Castlemaine Appropriate Assessment

Appropriate Assessment of the impact of mussel fishing and mussel, oyster and clam aquaculture on Castlemaine

Harbour SAC and SPA

April 2011

Marine Institute

Rinville

Oranmore

2

Contents

Section 1 - Introduction.................................................................................................................. 1

Section 2 - Details of the proposed operations/activities ............................................................... 4

Proposed activity 1: Mussels seed fishery and ongrowing .................................. 4 Proposed Activity 2: Intertidal/Seafloor aquaculture .......................................... 7 Activities with potential in combination effects ................................................ 14 Potential Disturbance effects ............................................................................. 16

Section 3 - Conservation objectives and interests at the site........................................................ 18

Qualifying interests in the Special area of Conservation ................................... 18 Conservation objectives for the SAC ................................................................. 21 Conservation Interests in the SPA ..................................................................... 22 Conservation Objectives for the Special Protection Area .................................. 22

Section 4 - Natura Impact Statement ........................................................................................... 23

Ecological effects ............................................................................................... 23 Section 5 - Appropriate Assessment Screening ........................................................................... 26

Section 6 - Appropriate Assessment: Special Area of Conservation ........................................... 29

Assessment of the effects of Shellfish Production and in combination effects on

the Conservation Objectives for the physiographic habitats for which the SAC is

designated .......................................................................................................... 29 Methods for Appropriate Assessment................................................................ 29 Assessment of sub-tidal fishing for seed mussel ............................................... 33 Assessment of Activity 2: Relaying of seed mussel on the inter-tidal sand flat

(fishery order and aquaculture license areas)..................................................... 36 Assessment of Activity 3: Dredging of half-grown mussel from the inter-tidal

area ..................................................................................................................... 39 Activity 4: Relaying and dredging of mussels in the sub-tidal channel of

Castlemaine Harbour ......................................................................................... 42 Activity 5: Impact of intertidal oyster culture.................................................... 45 Activity 6: Impact of intertidal clam culture ..................................................... 48 Activity 7: Predator control, winkle picking, discharges ................................... 51 Assessment of the effects of shellfish production and in combination effects on

the Conservation Objectives for Otter, Salmon and Lamprey ........................... 53 Section 7 - Appropriate Assessment: Special Protection Area .................................................... 56

Assessment of the effects of fisheries and aquaculture production on

Conservation Objective 1 (waterbirds) for the SPA .......................................... 56 The status of bird populations, of special conservation interest, in the SPA ..... 66

3

I. Assessment of mussel seed fishery ................................................................. 70 I. Assessment of the effects of intertidal mussel relay in the fishery order area:

effects of mussel cover on habitat suitability for waterbirds ............................. 77 II. Assessment of intertidal relay of mussels in the mussel order area: Effects of

human disturbance ............................................................................................. 84 III. Assessment of sub-tidal relaying of mussels ............................................... 88 IV. Assessment of sub-tidal mussel licenses and license applications outside the

mussel order area ............................................................................................... 94 V. Assessment of additional intertidal mussel licenses and license applications

outside the mussel order area ........................................................................... 100 VI. Assessment of oyster cultivation ............................................................... 107 VII. Assessment of clam licenses .................................................................... 115 VIII. Assessment of potential for cumulative impacts: the combination of

aquaculture activities ....................................................................................... 120 IX. Assessment of potential for cumulative impacts: recreation in association

with aquaculture ............................................................................................... 125 X. Assessment of the effects of mussel production on Conservation Objective 2

for the SPA. ..................................................................................................... 129 Section 8 - AA Conclusion Statement ....................................................................................... 130

SAC Features ................................................................................................... 130 SPA Features ................................................................................................... 131

Section 9 - Scope for additional monitoring and mitigation ...................................................... 134

Section 10 - References SAC interests ........................................................................................ 135

Section 11 - References SPA interests ......................................................................................... 137

Section 1 - Introduction

This document assesses the potential ecological impacts of fishing and aquaculture

activities in and adjacent to Castlemaine Harbour SAC and SPA (Natura site) on the

conservation objectives and special conservation interests of the Natura site. The

information upon which this assessment is based is the draft 5 year mussel fishery Natura

plan submitted, by the Castlemaine Mussel Producers Co-operative, to the Department of

Agriculture Food and Marine (DAMF) in March 2011 and a definitive list of licensed

aquaculture activities and applications submitted to DAMF as of the end of 2010. The

nature of these activities include fishing for seed mussels and the resulting on-growing of

mussels inter-tidally and sub-tidally as well as the aquaculture of oysters and clams inter-

tidally.

