Zooplankton Investigations in some Fjords in Western Norway during 1950-1951

At the end of February 1950 investigations on zooplankton were initiated in some fjords south of Bergen on the west coast of Norway, and continued during 1951. Simultaneously hydrographic observations were also taken. Of all copepods occurring Calanus finmarchicus was the most important. The highest numbers were observed in 1950 in May and July, and in 1951 in April and July. When the maxima of Calanus finmarchicus occurred the greater part of the stock was found in the upper 50 m. water layers. Spawning took place in Februar-March, May-June and in September, the most important one in May-June. Pseudocalanus minutus was, next to Calanus finmarchicus, the most important species in the upper 50 m. Maximum number occurred in July both years. Temora longicornis was found to be most numerous in July and Acartia clausi in July and September. The larger copepods Pareuchaeta norvegica, Calanus hyperboreus, Metridia longa, M. lucens and Chiridius armatus were found sparsely in the upper water layers. In the deeper hauls they were more numerous and because of their size made up a greater part of the volume, this was especially the case in the outer districts. Of other organisms Limacina retorversa was very abundant in July 1950 but sparsely present during 1951. The highest total number of organisms occurred in May, July and September 1950. The largest volume of plankton were found in May and July 1950 and in April and July 1951. A longitudinal section of the Hardangerfjord showed great differences from the inner to the outer part of the fjord, the volume of plankton being much higher in the outer part, especially in the deeper hauls. The Lusterfjord in Sogn was entirely different from the fjords in the Hardanger area. The total number of organisms and the volume of plankton were much smaller here. The greatest percentage of fat was found in May and July, and of protein in May, July and September in the upper 50 m. during 1950. The deeper hauls showed a great percentage of fat and protein in the late autumn. The maximum in olume of plankton and the highest percentage of fat coincided with the maximum in number of Calanus finmarchicus. A comparison is made with previous work in this and other areas.