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Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Contents
Executive summary ................................................................................................... 8
1. Introduction ....................................................................................................... 14
1.1. Belfast Lough SPA (site code- UK9020101) ............................................... 15
Attribute ............................................................................................................... 16
1.2. Belfast Lough Open water SPA (site code-UK9020290 ) ............................ 17
Attribute ............................................................................................................... 18
2. Impact Assessment .......................................................................................... 21
2.1. Current aquaculture activities within Belfast Lough ..................................... 21
2.2. GIS Assessment ......................................................................................... 24
2.2.1. Impacts of aquaculture activities on Belfast Lough SPA designated
features............................................................................................................. 24
2.2.2. Impacts of aquaculture activities on Belfast Lough Open Water SPA
designated features .......................................................................................... 26
2.3. Non native species ..................................................................................... 28
2.4. Benthic impacts of aquaculture ................................................................... 28
2.5. Carrying Capacity Assessment – SMILE .................................................... 29
3. Conclusions ...................................................................................................... 63
3.1. Belfast Lough SPA features ........................................................................ 63
3.2. Belfast Lough Open water SPA features .................................................... 64
3.3. Ecological carrying capacity of Carlingford Lough ...................................... 65
4. Recommendations ............................................................................................ 66
5. Assessment under Article six of the Habitats Directive ...................................... 67
6. References ....................................................................................................... 71
Annex I: Natura 2000 standard data form: Belfast Lough SPA ................................ 73
Annex II: Natura 2000 standard data form: Belfast Lough Open Water SPA ........... 77
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Table of Figures
Figure 1.1: Map showing the boundary of the Belfast Lough SPA – site code
UK9020101 ............................................................................................................. 19
Figure 1.2: Map showing the boundary of the Belfast Lough Open water SPA – site
code UK9020290 .................................................................................................... 20
Figure 2.1: Map showing DARD licensed aquaculture sites (as of July 2014).......... 32
Figure 2.2: Map showing DARD licensed aquaculture sites and the Belfast Lough
Open water SPA boundary (purple hashed area). ................................................... 33
Figure 2.3: Map showing DARD licensed aquaculture sites and the Belfast Lough
SPA boundary (blue hashed area). ......................................................................... 34
Figure 2.4: Modified Dutch Dredge (BIM 2012) ....................................................... 35
Figure 2.5: Starfish mop (BIM 2012). ....................................................................... 35
Figure 2.6: Map of Belfast Lough showing the WeBS count sections within the Lough
for the years up to an including 2007/08. ................................................................. 36
Figure 2.7: Map of Belfast Lough showing the WeBS count sections within the Lough
for the year 2008/09. ............................................................................................... 37
Figure 2.8: Map of Belfast Lough showing the WeBS count sections within the Lough
for the years after and including 2009/10. ................................................................ 38
Figure 2.9: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2006/07. .................................................... 39
Figure 2.10: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2007/08. .................................................... 40
Figure 2.11: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2008/09. .................................................... 41
Figure 2.12: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2009/10. .................................................... 42
Figure 2.13: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2010/11. .................................................... 43
Figure 2.14: Graph showing the observed numbers of Redshank within Belfast Lough
for the years 2002/03 to 2011/12 as counted through WeBS (Austin et al 2014). .... 44
Figure 2.15: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2006/07 along with processed Black Box data
for the same time period. ......................................................................................... 45
Figure 2.16: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2007/08 along with processed Black Box data
for the same time period. ......................................................................................... 46
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.17: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2008/09 along with processed Black Box data
for the same time period. ......................................................................................... 47
Figure 2.18: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2009/10 along with processed Black Box data
for the same time period. ......................................................................................... 48
Figure 2.19: Map of Belfast Lough showing the number of Redshank recorded within
WeBS Low tide counts for the winter of 2010/11 along with processed Black Box data
for the same time period. ......................................................................................... 49
Figure 2.20: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2006/07. ........................... 50
Figure 2.21: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2007/08. ........................... 51
Figure 2.22: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2008/09. ........................... 52
Figure 2.23: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2009/10. ........................... 53
Figure 2.24: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2010/11. ........................... 54
Figure 2.25: Graph showing the observed numbers of Great Crested Grebes within
Belfast Lough for the years 2002/03 to 2011/12 as counted through WeBS core
counts (Austin et al 2014). ....................................................................................... 55
Figure 2.26: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2006/07 along with
processed Black Box data for the same time period. ............................................... 56
Figure 2.27: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2007/08 along with
processed Black Box data for the same time period. ............................................... 57
Figure 2.28: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2008/09 along with
processed Black Box data for the same time period. ............................................... 58
Figure 2.29: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2009/10 along with
processed Black Box data for the same time period. ............................................... 59
Figure 2.30: Map of Belfast Lough showing the number of Great Crested Grebes
recorded within WeBS Low tide counts for the winter of 2010/11 along with
processed Black Box data for the same time period. ............................................... 60
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.31: Map showing the locations of the E2K boxes used within the SMILE
model. ..................................................................................................................... 61
Figure 2.32: Map showing the locations of currently licensed aquaculture sites within
the E2K boxes used within the SMILE model. ......................................................... 62
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Table of Tables:
Table 1.1: Belfast Lough SPA (site code UK9020101) selection feature objectives, as
taken from Annex I of the NIEA Conservation Objectives report for Belfast Lough
SPA. ........................................................................................................................ 16
Table 1.2: Belfast Lough Open water SPA (site code UK9020290) selection feature
objectives, as taken from Annex I of the NIEA Conservation Objectives report for
Belfast Lough SPA. ................................................................................................. 18
Table 2.1: Activities undertaken within licensed aquaculture sites within Belfast
Lough (BIM 2012). .................................................................................................. 22
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Executive summary
Introduction
Belfast Lough is a shallow semi-enclosed marine bay situated at the mouth of the
River Lagan, on the eastern coast of Northern Ireland, with the city of Belfast at its
head. Belfast Harbour is Northern Ireland’s main port. The Belfast Harbour Oil
Pollution Contingency Plan states that “In the order of 12,000 ship movements take
place in the Port per annum, which accounts for up to 60% of Northern Ireland’s
seaborne trade and 25% of the entire seaborne trade of Ireland” (Belfast Harbour
Commissioners 2010). Belfast Lough is approximately 130 km2 in size and has a
catchment of approximately 900 km2. The Inner Lough comprises a series of
mudflats and lagoons whilst the Outer Lough is composed of mainly rocky shores
with some small sandy bays.
There are currently two Natura 2000 designated sites within Belfast Lough; the
Belfast Lough Special Protection Area (SPA), designated for overwintering (non
breeding) Redshank and the Belfast Lough Open Water SPA, designated for
overwintering (non breeding) Great Crested Grebe.
Impact Assessment
Aquaculture activities within Belfast Lough have the potential to impact the
designated species of the Belfast Lough SPA (Redshank) and the Belfast Lough
Open water SPA (Great Crested Grebes) through;
Human presence within their preferred habitats
Damage/disturbance to feeding areas/species
This report examines the potential impacts of aquaculture activities on each of the
SPA designated species in turn. The Geographic Information System (GIS)
programme ArcGIS was used to map the distribution of designated features in
relation to licensed aquaculture sites.