The assessment follows guidance given in Anon (2009) Regulation 31 Guidance for the

ecological assessment of aquaculture and fisheries and DEHLG (2009) Appropriate

Assessment of Plans and Projects in Ireland: Guidance for Planning Authorities.

The AA is supported by a number of Annexes which contains detailed technical information

in support of the conclusions in the assessment.

- Annex I. The draft seed mussel fishery Natura plan 2011-2016 including stock

assessment methodologies

- Annex II. Impact of the relaying of seed mussel on the benthic fauna of the

intertidal sand flat in Castlemaine Harbour:

- Annex III. A survey of sediments and macrobenthos in the sub-tidal channel of

inner Castlemaine Harbour

- Annex IV. EPA survey of seagrass in 2009 and 2010 in Castlemaine Harbour.

- Annex V. Gittings and O Donohue (2011a). Castlemaine waterbird studies 1.

Assessment of the potential effects of mussel ongrowing within the mussel order

area and of the mussel seed fishery on the waterbird populations of Castlemaine

Harbour.

- Annex VI. Notes on Common Scoter at Dingle Bay.

- Annex VII. Gittings and O Donohue (2011b). Preliminary assessment of the

potential effects of oyster cultivation and additional intertidal mussel relay on the

spatial distribution of waterbirds in Castlemaine Harbour

- Annex VIII. Gittings and O Donohue (2011c). Preliminary assessment of the effects

2

of clam cultivation on the spatial distribution of waterbirds in Castlemaine Harbour.

- Annex IX. The effects of human disturbance associated with mussel production

and in combination activities on the distribution of birds in Castlemaine Harbour.

3

Figure 1. Castlemaine Harbour showing current and proposed areas for the fishing of mussel seed and production of mussel, oysters and clams.

4

Section 2 - Details of the proposed operations/activities

Proposed activity 1: Mussels seed fishery and ongrowing

Target species:

Blue mussel (Mytilus edulis)

Location:

The proposed activities are described in the draft mussel fishery Natura plan (2010)

(Annex I) and below.

The fishery plan is primarily concerned with the dredging and relaying of seed mussel

in a number of areas within the Castlemaine Harbour SAC (IE000343) and (SPA IE

4029).

The applicants are members of the Castlemaine Harbour Co-operative Society Ltd.

who hold the Mussel Fishery Order for the area from 1979.

There are three distinct phases to the production of mussels in Castlemaine

seed dredging

inter-tidal nursery

sub-tidal on-growing and dredge harvesting

Seed dredging is licensed through fisheries legislation and occurs outside of

Castlemaine Harbour (Figure 1). All mussel dredgers fishing seed are registered and

licensed as Aquaculture fishing vessels or work vessels. In addition the vessels

require annual authorizations and seed mussel allocations, to fish mussel seed, from

DAMF along with the relevant movement authorisations.

The seed fishery leads to relay of seed onto the intertidal area and subsequent

transfer to sub-tidal areas inside Castlemaine Harbour prior to harvesting

Duration:

The seed mussel fishery plan is for the period 2011-2016 inclusive.

5

Seed mussel dredge fishery

The proposed seed mussel fishery is described in the Draft Fishery Natura Plan

developed by the applicants (Annex I) and will be based on demonstrated availability

of seed mussel in the area as determined by annual seed mussel stock surveys

undertaken by BIM (Annex I).

The location of settlement of seed mussel varies annually. The fishable area in the

fishing plan is 317ha (Figure 1). A second area of 13ha occurs east of the main bed in

the entrance to the Harbour. Seed settlement east of Cromane Pt is rare. In any given

year the seed bed covers only a percentage of the fishable area at the mouth of the

Castlemaine Harbour. In 2009 and 2010 the % of the fishable area fished was

approximately 10%. Although the fishery plan describes an area along the north shore

of the Harbour as a potential mussel seed bed it does not incorporate this area

formally into the plan but indicates that a review of the plan could be initiated if a seed

bed did occur there. This area is, therefore, not included in this appropriate

assessment. Other areas, where seed may fall, and which are described in the plan as

areas unsuitable for fishing, are also not considered in this assessment.

The dredges used in the fishery are 2m mussel dredges with a flat bar that is designed

to skim the surface of the substrate and separate mussel seed from the underlying

sediment. Three or 4 large dredgers, and an unspecified number of small (

6

Once the seed has been relayed, there is no activity on the nursery areas apart from

checking the seed. A group member will walk the nursery area once a fortnight, on

spring tides, to check the condition of the seed. Access to a large proportion of the

intertidal nursery area is restricted to vessels at high water due to the soft sand-mud

substrate.

