MESH SELECTION OF COPEPODITE AND NAUPLIUS STAGES OF 4 CALANOID COPEPOD SPECIES

High-speed plankton nets, using mesh sizes of 61, 90, 124, 190 and 270-mu-m, were deployed in the North Sea to catch Calanus spp., Pseudocalanus minutus, Paracalanus parvus and Temora longicornis. These species were identified to their nauplii, copepodite and adult stages, and the numbers caught in each stage were converted to numbers m-3 seawater filtered. The width and length of a representative sample of each stage was measured, and the proportion caught by the different mesh sizes is presented. The selection pattern was described by a mathematical model, which showed that a mesh size of 75% of the copepod carapace width catches approximately 95% of the individuals of that size present in the seawater. Some recommendations for mesh sizes required to sample copepods are given.