Current aquaculture activities within Belfast Lough
At present all licensed aquaculture sites within Belfast Lough are within the subtidal
areas of the lough. Subtidal aquaculture within Belfast Lough involves the bottom
culture of the blue mussel Mytilus edulis. There are currently twenty one licensed
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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aquaculture sites within Belfast Lough, all of which are authorised for commercial
production as Aquaculture Production Businesses under the Aquatic Animal Health
Regulations (Northern Ireland) 2009. The total area of Belfast Lough currently
occupied by licensed aquaculture sites equates to approximately 1,264.203 hectares
(as calculated from DARD data). This is approximately 22.60% of the total area of the
Belfast Lough open water SPA. As all currently licence aquaculture sites within
Belfast Lough are subtidal there is therefore no spatial overlap with boundary of the
Belfast Lough SPA.
GIS Assessment
Overwintering (non breeding) bird species within Belfast Lough are counted through
the Wetland Bird Survey (WeBS).
1. Impacts of aquaculture activities on Belfast Lough SPA designated features
Redshank data has been extracted from WeBS low tide survey data for Belfast
Lough for the winters of 2006/07 to 2010/11 and processed in GIS for use within this
report. Redshanks are found throughout the intertidal area of Belfast Lough, with the
largest numbers generally being recorded in the inner lough.
Redshanks are waders feeding mainly in the intertidal zone (Goss-Custard and
Jones 1976). Therefore subtidal aquaculture activities within Belfast Lough will not
damage the feeding areas of these birds. As all mussel aquaculture within Belfast
Lough is subtidal these bivalves will not be available as a food source for waders. In
order to assess potential impacts of vessels undertaking husbandry activities at
subtidal aquaculture sites on feeding Redshanks, Black Box data for aquaculture
vessels operating within Belfast Lough was obtained from DARD. This data was then
filtered for speed, location and month (to coincide with the months counted during the
WeBS low tide counts for the years 2006/07 to 2010/11) and processed in ArcGIS
using Spatial Analysis tools. The areas of highest vessel activity for the winters of
2006/07 to 2010/11 did not occur adjacent to the areas where highest numbers of
Redshank were observed.
The most recent Site condition assessment undertaken for this SPA states that this
feature is in unfavourable condition (NIEA 2013a). The recent observed decline in
Redshank numbers (between 2009/10 and 2010/11) in Belfast Lough is in keeping
with trends within other Northern Irish sites as numbers recorded within Strangford
Lough in 2010 were their lowest since 2001/02 (Holt et al 2012). This is also in line
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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with current UK trends as numbers recorded in 2011/12 were at their lowest point for
over 25 years (Austin et al 2014). There is no evidence to suggest that aquaculture
activities within Belfast Lough are negatively impacting Redshank populations within
this area.
2. Impacts of aquaculture activities on Belfast Lough Open Water SPA
designated features
Great Crested Grebe data has been extracted from WeBS low tide survey data for
Belfast Lough for the winters of 2006/07 to 2010/11 and processed in GIS for use
within this report. Great Crested Grebes are widely distributed throughout Belfast
Lough, with no area consistently supporting high numbers.
Great Crested Grebes are diving waterbirds (Johnsgard, 1987; Wiersma et al 1995;
Gwiazda, 1997; Well et al, 2013) feeding primarily on fish (van Eerden et al, 1993;
Gwiazda, 1997; Doornbos, 1984) therefore shellfish aquaculture will not impact on
the availability of prey species for these birds. Studies in the Netherlands have
observed Great Crested Grebes foraging only at dawn and dusk in offshore waters
(Piersma, 1987 and van Eerden et al, 1993) and in Southern Poland this species
started to forage approximately one hour before sunrise finishing approximately one
hour after sunrise (Gwiazda 1997). Aquaculture activities within Belfast Lough are
predominantly undertaken during daylight hours, however on occasion vessels may
be operating on site during twilight hours. Therefore vessels undertaking husbandry
activities during twilight hours could potentially disturb feeding grebes. In order to
assess potential impacts of vessels undertaking husbandry activities at aquaculture
sites on rafting Great Crested Grebes, processed Black box data was mapped in GIS
alongside the processed WeBS Low tide count data for Great Crested Grebe. Areas
of observed highest vessel activity for the winters of 2006/07 to 2010/11 did not occur
adjacent to the count sectors where the highest numbers of Great Crested Grebes
were observed. High numbers of birds (ranging from 200-300) were observed during
several winters adjacent to the areas of high aquaculture activity.
Trends in Northern Ireland are in line with the shallow decline in this species
observed in Britain since 2003/04. However Holt et al (2012) noted that in 2010/11
this species “fared very poorly in Northern Ireland”. The fall in Great Crested Grebe
numbers between 2009/10 and 2010/11 in Belfast Lough may be attributable to low
winter temperatures (Holt et al 2012). The decline in numbers of Great Crested
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Grebe within Belfast Lough is in line with National trends which saw numbers of this
species continue to decline within the UK during 2011/12 counts (Austin et al 2014).
The most recent Site condition assessment undertaken for this SPA states that this
feature is in favourable condition (NIEA 2013b). There is no evidence to suggest that
aquaculture activities within Belfast Lough are negatively impacting Great Crested
Grebe populations within the Lough. It is important to remember that aquaculture
within Belfast Lough was well established before the Belfast Lough Open water SPA
was designated.
Non native species
Since 2008, when the slipper limpet (Crepidula fornicata) (a non native invasive
species) was discovered in Belfast Lough, movements of mussels from Belfast
Lough for relaying onto other licensed aquaculture sites has been prohibited (AFBI
2014).
Seed mussels used for the bottom culture of mussels in Belfast Lough are obtained
from naturally occurring seed beds (usually located within the UK and Ireland).
Imports of mussel seed from outside Northern Ireland must be accompanied by a
permit granted under the Molluscan Shellfish (Control of Deposit) Order (Northern
Ireland) 1972. Imports of seed are only permitted from areas known to be free from
populations of non-native species.
Benthic impacts
Activities undertaken at licensed aquaculture sites include seeding, maintenance,
predator control and harvesting. When dredging operations are undertaken on
aquaculture sites within Belfast Lough a modified Dutch Dredge is used which has
been engineered so as to reduce benthic impacts.
The bottom culture of mussels can change the composition of benthic sediments,
through a reduction in grain size and an increase in mud content (Ysebaert et al
2009). These effects however can be extremely localised, being confined to within or
directly adjacent to the mussel beds studied (Ysebaert et al 2009).
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Bottom culture of mussels can lead to increases in biodiversity with greater numbers
of eipbenthic species being observed within culture areas compared to similar areas
without bottom mussel culture (Smith and Shackley, 2004 and Ysebaert et al 2009).
Carrying capacity assessment
For the purpose of this assessment the SMILE model was applied to two scenarios,
which simulated the impact on the ecosystem of increasing the abundance of filter-
feeding organisms, through aquaculture activities, in Belfast Lough. Chlorophyll a
(Chl a) was used as a proxy for phytoplankton biomass within Belfast Lough. The two
scenarios represented the levels of Chl a present within the Lough if;
a) Run 1 - There was no aquaculture within the Lough (only wild species
present). This run is used as a baseline as wild species will always be
present.
b) Run 2- All currently licensed aquaculture sites were activated at a rate of
production (in terms of tonnage/ha) determined using the three year mean
from observed data (supplied by DARD) for the years 2010-2012. As wild
species is to be used as a baseline this component was also activated for this
run.
The results from these Runs show that aquaculture species reduce the overall
ecosystem phytoplankton biomass and hence food availability for other organisms
within Belfast Lough by up to 56%.
Analysis of measured monthly Chl a data from 16 sample stations within Belfast
Lough (taken from Charlesworth and Service 1998) shows up to a 41% annual
variation within Chl a values (using 90th percentile figures) recorded between
sampling years. From this we would recommend that, as a precaution, a minimum of
50%, of baseline values, of Chl a remains within the system available for wild
species. This therefore implies that aquaculture activities should not reduce Chl a
concentrations by greater than 50% of baseline values (Run 1).
