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Preliminary study on interaction between dolphins and small-scale fisheries in sicily: Learning mitigation strategies from agriculture


Abstract and Figures

Interactions between cetaceans and fisheries are probably as old as the fishing profession itself (Bearzi., 2002). Harvesting activities, in agriculture as well as fisheries, nowadays are victims of depredation committed mainly by ungulates and odontocetes which can lead to serious environmental, social and economic problems among farmers and fishermen (Snape et al., 2018). Here we provide an overview of depredations conflicts all over the world and of European regulation and financial instruments to compensate for damage caused by protected animals. We define a comprehensive and detailed outline of the state of regulation, and the constraints and opportunities of harvesting activities at local, regional and national level, focusing on cases of conflict with wild fauna. Through a structured investigation, we explore the small-scale fishing fleet of eastern Sicily, where a traditional and multipurpose fishery is threatened by a high rate of cetacean-fishery interaction, requiring urgent mitigation action. We hope this research is a starting point for recommendations for better, more sustainable management of conflicts between wildlife conservation and fisheries practices, and for implementing strategies aimed at reducing loss due to cetacean interference on fisheries.
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Republic of Moldavia: Academy of Economic Studies of Moldavia
Romanian Academy: Institute of Geography
Italy: “Parthenope” University of Naples, University of Catania, University of Verona,
“Simone Cesaretti” Foundation
General Association of Economists from Romania, SOCAR, National Institute of Research and
Development for Industrial Ecology
Media partner
“Quality – Access to Success” Journal
Florina BRAN Tudor George MĂRUNŢELU
Carmen Valentina RĂDULESCU Ştefania Cristina CUREA
11th edition
Bucharest, 07-08 March 2019
Supplement of “Quality-Access to Success” Journal
Volume 20, S2, 2019
The journal is published by the Romanian Society for Quality Assurance,
indexed in ESCI – WoS, SCOPUS, EBSCO, ProQuest databases and included in Cabell’s Whitelist
ISSN 1582-2559
Quality-Access to Success, 20(S2)
Research fellow, PhD, Department of Agriculture, Food and Environment, University of Catania, Catania, Italy;
Marecamp association, Aci Castello, Catania, Italy,
Mediterranean and Black Sea coordinator, Low Impact Fishers of Europe Platform, Brussels, Belgium,
Professor in Principles of bioeconomy, PhD, Department of Agriculture, Food and Environment, University of Catania, Catania,
Interactions between cetaceans and fisheries are probably as old as the fishing profession itself (Bearzi., 2002). Harvesting
activities, in agriculture as well as fisheries, nowadays are victims of depredation committed mainly by ungulates and
odontocetes which can lead to serious environmental, social and economic problems among farmers and fishermen (Snape et
al., 2018). Here we provide an overview of depredations conflicts all over the world and of European regulation and financial
instruments to compensate for damage caused by protected animals. We define a comprehensive and detailed outline of the
state of regulation, and the constraints and opportunities of harvesting activities at local, regional and national level, focusing on
cases of conflict with wild fauna. Through a structured investigation, we explore the small-scale fishing fleet of eastern Sicily,
where a traditional and multipurpose fishery is threatened by a high rate of cetacean-fishery interaction, requiring urgent
mitigation action. We hope this research is a starting point for recommendations for better, more sustainable management of
conflicts between wildlife conservation and fisheries practices, and for implementing strategies aimed at reducing loss due to
cetacean interference on fisheries.
Depredation, small-scale fisheries, agriculture, cetacean, wildlife, EMFF
The marine and terrestrial environments are changing in their structure and species composition. Biological and physical
characteristics of their ecosystems depend on ecological processes, community dynamics, human influences, climate change
(Coclet et al., 2019; Flanagan et al., 2019; Ren et al., 2019; Yahner, 1988). Many species facing environmental pressure such as
strong fragmentation and limited habitats respond by shifting their population distributions (Hofman-Kamińska and Kowalczyk,
2012). In this framework, the conversion of large forest areas into small patches embedded in an agricultural matrix increases
the interface between forest and agricultural lands, increasing the risk of conflict between growing populations of wild fauna like
ungulates and human activities such as forestry and agriculture (Michez et al., 2016). Likewise, overfishing creates variations in
the abundance and distribution of fish stocks and forces populations of cetaceans to vary their home range in relation to
resources availability, increasing cases of interference with fishing activities (Daskalov, 2002; Rose et al., 2000).
Available statistics on wildlife damage are outdated and incomplete. Partial data show the estimates of the loss suffered by many
European countries in agriculture and forestry, putting Sweden in first place with 50 million each year, followed by Italy (€10.3
million), England (€6.56 million), Hungary (€4.5 million), and Croatia (€685.000) (Huisman, 2017; Riga et al., 2009). Though the
lack of regional data on agriculture and forestry is a problem, even more serious is the dearth of information on the damage
caused by wild animals on the fisheries and aquaculture sector. Preliminary studies indicate that the economic damage due to
dolphin interaction with Mediterranean small-scale fisheries (SSF) amounts to €77.65 for 50 m of net per year (Goetz et al., 2014;
Maccarrone et al., 2014), with a mean economic cost of €2,561 per vessel annually (Revuelta et al., 2018; Bearzi et al., 2011);
while commercial fisheries claim annual economic damages caused by dolphin depredation up to €20,000 per vessel (Snape et
al., 2018).
Attack and depredation carried out by wildlife on cultivated areas and fishing gear respond to optimization models based on the
assumption that wildlife choose feeding strategies that are most likely to give them maximum benefit in comparison with the cost
incurred, choosing whether to feed in the wild or in the agricultural land/underwater net, time spent in searching for forage/prey,
and possible risks according to costbenefit optimization (Watve et al., 2016).
Considering that assessment and compensation programs for agriculture are widely used in many countries to mitigate wildlife-
human conflicts (Cusack et al., 2018; Hofman-Kamińska and Kowalczyk, 2012; Riga et al., 2011), this study explores regulations
and literature sources in order to find parallels between agriculture and fisheries sectors, comparing the two types of harvesting
activities and their interactions with wild fauna. Since we consider that farmers and fishermen have the same rights, and are
employed in different environments but with similar working settings, we will reflect on the challenge to develop tools that enable
relevant measurements of the damage to fishing gears to ensure fair financial compensation for fishermen and farmers alike.
This study also investigates the case of one small-scale fishing fleet subject to cetacean-fishery interaction in eastern Sicily,
deepening understanding through structured interviews with local fishermen to address the problem.
Small-scale fishermen operate in coastal waters on board vessels less than 12 meters Length overall and with low Gross
tonnage, using passive or not towed gears (FAO, 2018). In Sicily, multipurpose vessels and family management prevail, where
fishing trips are mainly performed by 1-2 fishermen within 6 miles of the coast and last a few hours. Income and catches
quantities are low, and direct sales and short supply chain are preferred (Soltanpour et al., 2017).
Quality-Access to Success, 20(S2)
To date, local and regional studies and measures regarding cetacean-fishery conflicts mostly address cases of accidental
capture of cetaceans in fishing operations (bycatch), considering the animals victims and not the fishermen (Gönener et al.,
2017). In spite of the fact that fisheries depredation by marine mammals has always occurred and represents an economic
concern worldwide, the nature of marine mammal depredation interactions still need to be understood in order to both provide
adequate protection of threatened marine mammal species and to support fishing economies. Moreover, the economic impact of
depredation is shouldered more directly by individual small-scale fishermen rather than large-scale and industrial corporations
(Snape et al., 2018; Northridge, 1992). In addition, while damage caused to agricultural holdings by growing populations of
ungulates are often addressed by reduction plans, cetaceans are protected by numerous international agreements and many
species are present on the Red List of the International Union for Conservation of Nature (IUCN) (Monaco et al., 2016; Mikez et
al., 2016).
