Medidas de Gestao das Pescarias Marinhas e Aquicultura 2019 The State of World Fisheries and Aquaculture 2018 | Page 172

PART 3 HIGHLIGHTS OF ONGOING STUDIES
land- and sea-based sources (GESA MP, 2016) and
can be categorized in two groups: primar y
microplastics that are intentionally manufactured
(pellets, powders, scrubbers) and secondar y
microplastics resulting from the breakdown of
larger material such as plastic bags, or from the
abrasion of car t yres during use. In the fisheries
and aquaculture sector, the construction, use,
maintenance and disposal of fishing gear, cages,
buoys, boats and product packages are sources of
secondar y microplastics. Lebreton et al. (2017)
estimated that 67 percent of plastic pollution in
marine environments comes from 20 rivers,
mostly in Asia.
drifting fish aggregation devices (FADs) used by
the purse seine industr y. At an FAO technical
consultation in Februar y 2018, member
countries agreed on a set of draft voluntar y
g uidelines on the marking of fishing gear,
which will be tabled for approval at the 2018
FAO Committee of Fisheries.
Recycling, repurposing and appropriate disposal
of end-of-life fishing gear can also reduce
ALDFG in the sea and its impact on marine life
and the ocean environment. Despite investment
in infrastructure, inappropriate disposal of
fishing gear, whether at sea or on land, adds to
the ALDFG problem. Ports should provide
adequate reception facilities for the disposal of
fishing gear in accordance with Annex V of the
International Convention for the Prevention of
Pollution from Ships (M A RPOL). However,
accessible low-cost disposal facilities for plastics
are still not available or are not properly
maintained in many fishing ports; and where
they do exist, fishers may have limited incentives
to use them. FAO engages with IMO on these
issues and provides technical assistance to FAO
Members on cleaner fishing harbours by
disseminating experiences, promoting good
practices, producing manuals and g uidelines,
facilitating capacit y development for harbour
masters and the fishing industr y, and promoting
stakeholder participation in the management of
fishing harbours and landing centres.
Currently, little is known on the occurrence of
microplastics in freshwaters, especially in
developing countries. In marine environments,
microplastics have been found in surface waters,
throughout the water column, on the seaf loor,
along the shoreline and in biota, but quantitative
information is still scarce. Efforts to estimate the
global distribution of plastic fragments have
generated var ying results because of the different
t y pes of assessment models used and definitions
adopted (Galgani, Hanke and Maes, 2015; Law,
2017). However, the Pacific, the Bay of Bengal
and the Mediterranean Sea are likely to have the
highest concentrations (GESA MP, 2015, 2016).
Microplastic uptake by aquatic fauna has been
reported in a wide range of habitats as well as in
aquaculture cages. Ingestion is the main means
of uptake, as plastic fragments can be confused
with small-sized natural prey or consumed
through filter feeding or ventilation. Over 220
species of marine animals (not counting birds,
turtles and mammals) have been found to ingest
microplastics in their natural environment, half
of them of commercial importance (Lusher,
Holman and Mendoza-Hill, 2017).
Microplastics
Plastic is a general term for a range of polymer
materials that are mixed with different additives
(such as plasticizers, antioxidants, f lame
retardants, ultraviolet stabilizers, lubricants,
colourants) depending on the requirement of the
end product. These materials can leach to the
surrounding environment. Although definitions
may var y, it is generally agreed that microplastics
include particles and fibres of plastic of different
shapes and colours measuring less than 5 mm,
including nanoplastics measuring less than
0.1 µm. Microplastics tend to attract persistent
and bioaccumulative contaminants that are
present in the water, as well as living organisms
(marine invertebrates, bacteria, fungi, viruses)
that use them as a substrate. Microplastics
entering the ocean come from a wide variet y of
In wild organisms, microplastics have so far been
obser ved only in the gastrointestinal tract (i.e.
g ut). The largest microplastics cannot penetrate
the cell membranes of the gastrointestinal tract
and enter the bloodstream of animals, including
humans. Fragments of less than 150 µm (the
smallest microplastics and nanoplastics) seem to
be able to cross cell membranes and lead to
internal exposure. However, there are currently
no methods available for detection and
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