Effect of spawning induced starvation on nutrient loss in males of the annual spawner Atlantic halibut (Hippoglossus hippoglossus)

publishedVersio

Family differences on triploid induction, sexual maturation and its contribution to sea cage performance of Atlantic cod, Gadus morhua

Early maturation has been one of the biological bottlenecks of commercializing Atlantic cod culture. To overcome the bottleneck, production of sterile fish through triploidy and other molecular techniques have been suggested and attempted. Although studies have been carried out on triploid performance of Atlantic cod, no studies have been conducted to see the performance of triploid fish at family level. We produced 29 triploid sibling families using standard hydrostatic pressure technique of newly fertilized eggs with parallel, untreated diploid families. Larvae were reared in separate tanks using standard rearing protocols until reaching 20 g and were PIT tagged. PIT tagged juveniles were transferred to sea cages in duplicate. At 34 months post-hatch, all the fish were sampled and body weight, liver weight and gonadal weight were recorded. Results showed that significant family differences exist between diploid and triploid families in gonadal development, especially for the females. Fish from triploid families had significantly smaller gonadosomatic index than fish from diploid families, but diploid families were heavier than the triploid families. Our result highlight the need for considering a parallel strategy for triploid family selection within the conventional diploid breeding program to exploit the existing variation in triploid performance.acceptedVersio

Effects of chilled storage and cryopreservation of sperm, and sperm to egg ratio on fertilization success in lumpfish (Cyclopterus lumpus)

publishedVersio

High temperature is detrimental to captive lumpfish (Cyclopterus lumpus, L) reproductive performance

There is increased commercial interest in the production of Lumpfish (Cyclopterus lumpus, Linnaeus, 1758) as a biological control for sea lice infections in Atlantic salmon farming. To ensure sustainability, reliable captive breeding is required however, optimal husbandry conditions for broodstock performance remain unknown. The present study investigated the effects of holding temperature on spawning productivity and gamete quality in captivity reared lumpfish. Sexually mature lumpfish (15 month old) were held on three temperature regimes (6 °C, 9 °C and 14 °C) from the onset of first spawning. Holding mature lumpfish at high temperatures (14 °C) resulted in a notable reduction in spawning activity with a significant reduction in sperm density (50% reduction compared to pre-treatment levels) and furthermore resulted in the production of non-viable oocytes (0% to eyeing rate). Holding lumpfish at 9 °C and 6 °C did not have a similar negative impact on gamete quality, however the spawning season for the 6 °C treatment was twice as long as the 9 °C treatment. These results indicate that holding temperature for lumpfish broodstock should not reach the 14 °C degree threshold, with a possible thermal optimum below 10 °C. The current findings are the first step in identifying optimal rearing conditions for captive Lumpfish broodstock

Welfare and performance of ballan wrasse (Labrus bergylta) reared at two different temperatures after a preparatory feeding trial with enhanced dietary eicosapentaenoic acid

publishedVersio

Optimization of the Balance between Protein, Lipid and Carbohydrate in Diets for Lumpfish (Cyclopterus lumpus)

The aim of this study was to investigate how the dietary balance between protein, lipid, and carbohydrate affects growth, welfare, and health with focus on immune responses, in lumpfish of body weight ranges 1.7-10 g and 15-50 g. A three-component mixture design, with simultaneous variation of the three macronutrients was applied. Growth, tissue and plasma nutrient composition, welfare, cataract frequency, and immune responses in leukocytes isolated from the fish head kidney were studied. Most responses were linear and driven by dietary lipid level, with minor effects of carbohydrate and protein. The growth in 1.7-10 g fish followed a special cubic model with no clear optimum. The fastest growth in the 15-50 g fish was obtained with the diet containing 55% protein, 17% fat, and 6% carbohydrate. The high dietary levels of lipid also gave high lipid levels in the tissues and a trend of improved welfare score, but there were no effects on cataract. The diets with minimum and maximum protein gave suboptimal immune responses in isolated head kidney cells of the 15-50 g fish, while the fastest growing fish showed normal immune responses. We propose that diets for lumpfish from 10-50 g body weight should contain approximately 55% protein, minimum 10% lipid, and maximum 10% carbohydrate. These diets will also be suitable for lumpfish of 1.7-10 g.publishedVersio

Soya saponins and prebiotics alter intestinal functions in Ballan wrasse (Labrus bergylta)

