%, 48% or 72% of the fish oil was replaced by soybean oil. Fish fed diet 72% reached a lower final weight (324 g) than fish fed diets 0%, 24% and 48% (349, 343 and 338 g respectively). Feed intake, protein efficiency ratio, body composition and economic profitability were not influenced by the amount of soybean oil in the diets, but muscle fatty acid composition differed with diets. Panellists observed significant sensory differences between fish fed diet 0% and diet 72%. These results verified the possibility of feeding sea bream until they reached commercial weight with a 48% dietary substitution of fish oil for soybean oil.

Journal ArticleDOI
TL;DR: Regression analysis using the broken-line methodology indicated that 76.5±2% is an optimum soybean substitution level in diets that contained fishmeal and soybean as the major protein sources for grow-out of juvenile white shrimp.
Abstract: The feasibility of substituting soybean meal for fishmeal diets for juvenile white shrimp Litopenaeus schmitti (035±001 g) was evaluated, and an adequate substitution level was determined Five diets were evaluated using 46%, 59%, 75%, 88% and 100% substitution levels Pellet water stability was significantly affected by dietary soybean content (P<005) Increased soybean content produced lower pellet stability, ranging from a dry matter loss of 14–22% after a 2-h immersion, and 20–33% after an 8-h immersion After 52 days, significant differences (P<005) were found in shrimp weight, feed conversion ratio and protein efficiency ratio The values were 064–106 g, 28–79 and 045–121, respectively, for the three measurements Overall, better results were obtained with diets where soybean meal was substituted for fishmeal up to 75% The 100% soybean meal diet resulted in poor growth performance of shrimp Survival rates were acceptable for all treatments (90% or higher) and no significant differences were found in survival between treatments Regression analysis using the broken-line methodology indicated that 765±2% is an optimum soybean substitution level in diets that contained fishmeal and soybean as the major protein sources for grow-out of juvenile white shrimp

Journal ArticleDOI
TL;DR: It is demonstrated that sole of 5–10 mg can be weaned, with high survival rates, and it is suggested that trypsin and alkaline phosphatase may be used as indicators of nutritional status in sole of <5 mg.
Abstract: To optimize Senegalese sole-weaning strategies, three experiments were performed. The first trial tested four weaning strategies with a 10 mg sole. Artemia-fed sole grew threefold less than fish fed an inert diet. Sudden weaning (abrupt change from Artemia to inert diet) and weaning with co-feeding produced larger sole than did a late weaning treatment; delayed weaning negatively affected fish growth. In the second experiment, the digestive capacity of early-weaned 1, 2 and 4 mg sole was investigated. The highest growth was observed in sole weaned at 4 mg. Digestive enzyme profiles suggest that sole have an adaptation period to inert diets, with reduced feed intake. This adaptation period is inversely proportional to post-larvae weight. The third experiment examined weaning with co-feeding at different weights (2, 5 and 11 mg). These studies demonstrate that sole of 5–10 mg can be weaned, with high survival rates. On the basis of the digestive enzyme profiles, the early introduction of inert diets in co-feeding with Artemia seems to affect intestinal processes in smaller postlarvae. This study also suggests that trypsin and alkaline phosphatase may be used as indicators of nutritional status in sole of <5 mg.

Journal ArticleDOI
TL;DR: The relative insensitivity of tambaqui to low pH confirms its acid tolerance and is in accordance with its natural occurrence in black water habitats.
Abstract: Tambaqui Colossoma macropomum (Cuvier) is a fish of primary importance in Amazon aquaculture. It has been described as an acid-resistant species that moves seasonally between white (muddy) water and black water rivers and enters the extremely dilute acidic areas of flooded jungle to feed during the rainy season. To analyse the pH tolerance of this species, tambaqui were exposed to three water pH levels for 40 days (pH 4.0, 6.0 and 8.0). The water was acidified slowly over 3 h, allowing the fish to acclimate. A similar protocol was used to adjust water pH to 8.0. No mortality was observed during the exposure period. Several haematological parameters were significantly changed in alkaline-exposed animals, with significant decreases in haematocrit (20%), haemoglobin concentration (8%) and red blood cells (12%). Tambaqui showed severe blood variations when exposed to alkaline pH. Fish final weight, condition factor and specific growth rate (SGR) was inversely proportional to a pH increase, and SGR were higher for fish reared in acidic water. The relative insensitivity of tambaqui to low pH confirms its acid tolerance and is in accordance with its natural occurrence in black water habitats.

