EurOCEAN 2000 - Vlaams Instituut voor de Zee

ACOUSTIC BASED METHOD TO PREVENT THE MORTALITY OF
SMALL ODONTOCETES IN FISHING GEARS
Salvatore Mazzola 1 , Angelo Bonanno 1 , Giuseppa Buscaino 1 , Bernardo Patti 1 , Angela
Cuttitta 1 , Gualtiero Basilone 1 , Antonio Mazzola 2 , Caterina Maria Fortuna 2
1 Istituto di ricerche sulle Risorse Marine e l'Ambiente-C.N.R., via L. Vaccara 61, 91026
Mazara del Vallo (TP) Italy; 2 Consorzio Nazionale Interuniversitario per le Scienze del Mare
(CoNISMa), Corso Rainusso 14, 16038 S. Margherita Ligure, Italy
INTRODUCTION
A wide variety of human activities threaten coastal cetacean populations world-wide in a
number of different ways. Although artisanal fisheries tend to be of lower environmental
impact when compared to industrial fishing there is still an effect.
Increasing attention has been paid in the last decades to the ways in which fisheries may affect
marine mammal populations and to the ways in which marine mammals might compete with,
or cause damage to, fisheries. In 1994 the International Whaling Commission stated that
marine mammal by-catches due to fishing operations are the main cause of mortality for
various marine mammal populations. On the other hand, fishermen argue that cetaceans
compromise their catch and cause serious damages to their nets. In particular, in Sicilian seas
the interaction between dolphins and the activities of small fisheries is intense because they are
mainly competing for the same resources (Mazzola et al. 1996). In this interaction both sides
lose something. Dolphins become entangled and wounded in fishing nets and often loose their
life; while fishermen suffer both damage to their nets and losses in their catches.
In order to reduce by-catches of cetaceans, in the recent past several experiments were
conducted to address this problem following two different approaches: 1) modifications to the
fishing gears, by using passive acoustic devices (Lien et al. 1990, Goodson 1993, IWC 1994,
Koschinski and Culik 1997); 2) installation on fishing gears of acoustic alarm devices (ADD)
and/or acoustic harassment devices (AHD) (Lien et al. 1990, IWC 1994, Gearin et al. 1996,
Dawson et al. 1997, Koschinski and Culik 1997, Kraus et al. 1997, Stone et al. 1997, Laake et
al. 1998, Johnston and Woodley 1998). The control of behaviour using acoustic devices seems
to be one of the best solutions to minimise the negative effects of such an interaction, also
contributing to the dolphins conservation. Looking at the results of these studies, it is clear that
the problem of repelling dolphins from fishing gear or preventing entanglement has not yet
been completely solved.
PROJECT FRAMEWORK
In 1994, in order to investigate the reactions of bottlenose dolphins (Tursiops truncatus) to
different acoustic stimula (Mazzola et al. 1996, MED/93/011) a set of experiments was
conducted in the «Severtsov' Institute of Evolutionary Morphology and Animal Ecology»
dolphinarium (Russian Academy of Sciences, Moscow). The experiments allowed us to select
two repelling signals: one emitted by a killer whale (Orcinus orca), the other one by a
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