The Oslofjord, once populated by ample cod, has seen a significant decline in this species, yet recent studies reveal a thriving population of herring (sild), sprat (brislng), and anchovy (ansjos). Researchers from the Institute of Marine Research conducted assessments using echo sounders and trawls, estimating nearly 3,000 tons of sprat and 2,700 tons of herring in the area. Furthermore, there are around 200 tons of anchovy present. These findings reveal that, while the biomass of these fish species has increased since the last survey over a year ago, the growth is primarily due to the aging of the fish, who are now larger rather than an increase in population numbers.