Results from SMILE Runs (Table 2.2) indicate that if all licensed sites within Belfast
Lough are active mussel production within three of the model boxes will be at the
ecological threshold. However at no time within the last four years (2010 to 2014)
have all licensed aquaculture sites within Belfast Lough been active simultaneously.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Conclusions
There is no spatial overlap between currently licensed aquaculture sites and the
boundary of the Belfast Lough SPA.
Approximately 22.60% of the total area of the Belfast Lough Open water SPA is
occupied by licensed aquaculture sites.
As Redshank are waders feeding mainly in the intertidal zone, subtidal
aquaculture activities will not damage feeding areas or impact food availability
for this species.
As Great Crested Grebes feed mainly on fish, shellfish aquaculture will not
impact the availability of prey for this species.
There is no evidence to suggest that licensed aquaculture activities within
Belfast Lough are negatively impacting the conservation objectives of the Belfast
Lough SPA or the Belfast Lough Open water SPA.
Recommendations
Aquaculture operators should avoid (where practical) activities on their sites
when large numbers of rafting Great Crested Grebes are observed in the area.
Activities at aquaculture sites should be minimised during twilight hours in order
to reduce potential disturbance to twilight foraging Great Crested Grebes.
Competent authorities should determine the flushing distances (in response to
disturbance by different types of vessels) of Great Crested Grebes within Belfast
Lough.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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1. Introduction
European Council Directive 92/43/EEC on the conservation of natural habitats and of
wild fauna and flora, and Directive 2009/147/EC on the Conservation of wild birds
(often referred to as the Habitats and Birds Directives respectively) were developed
with the aims of protecting habitats and species considered to be of European
interest. This is achieved through member states designating sites of Special areas
of Conservation (SAC) for the protection of habitats (as listed in Annex I of the
habitats directive) and species (as listed in Annex II of the habitats directive) and
Special Protection Areas (SPA) for the protection wild birds and the habitats of listed
species.
The Habitats and Birds Directives were brought into effect in Northern Ireland law by
the Conservation (Natural Habitats, etc.) Regulations (Northern Ireland) 1995, as
amended by The Conservation (Natural Habitats,etc.) (Amendment) Regulations
(Northern Ireland) 2012; also known as the Habitats Regulations. SAC and SPA
designated sites form the Natura 2000 network of sites (sometimes referred to as
N2K).
The Fisheries and Environment Division of the Department of Agriculture and Rural
Development (DARD) commissioned AFBI to undertake a Cumulative Impact
Assessment report for Aquaculture activities within Belfast Lough SPA and Belfast
Lough Open Water SPA. This document therefore assesses the potential impacts of
aquaculture activities on the designated features and conservation objections of the
Natura 2000 designated sites outlined above. This assessment is based on
information supplied by DARD, the Belfast Lough mussel producers (via BIM), the
Wetlands Bird survey (WeBS), The Northern Ireland Environment Agency (NIEA), the
Department of the Environment (DoE) Marine Division, and information collected by
AFBI.
Belfast Lough is a shallow semi-enclosed marine bay situated at the mouth of the
River Lagan, on the eastern coast of Northern Ireland, with the city of Belfast at its
head. Belfast Lough is approximately 130 km2 in size and has a catchment of 900
km2. The Inner Lough comprises a series of mudflats and lagoons whilst the Outer
Lough is composed of mainly rocky shores with some small sandy bays. There are
currently two Natura 2000 designated sites within Belfast Lough; the Belfast Lough
SPA and the Belfast Lough open water SPA. Natura 2000 data forms list designated
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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features as being classified either A, B, C, D, E etc. Only features classified as either
A, B, or C are considered as Natura 2000 features and need to be considered within
impact assessments.
1.1. Belfast Lough SPA (site code- UK9020101)
Belfast Lough SPA was classified in August 1998 and covers an area of
approximately 432.14 hectares (see Figure 1.1 for a map of the site boundary).
This site qualifies under Article 4.2 of EC Directive 79/409 on the Conservation of
Wild Birds by supporting populations of European importance of the following
migratory species;
Over Winter (non breeding)
Redshank (Tringa totanus). For the period 1991/92 to 1995/96 the five year
peak mean for Redshank at this site constituted 1.4% of the Eastern Atlantic
(wintering) population. The Natura 2000 standard Data form for this site lists a
winter population of 2,466 individuals (Annex I).
Up to date information regarding bird numbers and distribution for the above species
were purchased from the British Trust for Ornithology’s (BTO) Wetland Birds Survey
(WeBS) Low tide counts and used within the GIS project accompanying this report to
examine the potential impacts of aquaculture activities on this species.
Site Conservation Objectives (as provided by NIEA)
The conservation objectives for this site are “To maintain each feature in favourable
condition”. NIEA have also identified a number of component objectives for each
feature (see Table 1.1).
The most recent condition assessment undertaken by NIEA (2013a) states that the
designated features of this site i.e. Redshank populations are in unfavourable
condition.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Table 1.1: Belfast Lough SPA (site code UK9020101) selection feature objectives, as taken
from Annex I of the NIEA Conservation Objectives report for Belfast Lough SPA.
Attribute
Measure
Targets
Comments
* Redshank
wintering
population
Bird numbers
No significant
decrease in
population against
national trends,
caused by on-site
factors
Five year running averages will be used
to monitor population trends through
WeBS data. Decline to a level below the
Common Standards Monitoring baseline
over a five year period may indicate
unfavourable condition of the site.
*Habitat
extent
Area of
natural and
semi-natural
habitat
Maintain the area of
natural and semi-
natural habitats used
by notified species,
within the SPA,
subject to natural
processes.
Monitor once every reporting cycle by
aerial photography.
#Extent of
different
habitats
Extent of
different
habitats
Maintain the extent of
main habitat
components subject
to natural processes
Evaluate habitat quality should bird
populations decline due to on site
factors. Map any changes in area. This
may include mapping areas with different
vegetation structures where this would
lead to different usage by notified
species.
#Roost
sites
Location of
roost sites
Maintain all locations
of roost sites
Map roost site locations. Visit once every
reporting cycle to ensure sites are
available.
* = primary attribute. One failure among primary attribute = unfavourable condition
# = optional factors. These can be in unfavourable condition without the site being in
unfavourable condition.
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1.2. Belfast Lough Open water SPA (site code-UK9020290 )
Belfast Lough Open water SPA was classified in September 2009 and covers an
area of approximately 5,592.99 hectares (see Figure 1.2 for a map of the site
boundary).
This site qualifies under Article 4.2 of EC Directive 79/409 on the Conservation of
Wild Birds by supporting populations of European importance of the following
migratory species;
Over Winter (non breeding)
Great Crested Grebe (Podiceps cristatus). For the period 1996/97 to 2000/01
the five year peak mean for Great Crested Grebe at this site constituted
0.35% of the North-western European (wintering) population. The Natura
2000 standard Data form for this site lists a winter population of 1,677
individuals (Annex II).
Up to date information regarding bird numbers and distribution for the above species
were purchased from the BTO’s WeBS Low tide counts and used within the GIS
project accompanying this report to examine the potential impacts of aquaculture
activities on this species.
Site Conservation Objectives (as provided by NIEA)
The conservation objectives for this site are “To maintain each feature in favourable
condition”. NIEA have also identified a number of component objectives for each
feature (see Table 1.2).
The most recent condition assessment undertaken by NIEA (2013b) states that the
designated features of this site i.e. Great Crested Grebe populations are in
favourable condition.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Table 1.2: Belfast Lough Open water SPA (site code UK9020290) selection feature
objectives, as taken from Annex I of the NIEA Conservation Objectives report for Belfast
Lough SPA.
