ABSTRACT
Commercial fishing pressure has selective effect on the exploited fish stocks, usually targeting individuals with larger individual growth rate/size and older age. Therefore, variability in the spatial and temporal fishing pressure is believed to result in fluctuations of fish species individual traits, like age/size structure of fish stocks. The intensity of fishing pressure can strongly affect the stock structure, and even destabilize the stock. We used two different sources (fishery independent survey results and commercial fishery) to evaluate the indicators of spatial variability in fishing pressure in parallel to fisheries-independent survey information to evaluate the possible effects of spatial concentration of fishing on sprat (Sprattus sprattus) and Baltic herring (Clupea harengus membras) populations in the Northeastern Baltic Sea. The study revealed no evidence in linking spatial concentration of fishing pressure and change in age structure or average body weight of fishes. Variable fishing pressure was linked to variabilities in stock size, which indicates that fluctuating harvest may cause undesired fluctuations in stock decline scenario. The results also indicate high mobility and plasticity of Baltic pelagic fish species in intensively exploited areas.