With this discussion we attempt to shed light on the issue of the interaction and to offer a starting point for proposing better
managing of existing conflicts between wildlife conservation and fisheries practices, and for implementing strategies aimed at
reducing the cost of cetacean impacts on fisheries.
Until the Common Fisheries Policy (CFP)1 was introduced in the 1970s, European Member States managed fisheries within
agricultural policies. Only in 1994 the Financial Instrument for Fisheries Guidance (FIFG) was launched to specifically support
the European fisheries sector, definitively distinguishing it from the European Agricultural Guidance and Guarantee Fund
(EAGGF) set up in the sphere of the Common Agricultural Policy (CAP)2 established in 1962. The most recent updates of these
instruments are the European Agricultural Guarantee Fund (EAGF) which finances direct payments to farmers and establishes
measures to regulate agricultural markets, and the European Agricultural Fund for Rural Development (EAFRD), set up under
the CAP in 2007; and the European Maritime and Fisheries Fund (EMFF) established for 2014-2020 3, supporting the
implementation of the CFP and the EU Integrated Maritime Policy (IMP).
With the Treaty of Lisbon in 2009, the fisheries sector came under the exclusive domain of the European Union (EU). However,
some countries continue to administer agriculture and fisheries in a single ministry or department.
Regarding the context of primary agricultural production, the European Union Guidelines for State aid in the agricultural and
forestry sectors and in rural areas 2014 to 2020 (2014/C 204/01, chap. contemplate aids to compensate for the damage
caused by protected animals, recognising the growing problem in damaged equipment, infrastructure, animals and plants caused
by protected animals, and the need to integrate management plans addressed to conservation which at the same time resolve
conflicts between fauna and farmers. Union policies provide support for investments related to measures preventing damage by
protected animals, and grant compensation up to 100% of the eligible costs.
Italian framework law on the protection of warm-blooded wild animals and on hunting (D.Lgs. Aug./10/2018, n. 104; Feb./11/1992,
n. 157; Dec./27/1977, n.968) outline the principles upon which the regions adopt detailed rules. It declares that wildlife is a
heritage of which the State may not dispose and is protected in the interests of the national and international community, defining
a list of particularly protected species, also in terms of sanctions, including many species of birds and mammals, as well as all
species of cetaceans (Lucifero, 2018). A fund dedicated to prevention and compensation is established by each region to cover
damages caused by protected wildlife to cultivated and grazing land.
Sicilian Regional regulations (Aug./11/2015, n. 18; Sep./01/1997, n. 33) declare national law identifying as wildlife those animal
species of which populations or specimens exist in its territory, living permanently or temporarily in a state of natural freedom.
The responsible Department is authorized to pay farmers and breeders the total compensation for damages caused by wildlife to
agricultural and zootechnical productions, provided they are not within parks and reserves, in which case responsability falls on
the managing body of the park or reserve.
Concerning the fisheries sector, the European Commission (EC) with the regulation on the European Maritime and Fisheries
Fund4 established that the EMFF support investments in equipment for protecting gear and catches from protected mammals
and birds5. Furthermore, it provides that all appropriate measures are introduced to avoid physical damage to the predators
without undermining the selectivity of the fishing gear. In this framework, the EMFF may support operations such as schemes for
compensation for damage to catches caused by protected mammals and birds. Competent authorities of the Member States
shall ensure the formal recognition of such schemes and that no overcompensation for damage occurs as a result of the
combination of Union, national and private compensation schemes. The Fund aims also at preventing serious damage to
aquaculture through action implemented by competent authorities that can contribute to the development of the aquaculture
infrastructures6. However, the Italian Ministry of Agricultural, Food, Forestry and Tourism Policies in its National Program on
Fisheries and Aquaculture 2017-2019 (Decree Dec./28/2016) does not mention any specifications regarding damage caused by
wildlife, limiting itself to resuming the art. 35 of Regulation 508/2014 which provides for a contribution for fishing companies to
take out insurance to cover events such as environmental emergencies, accidents at sea, adverse weather events, provided they
have had losses on invoiced price of more than 30%. Consequently, the Italian regions are lagging behind with the
implementation of the priority 1, article 40 of the EMFF concerning compensation regimes in the framework of sustainable fishing
1 The CFP is the European Union policy for managing fishing fleets and conserving fish stocks in the waters of Member States. It allows fishermen to compete
fairly giving all European fishing fleets equal access to EU waters and fishing grounds.
2 The CAP is a European common policy aimed at providing affordable food for European citizens and a fair standard of living for its farmers. It promotes the
conjunction between agriculture and society, and among Europe and its farmers.
3 Fund established with the Regulation (EU) N. 508/2014 of the European Parliament and of the Council of 15 may 2014.
4 Regulation (EU) N. 508/2014 of the European Parliament and of the Council of 15 May 2014, repealing Council Regulations (EC) N. 2328/2003, (EC) N.
861/2006, (EC) N. 1198/2006, (EC) N. 791/2007, Regulation (EU) N. 1255/2011 of the European Parliament and of the Council.
5 It is referred to Council Directive 92/43/EEC and Directive 2009/147/EC of the European Parliament and of the Council.
6 Action taken under Article 9(1) of Directive 2009/147/EC or Article 16(1) of Directive 92/43/EEC.
Quality-Access to Success, 20(S2)
activities, with the exception of the Sardinian Region which has recently initiated preliminary investigations for compensation for
damage to fishing from protected birds, and has published procedural provisions, reserved to small-scale fisheries, for the
request for reimbursement for damage caused by protected mammals as cetaceans.
The Sicilian Region, which has allocated a financial contribution of 20.55% (€118.11 million) of the national allocation of the
EMFF, has provided 855,000 for the measure 1.40 but has not yet initiated any procedure to allocate this budget to fishermen.
Issues linked to wildlife conservation and its conflicts with agricultural activities occur worldwide and have serious consequences
for human wellbeing and biodiversity (Cusack et al., 2018). Damage from wildlife can affect agricultural crops, forests, livestock,
fish farming, fishing gears, gardens and parks, infrastructure, people and property. They are usually caused by birdlife or small
and large mammals, such as those belonging to the taxa of lagomorphs, ungulates, ursids, delphinids that may be permanent or
migrating in the area of interaction (López, 2012; Riga et al., 2011; Apollonio et al., 2010; Ciucci et al., 2005).
In order to be compensated for any damage suffered, specific regulation must exist that allows the assessment of the damage
and its subsequent repayment. Classic administrative procedures for the payment of compensation begin with the submission of
the claim for reimbursement by the injured party and end with the quantitative and economic assessments of the damage that
will lead to the disbursement of a refund or compensation. The refund is restitution paid to the owner of the economic good that
has suffered a damage, which allows the owner to fully restore the economic state previous to the damaging event.
Compensation, on the other hand, is the reimbursement to be paid to the owner of the damaged economic good, having a
restorative function not necessarily proportional to the damage suffered. Regulations often don’t specify if a damage is
refundable or compensable (Riga et al., 2011).
2.1. A focus on damages in agriculture caused by terrestrial wild fauna
According to a classification developed for agriculture by the Italian Higher Institute for Environmental Protection and Research
(ISPRA), crops for which it is possible to ask a compensation are the following: a) herbaceous crops such as lawns and
pastures, forage crops, cereal, industrial, oilseed; b) horticultural crops; c) permanent pastures; d) tree crops in current cultivation
such as orchards, olive groves, vineyards, chestnut trees.
Within the framework of annual herbaceous crops, the determination of the damage takes into account whether the product is in
the ripening phase or in the phase close to sowing or planting. During ripening or other periods in which re-seeding is not
possible, the amount of lost production is obtained by multiplying a) the area affected by the damage by b) average crop
production by c) the percentage of damaged product in the identified area. In the event of damage occurring close to sowing, it is
calculated on the basis of the costs necessary for re-seeding under the new conditions, and also takes into account any
reduction in yield.
