Observations on the influence of external factors on the duration of the embryonic development and on the molting rhythm of Cyclops vicinus. [Translation from: Oecologia 7, 342-355, 1971.]

Investigations on the control of the embryonic and post-embryonic development of arthropods have formed an intensively studied field of zoological research for a long time, Here in especially favourable cases the causal chain from the operation of external factors on the influence of physiological mechanisms, eg. of the hormone variety, is known right through to its primary influences. A comparative approach to the relevant questions was in the main only made in the case of the insects. For crustacea , investigations are available almost exclusively only for the malacostraca. This study examines the influence of the factors of temperature and photoperiod on the entire development of Cyclops vicinus. Tests were made on whether the light-darkness change serves as a regulator for a possible existing molting rhythm - a question which for the entire arthropods has been settled only very rarely. The basic material for the cultures that were examined originates from Lake Constance.

Fundamental aspects of the feeding of the amphipod Gammarus (R.) balcanicus (Crustacea, Amphipoda). [Translation from: Nauchn.Dokl.vyssh.Shkoly (Biol.Nauk) 1970(7) 12-16, 1970]

The amphipods are major food items for many commercial fishes, and they are used as protein food for agricultural animals. In the present paper are presented the results of four-year observations on the feeding of Gammarus balcanicus in nature and in an aquarium. Among the studied aspects were the dependence of daily food ration on sex and physiological state (with and without eggs) and feeding on different kinds of plant food. The study concludes that Gammarus balcanicus willingly feed on soft half-decayed plant residues; into their ration also enters food of animal origin. In contrast to other amphipods, G. balcanicus eats representatives of its own species very rarely, and only dead or immobile ones.

Diurnal periodicity of activity in the spawning perch P. fluviatilis L. [Translation from: Kalamies 1972(7) 3, 1972]

Diurnal periodicity of spawning in the perch so far are rather meagre and found to be partly contrary to experiences of perch anglers. Therefore a study was made on the spawning during a 5-day period in the spring of 1971 in the Kuusamo area. Observations were made during the main spawning season, between 4- 9 June 1971. The perch were often measured, weighed and then released back into the water. The differences between spawning and non-spawning perch were studied as well as the time of roe discharge in a 24 hour period. Activity and environmental factors such as light intensity were also taken into consideration.

Cultivation methods for Lemnaceae [Translation from: Wiadomosci Botaniczne 7(2) 153-164, 1963]

Representatives from the family of Lemnaceae (duckweed) make ideal experimental material for research into a succession of phytophysiological processes with regard to growth rate and vegetative reproduction. They are also easy to maintain in sterile cultures. Lemnaceae belong to the higher flowering plants (flowers are rarely produced), however they are distinguished by a much simplified morphological and anatomical structure. As water plants they possess the advantage, that they can be cultivated in synthetic media under laboratory conditions controlled by the application of both a known light intensity and temperature. This paper describes experimental research of growth of Lemnaceae in different conditions. Some of the variables were mineral media, illumination and aeration.

Biology of the amphipod Gammarus pulex L. in water-bodies of the Leningrad district, and its piscicultural importance [Translation from: Trudy Vsesoyuznogo Gidrobiologicheskogo Obshchestva 7 99-122, 1956]

Observations and laboratory experiments are summarised that examine the widely discussed issue of what Gammarus pulex feeds on. On the basis of the observations of the authors and data from the literature it can be noted that G. pulex belongs to the omnivorous organisms, but, depending on the conditions of subsistence, in its rations either plant or animal food can predominate.

Final report on the updating service on environmental chemicals in freshwater for the period 9.1.89 to 9.7.89

This report presents five batches of data which have been despatched to the Joint Research Centre, Ispra. The data as been allocated to various ECDIN (Environmental Chemicals Data and Information Network) files. The data comprises environmental chemicals in the freshwater environment, taking in paricular consideration: aquatic toxicity, bioaccumulation, metabolism and elimination biodegradation.

Workshop on turtle bycatch mitigation for longline fisheries: experimental design and data analysis, 7-8 November 2007, San Ramón de Alajuela, Costa Rica

Large numbers of fishing vessels operating from ports in Latin America participate in surface longline fisheries in the eastern Pacific Ocean (EPO), and several species of sea turtles inhabit the grounds where these fleets operate. The endangered status of several sea turtle species, and the success of circle hooks (‘treatment’ hooks) in reducing turtle hookings in other ocean areas, as compared to J-hooks and Japanese-style tuna hooks (‘control’ hooks), prompted the initiation of a hook exchange program on the west coast of Latin America, the Eastern Pacific Regional Sea Turtle Program (EPRSTP)1. One of the goals of the EPRSTP is to determine if circle hooks would be effective at reducing turtle bycatch in artisanal fisheries of the EPO without significantly reducing the catch of marketable fish species. Participating fishers were provided with circle hooks at no cost and asked to replace the J/Japanese-style tuna hooks on their longlines with circle hooks in an alternating manner. Data collected by the EPRSTP show differences in longline gear and operational characteristics within and among countries. These aspects of the data, in addition to difficulties encountered with implementation of the alternating-hook design, pose challenges for analysis of these data.

Comparative evaluation of the proximate composition of smoked and salted-dried Oreochromis niloticus

This study was carried out to evaluate and compare the shelf life of smoked and salted-dried Oreochromis niloticus over a relative time period. Improved traditional smoking kiln and salting were employed respectively. The smoking kiln was constructed with iron metal with a dimension of 120cm x 70cm and consisting of three smoking racks with dimension of 30 x 30cm each. Table salt was used for preservation of some of the specimens. A total of 30 samples weighing 7.1kg were used. Fifteen (15) samples each were used respectively for smoking and salting. Satisfactory smoking was achieved in two days while salting to dryness was accomplished in four days. The initial percentage proximate compositions of the smoked products were 7.94%, 66. 97%, 8.`84% and 2.96% for moisture, protein, lipid and ash respectively, while that of the salted products were 8.37%, 63.93%, 12.91% and 3.95% for moisture, protein, lipid and ash. Preliminary results of the proximate compositions of the two products at the end of the fifth week of storage were as follows; 8.23%, 65.70%, 10.63% and 2.23% for moisture, protein, lipid and ash respectively of the smoked products, while 6.33%, 64.25%, 11.28% and 2.38% represent the values of moisture, protein, lipid and ash of the salted-dried products. By the individual product proximate characterization, it was discovered that both products were still relatively in good and acceptable condition. However, the protein and moisture values of the smoked products were relatively greater than those of the salted-dried products, while on the other hand, lipid and ash were relatively greater in salted-dried products. The prevailed relative higher moisture in the smoked products constitutes a predisposing condition for microbial activity and spoilage of the products, while the relative higher percentage lipid in the salted-dried products predisposes the products to lipid oxidation and rancidity.

Campagne Nizery Togo 7 (19 au 21-O7-84): resultats des chalutages

This publication gives the results of the bottom trawlings made during the cruise TOGO 7 by the oceanographic research vessel Andre Nizery on the continental shelf of Togo during the estimation program of halieutic resources.