Journal ArticleDOI
TL;DR: The behavioural and metabolic responses of the largemouth bass Micropterus salmoides (Lacepede) to temperature were determined to define optimal thermal conditions and the results are discussed in relation to the use of this information in aquaculture.
Abstract: The behavioural and metabolic responses of the largemouth bass Micropterus salmoides (Lacepede) to temperature were determined to define optimal thermal conditions. The final preferendum of largemouth bass juveniles determined with acute and gravitation methods was independent of the method (29.0–28.1 °C). The displacement velocity in the horizontal thermal gradient of bass juveniles was 22.4 cm h−1 in the light phase and 22.6 cm h−1 in the dark phase. Oxygen consumption rates in the largemouth bass increased significantly (P<0.05) from 48.8 to 69.4 mg O2 Kg−1 h−1 with an increase in the acclimation temperature from 20 to 33 °C. The temperature quotient (Q10) in the juveniles was 1.37–2.00 in the range of acclimation temperatures of 26–29 and 29–32 °C. The optimum temperature range for growth calculated using Jobling's equation was 28.1–28.6 °C and for Q10 values 26–29 °C. The results are discussed in relation to the use of this information in aquaculture.

Journal ArticleDOI
TL;DR: The present results suggest that, for Nile tilapia, both SBM and FFSB supplemented with dl-methionine and l-lysine can completely replace dietary FM.
Abstract: This study was designed to determine the effect of complete substitution of fish meal (FM) by three plant protein sources including extruded soybean meal (SBM), extruded full-fat soybean (FFSB) and corn gluten meal (CGM) on growth and feed utilization of Nile tilapia Oreochromis niloticus and tilapia galilae Sarothrodon galilaeus. Four isonitrogenous of crude protein (ca. 28.0%) and isocaloric (ca. 19 MJ kg−1) experimental diets were formulated. The control diet (diet 1) was prepared with FM as the main protein sources. Diets 2–4, each FM control diet, were completely substituted with SBM (diet 2), FFSB (diet 3) and CGM (diet 4). l-lysine and dl-methionine were added to plant protein diets to cover the nutritional requirements of tilapia. Each treatment was allocated to three net pens and fed for 17 weeks. Nile tilapia fed the control diet showed significantly higher (P≤0.05) values for final body weight (FBW), feed intake (FI), weight gain (WG) and specific growth rate (SGR), whereas fish fed the diet with CGM achieved the lowest values. Tilapia galilae fed SBM diet recorded the highest (P≤0.05) values for growth performance. Better feed conversion ratio (FCR) for both Oreochromis niloticus and Sarothrodon galilaeus was observed when fish were fed SBM diet, whereas the worse FCR was recorded for FFSB diet. Feed utilization parameters including protein productive value (PPV), fat retention (FR) and energy retention (ER) showed significant differences (P≤0.05) for both the species fed different dietary protein sources. The present results suggest that, for Nile tilapia, both SBM and FFSB supplemented with dl-methionine and l-lysine can completely replace dietary FM. Meanwhile, S. galilaeus fed SBM diet exhibited comparable growth and feed utilization with those fish fed a fish-meal-based diet.

