In this paper we present our initial findings from investigating the dampening of acoustic signals through dense fish layers, referred to as shadowing. These findings are based on measurements which were performed in the Mediterranean Sea and off the Norwegian coast using gilthead seabream and Atlantic salmon respectively. The paper also presents the experimental setup for data acquisition. The results from the initial data analysis show that the shadowing effect is measurable and indicate that it can be compensated for. Future work will include the creation of a compensation strategy for this effect.