Cornelius Hammer

FATIGUE AND EXERCISE TESTS WITH FISH

Abstract The terminology and classification of swimming speeds are summarized. The physiological basis for the classification of swimming speeds is briefly explained with regard to burst, prolonged, cruising speed, and the velocity which is critical to fish. The protocols of fixed (fatigue) velocity tests and increased (incremental) velocity tests are reviewed. The experiments carried out by different authors are compared with respect to their methodological approaches, the main focus being on the different time intervals and velocity increments employed. From the comparison, it appears that time intervals between 2 and 75 min have been employed. Yet, it is shown that there is agreement that time intervals of longer than 15–20 min are not necessary if the critical velocity alone is needed. The dependency of the critical swimming speed (CSS) on factors such as race and population, size, season and temperature, sex, pollutants, light, food, training, and ambient gas content is outlined. The comparison shows that only the influence of pollutants and training on the CSS have been investigated in more detail, making further comparative studies on the dependence of the critical velocity on these factors necessary. Evaluation: since the CSS of fish depends on all these factors, it would appear to be a very sensitive measure for environmental or physiological factors. However, it is difficult to compare even intraspecific studies because of the individual variability and the dependence of swimming performance on the stock, population, gender and precondition level, making the calibration of the tests very complicated. It is shown that little is known about the mechanistic influence of internal or external factors on the CSS. Therefore, the CSS is of less interest for the physiologist than for the ecologist. Tests on the critical velocity have been successfully employed as an alternative to ld 50 tests, although, once again, it is difficult to standardize the tests, and environmental factors, such as pollutants, may themselves influence the swimming performance since the metabolism can, in turn, in some cases depend upon the level of swimming performance itself.

Quantification of age pigments (lipofuscin)

1. Three methods have hitherto been applied for age pigment quantification: (a) numerically from micrographs; (b) fluorimetrically from histological sections; (c) spectrofluorimetrically from dissolved age pigments. 2. The spectrofluorimetric method is at present the most commonly used technique for quantification of age pigments. 3. By comparing the related publications since introduction of the spectrofluorimetric method, it has become apparent that few authors specify fluorimetrically significant factors, such as temperature and pH which influence the sample fluorescence during measurement. 4. Recent developments in fluorimetrical age pigment quantification using chloroform/methanol as solvent have additionally revealed the necessity to measure and present the age pigments dissolved in both phases: the polar and non-polar solvents.

The Role of Stock Identification in Formulating Fishery Management Advice

Publisher Summary There is a marked difference in the perception and application of the concept of “stock” between fishery biologists and fisheries managers. For a particular stock, the Total Allowable Catches (TAC) advice given by fishery biologists refers to biological entities, while the official TAC in most cases refers to a management unit, and both do not necessarily match. This occasional mismatch has existed ever since the stock and TAC concepts have been implemented, and it is clear that, in order to avoid more misunderstanding, the managerial units need to be adapted as far as possible to biological realities. However, even if this were the case, such a management regimen is not able to cope with the fact that in a number of cases stocks migrate and mix with stocks from other management areas and are caught together. One has to acknowledge that the whole concept of stock separation and the idea of science supporting sensible management by defining biological entities has basic limitations. Such a concept could work only if methods exist to identify members of different stocks in the catches of mixed aggregations. Science is in need not only of better defining stock characteristics and boundaries but also of developing tools for stock separation from the catches. These developments will not be possible without far more basic research and data collection on a routine basis.

Accumulation of fluorescent age pigments in embryos and larvae of pike,Esox lucius (Esocidae, Teleostei) at different incubation temperatures

SynopsisAccumulation of fluorescent age pigments (FAP) was measured in pike,Esox lucius, during embryogenesis and larval development at different temperatures. Chloroform-as well as methanol-soluble age pigments from eggs and larvae were quantified. Chloroform-FAP accumulated linearly with embryonic and larval development. After yolksack resorption, FAP concentrations reached a maximum and declined thereafter. Chloroform-FAP accumulation was not temperature dependent. Similar patterns of methanol-soluble pigment accumulation were found but accumulation of methanol-FAP was, in contrast, significantly temperature dependent. As a result, methanol-FAP concentrations increased in direct proportion to the rising incubation temperature, but the maximum methanol-FAP fluorescence was found at 15°C and not at 180°C.

A review on herring, Clupea harengus (Actinopterygii: Clupeiformes: Clupeidae) recruitment and early life stage ecology in the western Baltic Sea

Herring, Clupea harengus L., is an important commercial fish species in the Baltic Sea region since medieval times. The western Baltic spring spawning herring (WBSS) is one of three major Baltic Sea herring stocks, supporting a significant over-regional fishery in the western Baltic Sea as well as in the Kattegat and Skagerrak area. One major component spawns in the vicinity of the German island of Rugen and the associated major spawning ground, the Greifswalder Bodden (GWB), a shallow, semi-enclosed sub-system of estuarine character. Research of herring biology and ecology has an extensive history in the area probably due to the long fishery tradition and the importance of this particular herring stock for the local Baltic coast economy. In this review most of the scientific findings about WBSS in its spawning areas, mainly the GWB, is summarized. This study is based on critical review of over 120 publications and scientific sources from the past 100 years containing relevant information on possible consequences of multiple environmental and anthropogenic induced stressors of herring recruitment and productivity. Besides current peer reviewed literature a significant amount of grey literature was included, consisting primarily of papers and reports written in German language and representing the only historical data sources and published documentation of regional western Baltic herring ecology.

Zum Beispiel Kabeljau und Hering: Fischerei, Überfischung und Fischereimanagement im Nordatlantik

Der Zustand der genutzten Fischbestande weltweit und in europaischen Gewassern ist vielfach besser, als landlaufig angenommen wird. Die entscheidende Rolle spielt dabei eine nachhaltige Bewirtschaftung. Das Kapitel zeigt am Beispiel des Herings, des Nordsee-Kabeljaus und des Nordost-Arktischen Kabeljaus, wie sich das europaische Fischereimanagement entwickelt hat und welche Herausforderungen fur Wissenschaft und Politik bevorstehen. Auserdem wird auf bedrohte marine Fischarten eingegangen.