An interview-based approach to assess sea turtle bycatch in Italian waters

The loggerhead sea turtle (Caretta caretta, Linnaeus, 1758) is the most abundant sea turtle species in the Mediterranean Sea, where commercial fishing appears to be the main driver of mortality. So far, information on sea turtle bycatch in Italy is limited both in space and time due to logistical problems in data collected through onboard observations and on a limited number of vessels involved. In the present study, sea turtle bycatch in Italian waters was examined by collecting fishermen’s information on turtle bycatch through an interview-based approach. Their replies enabled the identification of bycatch hotspots in relation to area, season and to the main gear types. The most harmful fishing gears resulted to be trawl nets, showing the highest probabilities of turtle bycatch with a hotspot in the Adriatic Sea, followed by longlines in the Ionian Sea and in the Sicily Channel. Estimates obtained by the present results showed that more than 52,000 capture events and 10,000 deaths occurred in Italian waters in 2014, highlighting a more alarming scenario than earlier studies. The work shows that in case of poor data from other sources, direct questioning of fishermen and stakeholders could represent a useful and cost-effective approach capable of providing sufficient data to estimate annual bycatch rates and identify high-risk gear/location/season combinations.

Using Behavioral Observations to Develop Escape Devices for Freshwater Turtles Entrapped in Fishing Nets

The drowning of freshwater turtles following incidental capture in fishing gear has the potential to cause population declines. Fyke nets can be equipped with bycatch reduction devices that enable the escape of turtles before they drown. We employed quantitative and qualitative behavioral observations (with action cameras deployed underwater) to develop a new, collapsible, escape bycatch-reduction device that mounts internally in the terminal end of a fyke net. We also used behavioral observations to identify areas of the net most used by turtles, thus revealing the most logical placement for an escape bycatch-reduction device. When turtles were introduced into modified nets, escape was rapid (mean of 12.4 min), with 100% escape for map Graptemys geographica and musk turtles Sternotherus odoratus and 94% escape for painted turtles Chrysemys picta. Our preliminary field trials indicated that modified fyke nets decreased the capture rate of turtles relative to unmodified nets. Escape devices can be used as a key component of a bycatch reduction program and be particularly effective when paired with exclusion bycatch-reduction devices. The escape device developed in this study can potentially be used in the local fishery or modified for other fisheries. The use of behavioral observation to guide the development of bycatch reduction devices may provide an extra tool for managers to increase selectivity and maintain sustainable harvests of target fish.