In 1991 the Tethys Research Institute began a study in the Inner Ionian Sea archipelago. Initially intended to be a long-term investigation on the ecology and behaviour of common dolphins in a central Mediterranean hotspot, the study instead became a documentation of their sharp decline.
Common dolphins, formerly abundant in the Inner Ionian sea Archipelago, suffered a dramatic decline between 1995 and 2007, which was convincingly linked to overfishing of sardines and anchovies, their main prey (See Bearzi et al. 2006, 2008, 2010; Piroddi et al. 2011b, 2017 included in IDP bibliography list). Unpublished data recently collected by the IDP indicate that these same dolphin individuals, which have reduced their occurrence in the Inner Ionian Sea Archipelago by 90%, are now using a much wider area along the coastal waters of the Ionian Islands, and occasionally still visit the Archipelago’s inner waters, but in lower densities; this is presumably caused by the area’s decreased carrying capacity due to overfishing. Monitoring of local fishing fleet and ecosystem modelling approaches indicated a specially adverse impact by purse seiners, making up only 3% of the total fishing fleet but removing on average 33% of the total biomass captured by local fisheries. Moreover, it is this kind of fishing gear the one that has the highest impact on common dolphin prey.
Bottlenose dolphins are also regularly present in the area but are in large part transient, occupying a wider area along the Eastern Ionian Sea coast (Bearzi et al. 2011). However about 20% of the photo-identified individuals display high levels of residency and stable trends (Bearzi et al. 2005). Our aim is to monitor their status with the objective of maintaining it at current levels.
Main threats here include negative interactions with fisheries and disturbance from pleasure boats. With respect to the latter, the number of recreational boats and flotilla sailing companies operating around the Ionian Islands has steadily increased during the last two decades. The activity of this large fleet not only offers a huge potential for the recording of opportunistic cetacean sightings (report your sightings here), but also calls for the design of adequate education and awareness initiatives addressed to boat users. IDP personnel has frequently witnessed sudden changes in behaviour by dolphin groups as result of the large concentration of recreational boats not maintaining a minimum distance or simply chasing them, which indicates that boat traffic and disturbance pose an added pressure on local cetacean populations and, as reported in other areas worldwide with similar scenarios, leading to the disruption of the dolphin’s natural behaviours causing them unnecessary stress. When being out there, please Be Dolphin SMART.
The Inner Ionian Sea Archipelago is one of the few Mediterranean areas where monk seals can still be predictably encountered, and some remote and uninhabited islets appear to be part of the species’ core habitat. The potentially adverse impact to this endangered marine mammal by fisheries and tourist boats poses particular concern. When being out there, please Be Monk Seal SMART.