Search

A total of 732 Thornback Rays (R. clavata) were examined for length, wingspan, weight, sex and food in two bays on the west coast of Ireland. The samples were taken by rod and line during angling festivals in Clew Bay in June 1971 and in Broadhaven Bay in September 1971. The length/wingspan relationship for both sexes in both areas was found to be linear and the wingspan/weight relationship was the same for both sexes. The males become mature between 15.0 and 17.0 inches (38 to 43 cm) wingspan, while the females become mature between 18.0 and 20.0 inches (45.5 to 50.5 cm) wingspan. The sex ratio of males to females in each of the two samples was 1:1 in Clew Bay and 1.4:1 in Broadhaven Bay. The main food items in the stomachs of the rays from Clew Bay were Macropipus spp. (44 per cent), Crangon (23 per cent), Carcinus (21 per cent) and Lamellibranchs (10 per cent). In Broadhavcn Bay Ammodytidae (21.5 per cent), other fishes (19.5 per cent) and Macropipus spp. (14 per cent) formed the bulk of food items. A total of 71 R. clavata were tagged in Broadhaven Bay in the summer of 1971 and to date there have been 8 recaptures 7 within Broadhaven Bay. The days at liberty varied from 0 to 775 and the greatest distance travelled was 14 miles.

The purpose of the present study was to confirm the migratory habits of the anchovy, Lycengraulis olidus (Günther), between fresh and sea water environments. Anchovies were examined from three freshwater localities: Bella Vista and Rosario (Paraná river) and Punta Lara (La Plata river), and from four marine localities; Mar del Plata, Bahia Blanca, San Blas and Patagones, all in the Argentine Republic. Five meristic and nine morphometric characters were selected for study, namely: vertebrae; dorsal, pectoral and anal fin rays; gill rakers on the first gill arch; head-length; body-depth; distance between the snout and dorsal, pectoral, ventral and anal fin; eye-diameter; snout and maxilary. The food of the anchovy in fresh and sea water consists principally of fish and crustaceans including copepods, paleamonids, sergestids and larvae of Brachyura. The condition factor of the anchovy was lower in the fresh-water samples and higher in the marine samples. (PDF has 32 pages (two pages on each) Reimpresión de Contribución científica. Serie Zoología, Universidad de Buenos Aires, Facultad Ciencias Exactas y Naturales vol.1(3):127-183 Submitted by: INIDEP Library

Johann Heinrich von Thunen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung – Information on Fishery research in 2010