Fish play an increasingly important role in national and local economies of many developing countries. Africa’s rivers, wetlands and lakes are especially important for poor rural households for whom they provide employment and income opportunities in areas where other economic alternatives are scarce or inexistent. They also provide nutritional safetynets in these regions with limited roads and access to market. However, policy makers and regional decision makers tend to underrate fisheries, in particular inland small-scale fisheries.
Gathering and recording of biological data vital to experiments in a genetic improvement program should be carried out with efficiency, precision and accuracy. This is important in order to avoid marking erroneous conclusion about the results. The GIFT team has so far standardized the methods of measuring some of the important phenotypic traits in tilapia. These traits are noted and measured during breeding and fry collection, stocking, rearing and harvesting activities. This manual lists the guideline required for sampling and recording of phenotypic traits.
This proceedings include the twenty-two papers which were originally presented in in a conference on The Theory and Application of Length-Based Stock Assessment Methods which took place on 11-16 February 1985 at the Istituto di Tecnologia della Pesca e del Pescato (ITPP) in Mazara del Vallo, Sicily, Italy. This conference was the first ever to be devoted solely to length-based methods for stock assessment.
A multiple regression model is derived, based on biomass estimates in 16 massbalance food web (Ecopath) models, which explains 68 % of the variation in the data at hand, and shows that the abundance of fish with trophic levels of 3.0 or more in the South China Sea area had declined, by 2000, to less than half its value in 1960. This is worrisome, as this generalizes to the entire region declining trends observed in local areas within the South China Sea. Moreover this estimate is almost surely too conservative, given the method we used.
Monte-Carlo simulations of fish populations with different biological characteristics were generated to test the accuracy of some recent methods for the assessment of growth in fishes on the basis of length data. Threemethods were investigated: D. Pauly and N. David's Electronic Length-Frequency Analysis (ELEFAN), J.G. Shepherd's Length Composition Analysis (SLCA) and the method derived by J.V.-Wetherall from the general model of D.G.
Details are given of techniques to be used in the handling of large amounts of data in the field of aquaculture. Two examples are given where different types of multivariate data analyses are performed on the compiled datasets to identify and quantify the effects of key variables governing growth and production of fish in manured pond systems cultivating tilapia and carp.
An equation is given for the selection of interval sizes for use in length frequency analysis of fish classes.
Details are given of the current database system used by the Collaborative Research Support Programme in PondDynamics/Aquaculture and Its Management. Suggestions are made regarding the design of a database.
A method for estimating the instantaneous mortality rate (Z) is presented which was developed from a truncated equation for average length. The model has zero bias at equilibrium, but has no explicit solution for Z so that its solution requires a numerical method.
This article examines the suitability of length-based methods for providing regular assessments of the stocks of the more important commercial fish species in Kuwait. To date, comparisons of age-based and length-based methods have been carried out for 3 species, the croaker Otolithes argenteus , red snapper, Lutjanus coccineus and the grouper Epinephelus tauvina . Results so far indicate a stock assessment reliability equal to that based on age composition data plus a saving in manpower and capital.