Fish communities in rivers to be affected by Roadford Reservoir

This is the Fish communities in rivers to be affected by Roadford Reservoir report produced by South West Water Authority in 1978. Surveys were carried, out on the Rivers Wolf, Thrushel, Lew and Lumburn, which are likely to be affected directly and indirectly by the construction and use of Roadford Reservoir. Of the upper reaches of three rivers to be affected directly by water releases, two were found to support abundant stocks of salmon and trout, and the third was found to contain abundant stocks of trout and eels. The River Thrushel will be affected indirectly and in this river salmon and trout stocks were present in slightly lower abundance than in others. Population estimates, densities, mean lengths and approximate biomass values were calculated. Other species were present in all rivers, usually in great abundance.

PCR-SSCP and Isoelectric Focusing as Screening Methods for Identification of (Sub-) Tropical Fish Species

To ensure the authentication of fishery products lacking biological characters, rapid species identification methods are required. Two DNA- and protein-based methods, PCR-SSCP (polymerase chain reaction - single strand conformation polymorphism) of a 464 bp segment of the cytochrome b – gene and isoelectric focusing (IEF) of water-soluble proteins from fish fillets, were applied to identify fillets of (sub-) tropical fish species available on the European market. Among the samples analysed were two taxonomically identified species from the family Sciaenidae and one from Sphyraenidae. By comparison of DNA- and protein patterns of different samples, information about intra-species variability of patterns, and homogeneity of batches (e.g. fillet blocks or bags) can be obtained. PCR-SSCP and IEF may be useful for pre-checking of a large number of samples by food control laboratories. Zusammenfassung Zur Sicherstellung der Authentizität von Fischerei-Erzeugnissen ohne biologische Merkmale sind schnelle Verfahren zur Speziesidentifizierung hilfreich. Zwei Methoden der DNA- bzw. Protein-Analyse wurden eingesetzt, um Filets (sub-) tropischer Fischarten, die auf dem europäischen Markt angeboten werden, zu identifizieren. Bei diesen Methoden handelt es sich um die PCR-SSCP (Polymerase-Kettenreaktion – Einzelstrang-Konformationspolymorphismus) – Analyse der PCR-Produkte und die IEF (isoelektrische Fokussierung) der wasserlöslichen Fischmuskelproteine. Unter den untersuchten Proben waren zwei taxonomisch bestimmte Arten aus der Familie Sciaenidae und eine Spezies aus der Familie Sphyraenidae. Durch Vergleich der DNA- bzw. Proteinmuster lassen sich Informationen über die intra-spezifische Variabilität solcher Muster und die Einheitlichkeit von Partien (beispielsweise Filetblöcke oder Filetbeutel) gewinnen. PCR-SSCP und IEF können in Laboratorien der Lebensmittelüberwachung als Vortest gerade bei hohen Probenzahlen sinnvoll eingesetzt werden.

The market for Egyptian farmed fish

Egypt’s aquaculture production (921,585 tonnes in 2010) is by far the largest of any African country. The aquaculture sector, dominated by semi-intensive pond production of tilapia, makes a significant contribution to income, employment creation and food and nutrition security in the country, all of which are national priority areas given low per capita income levels, rising population, worsening food and nutrition security indicators, and official unemployment levels which have remained at around 10% for the last ten years. The Improving Employment and Income through Development of Egypt’s Aquaculture Sector (IEIDEAS) project funded by the Swiss Agency for Development and Cooperation (SDC) is a three-year project which commenced in December 2011, and which aims to support the development of the aquaculture sector in Egypt so as to increase productivity, profitability, and employment in the sector, and the nutritional status of poor consumers. This report represents the output of a short two-week study to better understand the market for Egyptian farmed fish. The intention of the study was to provide an output which would cut-across, and potentially benefit, all five of the project outcomes.

Women fish vendors in Mumbai: a study report

Government development programmes and policies in fisheries are focused on the problems and needs of men though women are known to dominate the post-harvest sector in artisanal fisheries and are involved, to varying degrees, in pre-harvest and harvest activities. A lack of women’s participation in decision-making bodies within communities, fisheries organizations and government has resulted in a general neglect of their interests. This has led to a constant demand by women’s-rights activists and organizations to address market-related issues of women vendors. This study, “Women Fish Vendors in Mumbai”, aims to provide insights into the challenges faced by women fish vendors in the city of Mumbai (formerly Bombay).

Body shape variation and colour change during growth in a protogynous fish

Protogynous sequential hermaphroditism is very common in marine fish. Despite a large number of studies on various aspects of sequential hermaphroditism in fish, the relationship between body shape and colour during growth in dichromatic species has not been assessed. Using geometric morphometrics, the present study explores the relationship between growth, body shape and colouration in Coris julis (L. 1758), a small protogynous labrid species with distinct colour phases. Results show that body shape change during growth is independent of change in colour phase, a result which can be explained by the biology of the species and by the social control of sex change. Also, during growth the body grows deeper and the head has a steeper profile. It is hypothesized that a deeper body and a steeper profile might have a function in agonistic interactions between terminal phase males and that the marked chromatic difference between colour phases allows the lack of strict interdependence of body shape and colour during growth.

Geographical and morphological variation within and between colour phases inCoris julis(L. 1758), a protogynous marine fish

The possible differences between sexes in patterns of morphological variation in geographical space have been explored only in gonochorist freshwater species. We explored patterns of body shape variation in geographical space in a marine sequential hermaphrodite species, Coris julis (L. 1758), analyzing variation both within and between colour phases, through the use of geometric morphometrics and spatially-explicit statistical analyses. We also tested for the association of body shape with two environmental variables: temperature and chlorophyll a concentration, as obtained from time-series of satellite-derived data. Both colour phases showed a significant morphological variation in geographical space and patterns of variation divergent between phases. Although the morphological variation was qualitatively similar, individuals in the initial colour phase showed a more marked variation than individuals in the terminal phase. Body shape showed a weak but significant correlation with environmental variables, which was more pronounced in primary specimens.