In the case of perennial crops, we can distinguish damage to the product (fruit), from damage to the plant. The latter can be
either lethal, requiring the replacement of individual plants or of the entire plantation, or partial causing a decrease in productivity.
In the first case the damage is calculated taking into account the number of dead plants and the operations necessary for their
substitution and rearing; the second case is more complex and may require a double inspection to verify the real loss of
production at the time of harvest. Considering the herbaceous perennial crops, in case of damage to the product the procedure
for the quantitative estimate is the same used for the annual crops; if the damage occurs close to the installation, the procedure
for tree crops is followed (Riga et al., 2011).
In summary, the eligible costs of the European Guidelines 2014/C 204/01 include the following factors: a) damage for animals
killed or plants destroyed, based on their market value; b) indirect costs like veterinary costs for wounded animals and labour
costs for searching for missing animals; c) the material damage to farm equipment, machinery and farm buildings and stocks,
based on the repair cost or economic value. Besides compensation or subsidy schemes, mitigation strategies to reduce the
impact deriving from wild animals interacting with agriculture include population control through harvesting or culling, and the
placement of nonlethal deterrents or barriers. However, in order to successfully attenuate conflicts, the management efforts
should be adapted to current wildlife impact levels (Cusack et al., 2018).
2.2. A focus on damages in fisheries caused by cetaceans
Regarding losses due to marine wildlife depredation, damage of catches by crustaceans, cephalopods, conger and sharks were
reported to cause significant monetary loss, feeding on catches or baits trapped in the gears, as well as dolphins cause
scattering or sinking of entire fish schools, frequently leading to the complete loss of the catch of a fishing trip or the destruction
of the gear (Snape et al., 2018; Goetz et al., 2014; Wise et al., 2007). Damage to small-scale fisheries from small cetaceans
include preying on or damaging fish trapped in the nets, tearing of large holes in the fishing nets, loss of fishing time, and
disruption of fishing activities (Bearzi et al., 2011; Reeves et al., 2001). Large sections of nets can be damaged also when
dolphins get entangled in the gear. Minor damages lead fishermen to continue using the nets even if damaged in order to avoid
expensive repair costs but causing a reduction in the catch (Goetz et al., 2014).
The Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic area
(ACCOBAMS) gives guidelines for technical measures to minimise cetacean-fishery conflicts. Acoustic mitigation measures
represent a potential path that may lead to a solution, but the long-term effectiveness of existing devices is still controversial
(Hamilton and Baker, 2019; Northridge et al., 2006). Fixed to fishing nets, the same devices designed to prevent small cetaceans
from being victimized by bycatch are used to repel and prevent destruction by dolphins. The most experimented and used device
is the Acoustic Deterrent Device (ADD or better known as pinger) that is a low-intensity acoustic signal generator emitting mid to
high frequency sounds (Reeves et al., 2001). Other similar tools are Acoustic Harassment Device (AHD), Dolphin Dissuasive
Device (DDD, DDD01) and the Dolphin interactive Dissuasor (DiD). Pingers have been designed to turn away marine mammals
from fishing gear, causing them discomfort, scaring, deterring, masking acoustic detection senses, or simple confusion; however,
their exact behavioural mechanism is unclear (Northridge et al., 2006). The highly-developed brain in odontocetes probably
Quality-Access to Success, 20(S2)
reduces the likelihood that they will be deceived by pingers and results in unexpected behavioural patterns like ignoring the
deterrents (habituation), becoming attracted to pinger ("Dinner bell" effect), and aggressive behavior (attacking the devices)
(Goetz et al., 2014). One DiD costs about €380, considering that many fishing gears consists of netting up to 1000 m long, and
that DiDs has a range of about 350 meters, to obtain an effective dissuading effect multiple devices are required. There is
consensus among researchers that pingers may reduce the bycatch of small cetaceans but they are not yet a reliably effective
technical solution, thus more focused and new long-term investigations are urgently required (Hamilton and Baker, 2019;
Northridge et al., 2006).
The EMFF support investments in equipment for defending fishing gear and catches from dolphins, and to increase sustainability
and selectivity of the gear. Schemes to assess compensation for damage by marine mammals and birds take into account
factors such as type of fishing gear used and its length, numbers of fishing days in the period of the damage, target species with
quantities and commercial value of the period, financial turnover of the last years.
The progressive adaptation of wild species to farmland landscapes, linked to the large cover and abundance of food resources
provided by agricultural lands, allowed ungulates to become the most feared by farmers. In Europe, wild boar cause €80 million
of damage to crops annually (Michez et al., 2016). In addition, wild boar causes a selective pressure with rooting activities that
modify the vegetational structure of some wooded areas (Lenzi et al., 2018). In Italy, the annual average indemnity expense for
cases of predation of sheep by wolf, between 1991 and 1995 was €1,9 million (Ciucci et al., 2005). According to the National
Ungulates Database, the total compensation paid in 2004 amounts to €10 million, over 90% of the damage is caused by the wild
boar and geographical area reporting damage is increasing. Less frequent are case of interaction with fallow deer, mouflon, ibex
and chamois (Romano et al., 2014; Riga et al., 2011). In Poland, the amount of compensation paid for crop damage by wild
ungulates mainly wild boar and red deer, followed by roe deer, moose and European bison was 13.7 million in 2010. The
Polish State have to deal also with damage caused by protected species such as beavers, lynx, wolves, bears and bison to
arable crops, private forests and livestock. Here, between 2000 and 2010, the total cost of compensation was 196,200
(Hofman-Kamińska and Kowalczyk, 2012). The Wildlife Compensation Program in Canada finance crop losses caused by black
bear, moose, coyote, rabbit, skunk, raccoon, raven, crow, starlings, robins, seagulls, bluejays, waterfowl, birds of prey, beaver,
white-tailed deer. In Ontario, coyotes, bears, wolves and foxes are among the most common predators that kill or maim livestock
(Kunkel, 2019). The National Agricultural Statistics Service (NASS) of the United States reported wildlife damage of $944 million
during 2001. This consisted of field crop losses to wildlife ($619 million) including blackbird damage to rice crops, livestock and
poultry losses ($178 million), and losses of vegetables, fruits and nuts ($146 million). Fish-eating birds cause an estimated $5
million in annual losses to the Mississippi aquaculture industry. Moreover, American catfish producers reported losses to wildlife,
for example the case of pelicans which host a trematode parasite, which feed on catfish and generate huge infestations.
Although in all these cases national compensation programs exist, they do not work in the same way in other Countries like
Zambia and Botswana where currently policies do not allow for any compensation to rural farming households located inside
protected areas which incur damage to crops inflicted by wildlife (Subakanya et al., 2018). Assessment policies for paying
compensation to farmers are not always appropriate, this is the case of India where the current visual assessment method
results in an underestimate of the damage, and so it necessitate a radical rethinking in order to mitigate as well compensation for
crop damage caused by protected wildlife species (Bayani et al., 2016).
