Showing papers in "Aquaculture in 1983"

TL;DR: The EFA content ofrotifers supplied with yeast during the culture period was less favourable for larval fish growth than that of rotifers given marine Chlorella, and the nutritional value of yeast-fed rotifer may be improved by the use of the recently developed ω-yeast or by feeding with a mixture of homogenized lipids and baker's yeast.

TL;DR: The possibilities for improvement through selection are particularly good for growth rate and age at maturation, because of large genetic variance and because high fecundity makes strong selection possible.

TL;DR: It was concluded that the reduced growth in fish fed diets containing phytic acid was related to a reduction in protein availability rather than to an alteration in the bioavailability of Zn, Fe, or Cu.

TL;DR: Phenotypical feminization is induced successfully by using estradiol-17β, and particularly fruitful techniques for control of sex in aquacultured fish will involve the combination of steroid treatment with chromosome manipulation.

TL;DR: Starch digestibility in trout was investigated with two diets containing 70% of a common mixture and 30% corn starch which was either native or gelatinized, concluding that starch becomes a valuable source of energy when its digestibility is enhanced by gelatinization.

TL;DR: Using data from various sources, the genetic variability patterns at electrophoretically detectable loci were compared for four salmonid species, viz., Atlantic salmon, brown trout, rainbow trout, and sockeye salmon.

TL;DR: Non-lethal assays of ploidy were made in experimental lots of putative polyploids by flow cytometry by stained cells with DNA-RNA specific fluorescent dye, propidium iodide, and presented to the Ortho Cytofluorograf in liquid suspension.

TL;DR: Some possibilities for research are described, especially the production of monosex or polyploid hybrids, the genetic improvement of hybrids and the understanding of the mechanisms responsible for fertility and sterility.

TL;DR: The assessment of triploidy in a variety of fish farming or sea ranching contexts, the further refinement of diploid gynogenesis, possibly combined with self-fertilization following induction of hermaphroditism and the exploration of the manipulation of single chromosomes, or parts of chromosomes, either by incomplete destruction of the genome in gynogenic or by segregation within spermatogenesis in triploids are considered.

TL;DR: While the actual depression estimates varied widely between populations and inbreeding levels, significant levels of depression were found in many hatchery, field, and brood stock performance traits after only one generation of brother-sister mating.

TL;DR: Filtration rate at three different algal densities decreased with increasing densities, showing that C. gigas can regulate the filtration rate in that concentration range andAssimilation efficiency was found to be more or less constant, not being significantly dependent on body size or algal concentration.

TL;DR: The reason for the different digestibilities of carbohydrates was investigated and discussed in this paper, where the inclusion of soluble starch products in the diet increases the volume of intestinal juices and accelerates the passage through the intestine, thus reducing the time available for absorption.

TL;DR: The technique and relevant buffer systems and stains are described together with an account of the enzymes observed and their interpretation, and the results are expressed as relative mobilities of the observed isozyme bands, allowing direct comparison between all the species studied.

TL;DR: It is argued that the observed genetic changes are caused by founder effects and genetic drift rather than selection by some aspects of the artificial rearing regime, and the importance of using adequate numbers of parents in hatchery rearing is stressed.

TL;DR: The hatching quality of Reference Cysts and cysts from Canada and Argentina can be significantly improved by incubation of the cysts at low salinity, and for almost all commercial sources the use of decapsulated cysts results in a significant increase of the hatching output.

TL;DR: Experiments on short-term preservation of sperm were performed with Atlantic salmon and sea trout, finding differences were caused by the type of extender and the batch of gametes employed, and the very simple extender consisting of 0.3 M glucose and 10% DMSO only was the most successful.

TL;DR: It is demonstrated that the incidence of maturation of males at age 1+, as parr, was significantly higher among progeny of male parr than among progeni of males of total age 2+ and 3+ years, in selection experiments using mature parr as sires.

TL;DR: This review covers all aspects of quantitative genetics which are of direct or potential relevance to improving the efficiency of commercial production of farmed fish.

TL;DR: Both protein and fat were catabolized for energy by starving fish but the depletion of body fat was much more rapid and severe and age could not be identified as a primary factor in determing body composition.

TL;DR: It was found that changes in proximate body composition that occurred at different feeding levels were largely attributable to concurrent changes in weight, which largely explains C. lazera's efficient utilization of the feed for growth.

TL;DR: The effect of three levels of inbreeding on survival and growth in rainbow trout has been studied and at each level the inbreeding depression for survival of eyed eggs, alevins and fry was highly significant, but no linear relationship was found between level of in breeding and inbreeding depressed.

TL;DR: Triploid rainbow trout were produced by heat shock treatment of eggs soon after fertilization with either normal sperm or sperm from masculinised females, allowing the production of sterile all-female triploids, which should have considerable potential for aquaculture.

TL;DR: Electrophoretically analyzed tissue samples from a total of 1643 Atlantic salmon collected from naturally reproducing populations and hatchery stocks representing nine major river systems draining into the Baltic Sea showed a significantly lower amount of genetic variability than natural populations.

TL;DR: It was concluded that the limiting factor for the growth of carp in properly processed commercial soybean meals was not the residual antitrypsin, but inadequate lysine.

TL;DR: Shrimps fed the 40% protein diet produced the best growth, feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate, however, shrimps feeding the 30, 35 and 45% protein diets produced comparable results.

TL;DR: Sterile triploids potentially could be useful in salmon culture because of the management options available with a sterile population and the ease with which triploidy can be induced.

TL;DR: In trout given the lowest dietary vitamin E intake, tissue levels of vitamin E were lowest in skeletal muscle, concentrations in most other soft tissues were about threefold that in muscle but higher levels were found in brain and increased erythrocyte fragility occurred in those fish given diets low in vitamin E.

TL;DR: MBV disease may cause serious losses in compromised populations (especially in postlarvae and young juveniles), but under conditions favorable to the host, fewer mortalities occurred and only low-grade infections of the hepatopancreas were detected.

TL;DR: It is concluded that management procedures can have strong selective effects and that genetic changes may be expected to occur rapidly if the obvious genetic conditions are met.

TL;DR: Survival and speed of development from first zoea to first crab stage were maximized at temperatures approaching 27°C, and by increasing Artemia nauplii concentrations (food) from 5 to 30 ml−1 as the larvae progressed.