Marine Institute response to NPWS observations on the Appropriate
Assessment of the Irish Sea seed mussel fishery
20th August 2013
Scope
This response is limited to the issues raised by NPWS on the AA of the Irish Sea seed mussel fishery and
excludes any response to issues raised in relation to the risk assessment of other fisheries in the Irish Sea.
These will be responded to in due course. Comment is included on possible in combination effects of
other fisheries on Common Scoter as this species may utilise seed mussel beds as a food source. Neither
does this response include any assessment of the effects of fishing on underwater archaeology which is
outside the scope of the assessment which is investigating the interaction of fisheries with Natura 2000
conservation objectives.
SAC habitat related observations
NPWS: Assessment and consideration of any alternatives possible for achieving the desired servicing of
the seed mussel fishery in the Irish Sea without impacting on Natura 2000 sites.
MI response : Technically the AA could consider alternatives but it is clearly known that there are no
realistic alternatives. There are no alternatives to fishing to supply the mussel ongrowing sector. The
supply of seed mussel is generally a constraint on the mussel aquaculture industry and its availability and
the location of seed mussel resources are unpredictable year on year. Other sources of seed supply
include exploitation of seed beds outside of Natura 2000 sites and collection of seed on long line systems.
The AA includes assessment of fishing for seed outside Natura 2000 sites in the Irish Sea. Fishing for seed
outside of Natura 2000 sites may also have effects on bird species and this was included in the
assessment. Restriction of fishing to areas outside of Natura sites is not an alternative as in some years
the majority of seed may be within Natura 2000 sites. Collection of seed on long lines would require a
substantial increase in aquaculture licence applications and increase the aquaculture footprint some of
which would necessarily be in Natura 2000 sites. Furthermore, it would require considerable movement
of seed caught on the west coast bays (where longlines can be more easily deployed) to areas on the east
coast where the bottom grown mussel sector is concentrated. Production from long lines could not
realistically replace the production obtained from wild seed beds. Hatchery production of seed is not an
alternative because of the infra-structure requirement to produce the required volume of seed.
NPWS: A more detailed evaluation of the potential in-combination or cumulative impacts of the seed
mussel fishery (and other fishing activities) should be developed. This would include an examination of
other sectoral activities within the Irish Sea that alone or in combination may be acting to produce a
likely significant effect on designated sites.
MI response: The seed mussel fishery occurs in Blackwater Bank and Wicklow reef and in 0.3% of subtidal reef community complex in Rockabill to Dalkey. The AA recommends exclusion of the seed fishery
from the Wicklow reef. In effect, therefore, the only area where in combination effects could be relevant
is in Blackwater Bank. The benthic community with which the fishery overlaps in Blackwater Bank is not
sensitive to physical disturbance. The only other significant fishing activity in this area is whelk potting
which will not cause any significant additional disturbance and dredging for razor clams. The AA has
1
highlighted some uncertainty regarding the footprint of the razor clam fishery and recommended that it
be better defined through data collection. We are not aware of any other sectoral activity that poses a
physical disturbance pressure to the Nephhtys cirrosa and Bathyporeia elegans community complex and
therefore discount in combination effects.
NPWS: Some mitigation is proposed to reduce the potential interaction with designated sites
(e.g.exclusion of reef habitats from within Wicklow Reef SAC). This approach is supported and is likely
to negate any likely significant effect within designated areas.
MI response: the advice is that the seed mussel fishery be excluded from the reef community and that in
a 1km buffer zone around the reef area the VMS reporting frequency will be increased. This advice was
developed with DAFM and SFPA subsequent to the AA recommendation
Annex II Marine mammal related observations
All observations relate to the risk assessment of fisheries. MI will respond to these observations at a later
date. The seed mussel fishery is not expected to significantly impact on marine mammals.
Bird conservation observations
NPWS: Conservation Objectives are not set out in the report
MI response: The conservation objectives for seabirds, which are the main group considered in the
assessment, are generic across species and sites; the objective is to maintain populations and their
distribution. These objectives are set out by NPWS in site specific conservation objective statements
and supporting documents. Generally, the AA is looking for population effects and impacts on
distribution as it analyses spatially the distribution of seed mussel fishing and considers the SCIs in
SPAs or in proximity to SPAs in relation to the distribution of seed mussel fishing.
NPWS: The methodology for determining significance of impacts upon relevant bird species and
their specific habitats is not set out in the report
MI response: Generally the AA is assessing the likelihood that the seed mussel fishery will cause
changes in the distribution of populations of affected species or a decline in the populations of such
species. This is based on expert opinion including consideration of the biology, diet and foraging
behaviour of the species. Information on diet and foraging distances are presented so that the
geographic scope of the assessment of each species is identified.