Interaction between marine mammals and fisheries can be positive, e.g. when in purse-seining dolphins indicate the presence of
fish schools (Allen, 1985); negative, in case of incidental capture of cetaceans or bycatch; and cooperative, as the case of
bottlenose dolphins which drive fish towards local beach-casting fishermen, applying a bijective foraging tactic in southern Brazil
(Jaakkola et al., 2018; Daura-Jorge et al., 2012). Depredation be part of negative interferences for fishermen and involve many
species of odontocetes and pinnipeds. Damage from seals on gillnet sets in northern Europe, killer whales on demersal longlines
in the South Atlantic, false killer whales near pelagic longlines in the Pacific are a few examples (Snape et al., 2018). Dolphins
interact also with fish farms, like marine open cage aquaculture, near which they carry out predation and depredation activities
(Lopez., 2012; Piroddi e al., 2011). Damages to small-scale fisheries are mainly due to the common bottlenose dolphin, being a
purely coastal species that, not only feeds in the same area of action of small fishermen, but whose prey coincide with the target
species of artisanal fishing gear. Other small cetaceans involved in depredation are common dolphin and striped dolphin, even if
often fishermen overestimate their losses (Lapiccirella et al., 2018; Bearzi et al., 2011). However, preliminary investigations
indicate that the economic damage due to dolphin interaction with Mediterranean small-scale fisheries amounts to €2,561 per
vessel per year, calculating for the trammel net a loss of around 5.3% of their total catch value (Revuelta et al., 2018; Bearzi et
al., 2011). In Spain, Italy, and France studies on commercial fisheries have estimated the annual cost in terms of damage to
catch of up to €2,000, for a total annual depredation costs of up to €20,000 per vessel annually (Snape et al., 2018). Furthermore,
it has been estimated that impact from cetacean interaction in fisheries operating in the Pacific Ocean cause a total loss in
turnover of about $25-30 million per year. Costs derive from loss of catches, additional gear to compensate for losses, additional
fuel per depredated set, cost to repair gear, investment in mitigation devices, depredation avoidance measures such as leaving
the fishing zone and consequently increased fuel and crew cost (Maccarrone et al., 2014).
A review of literature and regulations was undertaken to provide a comprehensive and detailed outline about the state,
constraints and opportunities of harvesting activities at local, regional and national level, particularly to the cases of interaction
with the wild fauna. A stratified sample of 50 professionally active fishermen belonging to small-scale Sicilian fisheries was
interviewed anonymously, in the period 2015-2018. Face-to-face surveys were based on a structured questionnaire including
closed-ended and open-ended questions in order to provide quantitative and qualitative information about interviewee’s profile,
technical characteristics of the fishing gear used, target species, quantities of catches in normal conditions and in cases of
Quality-Access to Success, 20(S2)
interaction with cetaceans, on the types of damage suffered in case of depredation, type and frequency of interaction, losses and
costs incurred, mitigation measures employed, and on the presence of bycatch events. The selected sample included fishermen
operating in the only coastal waters of eastern Sicily and it is representative of the local fleet of the study area, taking into
account elements such as the type of fishing gear and the exploited resource (Table 1). Through a nautical map divided in small
sectors, we collected data on distribution and seasonality of fishing activities and cetacean-fishery interaction occurrence. We
also used cetaceans identification cards to allow fishermen to distinguish the various species.
Table 1. Sample of fishermen involved in the survey in relation to the number of units of SSF. Number of interviewees and
percentage by area.
Fleet area
Units of SSF
N. interviewees
(Source: our elaboration)
This research was conducted in a coastal area of east Sicily about 160 km in length that includes the districts of Messina,
Catania and Syracuse. Sicily is an autonomous region whose territorial waters extend for 12 NM. It has decision-making power
on issues related to fisheries under the responsibility of the Department of Mediterranean fisheries (Regional Law 15 May 2013
N. 9) of the regional Office of Agriculture, Rural Development and Mediterranean Fisheries which works for the promotion and
enhancement of the Sicilian fishery through the program EMFF 2014-2020. In 2015, the eastern Sicilian fleet comprised 375
small-scale fisheries vessels belonging to 17 harbours and using traditional multipurpose artisanal fishing gear such as lines and
hooks, pots, artisanal longlines, gillnets, trammels and driftnets. Despite the strong anthropogenic impact on the coastal area, a
high level of primary and secondary productivity favours the presence of cetacean all year round and two marine protected areas
are present. Populations of common bottlenose dolphins live in this zone in medium size herds with a fissionfusion grouping
pattern. Other regular species in the area and contiguous waters are striped dolphin, Risso’s dolphin, common dolphin, Cuvier’s
beaked whale, sperm whale and fin whale (Monaco et al., 2016).
Small-scale fisheries in eastern Sicily are active year round and their activities take place mainly within 3 NM from the coast.
They are subject to different types of negative interaction that affect their normal course more or less markedly. One hundred
percent (50) of the interviewees indicated as interaction factors: a) the weather and sea conditions on which the possibility to
carry out fishing trips depends; b) unfair competition from non-regulatory fishermen who exploit marine resources, hinder the
work of professional fishermen and cause a reduction of market prices; c) opportunistic predation and depredation by several
species of cetaceans on fishing gear, causing damage to nets, baits and catches, or scattering of fish. Fifty-eight percent (29)
said they were subjected to interaction with sport and recreational fishermen who, especially during summer, were too numerous
and became object of competition. Thirty-eight percent (19) complained about the growth of imports of seafood products on the
local market, with a consequent decrease of the value of their products. Thirty-two percent (16) described interactions of different
nature with the institutions (e.g. Port Authorities), and were frequently involved in disagreements with authorities due to
inconsistencies in control activities and lack of information. Twenty percent (10), reported interaction with fish farms and other
forms of aquaculture; ferry and large ships that often affect the use of some fishing areas or cause damage to the gears
deployed (14%; 7). Eight percent (4) said they had been victim of acts of prevarication or forced takeover (e.g. events of theft or
damage of fishing gears stowed in the boats, by unknown persons). While only 4% (2) had neutral cooperative relationships with
research institutions. From an environmental point of view, artisanal fishers unanimously protest on the constant trawling activity,
often performed in prohibited areas, that spoil the seabed causing a decrease in resource availability. In addition, fishermen
underline the increasing pollution of sea waters, a cause of death and mucilage that in some periods make fishing activity
impracticable, as well as the disappearance of some target species for the benefit of invasive species.
Based on interviews, cetacean-fishery interaction is limited to cases of depredation on catch, while bycatch events don’t exist.
Damage is caused by dolphins mainly on three different fishing gears: trammel, coastal artisanal longline and menaida,
frequently leaving characteristic signs of depredation on catch like bite marks or just the fish head in the gear. Common
bottlenose dolphin was the main species to apply the opportunistic behaviour of interaction on these gear (92%), while Risso’s
dolphin was observed occasionally during interaction (8%). Normally, 1-3 pest individuals interact with the same gear, rarely up
to 6 animals. In case of sighting of other cetacean species in proximity of the fishing vessels, no damage was found either in the
catch or in the fishing gear.
All the fishermen have declared to have purchased ADDs or DiDs devices without obtaining any real result in avoiding dolphins,
although DiDs have shown efficacy only in the first 4 months after their activation.
6.1. Trammel net
Trammel used in coastal water of eastern Sicily is a gillnet consisting of three layers of netting with a small slack mesh inner
netting between two layers of large mesh netting within which fish entangle. Mesh size is chosen according to season and target
species (n.5 to n.12 size). The net is kept vertical by floats on the headrope, usually made of plastic and either cylindrical or egg-
shaped, and by weights on the groundrope. It is typically employed as stationary gear at, or near to, the sea bottom at a
Quality-Access to Success, 20(S2)
maximum of -200 meters, and fishermen haul it back by hand or with a hauler. Catches average 3-4 kilos, corresponding to a
value of about €50. Target species change by season and are: European anchovy, European seabass, common sole, surmullet
and red mullet, sand steenbras, common pandora, European flounder, tub gurnard, brill, European spiny lobster, European hake,
common cuttlefish, white seabream, common octopus, red scorpionfish. Depending on the species to be caught, the net is left
fixed in the sea for a few minutes (e.g. for mullet), or from sunset to sunrise (for most of the species), or even 2 days (e.g. for
lobsters). In the zone of the marine protected area "Cyclops Islands", the gillnetter fleet has chosen to reduce submersion of the
nets to a few hours at sunrise in order to be more selective and also have less chance of being plundered by dolphins. The gear
is composed of 30 x 70 meters pieces joined together to form nets whose length depends on the number of the crew on board
(generally, about 200 meters for a single fisherman). A new trammel net in Sicily costs about €2,000. When fishermen observe
bottlenose dolphin near the gear they have two options: a) to hauled back the net before dolphins interfere and eventually
change fishing area (less catches because of the reduced time or more expenses for extra fuel and time/net save); b) to maintain
the net underwater taking the risk of the interaction (net save/catches save; or net save/less catches because of scattering fish
or partial prey depredation by dolphin; or net damaged/loss of most of the catch). We estimate 36% medium rate of probability
that the net be depredated by dolphins causing 30-200 medium-sized to large holes, tearing it to remove fish. This type of
damage can reduce the catch of the fishing trip to only 1 kilo or lead to a complete loss. In addition to the lack of income deriving
from the sale of the fish, fishermen have to re-establish fishing conditions according with the following options: a) to purchase a
new trammel; b) to repair the holes himself taking about 2 days for re-sewing; c) to purchase a new rough net (it costs about
€70,00) and arm it with floats and weights recovered from the damaged trammel. Local fishermen declare that, following these
options during the year, they lose 30% of their annual turnover which, in the last year, has been around an average of €10,000
per fishing unit (one vessel). Instead, in case of minimal damage to the trammel, sometimes fishers prefer to continue to fish with
the same gear, even lower yields.