Harvesting from the inter-tidal sandflat

Previously re-laid mussels will be dredged from the intertidal area 6-9months following

relay and deposited for on-growing on the sub-tidal area currently utilised by the co-op

(Figure 1). Intertidal dredging does not result in removal of all mussels from the

sandflat. The relaying and dredging activity and natural recruitment of mussels onto

the sandflat results in variable % cover of the sandflat with mussels.

Relaying on and dredging from the sub-tidal channel

Licensed mussel vessels and a number of licensed punts relay the stock by either

pumping it mixed with seawater from the hold of the boat onto the grow out plots or

manually loading and unloading the half grown mussels from the intertidal to the sub-

tidal area.

This stock movement represents approximately 28 days activity over a six month

period in spring and summer, with the larger boats working 4 hours per day.

Mussels are harvested, to order, by vessels from the sub-tidal plots. The owners only

remove market sized mussels from the sites after the 12-18 month grow-out period

and if orders have been placed with their companies. All harvesting and sales activity

is monitored by the SFPA staff through gatherers documents, VMS plotting,

establishment licensing and depuration centres. As it is mostly larger vessels that

harvest, the amount of time they require to harvest an order of 30 tonnes would lead to

vessel activity of a few hours at high water only.

No waste is generated as the harvested product is placed directed into one tonne bags

for export, via refrigerated truck from Cromane. Mussel production from this area was

3105 Tonnes in 2008, 2725 Tonnes in 2009 and 1294 tonnes in 2010 (source: BIM).

7

Proposed Activity 2: Intertidal/Seafloor aquaculture

This activity relates to intertidal aquaculture of the Pacific Oyster (Crassostrea gigas)

in bags on trestles and the culture of the Manila Clam (Tapes (Ruditapes)

philipanarium) and the Blue Mussel (Mytilius edulis) on the seafloor.

A. Target species:

Pacific Oyster (Crassostrea gigas), Manila Clam (Ruditapes philipanarium), Blue

Mussel (Mytilus edulis)

Location:

The intertidal culture of the Pacific oyster (Crassostrea gigas), Manila Clam (Ruditapes

philipanarium) and Blue Mussel (Mytilus edulis) occurs primarily in the inner part of the

Castlemaine (Figure 1).

In total there are 51 aquaculture licences that are either issued or in application stage

for the culture of oysters, mussels and clams. The majority of these are found on the

inner part of the Castemaine Harbour SAC/SPA (See Figure 2). The area covered by

these activities range from 0.44 to 44.99 hectares. The total area covered by these

activities is 372.08 ha (Table 1).

8

Figure 2. Spatial overlap of shellfish aquaculture (delineated by licence status) and access points within Castlemaine SAC/SPA

9

Table 1. Aquaculture licence for shellfish species in Castlemaine Harbour SAC/SPA

indicating number of licences, their licensing status and aerial cover.

ID Species Status Area (Ha) Expiration

1 T06/277B Oysters Licensed 0.93 25/9/2010

2 T06/289 Oysters Licensed 1.00 27/11/2011

3 T06/259A Oysters Licensed 6.04 10/03/2010








11 T06/267C Oysters Licensed 4.19 25/09/2010



14 T06/300A Clams Licensed 12.37 29/10/2013


16 T06/302A Mussels Licensed 14.33 12/08/2014


18 T06/315A Clams Licensed 10.09 26/05/2016


20 T06/301B Mussels Licensed 8.56 2/02/2014

21 T06/343A Oysters Application 0.88 N/A

22 T06/351A Mussels Application 42.32 N/A




10

ID Species Status Area (Ha) Expiration

26 T06/340B Mussels Application 17.40 N/A

27 T06/310B Oysters Application 5.38 N/A


29 T06/307B Mussels Application 3.86 N/A


31 T06/307C Mussels Application 4.34 N/A





36 T06/267D Oysters Application 2.31 N/A







43 T06/016D Mussels Application 0.49 N/A





48 T06/277C Oysters Application 3.38 N/A




Total Area 372.08 ha

11

Intertidal Oyster Culture

Pacific oysters are usually grown in plastic mesh bags secured to metal trestles in the

inter-tidal zone. The bags are held (suspended) above the substrate in order to allow

free movement of water above and below the oysters. Average annual production of

pacific oysters in the area under consideration was 145 tonnes in 2008 and 97 tonnes

in 2009 (BIM, annual aquaculture survey - personal communication).

