TursioNet & T-Buoy

sensing the world


Acoustic Buoy with raspberry acoustic signal classifier, 2.4GHz wlan, GSM remote control and Satellite GPS position transponder and beacon
(development 2022).
In an attempt to reduce depredation and mitigate conflict between bottlenose dolphins and fishermen, the use of acoustic deterrents has been proposed. These are devices attached to the net that are activated in the presence of the animals (by acoustic sensors) and emit deterrent sounds in an attempt to draw the animals away from the fishing gear. However, bottlenose dolphins have shown the ability to become accustomed to the sounds in a relatively short time and thus bypass the deterrent. Modern devices emit a variety of sounds to delay the learning process, but bottlenose dolphins appear to be able to 'generalise' the signal from the device and the long-term effectiveness of acoustic deterrents remains uncertain. Acoustic deterrents also contribute to noise pollution, potentially conflicting with descriptor 11 of the Marine Strategy Framework Directive (Introduction of energy, including underwater noise, is at levels that do not adversely affect the marine environment).

With regard to the impact on bottlenose dolphin population units, data collected through the diagnostic activity carried out by C.Re.Di.Ma. on cetacean carcasses beached in Liguria since 2015 (Reports Spiaggiamenti C.Re.Di.Ma. 2015-2016-2017-2018-2019) have revealed a non-negligible and certainly underestimated role of interaction with fishing activities and vessel impact as a cause of death in the area, and, in particular, a significant increase in bycatch injuries from 2020 to date.

The added value of the TursioNet Project in relation to the previous point:
From the above considerations comes the idea to develop the present project, with an alternative approach to the (in our opinion ineffective) use of acoustic deterrents. Our approach involves targeted monitoring activities and a continuous dialogue with fisheries operators, including through information and awareness-raising activities.
To achieve this, TursioNet intends to develop an automatic device (and protocol for its use) to detect and report interactions between bottlenose dolphins and artisanal fisheries. The information (i.e. the presence of bottlenose dolphins on the fishing gear) will be sent directly to a terminal on land and will be visible on a map updated in real time.

The device will be able to
  • report its position and correct functioning at the moment it is activated and placed on the net;
  • report the geographical position of the net during the set;
  • report the presence of bottlenose dolphins around the gear by means of an acoustic signal recognition system;
  • based on the acoustic signal analysed by the device (i.e. the acoustic behaviour of the bottlenose dolphins), report the interaction between bottlenose dolphins and fishing gear.

The use of the device (and its protocol) will make it possible to enhance and improve the monitoring of interactions between bottlenose dolphins and gillnets (and their evolution over time) and assess their impact on small-scale fisheries.
The information acquired through this new automatic monitoring technique will enable the following questions to be answered in the long term.

Which fishing areas/units are most affected?
Is there a seasonality in the depredation behaviour, possibly related to the behavioural ecology of the bottlenose dolphin and its usual prey?
Is the phenomenon of gillnet depredation increasing (in space and/or time)?
What is the impact on artisanal fisheries?
What solutions does greater knowledge of this behaviour suggest to mitigate the conflict (see action A8)?

In parallel to the study and monitoring of interactions between bottlenose dolphins and gillnets, an analysis of cetacean strandings in the intervention areas and of the main causes of death identified will be carried out, with the recovery of retrospective data and data from the ongoing monitoring activity.
During the project particular attention will be paid to the evaluation of the interaction with fishing activity through the application of standardized diagnostic frameworks developed within the LIFE DELFI18 NAT/IT/000942 Project, which will be shared with the partnership, in order to refine the identification of certain/probable cases and the estimation of a bycatch index in the intervention areas monitored during the project.
The information acquired thanks to the acoustic monitoring activity and to the surveys on stranded animals will allow, through a common pathway with the involved fishermen operating within the intervention areas, to identify possible conflict mitigation solutions (best practices).

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