1,721,194 research outputs found
The genetics of Asian seabass
No full text[Extract] From a geneticist's perspective, L. calcarifer is an interesting fish species to study due it its euryhaline, protandrous life-strategy, broad tropical geographic distribution, mass-spawning reproductive behaviour and economic importance to communities denizen to the area it naturally inhabits. The species is commercially exploited, both via wild fishery captures and through industrialized farming, and is also becoming a model tropical fish species for understanding the impacts of future climate change. As a result, various aspects of the genetics of this species have received considerable attention, both towards using genetic approaches to understand population structure, diversity and genetic connectivity for fishery management purposes, through to deciphering the genome and mapping of genes influencing traits of commercial importance to assist future aquaculture breeding programs.
This chapter summarizes the current state of genetic knowledge of L. calcarifer
Early development and seed production of Asian seabass, Lates calcarifer
No full text[Extract] The Asian seabass Lates calcarifer (Bloch) is widely distributed in the Indo-West Pacific. Because of its high commercial value, it is widely cultured in most of Asia and Australia. However, seed supply from the wild is not abundant; hence the aquaculture of seabass is based on mass seed production in hatcheries. Seabass spawn naturally in captivity (Toledo et al. 1991). Alternatively, they can be induced to spawn by hormonal or environmental manipulations (Kungavankij 1987, Garcia 1989a, b). the development of methods for broodstock management for reliable reproduction of seabass under captive conditions paved the way for studies on the environmental, physiological and nutritional requirements of the developing larvae and the development of protocols for seed production in the hatchery e.g., Parazo et al. 1998, Schipp et al. 2007).
Survival of marine fish larvae is dependent on the interplay of various environmental factors (e.g., temperature and water quality, as well as availability of good quality and nutritionally adequate food supply) with a suite of species-specific characteristics including egg and larval size, amount of energy reserves (volume of yolk and oil globule, if present), utilization rates of energy stores (resorption rates of yolk and oil globule), metabolic demand, initiation of feeding and feeding success, growth rates, swimming and feeding behavior. In general, size provides an advantage (i.e., large eggs give rise to large larvae with large yolk reserves which will sustain larval development and allow the larvae sufficient time to initiate feeding before the onset of irreversible starvation (May 1974)).
This Chapter outlines the characteristics of L. calcarifer eggs and larvae, the changes during embryonic and larval development, advances in seed production and at the same time highlights the relative ease in its mass production
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Infectious diseases of Asian seabass and health management
No full text[Extract] Disease problems constitute the largest single cause of economic loss in aquaculture. Despite reliable hatchery production and commercial expansion of the Asian seabass industry, a number of viral, bacterial, fungal and parasitic diseases threaten sustained production. Consequently, the focus and content of this chapter is on major viral, bacterial, fungal and parasitic diseases which have occurred in, and which may impact adversely on, production of Asian seabass. Where available, information is also provided on diseases inflicting wild seabass and a list of known infectious diseases (pathogens and parasites) of both wild and farmed Asian seabass has been compiled in Table 6.1 as a reference.
Asian seabass can be cultured in a variety of aquaculture systems (open, semi-closed and closed) in freshwater, brackish and marine environments, each which presents its own unique disease challenges. However, most of the losses caused by pathogens and parasites in Asian seabass aquaculture can be prevented by adopting appropriate biosecurity protocols. Common biosecurity measures may include routine health inspections, quarantine and treatment of wild-caught brood stock, egg disinfection, strict equipment sanitation, human traffic control, intake water treatment, effluent treatment, clean feeds, restricting movement of stock, appropriate disposal of mortalities and limiting interactions between wild and farmed organisms. Difficulties can arise once a disease has established and spread within a facility because eradication may be impossible. Following a disease outbreak, vaccination and chemoprophylaxis may need to be implemented to reduce outbreaks and minimise losses. Appropriate biosecurity is the most effective method of prevention of the numerous disease causing organisms described herein.
In this chapter a brief description of important diseases is given, together with diagnosis and possible treatment and/or control mechanisms that may be applied in aquaculture. Information on management and treatment is provided as a guide only, and the author recommends consultation should be made with government authorities to ascertain regulations associated with the use of chemotherapeutants. The author recognises that noninfectious disease and abnormalities due to environmental contaminants, or nutritional deficiencies, are equally important problems, but these were beyond the scope of this chapter which focuses on infectious disease issues. Furthermore, continued intensive production of Asian seabass will likely result in further occurrences of previously unknown or undescribed diseases
- …