Seeding/ Seed Source

Seed or spat oysters are purchased from hatcheries. They are available in a variety of

size grades, usually from 4 mm 30 mm shell length. The size grade quoted by

suppliers generally refers to the size of mesh used to sort the oyster seed (3 14 mm

mesh). Seeding is generally carried out in spring-time when seed (> 5 g or 10-15mm)

becomes available from hatchery. Oysters in Castlemaine are sourced primarily from

hatcheries in France or the UK. The majority of seed is triploid with some acquiring a

mix or both triploid and diploid seed.

Seed was historically purchased on an annual basis between April and June

(sometimes in March). More recently, however, seed has also been introduced

between October and November. This is due to a combination of factors; there has

been a shortage of seed in recent years and to minimise mortalities growers bring in

seed in autumn to harden it over the winter in the hope that it will be more resilient

during the following summer. In addition, some growers are now looking to sell stock

year round and therefore wish to have market sized animals available to fulfil this goal.

Sites are generally accessed on every suitable tide (1/fortnight) for checking but bag

turning takes place on the extreme low tides between march and November averaging

6 times/ year at each site.

Grading and Thinning and Growout

Where oysters are grown in bags to harvest, the size of the mesh in the bags is

increased progressively as the oysters grow. Oyster seed between 4 - 8 mm shell-

length is generally placed in 2 mm mesh bags. At 8 15 mm shell-length 4 mm mesh

is used. From 15 25 mm shell-length the bag is usually of 7 8 mm mesh and above

25 mm shell-length 14 mm mesh is used. By final harvest the bags are generally of 18

25 mm mesh. As general rule largest mesh that will still retain all the stock is used as

this promotes good water flow and optimises growth.

12

The density of the stock within the bags is also reduced progressively as the animals

grow. In Castlemaine, grading takes place 2-3 times during the growth cycle. After the

first 8-12 months depending on intake size, intake time and general growing conditions,

oysters are repacked at a density of approximately 1000 pieces / bag. Depending on

growth second grading may take place the following autumn to 500 pieces / bag. The

final grading repacks the oysters at a density of averaging 150 pieces /bag. For stock

grown over 2.5 years this takes place in springtime.

Harvesting

Harvesting is carried out predominantly during the months of November, December

and January. The stock is harvested when they attain suitable size and condition. This

can be from 75g (>85mm) upwards. It can take 2.5 3 years to first harvest. However,

as indicated above harvesting can also occur at other times of the year to fulfil market

demands.

Site access

Sites are generally accessed on every tide (once per fortnight) for checking but bag

turning takes place on the extreme low tides between March and November averaging

6 times/ year at each site. The majority of oyster growers access the sites by boat from

Cromane point where storage of equipment and grading of oysters also occur.

Intertidal Clam (Tapes (Ruditapes) philippinarum) Culture

Clam culture is carried out at two adjacent sites within Castlemaine Harbour SAC/SPA

(Figure 1 and 2) Clam seed are planted in the spring. Seed bought from hatchery from

July - September - 8-10 million (Size 2mm). The seed is placed in Nursery trays on-site

for approx 1 year. Thinned every 6-8 weeks (it takes 1 day per million). Within each

nursery frame approximately 1million seed is planted and as it grow it will be thinned

out until such a time as it is required for planting. By this time 6 trays will be required for

each 1x106 clams. In total 48 nursery tray are utilized. Seed is only planted on Spring

Tides. Planting of same seed following July-September, seed has to reach 8-10mm

before it can be planted. No further thinning is carried out when seed is planted.

Seed is planted directly in the seabed and overlayed with a net. The netting is

automatically laid with a tractor. Maintenance and cleaning of the net is only carried out

on a spring tide when accessible, and conducted using brushes which are towed by a

tractor.

13

Harvesting takes place on Spring Tides only. Harvesting is done by mechanical

harvester. Harvesting occurs on throughout the year, depending on demand.

During grading, thinning and harvest the seed is brought to higher intertidal areas

within the operational site to allow more time to work on grading, but it must also be left

in the water for as long as possible, as the young clam seed is very fragile. When seed

is purchased from the hatchery it is only 2mm. Also when harvesting, grading is carried

out on site, so clams can be put back in the water in trays to train, and allow to recover

from stress induced during harvest. Clam production in 2008 was 21 tonnes and 40

tonnes in 2009 (BIM, annual aquaculture survey - personal communication).