Attribute
Measure
Targets
Comments
* Great
Crested Grebe
wintering
population
Bird numbers
No significant
decrease in
population against
national trends,
caused by on-site
factors
Five year running averages will be used
to monitor population trends through
WeBS data. Decline to a level below the
Common Standards Monitoring baseline
over a five year period may indicate
unfavourable condition of the site.
*Habitat extent
Area of
natural and
semi-natural
habitat
Maintain the area of
natural and semi-
natural habitats used
by notified species,
within the SPA,
subject to natural
processes.
Monitor once every reporting cycle by
aerial photography.
#Extent of
different
habitats
Extent of
different
habitats
Maintain the extent of
main habitat
components subject
to natural processes
Evaluate habitat quality should bird
populations decline due to on site
factors. Map any changes in area. This
may include mapping areas with different
vegetation structures where this would
lead to different usage by notified
species.
#Roost sites
Location of
roost sites
Maintain all locations
of roost sites
Map roost site locations. Visit once every
reporting cycle to ensure sites are
available.
* = primary attribute. One failure among primary attribute = unfavourable condition
# = optional factors. These can be in unfavourable condition without the site being in
unfavourable condition.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Section 1 Figures (all maps are projected in ING)
Figure 1.1: Map showing the boundary of the Belfast Lough SPA – site code UK9020101
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 1.2: Map showing the boundary of the Belfast Lough Open water SPA – site code UK9020290
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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2. Impact Assessment
In order to undertake a comprehensive assessment of the impacts of aquaculture
activities within the boundaries of and in the vicinity of the Natura 2000 designated
sites within Belfast Lough the GIS programme ArcGIS was used to map the
distribution of designated features (where available) in relation to licensed
aquaculture sites (see sections 1.1 and 1.2 for detailed descriptions of the
designated features of these sites).
2.1. Current aquaculture activities within Belfast Lough
Aquaculture within Belfast Lough occurs on licensed sites within the subtidal areas of
the lough. Subtidal aquaculture within Belfast Lough involves the bottom culture of
the blue mussel Mytilus edulis. M. edulis seed is dredged from naturally settled wild
seed mussel beds (outside Belfast Lough) then relaid onto licensed aquaculture plots
within Belfast Lough for on growing to harvestable size.
The DARD Fisheries and Environment Division are responsible for the granting of
fish culture licences, shellfish fishery licences and marine fish fishery licences under
the Fisheries Act (Northern Ireland) 1966. Fish Culture Licences specify the species
which may be cultivated and define the area within which cultivation is authorised.
They are also granted subject to conditions to promote good standards of husbandry
and environmental practices. Fish farms, including shellfish farms, must also be
authorised as Aquaculture Production Businesses under the Aquatic Animal Health
Regulations (Northern Ireland) 2009 which implements Council Directive 2006/88/EC
on animal health requirements for aquatic animals and products thereof and the
control of certain diseases in aquatic animals.
There are currently twenty one licensed aquaculture sites within Belfast Lough, all of
which are currently authorised for commercial production (Figure 2.1). The total area
of Belfast Lough currently occupied by licensed aquaculture sites equates to
approximately 1,264.203 hectares (as calculated from DARD data). This is
approximately 22.60% of the area of the Belfast Lough open water SPA (Figure 2.2).
All currently licenced aquaculture sites within Belfast Lough are subtidal and there is
therefore no spatial overlap with boundary of the Belfast Lough SPA (Figure 2.3).
Table 2.1 below outlines the types of activities undertaken within the licensed
aquaculture sites in Belfast Lough (BIM 2012).
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Table 2.1: Activities undertaken within licensed aquaculture sites within Belfast Lough (compiled using information supplied by BIM
2012).
Activity
Equipment
Timing
Additional info
Seeding
Modified Dutch
Dredge
Usually Spring and
Autumn but is
dependent on seed
availability.
A modified Dutch dredge consists of a fixed toothless bar (also referred to as a mud bar)
between 2-4m width, and a frame with a net bag (composed of either a chain link matrix or
net mesh). Where a chain link matrix is used bits of chafed rope (also known as dollies)
are commonly attached to minimise seabed disturbance (Figure 2.4). Seed is mixed with
seawater in the vessels hold and then pumped onto the licensed sites.
Maintenance
Starfish mop
and Modified
Dutch Dredge
Throughout the
year.
The main husbandry activities are predator control and transfer of stocks within and
between licensed sites to maximise growth. Within Belfast Lough the main predators
encountered are starfish. Starfish are controlled through dredging using the dredges
described above or through the use of starfish mops (as shown in Figure 2.5).
Harvesting
Modified Dutch
Dredge
Market dependant
as stock is
harvested to order.
A modified Dutch dredge consists of a fixed toothless bar (also referred to as a mud bar)
between 2-4m width, and a frame with a net bag (composed of either a chain link matrix or
net mesh). Where a chain link matrix is used bits of chafed rope (also known as dollies)
are commonly attached to minimise seabed disturbance (Figure 2.4). Harvested mussels
are placed directly into one tonne bags for export.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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BIM (2012) state that “at maximum usage of all licensed sites in the Lough four large
vessels will undertake the required husbandry”. Maximum number of working days
per month is approximately twenty and vessels can work up to a maximum of eight
hours per day within the Lough.
A moratorium on the granting of any new Fish Culture Licences for the bottom culture
of mussels in Northern Ireland, including Belfast Lough, was introduced on 23rd
September 2002 and remains in place.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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2.2. GIS Assessment
All available information relating to the designated features of the Belfast Lough SPA
and the Belfast Lough Open water SPA were converted into a format that was
transferable to the GIS programme ArcGIS. This data was mapped alongside
information relating to aquaculture activities within the Lough. Sections 2.2.1 and
2.2.2 below detail the potential impacts of aquaculture activities on the designated
features of the Natura 2000 sites within Belfast Lough.
2.2.1. Impacts of aquaculture activities on Belfast Lough SPA designated
features
Redshank (Tringa totanus)
Aquaculture activities within Belfast Lough have the potential to negatively impact the
overwintering (non breeding) population of Redshank for which the Belfast Lough
SPA is designated through;
Human presence within their preferred habitats
Damage/disturbance to feeding areas/species
Each of these potential impacts will be discussed in turn within the subsequent
paragraphs.
Overwintering (non breeding) bird species within Belfast Lough are counted through
the Wetland Bird Survey (WeBS). This survey divides the lough into sections which
are counted at high tide throughout the year (WeBS core counts) and at low tide over
the winter months (WeBS Low tide counts) (Figures 2.6 to 2.8). The low tide count
data can provide higher counts of individuals than Core Counts (Holt et al 2012) and
therefore have been used within this report. WeBS low tide survey data for Belfast
Lough for the winters of 2006/07 to 2010/11 was purchased from BTO. Redshank
data has been extracted and processed in GIS for use within this report (Figures 2.9
to 2.13). As can be seen from Figures 2.9 to 2.13 Redshanks are found throughout
the intertidal area of Belfast Lough, with the largest numbers generally being
recorded in the inner lough.
WeBS Core Count data for Redshank within Belfast Lough for the winters 2002/03 to
2011/12 has been taken from Austin et al (2014) and is show graphically in Figure
2.14. The downward trend in Redshank numbers within Belfast Lough is in keeping
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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with trends in Britain (Holt et al 2012). Holt et al (2012) noted however that whilst
numbers of Redshank within Northern Ireland fell further in 2010/11 numbers in
Britain rose slightly. The fall in Redshank numbers between 2009/10 and 2010/11 in
Belfast Lough is in keeping with trends within other Northern Irish sites as numbers
recorded within Strangford Lough in 2010 were their lowest since 2001/02 (Holt et al
2012).