NPWS: In general and throughout the document, AA impact assessment and determination of
impact significance do not refer to SPA conservation objectives or species conservation condition,
or to SPA Conservation Objectives supporting documents (in cases where they have been
completed e.g. The Raven SPA).
MI response: As stated above the COs are generic across species and sites generally. The AA of the
seed mussel fishery is mainly concerned with seabirds. Only Common Scoter, as it feeds on benthic
bivalves, is potentially affected by this fishery although disturbing effects of the mussel fleet and
other fleets is also considered. Information on Common Scoter in the Raven SPA supporting
documentation is itself deficient in spatial information and time series data and as such there is little
to evaluate against. The AA recommends that additional information on distribution of Common
Scoter at sea is obtained. NPWS: Insufficient rationale/scientific basis is provided for some of the
conclusions drawn,
especially where supporting data are limited.
2
MI response: Which conclusions?
NPWS: Cumulative impacts are not addressed
MI response: The AA does consider the possible cumulative disturbing effects of fishing fleets in the
south Irish sea on the distribution of Common Scoter.
NPWS: It is not clear how potential significant impacts upon Common Scoter as a result of scallop
dredging have been discounted given the potential effects upon benthic habitats/communities,
the activities’ presence close to The Raven SPA, the mentioned lack of data for Common Scoter,
and the potential effects upon Common Scoter via indirect impacts upon non-target species
Common Mussel. Further scientific rationale and confidence levels should be applied.
MI response: A risk score of 3 is given (possible effects at individual level but no population level
effects). Although some scallop VMS points may be close to the Raven SPA the scallop fishery in the
south Irish Sea occurs offshore east of Blackwater bank SAC. The bivalve species Abra and Fabulina,
which are constituent species in sand bank habitats and also prey species for scoter, are unlikely to
be affected by scallop dredging.
NPWS: As the Draft Fishery Natura Plan does not specifically mention The Raven SPA is it the
intention of the FNP not to dredge for seed mussels within this designated site? Potential ex-situ
impacts on the Common Scoter population need to be clearly assessed in this regard.
MI response: Although the FNP does not explicitly mention the Raven SPA the FNP and the AA both
acknowledge, through presentation of 30 years of BIM survey data and 6 years of VMS data, that
seed mussel fishing can and may occur in different areas in the period 2013-2017. Although some
VMS points are close to the Raven SPA and the AA indicates that the fishery may therefore occur in
the site in reality the fishery does not occur to any extent inside the site but to the east of it. The
fishery will not occur within the site during the duration of the plan; see mussel fishing in the Raven
is prohibited and this will remain the case. The possibility of ex situ effects on Common Scoter are
clearly identified in the AA. Nevertheless, as seed mussel in this area may not be available to scoter
because of high current speeds, and as the fishery is unlikely to occur in the site and is also unlikely
to occur east of the site in every year there is no immediate threat to Common Scoter and it is
sufficient in the short term to collect additional data on the distribution of this species in the area.
NPWS: The consequence score for beam trawling is assigned a zero rating (i.e. non disturbing)
throughout although potential impacts may be similar to scallop dredging, and this activity occurs
within The Raven SPA (Figure 10, Page 41), potentially impacting on the foraging
habitat/distribution of Common Scoter. Further clarification is needed as to the risk score assigned
for Common Scoter.
MI response: The fishery does not occur in the Raven SPA. Isolated VMS points do not indicate the
presence of a directed fishery. The beam trawl fishery is in deep water east of Wicklow.
NPWS: With regard to the overall AA Conclusion Statement, further scientific rationale is needed
to explain how a ‘no effects’ conclusion can be drawn when there is a stated lack of data with
regards Common Scoter. EC guidance (EC 2012) suggests that assessments be carried out with
expert judgement, using a combination of fishing intensity and species sensitivity and also taking
into account a species conservation status/condition. But when effects are not known or
supporting data are limited then there is a requirement to use caution.
3
MI response: A no significant effects at population level for common scoter is concluded even in the
absence of good data because the seed mussel fishery is episodic, occurs for a very limited period of
time and exploits only one species of bivalve which may be used as a food source by common scoter.
Other species of bivalve will not be affected. In addition it is questionable whether seed mussel
beds, occurring in deeper current swept channels off sand banks are in fact available as a food
source for common scoter because of strong currents and relatively deep water. This rationale is a
synopsis of the expert judgement and considers the species diet and foraging behaviour. It is very
unlikely that the fishery poses an imminent threat to Common Scoter and the AA therefore
concludes that it is safe to pursue a data collection programme and to use these data to design
mitigations if the data suggests that this is necessary.
4