Influence of water temperature on the efficacy of diquat and endothall versus curlyleaf pondweed

determine the impact of water temperature on the efficacy of the contact herbicides diquat (6,7-dihydrodipyrido [1,2- α:2’,1’-c] pyrazinediium ion) and endothall (7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic acid) for control of the exotic nuisance species curlyleaf pondweed (Potamogeton crispus L.) across a range of water temperatures.

Analyse der Beifangreduktion durch Gitternetze in der kommerziellen Garnelenfischerei

Trials for the determination of the magnitude of bycatch reduction by sorting grids used in the commercial brown shrimp fishery were carried out from September to December 1997. Trawls with 9 m beam length were used on different fishing grounds in the estuary of the Elbe River near Cuxhaven. The sorting grids tested were made of stainless steel bars spaced at 18, 20, 22, 26 and 30 mm, built into a cylindrical stainless steel frame with a diameter of 65 cm at an angle of attack of 45 degrees. This frame was positioned between the forenet and codend. Simultaneous hauls were made with a trawl of equal construction but without a sorting grid, and the weighed catch components (fish, discard shrimps and commercial size shrimps) separated by means of a riddle were compared. The composition of the sorted out part of the catch of the sorting grid net could be calculated by comparise the corresponding catch components in both the standard trawl and the sorting grid trawl. According to this the total catch of the beam trawl with the sorting grid is reduced by 18 to 38 % depending on the space between the bars. 7 to 31 % of the sorted out part of the catch consists of fish. The use of the sorting grid, however, also leads to losses of 4 to 12 % in Oktober. Per hour of towing this means a loss of 10,3 % commerical size shrimps with a sorting grid of 18 mm space between the bars and of 12,4 % for a 26 mm grid.

Analyse der Beifangreduktion durch Trichternetze in der kommerziellen Garnelenfischerei

Trials for the determination of the magnitude of bycatch reduction by the sievenets used in the commercial brown shrimp fishery were carried out from September to December 1997. Trawls with 9 m beam length were the subjected to the investigation. They were used on different fishing grounds in the estuary of the Elbe near Cuxhaven. Sievenets with 50, 60 and 80 mm mesh opening were tested in 29 hauls and 31.6 h total duration. A trawl of equal construction without sievenets fished synchronously was used for comparison. The proportional catch composition in the codend was determined by weighing the catch components (fish, discard shrimps and commercial size shrimps) as separated by means of a riddle. The composition of the sorted out part of the catch could be calculated by comparison of the corresponding catch components both in standard trawl and sievenettrawl. According to this the total catch of a beam trawl with sievenet is diminished by 9 to 34 % depending on the mesh opening of the sievenet. 32 to 58 % of the sorted out part of the catch consists of fish. Use of a sievenet, however, also leads to a loss of 6 to 15 % of commercial size shrimps. Per hour of towing this means a loss of 8.7 kg commercial size shrimps with a sievenet of 60 mm mesh opening and of 1.8 kg for a mesh size of 80 mm.

West Cumbria Special Fisheries Advisory Group 9th March, 1983

This is the report from the West Cumbria Special Fisheries Advisory Group meeting, which was held on the 9th March, 1983. The report contains sections on Fish Passes at Yearl Weir River Derwent, Ennerdale, and Ehen; River Calder abstraction and augmentation from boreholes; and the augmentation of River Ehen by minewater to support increased abstraction by BNFL. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

On methods of evaluation of bacterial production. [Translation from: Lietuvas TSR Mokslu Akademijos Darbai, C Serija 2(55) 3-9, 1971.]

By now a great deal of work is known concerning the methods of determining the production of bacteria or similar questions; among these the problems of a common terminology is discussed. The article discusses formulae of production of bacterial populations over time.