6.2. Artisanal longline (hooks and lines)
Artisanal longlines most subject to depredations are those used within 6 miles from the coast of the study area. They are fishing
gears composed of connected lines, either set at the bottom or drifting, bearing up to 800 baited hooks which remain underwater
from 2 hours to 2 days. Lures (natural or artificial baits) placed on the hooks fixed to the end of a line, attract the fish which get
caught and held by the mouth until they are hauled aboard the vessel by hand. Catches average 40 kilos, and their value
depends on the species caught. Target species are mainly cod, followed by common pandora, European flounder, frigate tuna,
red porgy, common dolphinfish, Atlantic bonito, Atlantic horse mackerel, little tunny, European hake, Atlantic mackerel, common
dentex, saddled seabream, dusky grouper, European pilchard and, within the limits laid down by the law7, Atlantic bluefin tuna,
albacore and swordfish. A new complete longline has an average price of €5.500. In case of dolphin incursions, the catch may
be entirely lost, more rarely dolphin depredate lures like squids or sardines. Small-scale fisheries fleet of the study area fish with
longlines also within 12 NM from the coast. In this case the declared rate of interaction with dolphins is of 23% lower compared
to the rate measured inshore (30%). The damage received can be quantified in loss of the fishing day, investment in the baits
and loss of catches whose species determine its value (the albacore damaged for depredation in one fishing trip can lead to
losses up to €20,000, damages on cods have a minor impact).
6.3. Menaida
The menaida or menaide is a traditional gillnet used in the Gulf of Catania which has a centuries-long history and still survives in
very small niche. About 20 vessels use this fishing gear in the area, but only 6 practice the technique year round. It is an
important example of a sustainable and selective fishing technique, since its mesh size measures 1 cm (it is the n.25 size, but
other variants exist like n.29 and n.30) and permit exclusively the capture of the European anchovy (or in certain periods the
sardine). Similar to other types of gillnets, the menaide is a string of single nylon netting walls, deployed vertically in the water in
the proximity of the boat, near the surface, or in midwater at a maximum of -100 meters, in which fish will gill. It is held by a
series of floats, usually made of white quadrangular plastic situated at a distance of 15-20 meters from each other on the upper
line (headrope), and corks (5 for each meter) and weights on the ground-line (footrope). The gear is about 12 meters high and
can measure a maximum of 450 meters which can be left drifting, free or connected to the vessel. After 1-2 hours underwater,
then it is brought on board by a net hauler while fishermen free anchovies one by one, widening the mesh by means of a runner.
The principle of the menaida is that fishes, trying to pass through the net, are caught by their gills operculum in the net webbing
and, trying to escape, loose a lot of blood. Thus, the anchovies obtained by this method are more sweet and dainty, compared to
those fished with other nets. The price of a new menaida is about €4,000, quantities of its catches have an average of 50 kilos,
corresponding to a value of about €200. The interviewees declare that cases of interference with bottlenose dolphin have a
bimodal trend, being higher in spring and summer, when the Gulf is at its maximum productivity and anchovies are spawning,
and lower in other seasons (52% vs 16%). Type of damage, options and relief due to depredation are like those indicated for the
trammel. An event of depredation on the menaide can halve catches or reduce them to less than 10 kg, with annual losses that
can reach €6,000.
Increasing catch and harvest depredation among wildlife raises the need to address this phenomenon, which can lead to serious
well-being and economic problems for operators and in the budgets of local authorities, as well cause difficulties in territorial
planning that provides more effective management responses in the long-term without resorting exclusively to the payment of
7 Regulation (EU) 2016/1627 of the European parliament and of the Council of 14 september 2016 on a multiannual recovery plan for bluefin tuna in the eastern
Atlantic and the Mediterranean; Italian decree of 20 April 2018 on the breakdown of the national catch quotas for bluefin tuna for the three year period 2018-2020.
(18A03387) (GU General Series n.114 of 18-05-2018); Council Regulation (EU) 2018/120 of 23 January 2018 fixing for 2018 the fishing opportunities for certain
fish stocks and groups of fish stocks, applicable in Union waters and, for Union fishing vessels, in certain non-Union waters.
Quality-Access to Success, 20(S2)
damage. Small-scale fisheries techniques are undermined because of many interaction factors, among which stands out the
case of depredation by dolphins on the gillnet menaida, a great example of high degree of selectivity that, as a symbol of
tradition and sustainability, deserves to be supported. Unlike large-scale fishing, coastal fishing does not register bycatch cases
but is the more affected by cetacean-fishery conflicts, as it has a very narrow range of action that overlaps perfectly with the
distribution of the bottlenose dolphin, a species of excellence for the interaction with human activities. Above all, to date no real
remedy for this problem has been found. Nevertheless, in recent years the fishermen's opinion has changed, going from
repressor of the dolphins to conscious of their important role as indicators of the state of health of the sea. Furthermore, the
opportunity for fishers to request compensation for the depredation, requires a correct declaration of the turnover in order to
estimate the damage. This could also be a solution to reduce the informal seafood circuits and to improve the monitoring on the
fishing effort.
In closing, inspired by existing European agriculture policies, future options for action in the fishery sector are suggested here.
a) A multidisciplinary approach and cooperation between fishermen, researchers and decision makers are required in order to
develop management strategies adjusted to local conditions and minimize existing human-wildlife conflict; b) following the
example of agriculture on the annual herbaceous crops during ripening, any compensation to fishers should be proportional to
the extent of the loss and defined by expert, distinguishing damages to equipment from damage to the catch; c) every fisherman
should be able to receive subsidies for the purchase of preventive mitigation devices; at the same time, the development of new
mitigation techniques should be encouraged; d) Particularly bad sea-weather events should be compensated to the same extent
as natural disasters in agriculture; e) research activities should be implemented by means of experimental fishing in order to
better understand the fishing effort, and to assess cetacean abundance and their concurrence or interference with fishing
activities, deepening also temporal and spatial variability of interactions; f) fishing tourism and dolphin watching activities should
be encouraged only after training of operators, with a view to a new and more responsible blue tourism; g) studies on
sustainability and improvement of artificial bait, as well as innovative fishing techniques should be encouraged.
We wish to express our gratitude to all the fishermen involved in the study to have given their kindly contribute sharing their time,
information and expertise with us.
This study was conducted within the framework of the projects “Valutazione della sostenibilità dei sistemi agroalimentari locali”
WP4, financially supported by the University of Catania, and “Mainstreaming Small Scale Low Impact Fisheries in the
Mediterranean”, financed by MAVA foundation for the Low Impact Fishers of Europe (LIFE).
