Description: In April 1990, 488 marine fish belonging to 30 species from central Phillipine waters were examined for flesh parasitic infections that may affect their consumability. One species of hemirhamphids and 3 species of belonids harboured plerocercoids of Otobothrium penetrans Linton, 1907 (Proceedings of the U.S. National Museum33, 85–126). This is the first record of this parasite from Pacific fish species. The highest intensity of infection found was 8 in Tylosurus crocodilus. Most of the larvae were located between the dorsal spines of the vertebral column, only 32% were found in the fillets. Based on the present material we give a description of the plerocercoid stage of the species using scanning electron microscopy of the armature and morphometrical measurements. Comparison to results from earlier findings of O. penetrons by Linton (1907; 1924, Proceedings of the U.S. National Museum64, 1–114) and to O. kurisi by Shields (1985, International Journal for Parasitology15: 635–643) lead to the conclusion that the latter species is a synonym for O. penetrans.

Description: In the tidal Elbe River between Hamburg and the estuary an assessment of fish stocks and fish diseases had been carried out in 1981-1986. Despite the decline of local fisheries, the river today still carries a rich fish fauna. Smelt and shad together contribute to 70 % of the fish biomass of anchor net catches. The remaining fishery today is sustained by eel catches. In the early 1980s, 70 % of the yearly income was from the sale of consumable eel, another 20 % from stock eel. Marketing of Elbe eel for human consumption, however, is forbidden due to high levels of toxicants in the fish. A rough comparison with anchor net catches from the end of the last century does not indicate serious changes in the frequency of the dominating fish species, except for a significant decrease in ruffe and a significant increase in pikeperch. The reduced fishing mortality today is partly compensated by power plants, which together with the cooling water take considerable amounts of fish out of the river. Recent surveys revealed a !arge variety of disease types and highly pathogenic parasites, some of which occur at very high prevalences. An ecological evaluation of this finding at present is not possible due to lacking data from other streams. High disease prevalences and low nutritional condition of flounder in the central estuary are attributed to naturally fluctuating salinities, which prevent the establishment of larger zoobenthos communities which could serve as fish food. The most serious problem for fish is seen in oxygen depletion which is observed regularly every year. However, the majority of fish emigrates from the Iow oxygen zone into shallow side arms and tributary rivers or assembles downstream in front of the low oxygen zone. Efficient rehabilitation measures are seen in a reduction of discharge of fertilizing substances into the river and in a re-opening or new construction of larger side arms.