Journal ArticleDOI
Heidi Moe1, Tim Dempster1, Leif Magne Sunde1, Ulf Winther1, Arne Fredheim1 
TL;DR: It was concluded that netting materials for cod aquaculture must be resistant to cod bite or be repellent or uninteresting for cod, based on studies of cod interaction with traditional knotless netting and resulting fracture damage on netting fibres.
Abstract: The main goal of this PhD project was to develop a method for non-linear strength analysis of net structures applied in the aquaculture and fishing industries, e.g. net cages and trawls. The work focused on the aquaculture net cage, which was applied in experiments and analyses, and included research to establish knowledge within material properties and failure modes of traditional netting materials for aquaculture. It was chosen to focus on tensile properties and to study elastic and plastic behaviour, fracture, creep behaviour and cod bite damage. The project consisted of three main activities: tensile testing of netting materials, studies and testing of cod bite damage and resistance, and structural analysis of aquaculture net cages. Net cages are built as a system of ropes and netting. They are designed to transfer and carry all major forces through the ropes. Loads from current, waves, weights and handling induce forces in the net cage, which must be dimensioned to withstand this. Analyzing an aquaculture net cage is both complex and time consuming due to non-linear effects, detailed geometry and dynamic loads. The behaviour of the net cage is dominated by very large deformations and displacements, and materials with non-linear properties. There is a need for verified analysis methods and specific guidance on how to reduce the complexity of a net cage analysis. In order to perform a strength analysis of a net cage, it is crucial to know the material properties of the netting material. Traditionally, the material property of major interest for the aquaculture industry has been the tensile breaking strength of netting (mesh) and ropes, and comparatively little focus has been on their detailed stiffness properties and general behaviour prior to fracture. A new test method was established to determine the uniaxial tensile properties of knotless netting materials. It was applied on a variety of netting materials and stress-strain relations were developed. Data on temporary creep properties, recovery of strain post creep and post creep tensile properties of a selection of Raschel knitted netting materials was presented. Post creep tensile testing showed that the length and force at break were not significantly affected by the creep load history. Cod farmers have reported that cod interact with the cage netting through biting and thereby create wear and tear. The nature of the cod bite attack on traditional, multifilament netting materials was described based on studies of cod interaction with traditional knotless netting and resulting fracture damage on netting fibres. Field experiments were performed, subjecting panels of netting to cod bite in commercial cod cages. In addition, a test method was developed to simulate damage on traditional netting from cod bite, and a prototype bite-jig was designed and assembled. It was concluded that netting materials for cod aquaculture must be resistant to cod bite or be repellent or uninteresting for cod. A method for numerical analysis of net cages in constant uniform current was developed and verified for limited solidity, deformations and current velocities. Various new designs for aquaculture net cages were presented and compared to a traditional net cage with regard to stresses in the netting material and deformation of the net cage.

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TL;DR: Organic enrichment and particle size of sediments were closely associated with faunal groups particularly with polychaeta and mollusca and organic carbon contents showed significant differences among sampling stations.
Abstract: The impact of a sea bass (Dicentrarchus labrax L., 1758) farm on water quality and benthic community structure was investigated at a fish farm site in Engeceli Bay (western part of Izmir Bay) between April 2001 and February 2002. The characteristics of the water column in the fish farm were investigated in terms of physical and chemical parameters. Concentrations of nitrate, phosphate and ammonium ions in all sampling stations within the Bay were compared with the water quality parameters measured at the outer part of Izmir Bay (Eastern Aegean Sea). While there were significant differences from season to season of the levels of ammonium, orthophosphate, total phosphate and nitrite, there were no significant differences among stations. However, nitrate values and organic carbon contents showed significant differences among sampling stations. A reference station was selected to compare benthic groups. While the reference site is characterized by a sandy bottom with the lowest carbon and highest diversity values, the other stations with silty-clay bottoms showed higher organic enrichment and lower diversity with increasing abundance of polychaeta. Organic enrichment and particle size of sediments were closely associated with faunal groups particularly with polychaeta and mollusca.

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TL;DR: The significant differences between intestinal bacterial composition in Senegalese soles fed commercial diets and natural preys (polychaeta) reveal the necessity to develop specific optimized diets for the intensive rearing of this fish species.
Abstract: The aim of this study was to determine the influence of the feeding regimes in Senegalese sole (Solea senegalensis) cultured under extensive, semi-extensive and intensive production systems. A total of 254 bacterial isolates from guts of fish cultured under different production systems and feeding regimes were tested. Biochemical tests and genetic analyses based on the 16S rDNA sequence analysis were conduced to identify bacterial strains. Vibrio species were the most represented taxonomic group in the culturable microbiota of S. senegalensis guts tested. Particularly, Vibrio ichthyoenteri was the most frequently isolated Vibrio species. Comparison among diets showed a significant reduction (P<0.05) in vibrio percentages and a higher occurrence of Shewanella species in Senegalese soles fed polychaeta. In addition, a major influence of environmental temperature on microbiota composition was detected. Cold temperatures brought about a change in the percentages of Vibrio species and a higher representation of α-Proteobacteria in both outdoor systems (extensive and semi-extensive). The significant differences between intestinal bacterial composition in Senegalese soles fed commercial diets and natural preys (polychaeta) reveal the necessity to develop specific optimized diets for the intensive rearing of this fish species.