A 5-week feeding trial was conducted in the cleaner fish Ballan wrasse (Labrus bergylta) for a better understanding of the basic biology of the intestinal functions and health in this stomach less species. During the trial, Ballan wrasse was fed either a reference diet, the reference diet supplemented with (i) a commercial prebiotic (Aquate™ SG, 0·4 %) expected to have beneficial effects, (ii) soya saponins (0·7 %) expected to induce inflammation or (iii) a combination of the prebiotics and the soya saponins to find a remedy for gut inflammation. Blood, intestinal tissue and gut content from four consecutive intestinal segments (IN1 – IN4) were collected. No significant differences in fish growth were observed between the four dietary groups. Saponin supplementation, both alone and in combination with prebiotics, increased weight index of IN2 and IN3 and decreased blood plasma glucose, cholesterol and total protein. Dry matter of intestinal content and activity of digestive enzymes were not affected by diet. Histomorphological analyses revealed a progressing inflammation with increased infiltration by immune cells particularly into the distal parts of the intestine in fish fed diets with saponins, both alone and in combination with prebiotics. Gene expression profiles obtained by RNA sequencing and quantitative PCR mirrored the histological and biochemical changes induced by the saponin load. The study demonstrated that Ballan wrasse gut health and digestive function may be markedly affected by feed ingredients containing antinutrients.publishedVersio

A Screening Study on Effects Varying Dietary Macronutrient Composition on Gut Functions in Lumpfish (Cyclopterus lumpus)

publishedVersio

Technical feed quality influences health, digestion patterns, body mineralization and bone development in farming of the stomachless cleaner fish ballan wrasse (Labrus bergylta)

Farmed ballan wrasse (Labrus bergylta) is an efficient cleaner fish used for non-medicinal delicing of Atlantic salmon in sea cages replacing to an increasing degree wild wrasse due to considerations for biodiversity and risk of overfishing local wrasse populations. Farming of ballan wrasse has been hampered by low growth rates, high prevalence of skeletal deformities and other welfare related pathologies. In this study we investigated how diets identical in composition but differing in their technical characteristics, by being prepared using different feed production technologies, affect fish performance, mineralization, bone development and gut health of the ballan wrasse larvae and juveniles. The different production technologies include the commonly used ‘high temperature’ extrusion, cold extrusion, and agglomeration, resulting in feed pellets with distinctive physicochemical properties. The results revealed that prolonged feeding periods with extruded pellets during ballan wrasse larvae weaning result in low body mineralization and the development of severe skeletal deformities. In juvenile ballan wrasse, the extruded pellet treatment resulted in higher mortality rates, fish with larger livers, indication for increased serum TAG and cholesterol in a similar manner, and increased activity of the digestive enzymes LAP and maltase, most probably as a compensatory mechanism to the assumed reduced availability of protein and carbohydrates of extruded pellets for this fish species. Smaller dietary effects were identified in terms of intestinal morphology and gene transcription rates.publishedVersio

Ova lipid profiling and egg quality in wild and captive lumpfish, Cyclopterus lumpus (Linnaeus, 1758)

Lumpfish (Cyclopterus lumpus) serves an important role as cleaner fish for removing salmon lice in salmon aquaculture. For this use, cultivated lumpfish are preferred over wild-caught fish to avoid overexploitation of natural stocks and provide a stable production of good quality eggs and larvae. To support this, high quality eggs containing the necessary building blocks to support high fertilization success, development into a normal embryo and high hatching success is needed. Ova from wild-caught and captive lumpfish females were collected and assessed to identify how wild and domesticated lumpfish differ in terms of ova lipid profiles, egg and larvae quality. Wild-caught lumpfish displayed higher fertilization and hatching success compared to captive lumpfish, whereas other biological variables like egg size, egg/larvae dry weight and respiration, and larval morphometry, were not significantly different between wild and captive lumpfish. Ova lipid profiles (total lipid, lipid classes, fatty acid composition and lipidomics) can separate egg batches based on their geographic origin of wild-caught females and composition of diets used for captive broodstock (lipid and carbohydrate content). Multivariate statistics were applied to identify lipid markers that can be used to predict the quality of lumpfish ova. Lumpfish ova lipidomic profiles covaried with several biological parameters, indicating that the former can be used to predict the latter. Lumpfish eggs were mostly composed of triacylglycerides (TAGs) with some phosphatidylethanolamines (PEs) and phosphatidylcholines (PCs), and their lipid profiles were more sensitive to the different origins, mother weight/size and fertilization success than variables such as eggs size or larvae morphometric measures. PC and PE content of lumpfish eggs were positively correlated to both hatching success and fertilization rates, thus the lipidomic profiles, with some key highlighted lipid species were putative predictors of egg quality.Ova lipid profiling and egg quality in wild and captive lumpfish, Cyclopterus lumpus (Linnaeus, 1758)publishedVersio