Forekomst av egg og yngel av fisk i vest- og nordnorske kyst- og bankfarvann våren 1960

Abstract

In 1960 cod eggs and larvae were more abundant at Skrova in the Lofoten area than in the previous year (Table 1). Maxima of spawning and hatching occurred 14 days earlier than in 1959. On the western side of the Lofoten islands, at Eggum, cod eggs and larvae were scarce in 1960. On 31. March and 1. April cod eggs and larvae were numerous in the inner part of the Lofoten area (Fig. 3). The Nansen net and the Clarke-Bumpus plankton sampler have proved to be equally effective in catching eggs and newly hatched larvae of the cod (Table 2). In March-April 196O eggs of cod were found in smaller numbers over larger areas of the west coast with moderate concentrations at the Møre and Halten banks (Fig. 3). Haddock eggs were scarce along the slope from Træna to Andenes. In April eggs of saithe and Norway pout occurred in moderate numbers in the Vestfjord, but major concentrations were only met with farther south, from the Halten bank to Stad (Fig. 4). In March-April 1960 herring larvae were found in the coastal area from south of Bergen to Andenes, with major concentrations on the Møre-, Frøya-, Sklinna- and Halten-banks, in the order mentioned, mean numbers per m^2 of sea surface 630-230 (Fig.s 5, 6). The statement by various workers that herring larvae are caught to a greater extent by night than by day in traditional nets, was confirmed. A comparison between the catches in hauls with Nansen net and Clarke-Bumpus plankton sampler (Table 3) showed that during the night the two gears caught nearly the same number of herring larvae, 8-13 mm in length, per m^2 of sea surface (Table 3). When all hauls were included, the Nansen net took more than ten times as many, Clarke-Bumpus sampler nearly twice as many herring larvae during the night, as during the day. If three night hauls with high numbers of larvae were excluded from the mean, the night to day ratio for the Nansen net was 4.5/1, for the Clarke-Bumpus sampler 1.3/1. It is therefore assumed that the Clarke-Bumpus sampler is more effective than the Nansen net in catching herring larvae of the size mentioned, and may be used with a certain degree of reliability also during the day. In the middle of May larvae of capelin were abundant near Northcape (Table 4). Redfish larvae were numerous along the coast in May-June (Fig. 7).