EPA - Ireland's Environment 2016 - An Assessment

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Ireland’s Environment – An Assessment 2016 74
Dredging of Marine Harbours and
Marinas
Material that is dredged and dumped at sea has to be
licensed and monitored.
The removal of seabed material for maintenance and
navigational purposes is a common occurrence in harbours
and marinas around Ireland. In 2013, approximately
350,000 tonnes (dry weight) of material was dredged
and deposited at four licensed disposal sites around
the Irish coast (OSPAR, 2015). As part of the licensing
process, sediment chemistry of dredged material must be
analysed to ensure that release of harmful contaminants
at the disposal site is minimised. The quantity of dredged
material dumped at sea each year is reported to the OSPAR
Commission by the Marine Institute.
Marine Fisheries and Aquaculture
An important sector for the economy in Ireland, but
there are a number of key environmental pressures to
resolve to ensure sustainability.
In 2014, the value of commercial fish and shellfish landings
was just under €346 million, with landings of demersal
(bottom feeders) and pelagic (openwater feeders) species
contributing just over €250 million of the total (Source:
SFPA7). In the aquaculture sector, the value of production
in 2014 was €116 million; this is less than the peak value
of €131 million achieved in 2012.
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The most obvious pressure on the environment from
fishing is the harvesting of target species and the
unintentional catching of non-target fish species and other
species such as cetaceans, seals, seabirds and benthic
organisms. Fishing activities such as trawling and dredging
can injure or kill benthic organisms and can result in
damage to and destruction of habitats.
The main issues in relation to aquaculture are the effects
of discharges of uneaten fish-food material and fish waste
from fish farms, the introduction and spread of disease and
parasites and the use of chemotherapeutics and anti-fouling
agents. Other issues include the introduction of alien species,
the impact of escaped farmed salmon on the genetic
integrity of wild stocks and the visual impact of aquaculture
facilities on the aesthetic quality of the environment.
Impacts of Commercial Fishing
It is estimated that 36% of commercial fish stocks are
sustainably fished, but 26% of stocks are overfished.
Fishing impacts are assessed every year in the Marine
Institute’s annual Stock Book.8 This collates information on
fishing pressures and the biological state of commercially
exploited species.
The 2015 Stock Book reports that, of 72 commercial
stocks, 36% are considered to be sustainably fished.
Overfished stocks have declined to 26%, and 38% remain
at an unknown status. Nineteen per cent of commercial
species are considered to have been depleted.
The International Council for the Exploration of the
Seas (ICES) recently published (Source ICES, 20169) an
ecosystem overview of the Celtic Sea, which includes a
large part of the Irish Exclusive Economic Zone (EEZ) (see
Figure 5.1). It found that:
n Overall fishing pressure on the commercial fish
and shellfish stocks in the Celtic Sea ecoregion has
decreased since its peak in 1998.
n Overall biomass of commercial fish and shellfish stocks
in the Celtic Sea has increased since the late 1990s.
n The fishing footprint and the average number of times
the seabed is trawled per year have reduced.
However, there are still a number of species with very
low spawning stocks in some areas, particularly cod,
whiting, sole and herring. According to the ICES ecosystem
overview: “Several fish species have been depleted by
fishing in the past and are now on the OSPAR list of
threatened and declining species, including spurdog
Squallus acanthias, common skate complex Dipturus spp.,
angel shark Squatina squatina, porbeagle Lamna nasus,
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