Intertidal and Subtidal Mussel culture as above (B and C).

14

Activities with potential in combination effects

A. Predator control

Up to 6 punts (current 3 are active) are engaged in predator control on an ongoing

basis all year round. Predator control takes place only in the order area using 11 lines

of baited pots each with 25 pots. The pots are left to fish for 24 hours and hauled every

day weather permitting. Approximately 300 tonnes of green crab are extracted

annually.

Commercial picking of periwinkles occurs in intertidal areas of Castlemaine Harbour at

low tide. The location, quantity of activity generated and total out-take is unknown.

However, some such activity was observed and quantified in the mussel nursery area

in spring of 2010 and its impact on bird habitat use assessed.

Effluent Discharge

Currently there are 5 wastewater treatment plants operating in the general vicinity of

the Castlemaine SAC/SPA (Table 2).

Table 2. Urban waste water treatments plants in vicinity of Castlemaine SAC/SPA

(source: Dept. Environment Heritage and Local Government).

Name Treatment level

Castlemaine Primary

Glenbeigh Secondary

Killorglin Secondary

Milltown Primary

Rossbeigh Primary

The following is the position with the key waste water treatment plants identified:

Castlemaine: The scheme is included in the current Water Services Investment

Programme 2007-2009 (National Spatial Strategy Hub Cluster Sewerage Scheme) to

upgrade the existing sewerage infrastructure and provide secondary treatment. An

application for a certificate of authorisation will be made by Kerry County Council by

December 2009 pursuant to the requirements of the Waste Water Discharge

(Authorisation) Regulations, 2007.

15

Glenbeigh: The scheme is included in the current Water Services Investment

Programme 2007-2009 (Villages Sewerage Scheme Phase 1 Refurbishment) to

upgrade the existing sewerage infrastructure and provide secondary treatment. A

licence application was made by Kerry County Council in March 2009 pursuant to the

requirements of the Waste Water Discharge (Authorisation) Regulations, 2007.

Killorglin: A licence application was made by Kerry County Council in September 2008

pursuant to the requirements of the Waste Water Discharge (Authorisation)

Regulations, 2007.

Milltown: A new plant is being constructed to provide secondary treatment under the

current Water Services Investment Programme 2007-2009 (National Spatial Strategy

Hub Cluster Sewerage Scheme). The sewerage infrastructure has been completed

under the scheme. A licence application was made by Kerry County Council in March

2009 pursuant to the requirements of the Waste Water Discharge (Authorisation)

Regulations, 2007.

Rossbeigh: A new plant is being constructed to provide secondary treatment. An

application for a certificate of authorisation will be made by Kerry County Council by

December 2009 pursuant to the requirements of the Waste Water Discharge

(Authorisation) Regulations, 2007.

In the cases above, compliance with any EPA Wastewater Discharge Authorisation

will require detailed actions including infrastructural works, if required, by the licensee

within specified time-frames if the discharge does not comply with the above

Regulations. Each licence granted will be subject to enforcement by the EPA.

Recreation

The area supports a variety of recreational activities including bird-watching, walking,

horse riding, recreational off road vehicles, angling, sailing and windsurfing (NPWS

2011a).

16

Potential Disturbance effects

Human activities related to mussel production and in combination activities in the form of

fishing vessel and foot traffic occur in the SAC and SPA. A number of large and smaller

vessels operate in the area and growers access the intertidal area at low tide to tend to the

mussel beds.

The location, timing and level of activity generated by the main activities relating to mussel

production process and activities that act in combination are summarised qualitatively in

Table 3. These disturbances occur during daylight hours and either at high tide or at low

tide. The timing, nature, intensity and frequency of these activities will determine the

disturbance effect they have on waterbirds.

17

Table 3. Seasonal, daily and tidal profile of activities associated with mussel production in

Castlemaine Harbour.

Activity

Low

tide

Hig

h tid

e

Day

Nig

ht

J F M A M J J A S O N D

1 SEED MUSSEL FISHERY:

Dredging of seed mussel in the

fishery area outside of Castlemaine

harbour

0 1 1 0 L H

2 NURSERY: Placement of seed in

the nursery and husbandry of

seed

1 1 1 0 L L L L L H L L L

3 ONGROWING: Dredging of

transplanted seed mussel from

inter-tidal to sub-tidal ongrowing

areas

0 1 1 0 H H H

4 HARVESTING: Dredging of

mussels from the sub-tidal channel

for harvest and sale

0 1 1 0 H L L L H H H

5 Oyster and clam culture acting in

combination with the seed mussel

fishery

1 0 1 0 H L L L H H L L L L H H

6 Disturbance (related to mussel

production, other fishing and

aquaculture and recreation)

1 1 1 0 L L L L L L L L L L L L

H = high levels of activity, L = low levels of activity, Blank = no activity. 0 = no activity, 1 = activity.