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Supplementary resource (1)

... Gillnets are a still a cause for concern in small-scale fisheries (20 studies), with a higher proportion of reported marine mammal depredation than any other gear (Bordino et al., 2002;Rechimont et al., 2018). In small-scale fisheries, gear damage and catch loss were reported for most gear types, irrespective of the level of reported depredation (Bearzi et al., 2011;Monaco et al., 2019; Figure 4). ...
... Monetary compensation (Güçlüsoy, 2008) and subsidies on more selective gear and mitigation devices (Monaco et al., 2019) have also been implemented to o set the cost of gear damage and catch loss to fishers caused by depredation or incidental entanglements. Levies and subsidies on commercial fisheries, based on allotted quotas, have been introduced to encourage adequate reporting, and reduction of marine mammal bycatch (Bisack and Das, 2015). ...
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Marine mammal interactions with fisheries, such as bycatch and depredation, are a common occurrence across commercial and small-scale fisheries. We conducted a systematic review to assess the management responses to marine mammal interactions with fisheries. We analyzed literature between 1995 and 2021 to measure research trends in studies on direct and indirect interactions for: (i) high and low to middle-income countries, (ii) fishery operations (commercial and small-scale), and (iii) taxonomic groups. Management responses were categorized using the framework described previously in peer-reviewed studies. Marine mammal bycatch remains a major conservation concern, followed by marine mammal depredation of fishing gear. A high proportion of studies concentrated on commercial fisheries in high-income countries, with an increase in small-scale fisheries in low to middle-income countries between 1999 and 2020. The insufficient understanding of the social dimensions of interactions and the inevitable uncertainties concerning animal and human behaviors are major challenges to effective management. Despite the key role of human behavior and socioeconomics, we found only eight articles that incorporate human dimensions in the management context. Integrating social dimensions of marine mammal interactions with fisheries could help in setting pragmatic conservation priorities based on enhanced understanding of critical knowledge gaps. An area-specific adaptive management framework could be an effective tool in reducing the risk to marine mammals from fisheries by coupling technical solutions with socio-economic and political interventions. We conclude that despite the vast body of literature on this subject, a “silver bullet” management solution to marine mammal interactions with fisheries does not yet exist.
... Being a coastal species, the bottlenose dolphin (Tursiops truncatus) commonly forages in the same area exploited by small-scale artisanal fisheries, pursuing overlapping prey organisms with the target species of the artisanal fishing gear (Monaco, Cavallé & Peri, 2019). ...
... For the individual depredator, exploiting fishing resources represents a more efficient strategy than natural foraging (there are lower costs in terms of energy, time, and travel for locating or acquiring prey; Fertl & Leatherwood, 1997). However, the nature and degree of dolphins' depredation interactions still needs to be clearly understood (Monaco, Cavallé & Peri, 2019). ...
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... Furthermore, several studies have reported cetaceans using pingers as cues to locate fisher nets [14]. The economic cost effort caused by the presence of holes in the nets, bent hooks, reduction in the amount or value of the catch caused by wild animals, and the lack of compensation for such damage (or the difficulty to obtain) make the situation critical [15,16]. There are different examples of bottlenose dolphins' injuries exerted by fishers in Sicily, in the Aeolian archipelago, where mutilations due to gunshot wounds have been reported [17]. ...
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... More recent studies in the Mediterranean continue to report damage on nets (gill nets and trammel nets), more than on any other fishing gear (Table 6) lihoods. Fishers operating trammel nets in Sardinia report a 30% reduction of their annual turnover, which corresponds to an average of €10,000 (Monaco, Cavallé, and Peri, 2019), whereas Maccarrone et al. (2014) estimate total economic loss due to missed catches at €1,397 for 900 m of gill nets. In the northern Adriatic, Casale (2002) estimated mean yearly economic loss of approximately €7,700. ...
Dolphin interactions with coastal fisheries are of major concern, reportedly leading to gear damage, which increases the cost of coastal fishing globally and in the Mediterranean Sea. The aim of this study was to determine the effect that gear, target species, mesh size, depth, soaking duration, fishing area, and season have on net depredation frequency and to offer insights on possible mitigation solutions. From November 2013 to February 2016 we monitored 107 active coastal fishers in 22 ports of the northern Aegean Sea coastline, identified the main target species of the fishery and recorded the damages on gill nets and trammel nets caused by dolphins, mainly the common bottlenose dolphin (Tursiops truncatus ). Quasi‐binomial generalized linear models were used to determine the relationship between the examined factors and depredation frequency. The analysis revealed that the gears mostly depredated were gill nets and trammel nets with small mesh sizes, mainly targeting surmullet (Mullus surmuletus ), red mullet (Mullus barbatus ), common sole (Solea solea ), European hake (Merluccius merluccius ), and caramote prawn (Melicertus kerathurus ). The probability of depredation was also significantly dependent on the fishing area.
... There is no optimal solution, and the formulation and existence of the problem are deeply embedded in the perspectives of the stakeholders (Rittel and Webber 1973;Whyte and Thompson 2012). The dynamics of human-in-nature systems (or socialecological systems) raises issues of resilience, adaptation, and transformation and requires changing the focus from seeking optimal states and maximum sustainable yield to comanagement (Jentoft and Chuenpagdee 2009), capacity of self-organization (Folke et al. 2002) and resilience analysis (Holling 1973;Walker et al. 2004;Monaco et al. 2019). ...
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While the European Union’s fishing policy is mainly based on maximum sustainable yield, at the local fishing community level, fishers’ main incentive to sustain fish stocks appears to be maintenance of social relationships. Divergence of the stakeholders’ objectives on the management of marine resources creates conflicts of interest that can be overcome through a process of negotiation. The formulation of the solution is embedded in the perspective of the stakeholders. In this paper we analyze the negotiation mechanisms between the French Mediterranean local fishing communities and the European Union common fishery policy. Inspired by interactive governance theory, the performance of Prud’homies, a local governance entity in the French Mediterranean, has been analyzed through their capacity to cooperate and represent the fishers’ voice in formal institutes. We are witnessing a declining representation of this local institute among the official decision-makers of the marine resource governance.
... Regarding the economic aspects a mean loss of 13,000 (SD±11,229) €/year was estimated considering both gear damage and catch loss. Similarly, in the eastern coast of Sicily Monaco et al. [11], based on fisher's interviews, found a mean economic loss of 10,000 €/year for trammel net while for long-line up to 20,000 €/year. In the Mediterranean, different attempts were made to mitigate the interactions between dolphins and fisheries e.g. ...
Technical Report
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This report includes the main joint results and conclusions of a Mediterranean sea regional study carried out in Italy, Malta and Spain to improve the knowledge on the interactions between cetaceans and small scale fisheries. It based on standardized systematic research protocols and survey sheets shared between the participating countries in order to allow its extension to other areas and to enable comparison of the results across the Mediterranean in the future. The activities were carried out among the different fleets chosen through stratified sampling and applying a multidisciplinary, participative and cooperative approach. A good part of the investigation has been addressed to depredation events which correspond to the partial or complete removal of bait or captured fish in the fishing gears by marine wildlife such as cetaceans, fishes, birds, and turtles, that often find in the nets an easy way to exploit food resources.
