To the best of our knowledge, this is the first study combining observational data of the "dinner-bell" effect of pingers with audibility tests in captive grey seals. Results from the study in the Baltic Sea did not provide significant evidence that the Aquamark100 pinger is audible to seals, and thus, produces a “dinner-bell effect”. However, the hearing thresholds obtained from the audibility tests in captive seals revealed that the Aquamark100 pinger should be heard up to distances of around 1.6 km. Therefore, there is a great potential for this pinger to produce a “dinner-bell” effect on seals. This supports a previous finding of the “dinner-bell” effect by Königson et al. (2007).

Even though no apparent “dinner-bell” effect was found on grey seals in the Baltic Sea towards the Aquatec2446 and Banana pinger, this study did not provide significant evidence that these pingers are indeed inaudible to seals (i.e. no significant evidence that these pingers do not cause a “dinner-bell” effect). Nonetheless, based on published audiograms (Ridgway & Joyce, 1975) and taking the frequency spectrum of the Aquatec 2446 and Banana pingers into account, it is suggested that these pingers are audible only for 58 and 76 m, respectively, meaning that their possible “dinner-bell” effect would be very limited. This suggests that both pingers could be considered inaudible to grey seals supporting, thus, a previous study by Cornwall Wildlife Trust (2013) that also found grey seals not to be significantly attracted to the 2012-generation of Fishtek Banana pinger.

Future studies may benefit from a “more realistic” scenario, where the use of live fish is taken into consideration as they seem to be more attractive to seals than dead fish. Moreover, a study where pingers are tested close to fisheries or hauling sites while using the same fishing gear that seals normally damage and create conflicts with fishermen would be beneficial. If the same set-up as in this study should be used, it would be adequate to investigate sites where seals cause the most severe damage and losses, for instance, the Golf of Bothnia (Fjälling 2006). Furthermore, in order to further investigate seals’ suspected investigative behavior to this ‘novel’ object, it would be appropriate to test pingers in stations/fishing gear with and without fish as bait. This would go along with underwater cameras to investigate seal behavior around the gear.