The temperature dependence of the development of the embryo in Mesocyclops leuckarti (Claus) and Cyclops scutifer

This work is mainly intended as an addition to the studies of the populations dynamics of Cyclops scutifer, which is part of the ”Latn ja jaure project” (a study of the principles involved in the ecosystem of a small -initially fish free- mountain lake, before and after the introduction of fish). The field work consisted of sampling in Lake Erken in Roslagen in June, July and September, as well as in Latn ja jaure in the Abisko mountains in August and September of 1965. Additional sampling was done in Latn ja jaure for the study of the horizontal, vertical and temporal distribution of Cyclops scutifer, as well as the in situ development of the different stages. These samples have been analysed in such a way as to fit into the frame work of future studies on the population dynamics of Cyclops scutifer, The main aim of the present investigation is the determination of the dependence upon tempera- tare of the development of the embryo in the subarctic Cyclops scutifer as compared with the conditions found in the warm water species Mesocyclops leuckarti.

Contributions to the knowledge of larval development in Cyclops leuckarti Claus [Translation from: Natura, Milano 19, 89-96, 1928]

Taxonomic observations on the larval forms of Cyclops leuckarti are being discussed and compared with Cyclops oithonoides var. hyalina. Observations include Nauplius and Metanauplius stages. The author concludes that specific differences are recognisable even in the nauplius stages.

Der Haftwasseranteil bei Heringsanlandungen über Bandwaagen

In 2004 the fish processing company Euro-Baltic Fischverarbeitungs GmbH Mukran, went into operation on the Isle of Rügen at the Baltic coast of Germany. About 20 % of the herring landed there is discharged from the cutters into the processing plant by pipes, driven by pumps, in case that the landed volume exceeds 10 t fresh weight. In such case the herring is transported in water suspension by means of a pressure-vacuum suction pump system into containers and further transported via conveyer belt to a flowscale. During this process most of the water runs off. It is however unknown how much water remains with the fish and is eventually weighted as fish. To estimate this proportion the mixture of water and fish was stored in special transport containers, which allow the measurement of the run-off. As a result the study shows that on average 2 % of weight measured by the tape scale is water. Along with this factors were determined which influence the variability of the proportion of water.

Sind die bestehenden Regulierungsmaßnahmen für die Flunderfischerei in der südwestlichen Ostsee sinnvoll?

The reliability of the international minimum landing size of 25 cm for the flounder stock of ICES Sub-divisions 24 and 25 as well as national bans on landing female flounder during the spawning time is investigated on German samples taken in Sub-division 24. The results of the analyses of growth, sex ratio, the proportion of mature flounder, and yield curves show that 25 cm is a convenient regulation measure but it would be reliable to have an international ban on landing female as well as male flounder during spawning time.

Der Anteil Transportwasser bei Heringsanlandungen mittels Vakuumsauganlage in Großraumbehältern

Estimation of the water content of herring landings caused by pressure-vacuum double tank pumps and using of multi purpose transport containers About 80 % of herring that is landed in the fish processing company Euro-Baltic Fischverarbeitungs GmbH Mukran, on the Isle of Rügen at the Baltic coast is transported from the cutter into the processing plant by pumping. For this purpose 700 l-Euro-size polyethylene tubs (containers) are filled with herring by means of a pressure-vacuum pump-systems during the unloading of the cutter. To be able to pump the fish from the hold on board it is kept floating in water (transport water). At the end of the pumping/transporting process the fish ends in a dewatering box before reaching the tub, where the transport water is separated from the fish. Then, the not completely dewatered fish is slipped into the transport containers. The amount of transport water reaching the containers depends on the type of PV-equipment and on the amount of transport water in the fish holds of the different cutters. Methodologically the mixture of fish and water must be weighed together. For the experiments specially designed transport container were used which allow the measurement of the run-off of the water to be quantified and thus to measure the proportion of water remaining with the fish. Based on 30 experiments it could be shown that on average 6 % of remaining weight of the mixture is water. Furthermore, factors were detected which influence the variability of the proportion of water.

Sind südliche Arten in Nord- und Ostsee auf dem Vormarsch?

The long and warm summer 2003 resulted in water temperatures of about 2°C above the average. This promoted the immigration of southern species like the Anchovy, the Sardine, the Red Mullet and different Squid species. The possible conclusions of such invasions concerning the ordinary species of the area are rather contradictory: For the Western Baltic a positive correlation between the occurrence of Anchovy and a good Cod year-class is shown. For the southern North Sea, stomach investigations of Squid make a negative effect on fish eggs and larvae more likely.

Ein Modell der mathematischen Optimierung zur Bestimmung der optimalen Größe und Struktur der deutschen Fischereiflotte unter stochastischen Bedingungen

A mathematical model to optimize the German fishing fleet is draftet and it’s data basis is described. The model has been developed by Brodersen, Campbell and Hanf in 1994 to 1998. It could be shown, that this model is flexible enough to be applied successfully to a lot of very different political questions, if adapted accordingly. The economic consequences of measures of fishery politics, the effects of technical advances, but also increasing incertainties can, to some degree, appropriately be assessed quantitatively. Finally it could be shown that, principally, the available account of data is a good basis for investigations into fishery economics and fishery politics. However there is a need to treat the source of data continuously and competently in order to make these informations available quickly. Statistical data to reflect the fishery sector are valuable. However, they obtain their full value only when judged by experts from the fishing industry, biology and technical fishery research.

Aktuelle Aspekte und Besonderheiten der deutschen Flunderfischerei in der Ostsee im Jahr 2002

Although the fishery on flounder in the German fishery zone in 2002 was characterised by good catch possibilities, a dramatic decrease of landings was observed because of marketing problems and low prices. Due to increasing international fishery pressure on flounder a quota system should be established in the future. The German flounder landings could be increased by a better marketing strategy to meet the optimal requirements for a reliable German quota. For 2003 the stock condition is expected to be good which could ensure a successful flounder fishery. It is necessary to stabilize the present technical measures for a better selection of the codend in the medium term.