18

Section 3 - Conservation objectives and interests at the site

Qualifying interests in the Special area of Conservation

Castlemaine Harbour Special Area of Conservation (site code IE 000343)

All qualifying interest(s):

- 1095 Sea lamprey (Petromyzon marinus)

- 1099 River lamprey (Lampetra fluviatilis)

- 1106 Salmon (Salmo salar)

- 1130 Estuaries with the community types outlined in Table 4 and Figure 3.

- 1140 Mudflats and sandflats not covered by seawater at low tide with the

community types outlined in Table 4 and Figure 3

- 1210 Annual vegetation of drift lines

- 1220 Perennial vegetation of stony banks

- 1310 Salicornia and other annuals colonizing mud and sand

- 1330 Atlantic salt meadows (Glauco-Puccinellietalia maritimae)

- 1355 Otter (Lutra lutra)

- 1395 Petalwort (Petalophyllum ralfsii)

- 1410 Mediterranean salt meadows (Juncetalia maritimi)

- 2110 Embryonic shifting dunes

- 2120 Shifting dunes along the shoreline with Ammophila arenaria (white dunes)

- 2130 Fixed coastal dunes with herbaceous vegetation (grey dunes)

- 2170 Dunes with Salix repens ssp. argentea (Salix arenariae)

- 2190 Humid dune slacks

- 91E0 Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno Padion,

Alnion incanae, Salicion albae)

The distribution of inter-tidal biological communities within Castlemaine Harbour is closely

related to exposure levels and sediment types (Figure 2). In addition, there is a strong

influence of both river channels (River Maine to the north and the River Laune to the south)

within the main harbour, in addition to the Caragh River, which drains into Rossbehy

19

Creek, on the distribution of estuarine communities within Castlemaine Harbour.

Table 4. Communities within habitat 1140 (Mudflat and sandflat not covered by seawater at

low tide) and 1130 (Estuaries) in Castlemaine Harbour (NPWS 2011)

Habitat No. Community Characterising species Area

(Hectares)

1140 1 Intertidal muddy fine sand

community complex.

Tharyx sp A, Polydora cornuta,

Gammarus locusta, Macoma balthica,

Hediste diversicolor, Corophium volutator,

Heterochaeta costata, Pygospio elegans,

Crangon crangon

554

1140/1130 2 Fine to muddy fine sand

with polychaetes

community complex

Pygospio elegans, Eteone longa,

Scoloplos armiger, Spio martinensis,

Macoma balthica, Capitella capitata,

Angulus tenuis

3555

1140/1130 3 Intertidal sand with

Nephtys cirrosa

Nephtys cirrosa, Bathypoeia pilosa,

Scolelepis squamata

861

1140/1130 4 Zostera dominated

community

Zostera sp. 234

1130 5 Mixed sediment community

complex

Mytilus edulis, Corophium acherusicum,

Caprella acanthifera, Pholoe

synophthalmica, Nemertea indet,

Pomatoceros lamarckii, Microprotopus

maculatus, Abludomelita obtusata,

Amphipholis squamata, Jassa pusilla,

Eumida sanguinea, Nephtys cirrosa,

Ammothella longipes, Angulis tenuis,

Gastrosaccus spinifer

588 (within

habitat 1130

- Estuaries)

6 Fine sand with Donax

vittatus and polychaetes

community

Donnax vittatus, Spiophanes bombyx,

Magelona mirabilis etc.

Not given in

NPWS 2011

20

Figure 3. Distribution of inter-tidal and subtidal benthic communities in Castlemaine Harbour.

21

Conservation objectives for the SAC

NPWS (2010a) provide a description of the conservation objectives for all qualifying

interests of the SAC.

The proposed activity overlaps habitat 1130 (Estuaries) and 1140 (Mud and sand flats not

covered by seawater at high tide) in particular.

Estuaries (1130) and Mud and sand flats not covered by seawater at high tide (1140):

In the case of these habitats the important attributes that must be conserved are Habitat

area and Habitat structure and function.

Habitat area: The likely area occupied by the constituent communities of Habitats 1130 and

1140 should be stable or increasing with overall target areas of 5696ha and 4287ha

respectively

Habitat structure and function: The communities of habitats 1130 and 1140 should be

stable in distribution and composition (as outlined in Table 4).

