ABSTRACT
Production is the increase of biomass in time: P = dB/dt. High productivity is attained by rapid growth of individuals or/and population. Both patterns apply for gobies. Prior conditions to gain values of productivity are investigations of biomass at least two times during a year, optimally at the start and the end of the vegetation time. Zander and Hagemann (1986) found in the SW Baltic Sea under regard of seven samples in the year with mean densities of 247 two-spotted gobies (Gobiusculus fl avescens) and 107 sand gobies (Pomatoschistus minutus), maximally even 937 or 429 specimens above 1 m2, respectively. Production was calculated by the weights which increased in the course of a year. Th e great density of gobies amount to production values of 2.7 (G. fl avescens) or 2.6 g/m2 and year (P. minutus). Whereas these results are found in the near of a mussel belt at the shore, P. minutus and P. pictus together attain in a 6 m deep habitat values of only 0.6 g/m2 and year. At the Swedish west coast Th orman and Fladvad (1981) found values of maximally 0.75 g/m2 and year in G. fl avescens and Pomatoschistus microps each.