Human presence within preferred habitats
Redshanks are waders which feed mainly in the intertidal zone (Goss-Custard and
Jones 1976). All current licensed aquaculture sites within Belfast Lough are subtidal.
In order to assess potential impacts of vessels undertaking husbandry activities at
aquaculture sites on feeding Redshanks, Black Box data for aquaculture vessels
operating within Belfast Lough was obtained from DARD. Black box data was filtered
for vessel speed (<3.5 knots), location (licensed aquaculture sites) and month (to
coincide with the months counted during the WeBS low tide counts for the years
2006/07 to 2010/11) and processed in ArcGIS using Spatial Analysis tools. The
vessel black box system is activity dependent and records a position from 10
seconds to 15 minutes depending on the vessel activity taking place e.g. fishing,
steaming and mooring. This data has been processed to represent density (i.e.
number of logged positions) per square kilometre. This gives a picture of the overall
intensity of usage of the Lough by aquaculture servicing vessels within the selected
time period. The processed data was then mapped in GIS alongside the processed
WeBS Redshank data (Figures 2.15 to 2.19). As can been seen within Figures 2.15
to 2.19 the areas of highest vessel activity for the winters of 2006/07 to 2010/11 did
not occur adjacent to the areas where highest numbers of Redshank were observed.
There is nothing to suggest that vessel activity was negatively impacting numbers of
Redshank utilising the intertidal zone.
Damage/disturbance to feeding areas/species
As mentioned above Redshanks are waders which feed mainly on worms, bivalve
molluscs and crustaceans in the intertidal zone (Goss-Custard and Jones 1976).
Therefore subtidal aquaculture activities within Belfast Lough will not damage or
disturb the feeding areas of these birds. As all mussel aquaculture within Belfast
Lough is subtidal these bivalves will not be available as a food source for waders.
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2.2.2. Impacts of aquaculture activities on Belfast Lough Open Water SPA
designated features
Great Crested Grebe (Podiceps cristatus)
Aquaculture activities within Belfast Lough have the potential to negatively impact the
overwintering (non breeding) bird populations for which the Belfast Lough Open
Water SPA is designated (namely Great Crested Grebe) through;
Human presence within their preferred habitats
Damage/disturbance to feeding areas/species
Great Crested Grebe data was extracted from WeBS low tide survey data for Belfast
Lough for the winters of 2006/07 to 2010/11 and processed in GIS for use within this
report (Figures 2.20 to 2.24). As can be seen from Figures 2.20 to 2.24 Great
Crested Grebes are widely distributed throughout Belfast Lough, with no area
consistently supporting high numbers.
WeBS Core Count data for Great Crested Grebes within Belfast Lough for the
winters 2002/03 to 2011/12 has been taken from Austin et al (2014) and is show
graphically in Figure 2.25. Trends in Britain for this species show a shallow decline
since 2003/04 which is in keeping with populations elsewhere (Holt et al 2012).
Trends in Northern Ireland are in line with this; however Holt et al (2012) noted that in
2010/11 this species “fared very poorly in Northern Ireland”. The fall in Great Crested
Grebe numbers between 2009/10 and 2010/11 in Belfast Lough may be attributable
to low winter temperatures (Holt et al 2012).
Human presence within preferred habitats
When not foraging (i.e. roosting) Great Crested Grebes assemble in rafts on shallow
water (less than 2m) (Piersma, 1987). In order to assess potential impacts of vessels
undertaking husbandry activities at aquaculture sites on rafting Great Crested
Grebes, processed Black box data was mapped in GIS alongside the processed
WeBS Low tide count data for Great Crested Grebe (Figures 2.26 to 2.30). Please
refer to section 2.2.1 for details of Black Box data processing. As can be seen in
Figures 2.26 to 2.30 areas of highest vessel activity for the winters of 2006/07 to
2010/11 did not occur adjacent to areas where the highest numbers of Great Crested
Grebes were observed. High numbers of birds however were observed adjacent to
areas of high aquaculture activity (Figures 2.26 to 2.30).
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At the time of writing there is no information available on the impacts (in terms of
flushing distance) of vessel activity on rafting Great Crested Grebes. Piersma (1987)
observed rafting behaviour in Great Crested Grebes on Lake Ijsselmeer in the
Netherlands at both mid-day and mid-night. Aquaculture activities within Belfast
Lough are predominantly undertaken during daylight hours, however on occasion
vessels may be on site during twilight hours. Therefore vessels undertaking
husbandry activities could potentially disturb rafting grebes. In order to minimise any
potential impact of aquaculture activities on this species operators should avoid
activities within their licensed area if large numbers of Great Crested Grebes are
observed rafting within the area.
Damage/disturbance to feeding areas/species
Great Crested Grebes are diving waterbirds (Johnsgard, 1987; Wiersma et al 1995;
Gwiazda, 1997; Well et al, 2013) feeding primarily on fish, mainly Smelt (Osmerus
eperlanus) in Lake Ijsselmeer, the Netherlands (van Eerden et al 1993), Bleak in
Dobczyce Reservoir, South Poland (Gwiazda 1997), and gobiid fish on Lake
Grevelingen, the Netherlands (Doornbos, 1984). At the time of writing, no studies
have been undertaken to determine the preferred prey of the Great Crested Grebes
that utilise Belfast Lough. Studies in the Netherlands have observed Great Crested
Grebes foraging only at dawn and dusk in offshore waters (Piersma, 1987 and van
Eerden et al, 1993). In this instance the birds foraging activities were governed by the
activities of their prey which were migrating to the surface to feed at dawn and dusk.
On the Dobczyce Reservoir in Southern Poland Great Crested Grebes started to
forage approximately one hour before sunrise finishing approximately one hour after
sunrise (Gwiazda 1997). Aquaculture activities within Belfast Lough are
predominantly undertaken during daylight hours, however occasionally aquaculture
vessels may be on site during twilight hours. Therefore vessels undertaking
husbandry activities during twilight hours could potentially disturb feeding grebes.
Great Crest Grebes feed primarily on fish species (Doornbos, 1984; van Eerden et al
1993; Wiersma et al, 1993 Gwiazda 1997; Wells et al 2013) therefore shellfish
aquaculture will not impact on the availability of prey species for these birds.
There is no evidence to suggest that aquaculture activities within Belfast Lough are
negatively impacting Great Crested Grebe populations within Belfast Lough. It should
be noted that aquaculture within Belfast Lough was well established before the
Belfast Lough Open water SPA was designated.
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2.3. Non native species
The slipper limpet (Crepidula fornicata) (a non native invasive species) was
discovered in Belfast Lough in March 2008. Since this time all movements of mussels
from Belfast Lough for relaying onto other licensed aquaculture sites outside the
Lough have been prohibited (AFBI 2014).
Seed mussels used for the bottom culture of mussels in Belfast Lough are obtained
from naturally occurring seed beds (usually located within the UK and Ireland).
Imports of mussel seed from outside Northern Ireland must be accompanied by a
permit granted under the Molluscan Shellfish (Control of Deposit) Order (Northern
Ireland) 1972. Imports of seed are only permitted from areas known to be free from
populations of non-native species.