22

Conservation Interests in the SPA

Special Conservation Interests for Castlemaine Harbour Special Protection Area (site code

IE 4029) are:

- A001 Redthroated Diver (Gavia stellata)

- A017 Cormorant (Phalacrocorax carbo)

- A046 Lightbellied Brent Goose (Branta bernicla hrota)

- A050 Wigeon (Anas penelope)

- A053 Mallard (Anas platyrhynchos)

- A054 Pintail (Anas acuta)

- A062 Scaup (Aythya marila)

- A065 Common Scoter (Melanitta nigra)

- A130 Oystercatcher (Haematopus ostralegus)

- A137 Ringed Plover (Charadrius hiaticula)

- A144 Sanderling (Calidris alba)

- A157 Bartailed Godwit (Limosa lapponica)

- A162 Redshank (Tringa totanus)

- A164 Greenshank (Tringa nebularia)

- A169 Turnstone (Arenaria interpres)

- A346 Chough (Pyrrhocorax pyrrhocorax)

- A999 Wetlands & Waterbirds

Conservation Objectives for the Special Protection Area

NPWS (2010a) provide a description of the conservation objectives and targets for species

of waterbirds and the wetlands which support them.

1. Population trends and Distribution, as measured by the % change in population

size and the numbers of birds and range of areas used, should be stable or

increasing.

2. The area of subtidal, intertidal and supratidal habitats should be stable or

increasing and not less than the areas of 7471, 3983 & 312 hectares for subtidal,

intertidal and supratidal habitats, respectively other than that occurring from natural

patterns of variation.

23

Section 4 - Natura Impact Statement

Ecological effects

The potential generic ecological effects on the qualifying interests of the site relate to the

physical and biological effects of dredging and culture of shellfish species which overlap

with invertebrate communities (Figure 4, Table 4) found in inter-tidal and sub-tidal habitats.

Bird populations may also be affected by these habitat changes and by disturbance caused

by fishing vessels, by human disturbance on the shore associated with shellfish production

and also by changes in the availability of prey species as a result of changes in habitat

brought about by mussel production.

Details of potential ecological effects of each activity described above, on the SAC and

SPA conservation objectives, their sources and the mechanism by which the impact may

occur are provided in Table 5.

The potential ecological effects on the SPA are of 4 types:

1. Type 1: Direct disturbance of any bird activities

2. Type 2: Competition between birds and mussel producers for a common resource

3. Type 3: Direct impacts of fishery/production activities on habitats and non-target

organisms of importance to birds

4. Type 4: Indirect impact on waterbirds such as increased competition between

individuals leading to reduced population viability

24

Table 5. Indicative effects of shellfish production on the qualifying interests and

conservation interests of Castlemaine Harbour.

Potential Effect Potential Sources

1. Smothering causing a change in the biological

composition and/or availability of prey items

Placement of mussel seed

Settlement of mussel larvae in high

densities

2. Noise / visual disturbance causing displacement of

species

Use of vessels

Use of vehicles on shore

3. Changes in turbidity/ sediments causing a change in

the biological composition and/or availability of prey items


Dredging of mussels

Baffling effect of structures on shore.

4. Changes in oxygen levels causing a change in the

biological composition and/or availability of prey items


Increased organic loading on seabed

beneath oyster trestles

5. Introduction of non-native species causing a change in

the biological composition and/or availability of prey items

Cultivation of Crassostrea gigas

6. Abrasion/Physical disturbance/Compaction causing a

change in the biological composition and/or availability of

prey items

Dredging of mussels

Use of vehicles on shore

Foot traffic on shore

7. Displacement or relocation of species Dredging of mussels

Dredging of clams

8. Selective extraction of target species causing a change

in the biological composition and/or availability of prey

items

Dredging of mussels

Potting crab

9. Selective extraction of non-target species causing a

change in the biological composition and/or availability of

prey items

Dredging of mussels

Potting crab

25

Figu

re 4

. Spa

tial o

verla

p of

pro

pose

d sh

ellfi

sh c

ultu

re a

nd s

eed

mus

sel f

ishi

ng a

ctiv

ities

and

ben

thic

hab

itat t

ypes

in C

astle

mai

ne H

arbo

ur S

AC

.

(See

Fig

ures

1 a

nd 3

for l

egen

ds).

