Vertical and Seasonal Variability of Fish Eggs and Larvae at Ocean Weather Station “India”

Abstract

The vertical distribution of the zooplankton in the upper 500 m atstation 'India' (50{degree}00'N-19{degree}00'W) was determined froma series of olbique hauls using Longhurst-Hardy Plankton Recorders.The hauls were taken at weekly intervals from the end of March tothe beginning of Oct during 197l and 1972. Included in this samplingprogramme was an intensive study of primary production by the C Sub(14)method, chlorophyll a, spp composition of the phytoplankton, nutrients,temp and salinity. Fish eggs and larvae were identified and theirdistributions plotted in no/m Super(3) over the sampling period.The most abundant fish eggs were the characteristic eggs of Maurolicusmuelleri (Gmelin), which first appeared in early April and reachedpeaks of abundance in both years of 5 eggs/m Super(3) in late Juneat depths between 150 m and 200 m. During l971 the eggs were distributeddown to 500 m in late July and Aug. The distribution of Maurolicuseggs closely followed the 9{degree}C isotherm, the eggs remainingin water between 8.8{degree} and l0{degree}C. Nine spp of fish larvaewere identified from the LHPR hauls. These were: Argyropelecus hemigymus(Cocco, l829), Benthosema glaciale (Reinhardt, 1937), Cyclothonebraneri (Jespersen and Taning, l926), Maurolicus muelleri, Micromesitiuspoutassou (Risso, l826), Molva byrekelange (Walbaum, l788), Myctophumpunctatum (Rafinesque, l810), Onogadus (Gaidropsarus) argentatus(Reinhardt, 1842).The most abundant of these larvae were those ofM. meulleri which reaches densities of 20 larvae/m Super(3) in thesurface waters (0-30 m) in Sept 1971. The majority of the larvaewere distributed in the upper 200 m in both years. The annual distributionof abundance of the fish larvae were correlated with the availablefood, the main predators such as Sagitta maxima (Connant, l896) andthe prevailing physical parameters.