Marine Institute response to Coastwatch observations on the Appropriate
Assessment of the Irish Sea seed mussel fishery
23rd August 2013
Scope
This response is limited to the issues raised by Coastwatch on the AA of the Irish Sea seed mussel fishery
and excludes any response to issues raised in relation to the MSFD or the status of shellfish stocks in the
Irish Sea. The status of shellfish stocks in the Irish Sea is generally not the focus of the conservation
objectives for Natura sites and as such the status and management of these stocks is not evaluated in the
assessment other than when there is a direct link between an SCI species and the status of shellfish beds
within and outside of Natura sites. In the assessment of the seed mussel fishery this direct link is limited
to Common Scoter as Scoter may use seed mussel as a food source.
Issues of context
Coastwatch: Contrary to what it says on the department’s website inviting comment, it does not
cover aquaculture. Seed dredging and bottom mussel culture are directly linked and taking place in
the Irish Sea. No (eco)logical reason for omitting it was provided. Action: The plan should also cover
aquaculture as this is also taking place in the N 2000 sites. This same comment was already made in
Castlemain harbour earlier this year and 2 years ago. If this is neither changed nor the reasons for
the split provided it is difficult to call this public participation.
MI response: The assessment covers fisheries only. The impact of relaying of seed mussel into
aquaculture plots in Natura 2000 sites is being assessed on a site by site basis and has been
completed for Castlemaine and Lough Swilly to date.
General concerns
Coastwatch: The first concern one has when reading the Marine Institute Irish Sea shellfisheries
assessment is how little we seem to know about some of the activities in this shared sea – eg
Trammel nets or periwinkle gathering and bait digging ( which isnt covered at all) For species where
the authors know a lot e.g. mussels where ‘ distribution of seed beds very well defined. VMS data all
vessels’ the actual data presented on fishing intensity in time and space, biomass and tonnages
harvested are surprisingly rough or missing.
MI response: The data on trammel netting, periwinkle gathering and bait digging is poor. Bait
digging is not licenced by the DAFM; it is a recreational activity. The actual data presented on seed
mussel includes the location of historic survey and VMS data which collectively show where seed
beds and fisheries have occurred in the past. This is the essential data for the assessment.
Coastwatch: point 4 relating to the use of 15% as threshold of significance.
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MI response: The assessment uses the guidance provided by NPWS on thresholds for significant
effects. Coastwatch should refer to NPWS for clarification. Reference by Coastwatch to the 15%
threshold on reef habitat is incorrect. Reef habitat is provided higher levels of protection and the
15% threshold does not apply. The threshold applies to broad sedimentary habitats only. Even then
any indication of sequential and cumulative impacts on sedimentary habitats would not be assessed
as insignificant even if in any single year the footprint was disturbing to less than 15% of the habitat.
In such cases recovery of the impacted area would need to be demonstrated before another fishing
event could occur in another part of the habitat. This for instance has been the approach in Dundalk
Bay, in relation to cockle fishing, where annual monitoring shows stability in composition and
distribution of benthic habitats.
Coastwatch: We are told in section 8.2 (p 67) ‘The risk assessment framework follows, where
feasible, EC guidance (2012) and includes elements of risk assessment from Fletcher (2002). The
qualitative and semi-quantitative framework is described in Marine Institute (2013) and criteria for
risk categorization is shown … COMMENT: The ‘where feasible’ needs to be explained. We already
commented on the Marine Institute 2013 framework weaknesses in the context of the Castlemain
harbour Natura plan. Now we are commenting on the next. There is no evidence that any earlier
comment has been taken into account. Indeed the risk assessment framework is a sad example of
where the Aarhus Convention regarding public participation is not working. The planning and logics
are all made totally behind closed doors.
MI response: The EC guidance (2012) falls short of providing adequate guidance on assessment of
species and it is ‘not feasible’ to use it to assess impact to species. Elements from other frameworks
have therefore been incorporated. We don’t understand how Coastwatch could have commented
on a 2013 publication in the context of the Castlemaine Harbour natura plan which was produced in
2011. The RA framework was developed by MI and has been discussed and agreed, through open
doors, with NPWS, BIM, SFPA and DAFM.
Coastwatch: Statements on impacts are bizarre. E.g. on page 9: re the Black water bank SAC. ‘In any
case the characterizing species of the protected habitat within the site is not sensitive to physical
disturbance pressure that seed mussel dredging would cause. The possibility of significant effects of
the fishery on these sites can be discounted. Or The seed mussel fishery will not have any significant
effect on designated bird species in the Irish Sea.
Coastwatch would maintain that there is no information provided to support the contention that the
impact of dredging on the sea floor or on birds would be so insignificant that it can be discounted.
MI response: Bizarrely, the full text on the possible effects of mussel fishing on Blackwater Bank is
not contained in the executive summary (p.9) but on page 72 in the body of the assessment. It
states, based on a comprehensive literature review that “Species associated with sand sediments
are predominantly infaunal and hence have some protection against surface disturbance.
Macrobenthic communities from high energy environments (characterised by clean sediments) tend
to be less affected by fishing as they are subject to natural sediment disturbance. Nevertheless, in a
moderately disturbed environment, fishing impacts on benthic community structure are
distinguishable from those resulting from natural variation. The frequency and intensity of
environmental disturbances such as storms may be among the key factors determining the resilience
of the benthic community to fishing”. But ‘in any case’ the fishery does not occur on the sand bank
proper but in deep channels to the west and east of the bank. This habitat is not a designated
marine community in the conservation objectives for the site.
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The seed mussel fishery will not have an effect on seabirds in the Irish Sea. Common Scoter is the
only species potentially feeding on seed mussel although it preys on a range of bivalve species. No
seed mussel fishing is to occur in the Raven SPA (SI 347/2008). Prohibitions in SI347/2008 will
remain other than for the sites listed in the title page of the FNP. Seed mussel at the base of the
Blackwater and Long Bank SACs are unavailable to Scoter because the beds are too deep. To the
north off Wicklow it is unlikely that scoter can utilise seed mussel because of strong currents in these
areas. However, as recommended seed fishing will be prohibited in part of the Wicklow reef SAC.
Because Scoter may in some areas utilise seed mussel as a food source and because of the possible
cumulative disturbance effects of fishing generally (all fleets) in the south Irish Sea east of the Raven
SPA the assessment recommends that new data on the spatial distribution of Scoter in this area be
obtained.
END
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