Factores que afectan la distribución de salmónidos en Argentina

The introductions of salmonids in Argentina can be considered as successfull. The have become established as reproducing populations in southern and middle-western lakes and reservoirs. An extensive sampling programme on 112 lakes and reservoirs was carried out during the summers of 1984 to 1987. Environmental features that determine their present distribution were analyzed. The hypothesis, which we used as starting-point, is that it has been attempted to introduce at least once and least one species of salmonids in all lakes and reservoirs of Argentina.

WEFTA-Laborvergleichsuntersuchungen zur pH-Bestimmung in Fischerei-Erzeugnissen - Eine gemeinsame Aktion der Western European Fish Technologists' Association

12 samples (6 original samples and 6 diluted samples) were analysed by 14 WEFTA laboratories for their pH values in an inter-laboratory comparison exercise. As a result it can be stated that the majority of participating laboratories could determine the pH values very exactly. The pH values obtained are ranging only little around the calculated mean (less than 0.1 pH unit). It could also be demonstrated that the participating institutes could analyse both, pH values in fishery products and aqueous salt solutions. However, also in this exercise a number of outliers and deviating values have been detected. Therefore it is of utmost importance to calibrate the pH electrodes in regular intervals and to maintain them carefully. Intra-laboratory comparison measurements are recommended to detect weak points.

Sulfide as a toxicant in aquatic habitats

The toxic effects of sulphide are best understood in mammals and are generally similar in aquatic organisms. At the physiological level sulphide has 2 major effects on mammals: 1) local inflammation and irritation of moist membranes including the eye and respiratory tract; and, 2) cardiac arrest due to paralysis of the respiratory centres of the brain. The toxicity of sulphide to plants, macroinvertebrates, freshwater fish and marine fish is discussed in detail. It is concluded that the role of sulphide in mass kills of fish, shrimp and other animals in brackishwater earthen ponds, lakes and sea cages should be determined.