Technical Report
The fishing sector in Malta has always been one of a smallscale nature with 93% of the vessels being under 12 metres and engaging in small-scale fishing (non-towed gears), utilizing a variety of artisanal fishing gear (see Section 1.2. below). Several types of gears are used in such fisheries, such as surface longlines which are mainly used to target swordfish and tuna and bottom-longlines, trammel nets and entangling nets which are used to target groupers, various species of bream, red snappers and red porgies. Pots and traps are generally used to captured octopus and bogue. Some vessels also use fishing aggregate devices to fish for dolphinfish. One of the main fisheries interactions with ceteceans includes the presence of dolphins. Cetaceans have been appearing in Maltese waters for a number of years and fishers remark that interactions with cetaceans are constantly increasing. It is therefore essential that proper monitoring is carried out in order to assess the factors that drive the interactions and the impact of dolphin depredation on the fishing sector to inform management measures. The focus of this study was essentially to qualify and quantify depredation factors by investigating the realities as perceived and lived by the smallscale fishing sector. 7 Questionnaires were mostly focused in Malta’s major fishing ports, specifially Marsaxlokk in the Southern part of the island, and St Paul’s Bay, towards the North. A few were conducted in other fishing ports to get a snapshot of the issues arising around the Maltese coastline. Data about technical characteristics of the fishing fleet, fisher perception of cetacean interaction with respect to gear, interaction characteristics, encounter frequency and bycatch, fishing gear characteristics and interaction damage and losses were all collected. Results show that the regular presence of bottlenose dolphins seems to have increased over the last 5 years, particularly in the vicinity of bluefin tuna, seabream and seabass fish farms locations. While the use of trammel nets remains by far the most popular gear type employed by Maltese fishers, this study showed that an around 33% of the fishing gear deployed in the past year suffered damages which account to an average of €178.33 in damages per fisher, annually. The authors hence recommend that new prevention and mitigation measures are tested in order to try and reduce the risk of depredation by cetaceans. With existing acoustic devices not being yet sufficiently effective, it is ncessary to identify and test new devices that could address the cetacean bycatch and depredation incidents. These could include innovative projects such as DEPRED devices that include long streamers that repel cetaceans from approaching the fishing gear, as well as enhanced communicative systems where fishers communicate high risk areas frequented by dolphinfish such that hotspot areas are avoided.
The sustainable mitigation of human–wildlife conflicts has become a major societal and environmental challenge globally. Among these conflicts, large marine predators feeding on fisheries catches, a behaviour termed “depredation,” has emerged concomitantly with the expansion of the world’s fisheries. Depredation poses threats to both the socio‐economic viability of fisheries and species conservation, stressing the need for mitigation. This review synthesizes the extent and socio‐ecological impacts of depredation by sharks and marine mammals across the world, and the various approaches used to minimize it. Depredation was reported in 214 fisheries between 1979 and 2019 (70% post‐2000) and affected fleets from 44 countries, in all sectors (commercial, artisanal and recreational), and in all major fishing techniques (nets, traps and hook‐and‐lines). A total of 68 predator species were involved in depredation (20 odontocetes, 21 pinnipeds and 27 sharks), and most (73%) were subject to either by‐catch and/or retaliatory killing from fishers when interacting with gear. Impacts on fishers were primarily associated with catch losses and gear damage but often lacked assessments. Deterrence was a major mitigation approach but also the least effective. Gear modifications or behavioural adaptation by fishers were more promising. This review highlights the need for improved monitoring, and interdisciplinary and integrated research to quantify the determinants and impacts of depredation in the socio‐ecological dimension. More importantly, as the conflict is likely to escalate, efforts directed towards changing perceptions and integrating knowledge through adaptive co‐management are raised as key directions towards coexistence between fisheries and large marine predators.
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Unraveling the relative importance of both environmental conditions and ecological processes regulating bacterioplankton communities is a central goal in microbial ecology. Marine coastal environments are among the most urbanized areas and as a consequence experience environmental pressures. The highly anthropized Toulon Bay (France) was considered as a model system to investigate shifts in bacterioplankton communities along natural and anthropogenic physicochemical gradients during a 1-month survey. In depth geochemical characterization mainly revealed strong and progressive Cd, Zn, Cu, and Pb contamination gradients between the entrance of the Bay and the north-western anthropized area. On the other hand, low-amplitude natural gradients were observed for other environmental variables. Using 16S rRNA gene sequencing, we observed strong spatial patterns in bacterioplankton taxonomic and predicted function structure along the chemical contamination gradient. Variation partitioning analysis demonstrated that multiple metallic contamination explained the largest part of the spatial biological variations observed, but DOC and salinity were also significant contributors. Network analysis revealed that biotic interactions were far more numerous than direct interactions between microbial groups and environmental variables. This suggests indirect effects of the environment, and especially trace metals, on the community through a few taxonomic groups. These spatial patterns were also partially found for predicted bacterioplankton functions, thus indicating a limited functional redundancy. All these results highlight both potential direct influences of trace metals contamination on coastal bacterioplankton and indirect forcing through biotic interactions and cascading.
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Fisheries bycatch is one of the biggest threats to marine mammal populations. A literature review was undertaken to provide a comprehensive assessment and synopsis of gear modifications and technical devices to reduce marine mammal bycatch in commercial trawl, purse seine, longline, gillnet and pot/trap fisheries. Successfully implemented mitigation measures include acoustic deterrent devices (pingers) which reduced the bycatch of some small cetacean species in gillnets, appropriately designed exclusion devices which reduced pinniped bycatch in some trawl fisheries, and various pot/trap guard designs that reduced marine mammal entrapment. However, substantial development and research of mitigation options is required to address the bycatch of a range of species in many fisheries. No reliably effective technical solutions to reduce small cetacean bycatch in trawl nets are available, although loud pingers have shown potential. There are currently no technical options that effectively reduce marine mammal interactions in longline fisheries, although development of catch and hook protection devices is promising. Solutions are also needed for species, particularly pinnipeds and small cetaceans, that are not deterred by pingers and continue to be caught in static gillnets. Large whale entanglements in static gear, particularly buoy lines for pots/traps, needs urgent attention although there is encouraging research on rope-less pot/trap systems and identification of rope colours that are more detectable to whale species. Future mitigation development and deployment requires rigorous scientific testing to determine if significant bycatch reduction has been achieved, as well as consideration of potentially conflicting mitigation outcomes if multiple species are impacted by a fishery.
Conference Paper
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Le popolazioni degli Ungulati selvatici (soprattutto Cinghiale, Cervo e Capriolo) sono da alcuni anni in continua fase di incremento sia dell’area di distribuzione, sia delle consistenze. Tale espansione, che interessa le aree alpine ed appenniniche, è dovuta all’azione sinergica di molti fattori, quali ad esempio: l’abbandono di molte aree collinari e montane precedentemente coltivate, l’istituzione di aree protette, interventi di reintroduzione (pianificati o meno), la riduzione del bracconaggio e la regolamentazione dell’attività venatoria. L’incremento di tali specie, oltre ad essere un elemento positivo (incremento della biodiversità, presenza di possibili prede per specie a rischio di conservazione, facilità di osservazione in natura, possibile sfruttamento turistico, prelievo venatorio, ecc.), presenta, ormai, alcuni aspetti problematici, legati soprattutto ai danni alle colture agro-forestali ed agli incidenti stradali. Sebbene il principale responsabile dell’impatto sulle attività antropiche sia il Cinghiale, negli ultimi anni anche il Cervo ed il Capriolo incominciano ad essere identificati come specie “problematiche”, soprattutto dalle rappresentanze agricole. Una recente indagine a livello nazionale realizzata dall’ISPRA, ha evidenziato che nel 2004 sono stati spesi per indennizzare i danni causati dagli Ungulati circa 8,9 milioni di euro (causati per il 90% dal Cinghiale). Si tratta sicuramente di una sottostima del problema reale sia perché molte Amministrazioni non hanno partecipato all’indagine, sia perché si tratta solo della cifra indennizzata e non di quella accertata. Attualmente la situazione si è ulteriormente aggravata (anche a causa dell’incremento dei prezzi dei prodotti agricoli), provocando la motivata reazione negativa degli agricoltori e delle Amministrazioni pubbliche. La gestione di tale problema, tralasciando le reazioni emotive e le richieste estemporanee, si deve basare sull’attuazione di una strategia condivisa da tutte le componenti sociali e basata su interventi differenziati da realizzare sia nelle aree protette, sia nel territorio cacciabile. Come più volte indicato dall’ISPRA le azioni prioritarie sono: realizzazione di una pianificazione territoriale che preveda la reale istituzione ed il funzionamento delle aree contigue ai parchi, l’identificazione di densità obiettivo “credibili” e basate sull’idoneità ambientale per le popolazioni delle principali specie problematiche, il ricorso ad interventi di prevenzione dei danni, un prelievo venatorio commisurato alla reale consistenza delle popolazioni e che tenga conto delle situazioni locali, strumenti che consentano un iter rapido per la perizia e l’indennizzo dei danni, interventi di controllo numerico delle popolazioni (da attuare la normativa vigente (LN 394/91 e 157/92). Appare, quindi, evidente la necessità di una collaborazione e coordinamento tra tutte le componenti sociali a vario titolo interessate al problema (imprenditori agricoli, ambientalisti, cacciatori, ecc.) e gli Enti pubblici e privati responsabili della gestione del territorio (Amministrazioni provinciali e regionali, Enti Parco, ATC e CA, Aziende faunistico-venatorie, ecc.). Inoltre è necessario migliorare le metodologie utilizzate per la stima della consistenza delle popolazioni animali, per l’accertamento e la quantificazione dei danni (maggiore uniformità e georeferenziazione) e per la creazione di banche dati specifiche. Infine si dovrebbero sperimentare tecniche di caccia differenziate a seconda dei contesti locali (ad es. per il cinghiale affiancare la classica braccata con la girata e la caccia di selezione).
