The aim of this paper was to determen the change in composition of trammel nets in the Medulin bay during the transition from the cold to the warm part of the year, from March – July 2020. The trammel nets, with an eyes width of 32 and 40 mm respectively, were layed in the evening hours twice a month and pulled during the next morning. An analysis was conducted for each eyes width separately, and the catch was categorised into the following groups: fish, invertebrates, damaged fish, damaged invertebrates, seagrass, alge and anorganic material. The fish and invertebrate were additionaly grouped into two groups depending on existing economic value. The results showed a trend of decreesing amounts of economicaly valuable species during the sampling period. Invertebrates were numericaly the most abundant, while fish dominated in respect to biomass. The highest biomass caught belonged to the species Scorpaena porcus, for fish, and Sepia officinalis, for invertebrates. The tremmel net with an eye width of 32 mm had recorded a significantly larger amount of damaged individuals as well as untargeted flora and fauna and leads to the conclusion of a much larger negative impact on the suroundings in comparison to the trammel net with the larger eyes width.