2.4. Benthic impacts of aquaculture
As described within previous sections subtidal aquaculture within Belfast Lough
involves Mytilus edulis seed (which is dredged from naturally settled wild seed
mussel beds outside Belfast Lough) being relaid onto licensed aquaculture plots for
on growing to harvestable size. Activities undertaken at licensed aquaculture sites
include seeding, maintenance, predator control and harvesting. These activities are
described in Table 2.1. As is outlined within Table 2.1 when dredging operations are
undertaken on aquaculture sites within Belfast Lough a modified Dutch Dredge is
used (Figure 2.4) which has been engineered so as to reduce benthic impacts.
The bottom culture of mussels can change the composition of benthic sediments,
through a reduction in grain size and an increase in mud content when compared to
similar culture free sediments (Ysebaert et al 2009). Ysebaert et al. (2009) found
however that these effects were extremely localised, being confined to within or
directly adjacent to the mussel beds studied.
Bottom culture of mussels can also change benthic biodiversity with increased
numbers of eipbenthic species being observed within culture areas compared to
similar areas without bottom mussel culture (Smith and Shackley, 2004 and Ysebaert
et al 2009).
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2.5. Carrying Capacity Assessment – SMILE
The Sustainable Mariculture in northern Irish Lough ecosystems (SMILE) model is a
model used for the collation and processing of scientific information. The model
enables the application of an integrated framework for the determination of
sustainable carrying capacity in shellfish production areas. This framework combines
field data, experimental results and several different types of models, ranging from
individual shellfish growth models (ShellSIM) to broad-scale ecosystem models
(Ecowin 2000 (E2K)). The process by which these models are integrated and
coupled is designed to capture the essential information at each simulation scale,
while also allowing multi-year runs. These runs provide results on cultivation of
commercial species, nutrient and chlorophyll cycling and other outputs of interest to
decision makers. The complete modelling framework facilitates integrated analyses
of animal-environment interrelations affecting overall production at system-scales,
according to different temporal and spatial scenarios. The model also accounts for
conservation aspects such as the presence of wild species. Models like SMILE allow
managers to examine the potential outcomes of different development options
without the social consequences of experimental implementation.
For the purpose of this assessment the SMILE model was applied to two scenarios,
which simulated the impact on the ecosystem of increasing the abundance of filter-
feeding organisms, through aquaculture activities, in Belfast Lough. Chlorophyll a
(Chl a) was used as a proxy for phytoplankton biomass within Belfast Lough. The two
scenarios represented the levels of Chl a present within the Lough if;
a) Run 1 - There was no aquaculture within the Lough (only wild species
present). This run is used as a baseline as wild species will always be
present.
b) Run 2- All currently licensed aquaculture sites were activated at a rate of
seeding (in terms of tonnage/ha) determined using the three year mean from
observed data (supplied by DARD) for the years 2010-2012. As wild species
is to be used as a baseline this component was also activated for this run.
Analysis of measured monthly Chl a data from 16 sample stations within Belfast
Lough (taken from Charlesworth and Service 1998) shows up to a 41% annual
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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variation within Chl a values (using 90th percentile figures) recorded between
sampling years. The change in Chl a values ranged from 22% to -41%. From this we
would recommend that, as a precaution, a minimum of 50%, of baseline values, of
Chl a remains within the system available for wild species. This therefore implies that
aquaculture activities should not reduce Chl a concentrations by greater than 50% of
baseline values (Run 1). Therefore all boxes with > 50% Chl a reduction are
highlighted in Table 2.2. The location of the SMILE model boxes (also known as E2K
boxes) within Belfast Lough are shown in Figure 2.31. The locations of licensed
aquaculture sites within SMILE model boxes are shown in Figure 2.32.
From Table 2.2 below it can be seen that aquaculture species reduce the overall
ecosystem phytoplankton biomass, and hence food availability for other organisms
within Belfast Lough by up to a maximum of 56%. This value ranges from 9.5 to 56%
within model boxes. Impact (in terms of reduction in Chl a values) was observed in
model boxes within which little or no aquaculture was undertaken due to the knock-
on effect of aquaculture activities within adjacent boxes. This is due to the movement
of phytoplankton by water currents and shifts of water between boxes. This data
indicates that if all licensed sites within Belfast Lough are active mussel production
within three of the model boxes will be at the ecological threshold. If all licensed sites
within Belfast Lough are active mussel production throughout the rest of the Lough
will however be below this ecological threshold.
It should be noted that all 21 of the currently licensed aquaculture sites within Belfast
Lough were activated within Run 2 of the model, however in reality this is not the
case. At no time within the last four years (2010 to 2014) have all licensed
aquaculture sites within Belfast Lough been active simultaneously.
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Table 2.2: Simulated Chl a values (percentile 90 values calculated from data produced
from the final two years of the model runs). Results from Run 1 were used as a
baseline and the % reduction of Chl a is shown to illustrate the impact when filtration
by aquaculture species within all current licensed sites is taken into account (Run 2).
Boxes highlighted in pink represent E2K boxes which have a reduction in Chl a as (a
result of aquaculture) >50%. The locations of these boxes are shown in Figure 2.31.
E2K Box
Run 1
Run 2
% reduction
Box 42
4.69
2.06
56.04
Box 39
3.83
1.75
54.40
Box 41
3.84
1.81
52.77
Box 36
4.83
2.60
46.27
Box 35
3.46
1.93
44.39
Box 40
2.87
1.65
42.44
Box 38
3.29
2.03
38.24
Box 30
5.42
3.89
28.25
Box 34
3.43
2.49
27.40
Box 29
4.08
2.98
26.97
Box 37
2.15
1.58
26.49
Box 31
5.19
4.07
21.55
Box 33
2.30
1.81
21.51
Box 26
5.33
4.23
20.79
Box 28
2.63
2.11
19.85
Box 25
2.75
2.32
15.72
Box 27
7.51
6.56
12.71
Box 32
1.26
1.14
9.49
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Section 2 Figures (all maps are projected in ING)
Figure 2.1: Map showing DARD licensed aquaculture sites (as of July 2014).
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.2: Map showing DARD licensed aquaculture sites and the Belfast Lough Open water SPA boundary (purple hashed area).
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.3: Map showing DARD licensed aquaculture sites and the Belfast Lough SPA boundary (blue hashed area).
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.4: Modified Dutch Dredge (BIM 2012)
Figure 2.5: Starfish mop (BIM 2012).
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.6: Map of Belfast Lough showing the WeBS count sections within the Lough for the years up to an including 2007/08.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.7: Map of Belfast Lough showing the WeBS count sections within the Lough for the year 2008/09.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.8: Map of Belfast Lough showing the WeBS count sections within the Lough for the years after and including 2009/10.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.9: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2006/07.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.10: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2007/08.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.11: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2008/09.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.12: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2009/10.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.13: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2010/11.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.14: Graph showing the observed numbers of Redshank within Belfast Lough for the years 2002/03 to 2011/12 as counted through WeBS (Austin et
al 2014).
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.15: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2006/07 along with processed
Black Box data for the same time period.
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Figure 2.16: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2007/08 along with processed
Black Box data for the same time period.
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Figure 2.17: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2008/09 along with processed
Black Box data for the same time period.
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Figure 2.18: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2009/10 along with processed
Black Box data for the same time period.
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Figure 2.19: Map of Belfast Lough showing the number of Redshank recorded within WeBS Low tide counts for the winter of 2010/11 along with processed
Black Box data for the same time period.
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Figure 2.20: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2006/07.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.21: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2007/08.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.22: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2008/09.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.23: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2009/10.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.24: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2010/11.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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Figure 2.25: Graph showing the observed numbers of Great Crested Grebes within Belfast Lough for the years 2002/03 to 2011/12 as counted through WeBS
core counts (Austin et al 2014).
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Figure 2.26: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2006/07 along with
processed Black Box data for the same time period.