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Damage to crops from wildlife interference is a common threat to food security among rural communities in or near Game Management Areas (GMAs) in Zambia. This study uses a two-stage model and cross-sectional data from a survey of 2769 households to determine the impact of land use planning on the probability and extent of wildlife-inflicted crop damage. The results show that crop damage is higher in GMAs as compared to non-GMAs, and that land use planning could be an effective tool to significantly reduce the likelihood of such damage. These findings suggest that there is merit in the current drive to develop and implement land use plans to minimize human-wildlife conflict such as crop damage. This is especially critical as Zambian conservation policies do not explicitly provide compensation for damage caused by wildlife.
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In recent decades, a number of studies have examined whether various non-human animals understand their partner's role in cooperative situations. Yet the relatively tolerant timing requirements of these tasks make it theoretically possible for animals to succeed by using simple behavioural strategies rather than by jointly intended coordination. Here we investigated whether bottlenose dolphins could understand a cooperative partner's role by testing whether they could learn a button-pressing task requiring precise behavioural synchronization. Specifically, members of cooperative dyads were required to swim across a lagoon and each press their own underwater button simultaneously (within a 1 s time window), whether sent together or with a delay between partners of 1-20 s. We found that dolphins were able to work together with extreme precision even when they had to wait for their partner, and that their coordination improved over the course of the study, with the time between button presses in the latter trials averaging 370 ms. These findings show that bottlenose dolphins can learn to understand their partner's role in a cooperative situation, and suggest that the behavioural synchronization evident in wild dolphins' synchronous movement and coordinated alliance displays may be a generalized cognitive ability that can also be used to solve novel cooperative tasks.
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Fisheries depredation by marine mammals is an economic concern worldwide. We combined questionnaires, acoustic monitoring, and participatory experiments to investigate the occurrence of bottlenose dolphins in the fisheries of Northern Cyprus, and the extent of their conflict with set-nets, an economically important metier of Mediterranean fisheries. Dolphins were present in fishing grounds throughout the year and were detected at 28% of sets. Net damage was on average six times greater where dolphins were present, was correlated with dolphin presence, and the associated costs were considerable. An acoustic deterrent pinger was tested, but had no significant effect although more powerful pingers could have greater impact. However, our findings indicate that effective management of fish stocks is urgently required to address the overexploitation that is likely driving depredation behaviour in dolphins, that in turn leads to net damage and the associated costs to the fisheries. Electronic supplementary material The online version of this article (10.1007/s10745-018-9989-7) contains supplementary material, which is available to authorized users.
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The management of conflicts between wildlife conservation and agricultural practices often involves the implementation of strategies aimed at reducing the cost of wildlife impacts on crops. Vital to the success of these strategies is the perception that changes in management efforts are synchronised relative to changes in impact levels, yet this expectation is never evaluated. We assess the level of synchrony between time series of population counts and management effort in the context of conflicts between agriculture and five populations of large grazing birds in northern Europe. We reveal inconsistent patterns of synchrony and asynchrony between changes in population counts and impact management effort relating to population harvesting, monetary payments or scaring practices. This variation is likely due to differing management aims, the existence of lags between management decisions and population monitoring, and the inconsistent use of predictive models across case studies. Overall, our findings highlight the need for more adaptive and timely responses of management to changes in target species numbers so as not to unexpectedly increase social conflicts and jeopardise the status of wildlife populations.
Land use/land cover (LULC) change models are powerful tools used to understand and explain the causes and effects of LULC dynamics, and scenario-based analyses with these models can support land management and decision-making better. This paper provides a synoptic and selective review of current LULC change models and the novel frameworks that are being used to investigate LULC dynamics. Existing LULC models that explore the interactions between human and the environment can be pattern- or process-based, inductive or deductive, dynamic or static, spatial or non-spatial, and regional or global. This review focuses on the spectrum from pattern- to process-based approaches and compares their strengths, weaknesses, applications, and broad differences. We draw insights from the recent land use change literature and make five suggestions that can support a deeper understanding of land system science by: (1) overcoming the difficulties in comparing and scaling Agent Based Models; (2) capturing interactions of human-environment systems; (3) enhancing the credibility of LULC change modeling; (4) constructing common modeling platforms by coupling data and models, and (5) bridging the associations between LULC change modeling and policy-making. Although considerable progress has been made, theoretical and empirical efforts are still needed to improve our understanding of LULC dynamics and their implications for policy-oriented research. It is crucial to integrate the key elements of research involved in this study (e.g., use of common protocols and online portals, integration of top-down and bottom-up approaches, effective quantification and communication of modeling uncertainties, generalization and simplification of models, increased focus on the theoretical and empirical bases of models, and open comparative research) to bridge the gaps between small-scale process exploration and large-scale representation of LULC patterns, and to use LULC change modeling to inform decision-making.
Coastal waters of the Valencia region are important habitats for bottlenose dolphins, but also important fishing grounds for artisanal fisheries. No studies have been carried out here to investigate the overlap and interactions between the fishing grounds and dolphin habitat. The present study aims to assess the potential occurrence of interactions between artisanal fisheries and bottlenose dolphins in these waters. Face to face interviews were conducted to investigate for the first time artisanal fishermen's perceptions of their interactions with bottlenose dolphins. A total of 131 fishermen (40.1% of the artisanal fleet for the Valencia region) participated of research. Among the interviewed fishermen, 86.1% perceived that dolphins damaged fishing gear as they attempted to feed, and they also detected significant direct damage to fish. Of all fishermen reporting a negative interaction with bottlenose dolphins, 76.3% also reported financial loss (2907.1 ± 2512.7 €/year (100–12,000). Despite the high level of interaction with dolphins reported, fishermen do not consider bycatch to be an important threat for bottlenose dolphins. Our results show geographical differences in fishermen's perceptions of damage caused by dolphins: while dolphins were considered to be the second cause of economic loss in the southernmost ports, fishermen from the northern ports considered interaction with bottom trawl boats to be more harmful than interaction with dolphins. The more intense interaction reported by fishermen in fishing ports in the southern study area may be associated with higher presence of bottlenose dolphin in these zones. Our study provides a useful insight into fishermen's perceptions of interaction between bottlenose dolphins and artisanal fisheries in this key area for the species in the western Mediterranean Sea. It also highlights the need for future work including direct observations of interactions and damage to gather reliable data to assess the need for conservation measures.