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TL;DR: Clinical chemistry analyses in blood plasma indicated decreased levels of total protein, glucose and total calcium and an increase in the urea level and electrophoretic analyses of the plasma protein indicated a reduced level of albumin.
Abstract: Mass death of farmed brook trout Salvelinus fontinalis reared in raceway culture on a commercial fish farm was recorded in May. The condition was caused by natural infection with external signs of Flavobacterium columnare. Haematological analyses were carried out from peripheral blood from 10 fish from each group. Anaemia was characterized by a reduced erythrocyte count and lower haemoglobin levels; the values of mean corpuscular volume and mean corpuscular haemoglobin were higher and the values of mean corpuscular haemoglobin concentration were decreased. Clinical chemistry analyses in blood plasma indicated decreased levels of total protein, glucose and total calcium and an increase in the urea level. Among the four enzymes analysed, a catalytic activity reaching multiples of the normal level was found in alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase. The catalytic concentration of alkaline phosphatase was decreased. Electrophoretic analyses of the plasma protein indicated a reduced level of albumin. The moribund fish had a higher hepatosomatic index and their condition coefficient after Fulton and after Clark was also higher.

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TL;DR: The ovarian development was correlated closely to the gonadosomatic index, oocyte diameter, and ovarian histology, and provides baseline information for further studies on reproductive biology and provides a guide for broodstock management in the hatchery.
Abstract: Ovarian maturation in adult wild-sourced and pond-grown Scylla serrata (Forsskal) was determined based on gross morphology and histological appearance There were no significant differences noted in the histological features of both wild and pond-reared S serrata females Ovarian maturation was classified into five stages: immature, early maturing, late maturing, fully mature and spent The immature ovaries are thin and translucent to off white and contain oogonia, primary oocytes with large nuclei The follicle cells were found around the periphery of the lobes and an area among groups of oogonia and oocytes The follicle cells gradually enclosed the oocytes The early-maturing ovaries were yellow and small yolk globules started to appear in larger oocytes In late-maturing ovaries, the colour became light orange and lobules were apparent Yolk globules occurred in the cytoplasm with larger globular inclusions towards the periphery, while follicle cells were hardly recognizable Fully mature ovaries were orange to deep orange and had swollen lobules Large yolk globules were apparent in the entire cytoplasm Follicle cells were hardly seen Spent ovaries were similar to the early-maturing and late-maturing stage in partially spawned females The ovarian development was correlated closely to the gonadosomatic index, oocyte diameter, and ovarian histology The classification of ovarian maturation provides baseline information for further studies on reproductive biology Likewise, the information provides a guide for broodstock management in the hatchery


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TL;DR: Addition of phytase significantly increased daily feed intake, but only led to a marginal improvement in the weight gain, SGR and FCR of fish fedPHYT2 and PHYT4 compared with fish fed D0, and fish fed DP showed the best growth performances.
Abstract: The effect of dietary phytase on phosphorus (P) digestibility, growth, bone mineralization and plasma P of common carp (Cyprinus carpio) was investigated Five diets, D0, DP, PHYT1, PHYT2 and PHYT4, were used D0 contained no supplement DP was supplemented with 26 g P (Na₂HPO₄x 2H₂O) kg⁻¹ PHYT1, PHYT2 and PHYT4 comprised 1000, 2000 and 4000 U phytase [Ronozyme P (CT)] kg⁻¹ D0, PHYT1, PHYT2, PHYT4 had average of 795 g P kg⁻¹; DP contained 103 g P kg⁻¹ After 126 days of feeding, fish grew from 115 to 347 g (D0), 5837 g (DP), 3526 g (PHYT1), 3933 g (PHYT2) and 4064 g (PHYT4) Addition of phytase significantly increased daily feed intake, but only led to a marginal improvement in the weight gain, SGR and FCR of fish fed PHYT2 and PHYT4 compared with fish fed D0 Fish fed DP showed the best (P<005) growth performances Fish fed DP and PHYT4 significantly digested dietary P more than the fish fed D0 Fish fed D0, PHYT1, PHYT2 and PHYT4 retained higher (P<005) Zn in their bones than fish fed DP However, there was no further effect on bone mineralization Plasma P scarcely improved by between 14% and 26% in fish fed PHYT2 and PHYT4 relative to fish fed D0 P concentration of the faeces was reduced by about 9-22% in fish fed PHYT1 and PHYT4 compared with fish fed D0


