Poland, south part of Zatoka Popmorska between Swinoujscie to Miedzyzdroje, coastal waters 3 miles from the coastal line (14° 17'E - 14° 26'E and 53° 55'N - 54° 00'N)

Fish abundance in water bodies; Salinity of the water column; Temperature of the water column

The aim of the investigations is the spatial and temporal localisation of spawning grounds of herring on the basis of density, distribution and growth ratio of its larvae, determination of differences in intensity and effectiveness of herring spawning in the years 1982-1995, and determination of species composition, distribution and density of the rest of ichthyoplankton. Samples are taken on the grid of stations (6-10 stations) approximately every 15 days during the months of April, May, June each year. At each station temperature and salinity are measured in surface and bottom layers of waters and Bongo is towed by 15-20 minutes, filtering between 800-1000m**3 of water. Plankton is preserved in formalin and ichthyoplankton (eggs of Sprattus sprattus, larvae of Spratus spratus, Clupea harengus, Gobiidae, Osmerus eperlanus, Pleuronectiformes, Cottidae, Syngnathidae, Belone belone) is extracted from it. The number of larvae is calculated on 1000 m**3. The standard length (SL) of herring larvae caught at each station is measured in time series. This allows the calculation of the growth ratio on the basis of the increasing mean SL in the temporal series. The intensity and effectiveness of herring spawning are determined from density, distribution and growth ratio data. The data are stored in paper files (14 files for the years 1982-1995). Each file contains 2 to 7 paper jackets (66 jackets), each jacket contains 2 to 17 paper cards (499 cards). One card contains the following information: day, months, year of sampling, symbol of station (corresponding with geographical position), depth of waters, salinity and temperature of surface and bottom waters, number of flowmeters' revolutions and volume of filtrated water (m**3), time of Bongo tow, species identification, the number of fish larvae (caught and in 1000m**3) and the length frequency of herring larvae.

Sea Fisheries Institute, Research Station in Swinoujscie
pl. Slowianski 11
Swinoujscie
Zachodniopomorskie
72-600
Poland