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Figure 2.27: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2007/08 along with
processed Black Box data for the same time period.
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Figure 2.28: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2008/09 along with
processed Black Box data for the same time period.
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Figure 2.29: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2009/10 along with
processed Black Box data for the same time period.
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Figure 2.30: Map of Belfast Lough showing the number of Great Crested Grebes recorded within WeBS Low tide counts for the winter of 2010/11 along with
processed Black Box data for the same time period.
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Figure 2.31: Map showing the locations of the E2K boxes used within the SMILE model.
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Figure 2.32: Map showing the locations of currently licensed aquaculture sites within the E2K boxes used within the SMILE model.
Cumulative Impact Assessment: Belfast Lough aquaculture 2014
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3. Conclusions
All currently licensed aquaculture sites within Belfast Lough are subtidal and
therefore there is no spatial overlap between these sites and the boundary of the
Belfast Lough SPA. The total area of seabed currently licensed for aquaculture within
Belfast Lough equates to approximately 1,264.203 hectares (calculated from figures
provided by DARD). The total area of the Belfast Lough Open water SPA is 5,592.99
hectares. All currently licensed aquaculture sites in Belfast Lough are within the
boundary of the Belfast Lough Open water SPA. This equates to approximately
22.60% of the total area of the SPA.
3.1. Belfast Lough SPA features
Redshank populations
Redshanks are found throughout the intertidal area of Belfast Lough, with the largest
numbers generally being recorded in the inner lough. Redshanks are waders feeding
mainly on, bivalves and crustaceans in the intertidal zone (Goss-Custard and Jones
1976). All current licensed aquaculture sites within Belfast Lough are subtidal and
therefore there is no spatial overlap between these sites and the boundary of the
Belfast Lough SPA. In order to assess potential impacts of vessels undertaking
husbandry activities at aquaculture sites on feeding Redshank, Black Box data was
processed to represent the overall intensity of usage of the Lough by aquaculture
servicing vessels within the selected timeframes. When mapped alongside the WeBS
low tide data for Redshank (for the same time periods) it was noted that areas of
highest vessel activity did not coincide with areas where highest numbers of
Redshank were observed. There is nothing to suggest that vessel activity is
negatively impacting numbers of Redshank utilising the intertidal zone.
The most recent Site condition assessment undertaken for this SPA states that this
feature is in unfavourable condition (NIEA 2013a). The recent fall in Redshank
numbers (between 2009/10 and 2010/11) in Belfast Lough is in keeping with trends
within other Northern Irish sites as numbers recorded within Strangford Lough in
2010 were their lowest since 2001/02 (Holt et al 2012). The observed decline within
Belfast Lough in line with current UK trends as numbers recorded in 2011/12 were at
their lowest point for over 25 years (Austin et al 2014).There is no evidence to
suggest that aquaculture activities within Belfast Lough are negatively impacting
Redshank populations within this area.
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3.2. Belfast Lough Open water SPA features
Great Crested Grebe populations
Great Crested Grebes are widely distributed throughout Belfast Lough, with no area
consistently supporting high numbers. Great Crested Grebes are diving waterbirds
(Johnsgard, 1987; Wiersma et al 1995; Gwiazda, 1997; Well et al, 2013) feeding
primarily on fish (van Eerden et al, 1993; Gwiazda, 1997; Doornbos, 1984). When not
foraging Great Crested Grebes assemble in rafts over shallow water (less than 2m)
(Piersma, 1987). In order to assess potential impacts of vessels undertaking
husbandry activities at aquaculture sites on rafting Great Crested Grebes, processed
Black box data was mapped in GIS alongside the processed WeBS Low tide count
data for Great Crested Grebe. Highest vessel activity for the winters of 2006/07 to
2010/11 did not occur adjacent to areas where the highest numbers of Great Crested
Grebes were observed (within WeBS counts), and high numbers of birds (between
200-300) were observed adjacent to areas of high aquaculture activity. No data is
currently available as to the distribution of this species within the subtidal areas of
Belfast Lough not covered by WeBS count sectors.
Trends in Northern Ireland are in line with the shallow decline in this species
observed in Britain since 2003/04, however Holt et al (2012) noted that in 2010/11
this species “fared very poorly in Northern Ireland”. The fall in Great Crested Grebe
numbers between 2009/10 and 2010/11 in Belfast Lough may be attributable to low
winter temperatures (Holt et al 2012). The observed decline in numbers of Great
Crested Grebe within Belfast Lough is in line with National trends as numbers of this
species continued to decline within the UK during 2011/12 counts (Austin et al 2014).
The most recent Site condition assessment undertaken for this SPA states that this
feature is in favourable condition (NIEA 2013b). There is no evidence to suggest that
aquaculture activities within Belfast Lough are negatively impacting Great Crested
Grebe populations within the Lough. It is important to remember that aquaculture
within Belfast Lough was well established before the Belfast Lough Open water SPA
was designated.
It should also be noted that Belfast Harbour is Northern Ireland’s main port. The
Belfast Harbour Oil Pollution Contingency Plan states that “In the order of 12,000
ship movements take place in the Port per annum, which accounts for up to 60% of
Northern Ireland’s seaborne trade and 25% of the entire seaborne trade of Ireland.”
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(Belfast Harbour Commissioners 2010). Therefore aquaculture servicing vessels
represent a small fraction of the overall vessel activities within Belfast Lough.
3.3. Ecological carrying capacity of Belfast Lough
Aquaculture species reduce the overall ecosystem phytoplankton biomass and hence
food availability for other organisms within Belfast Lough by up to 56%. This value
ranges from 9.5 to 56% within Belfast Lough model boxes. This value was highest
within three model boxes in the inner Lough area (boxes 42, 39 and 41). Impact (in
terms of reduction in Chl a values) was observed in model boxes within which little or
no aquaculture was undertaken due to the knock-on effect of aquaculture activities
within adjacent boxes. This is due to the movement of phytoplankton by water
currents and shifts of water between boxes.
Analysis of measured data (taken from Charlesworth and Service 1998) shows up to
-41% annual variation within Chl a values (using 90th percentile figures) recorded
between sampling years. From this we would recommend that a minimum of 50%, of
baseline values, of Chl a remains within the system available for wild species. This
therefore implies that aquaculture activities should not reduce Chl a concentrations
by greater than 50% of baseline values.
This data indicates that with all licensed aquaculture sites active mussel production
within three of the model boxes (E2K Boxes 42, 39 and 41) is over the ecological
threshold, whilst this threshold is not breached within the rest of the model boxes.
Therefore there is no scope for increased aquaculture activities within boxes 42, 39
and 41.
It should be noted however that for Run 2 of the model all licensed aquaculture sites
were activated (to represent a worst case scenario situation) this is however not the
case in reality. At no time within the last four years (2010 to 2014) have all licensed
aquaculture sites within Belfast Lough been active simultaneously.
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4. Recommendations
In light of the information contained within the above sections AFBI have the
following recommendations for the management of aquaculture activities within
Belfast Lough:
a) In order to minimise any potential impact to rafting Great Crested Grebes
operators should avoid (where practical) activities on their sites when large
numbers of rafting Great Crested Grebes are observed in the area.
b) Activities at aquaculture sites should be minimised during twilight hours to
reduce potential disturbance to Great Crested Grebes foraging at twilight and
roosting on the water during the hours of darkness.
c) Investigations should be undertaken by competent authorities to determine
the flushing distances (in response to disturbance by different types of
vessels) of Great Crested Grebes within Belfast Lough.