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TL;DR: The rapid expansion of aquaculture is accompanied by an increasedawareness concerning the impact of¢sh rearing on the environment, which masks the potential environmental conse-quences on the coastal zone.
Abstract: Morethan25%of Greek¢shfarmsand20%of Greekhatcheries of gilthead sea bream (Sparus aurata)andsea bass (Dicentrarchus labrax) are located along theWestern Hellenic coast. The part of sea bream pro-duction is about 60% of thetotalproductionof thesespecies. During the last decade, a spectacular in-creaseinboththenumberoffarmsandtheirproduc-tion, accompanied by a substantial price decreaseand modi¢cation of their structure and functioning,has been recorded. These changes resulted in themaintenanceincagesoflargeindividuals(morethan500g) of gilthead sea bream which are potentialspawners. The study, based on both the maturitystage and the decrease in individual mean weightsduring the reproductive period of the species, con-¢rmed reproduction in cages. In parallel, during thelast5yearsaremarkableincrease(about80%)inseabream landings from the ¢sh trap ¢sheries of theMessolonghi-Etoliko lagoon, which is a typical nur-sery for the species, was recorded.The increase wasaccompanied by a decrease both in price and meansize of the 0-group individuals. The possible in£u-ence of the rearingactivities inthearea, thedensity-dependent mechanisms and the negative impacts ofthis unintentional enhancement of the traditionallagoon¢sheriesof theareaarediscussed.Keywords: aquaculture, gilthead sea bream, eco-logical impact, carrying capacity, density depen-dence, Messolonghi-EtolikolagoonIntroductionThe rapid expansion of aquaculture is accompaniedbyan increasedawareness concerning the impact of¢sh rearingonthe environment.These environmen-taleiectsareexpressedatalargevarietyof¢eldsandspatiotemporal scales (Machias, Karakassis, Gian-noulaki, Papadopoulou, Smith & Somarakis 2005).However,therecentspectacularevolutionof theHel-lenicaquacultureindustry,basedmainlyongiltheadseabream(Sparusaurata)andseabass(Dicentrarchuslabrax), masks the potential environmental conse-quences on the coastal zone. In particular, duringthe last 20 years both the number of ¢sh farms andtheir production have increased greatly from12 and100t in 1985, to 269 and 85000t in 2004 respec-tively (source: Mariculture Federation of Greece),with the relative contribution of the two species re-maining rather stable during this period (60% of seabream). In Hellenic waters, the impacts of ¢sh farmsonthemarineecosystemhavebeenwidelyinvesti-gated,includingeiectsonthewaterqualityininten-sive rearing areas (Western Hellenic coast: Belias,Bikas, Dassenakis & Scoullos 2003), on the sea bedand the watercolumn (Aegean and Ionian Sea: Kar-akassis,Tsapakis, Hatziyanni, Papadopoulou & Plaiti2000) and on possible changes of ¢sh assemblagestructureanddiversityclosetotheseafarms(AegeanSea: Machias, Karakassis, Labropoulou, Somarakis,Papadopoulou& Papaconstantinou2004).Worldwide, the interactions between wild andfarmed populations are frequently focused on the

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TL;DR: Dietary astaxanthin supplementation of 80 mg kg � 1 is recommended for juvenile L. vannamei cultured in low-salinity water because it improved growth, survival and moult frequency in shrimp.
Abstract: The eiects of dietary astaxanthin supplemented at 0, 40, 80 or 150 mg astaxanthin kg � 1 on growth, survival, moult frequency, osmoregulatory capacity (OC) and selected metabolic and haematological variables in Litopenaeus vannamei acclimated to low-salinity water (3 g L � 1 ) were evaluated. Supplemented astaxanthin at 80 mg kg � 1 improved growth, survival and moult frequency in shrimp. The lowest OC was also exhibited in shrimp fed with dietary astaxanthin at 80 mg kg � 1 . Shrimp haemolymph concentrations of glucose, lactate, haemocyanin and total haemocyte count were all signi¢cantly enhanced by feeding the diet supplemented with 80 mg astaxanthin kg � 1 compared with shrimp fed with the other diets. On the basis of these results, dietary astaxanthin supplementation of 80 mg kg � 1 is recommended for juvenile L. vannamei cultured in low-salinity water.