Entwicklungstendenzen der Steinbuttfischerei in der Ostsee

The economical value of turbot (Psetta maxima) from the Baltic Sea has distinctly increased in the past decade. Compared to the eighties the catches of this species on the main fishing grounds increased threefold. Besides a more directed fishery on this species and an improved catch statistic the main reason for this fact is probably an increased stock size. Improved protection measures caused three consecutive strong year-classes. The main parameters of the turbot stock are presented.

Aspekte der Plattfischfischerei Mecklenburg-Vorpommerns in der Ostsee 1992

Von den wirtschaftlich genutzten Fischarten in der Ostsee haben die Plattfische nach Hering, Dorsch und Sprott den vierthöchsten Fanganteil. Mit dem Rückgang des Dorschbestandes wuchs ihr Stellenwert weiter, zumal sie ohnehin eine wertvolle Sortimentsbereicherung für die im Vergleich zur Nordsee deutlich geringere Artenvielfalt an Konsumfischen darstellen. Absolut dominierend ist die Flunder. Hauptfanggebiete der deutschen Plattfischfischerei in der Ostsee sind die Mecklenburger Bucht und die Arkonasee.

On the ecology of species belonging to the genus Mesocyclops Sars (Crustacea, Copepoda) dwelling in the water-bodies of the Urals and Pri-Ural territory. [Translation from: Zoologicheskie Zhurnal 44(1) 127-130, 1965. ]

In the waterbodies of central Russia, the Urals and western Siberia four species of Crustacea, related to the genus Mesocyclops, are widely distributed: M. (s.str.) leuckarti (Claus), M. (Thermocyclops) oithonoides Sars, [M.](Th.) crassus (Fisch.) and M. (Th.) dybowskii (Lande). Numbers and biomass of Mesocyclops oithonoides in the pelagic water of various water-bodies of the Urals are presented and observations on the above mentioned species are discussed.

Accumulation of Heavy Metals in Franciscanas from Buenos Aires Province, Argentina

Marine mammals accumulate heavy metals in their tissues at different concentrations according to trophic levels and environmental conditions. The franciscana (Pontoporia blainvillei) is a small coastal species inhabiting the marine and estuarine areas of the Southwestern Atlantic Ocean. Its diet includes numerous species of small fish, squid and crustaceans. The aims of this study were to (i) assess the heavy metal concentration and burden distribution in different franciscana age classes and sex, and to (ii) evaluate both the accumulation processes and the transplacental transference of zinc, cadmium, copper and total mercury. Heavy metal concentrations (wet weight) were determined in eighteen dolphins by Atomic Absorption Spectrophotometry (AAS), by the cold vapour technique (mercury) or with air/acetylene flame (cadmium, zinc and copper). Liver showed the highest concentrations of mercury (max. 8.8 mg/g), zinc (max. 29.7 mg/g) and copper (max. 19.0 mg/g), whereas the highest cadmium concentrations (max. 6.7 mg/g) were found in kidney. Adults contained the highest concentrations for all heavy metals, followed by juveniles and calves in decreasing order, suggesting an age-related accumulation. No differences (p<0.05) were found between sexes within each age class. Organ burden distribution followed the same pattern for all metals and age classes: liver tissues contained maximum burdens. Mercury concentrations were higher than those of cadmium in both foetuses and newborns; and neither metal could be detected in the foetus. The analysed data suggested differences in the placental transference between metals, being significant for mercury and almost null in the case of cadmium. We can conclude that franciscana accumulates heavy metals and, due to its coastal distribution, it may be considered as a biomonitor of its environment. SPANISH: Los mamíferos marinos acumulan metales pesados en sus tejidos cuyas concentraciones están en relación con su nivel trófico y las condiciones ambientales. La franciscana (Pontoporia blainvillei) es una especie costera que habita áreas marinas y estuariales en el Atlántico Sudoccidental. Su dieta está constituída por peces, como item alimentario principal, calamares y crustáceos. El objetivo del presente trabajo es estudiar la distribución de metales pesados en diferentes clases de edad y en ambos sexos, evaluando procesos de acumulación y cargas de cadmio, mercurio total, cinc y cobre. Las concentraciones de metales pesados (en peso húmedo) fueron determinadas en dieciocho delfines por Espectrofotometría de Absorción Atómica (EAA), usando la técnica de vapor frío (mercurio) o llama de aire/acetileno (cadmio, cinc y cobre). El hígado presentó las concentraciones más altas de mercurio (máx. 8,8 mg/g), cinc (máx. 29,7 mg/g) y cobre (máx. 19,0 mg/g), mientras que las más altas de cadmio (máx. 6,7 mg/g) fueron encontradas en el riñón. Los adultos presentaron los niveles más altos, presentando los juveniles y cachorros concentraciones menores, lo cual sugirió una acumulación con la edad. No se encontraron diferencias significativas (p < 0,05) entre sexos dentro de cada clase de edad. Las cargas de metales pesados en los órganos presentaron la misma disribución para todos los metales y clases de edad. Los valores más altos fueron encontrados en el hígado, incluyendo los correspondientes a cadmio. Las concentraciones de mercurio y cadmio fueron no detectables en el feto, mientras que las de mercurio fueron superiores a las de cadmio en los cachorros. Los datos encontrados en el feto sugieren una transferencia nula a través de la placenta. Podemos concluir que P.blainvillei acumula metales pesados en sus tejidos y debido a su distribución costera, esta especie puede ser considerada como un biomonitor de su ambiente.