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5. Assessment under Article six of the Habitats Directive
In accordance with Regulation 43(1) of the Conservation (Natural Habitats, etc)
(Northern Ireland) 1995 (as amended), the Department of Agriculture and Rural
Development (DARD) has considered whether the project, plan or proposal either
alone or in combination (neither being directly connected with or necessary to the
management of the site) is likely to have a significant effect on the Natura 2000 site.
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Screening Matrix: Aquaculture Activities within and adjacent to Natura
2000 sites in Belfast Lough.
Name of Project or Plan.
Belfast Lough licensed aquaculture sites.
Name and location of
Natura 2000 site (s)
Belfast Lough SPA
Area: 432.14 hectares
Site code: UK 9020101
Date Classified: 05/08/98
(see Figure 1.1 for a map of the site boundary)
Belfast Lough Open Water SPA
Area: 5,592.99 hectares
Site code: UK 9020290
Date Classified: 20/09/09
(See Figure 1.2 for a map of the site boundary)
Natura 2000 site features:
See Sections 1.1 and 1.2 and Annex I and II for a full
description of the Natura 2000 designated features.
Description of the Project or
Plan
See Sections 2.1 and 2.2
Is the Project or Plan directly
connected with or necessary to
the management of the site
(provide details)?
No
Describe the individual
elements of the project (either
alone or in combination with
other plans or projects) likely
to give rise to impacts on the
Natura 2000 site.
See Sections 1-3
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N2K Feature: Mention
all features
Describe any likely direct,
indirect effects to the N2K
features arising as a result of:
Loss, reduction of habitat area;
disturbance; habitat or species
fragmentation; reduction in
species density; changes in key
indicators of conservation value
(e.g. water quality, climate
change).
*Effect Significant/Not
Significant? Why?
Redshank
Aquaculture activities have the
potential to cause disturbance
through human presence within
preferred habitats and
damage/disturbance to feeding
areas/species.
Redshanks are waders therefore
subtidal aquaculture sites will not
interfere with the feeding areas of
this species.
Further information can be found in
sections 2.2.1 and 3.
Great Crested Grebe
Aquaculture activities have the
potential to cause disturbance
through human presence within
preferred habitats and
damage/disturbance to feeding
areas/species.
Fish are the main food source for
Grebes so therefore shellfish
aquaculture will not impact on prey
availability. Great Crested Grebes
assemble in rafts over shallow water
when not foraging. As far as
practical operators should avoid
vessel activities on site when rafts
containing large numbers of Great
Crested Grebes are observed in the
vicinity.
Further information can be found in
sections 2.2.2 and 3.
Describe any potential effects on
the Natura 2000 site as a whole in
terms of: interference with the key
relationships that define the
structure or function of the site
Please refer to sections 1 - 4 of this report.
Investigations have demonstrated that licensed aquaculture
sites within Belfast Lough are not negatively impacting the
conservation objectives of the designated features of the
two designated Natura 2000 sites within the Lough.
Provide details of any other projects or
plans that together with the project or plan
being assessed could (directly or indirectly)
affect the site.
Ferry activity, cruise ship activity, tanker activity,
yachting, pleasure boating, dog walkers,
agriculture, bait collectors, seaweed collectors,
recreational walkers, sewage discharges, scientific
research, other fisheries and other leisure
activities.
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Is the potential scale or magnitude of any effect likely to be significant? :
Alone?
Yes No
In-combination with other projects of plans?
Yes No
List of Agencies / Organisations Consulted:
Provide contact name and telephone or email
address.
Dr Liz Pothanikat – NIEA, CDP
Habitats Regulations Assessment Summary
See sections 2-4
Conclusion: Is the proposal likely to have a
significant effect on an N2K site?
Yes No
Data collected to carry out the assessment
Who carried out the assessment?
The Agri-food and Bioscience Institute (AFBI)
acting on behalf of the Department of Agriculture
and Rural Development.
Sources of data
WeBS – Low tide data for Belfast Lough for the
years 2006/07 to 2010/11
DARD – Northern Ireland aquaculture shapefiles,
vessel black box raw data, Northern Ireland
production data
BIM- Husbandry information
NIEA/DoE Marine Division – Site condition
monitoring reports
Level of assessment completed
Stage one: Screening
Where can the full results of the assessment
be accessed and viewed?
DARD
Fisheries Division
Dundonald house
Belfast
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6. References
AFBI 2014. Crepidula fornicate Survey: Belfast Lough September 2013. 19pp
Austin, G.E., Read, W.J., Calbrade, N.A., Mellan, H.J., Musgrove, A.J., Skellorn, W.,
Hearn, R.D., Stroud, D.A., Wooton, S.R. and holt, C.A. 2014. Waterbirds in the UK
2011/12: The Wetland Bird Survey. BTO/RSPB/JNCC, Thetford.
Belfast Harbour Oil Pollution Contingency Plan, 2010. Belfast Harbour Commissioners.
56pp.
BIM, 2012. Fisheries Plan (Mytilus edulis) Belfast Lough. 7 pp
Doornbos, G. 1984. Piscivorous birds on the saline Lake Grevelingen, The Netherlands:
Abundance, prey selection and annual food consumption. Netherlands Journal of Sea
Research 18 (3/4):457-479
Goss-Custard, J.D., and Jones, R.E. 1976. The Diets of Redshank and Curlew. Bird Study
23 (3): 233-243
Gwiazda, R. 1997. Foraging ecology of the Great Crested Grebe (Podiceps cristatus L.) at
a mesotrophic-eutrophic reservoir. Hydrobiologia 353: 39-43
Holt, C.A., Austin, G.E., Calbrade, N.A., Mellan, H.J., Hearn, R.D., Stroud, D.A., Wotton,
S.R. and Musgrove, A.J. 2012. Waterbirds in the UK 2010/11: The Wetland Bird Survey.
BTO/RSPB/JNCC, Thetford. 183 pp
Johnsgard, P.A. 1987. Diving birds of North America: 3 Comparative Egocentric and
Locomotory Behaviours. In Diving Birds of North America. pp 26-36
NIEA 2013a. Belfast Lough SPA: Monitoring Report 2013 3 pp
NIEA 2013b. Belfast Lough Open Water SPA: Monitoring Report 2013 2 pp
Piersma, T. 1987. Population turnover in groups of wing-moulting waterbirds: the use of a
natural marker in Great Crested Grebes. Wildfowl 38: 37-45
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Smith, J., and Shackley, S.E. 2004. Effects of a commercial mussel Mytilus edulis lay on a
sublittoral, soft sediment benthic community. Marine Ecology Progress Series. 282: 185-
191
Van Eerden, M.R., Piersma, T., and Lindeboom, R. 1993. Competitive food exploitation of
smelt Osmerus eperlanus by great crested grebes Podiceps cristatus and perch Perca
fluviatilis at Lake Ijsselmeer, The Netherlands. Oecologia 93: 463-474
Wells, K., Dolich, T., Whal, J., and O’Hara, R.B. 2012. Spatio-temporal dynamics in
waterbirds during the non-breeding season: Effects of local movements, migration and
weather are monthly not yearly. Basic and Applied Ecology 14: 523-531
Wiersma, P., Piersma, T., and van Eerden, M.R. 1995. Food intake of Great Crested
Grebes Podiceps cristatus wintering on cold water as a function of various cost factors.
Ardea 83: 339-350
Ysebaert, T., Hart, M., Herman, P.M.J. 2009. Impacts of bottom and suspended cultures of
mussels Mytilus spp. on the surrounding sedimentary environment and macrobenthic
biodiversity. Helgol. Mar. Res. 63: 59-74
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Annex I: Natura 2000 standard data form: Belfast Lough SPA
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Annex II: Natura 2000 standard data form: Belfast Lough Open
Water SPA
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