26

Section 5 - Appropriate Assessment Screening

If the qualifying interest overlaps spatially with the proposed activity appropriate

assessment of the potential impact of the activity on the conservation objectives for the

qualifying interest is warranted. If there is no spatial overlap no impact is deemed possible

and further assessment of possible effect is not necessary (Table 6).

Table 6. Potential overlap of activities and qualifying interests at Castlemaine Harbour SAC

and SPA.

All Qualifying Interests Annex qualifying

interest

Is further

assessment

required?

Justification

Petalophyllum ralfsii (Petalwort) Annex II No No spatial overlap

Salmo salar (Atlantic Salmon) Annex II Yes Further assessment

required

Petromyzon marinus (Sea Lamprey) Annex II Yes Further assessment

required

Lampetra fluviatilis (River Lamprey) Annex II Yes Further assessment

required

Lutra lutra (Otter) Annex II, IV Yes Further assessment

required

Fixed coastal dunes with herbaceous

vegetation (grey dunes)

Annex I No No spatial overlap

Mediterranean salt meadows

(Juncetalia maritimi)


Atlantic salt meadows (Glauco-

Puccinellietalia maritimae)


Dunes with Salix repens ssp.argentea

(Salix arenariae)


Shifting dunes along the shoreline with

Ammophila arenaria (white dunes)


Embryonic shifting dunes Annex I No No spatial overlap

Annual vegetation of drift lines Annex I No No spatial overlap

Spartina swards (Spartinion maritimae) Annex I No No spatial overlap

Estuaries Annex I Yes Further assessment

27


interest

Is further

assessment

required?

Justification

required

Perennial vegetation of stony banks Annex I No No spatial overlap

Salicornia and other annuals colonizing

mud and sand


Alluvial forests with Alnus glutinosa and

Fraxinus excelsior (Alno-Padion, Alnion

incanae, Salicion albae)


Humid dune slacks Annex I No No spatial overlap

Mudflats and sandflats not covered by

seawater at low tide

Annex I Yes Spatial overlap/effects

possible further

assessment required

Red-throated Diver SCI in SPA Yes Further assessment

required

Cormorant SCI in SPA Yes Further assessment

required

Light-bellied Brent Goose SCI in SPA Yes Further assessment

required

Wigeon SCI in SPA Yes Further assessment

required

Mallard SCI in SPA Yes Further assessment

required

Pintail SCI in SPA Yes Further assessment

required

Scaup SCI in SPA Yes Further assessment

required

Common Scoter SCI in SPA Yes Further assessment

required

Oystercatcher SCI in SPA Yes Further assessment

required

Ringed Plover SCI in SPA Yes Further assessment

required

Sanderling SCI in SPA Yes Further assessment

required

28


interest

Is further

assessment

required?

Justification

Bar-tailed Godwit SCI in SPA Yes Further assessment

required

Redshank SCI in SPA Yes Further assessment

required

Greenshank SCI in SPA Yes Further assessment

required

Turnstone SCI in SPA Yes Further assessment

required

Chough SCI in SPA No No spatial overlap

The wetland habitat and the waterbirds

that rely on it

79/409/EEC

Wetland &

Waterbirds

protection

Yes Further assessment

required

29

Section 6 - Appropriate Assessment: Special Area of Conservation

Assessment of the effects of Shellfish Production and in combination effects on

the Conservation Objectives for the physiographic habitats for which the SAC is

designated

Appropriate Assessment Screening (Section 5) failed to exclude the possibility of significant

impacts to a number of qualifying interests because these activities spatially overlap with the

distribution of the qualifying interests concerned. Such activities are subject to appropriate

assessment on the basis that they overlap the qualifying interest and the Natura impact

statement identifies possible ecological effects.

Methods for Appropriate Assessment

Determining significance

The significance of the possible effects of the proposed activities on habitats, as outlined

in the Natura Impact statement, is determined here in the appropriate assessment. The

significance of effects is determined on the basis of Conservation Objective guidance for

constituent habitats (NPWS 2011b) (Figure 5).

1. The degree to which the activity will disturb the qualifying interest. By disturb is

meant change in the characterising species, as listed in the Conservation Objective

guidance (NPWS 2011b) for constituent habitats.

2. The persistence of the disturbance in relation to the resilience of the habitat

3. The area of habitats or proportion of populations disturbed. In the case of habitats

disturbance of less than 15% of the habitat area is deemed to be insignificant.

30

Figure 5. Determination of significant effects on community distribution, structure and

function (following Marine Advice Notes, NPWS 2011b.

Effects will be deemed to be significant when cumulatively they lead to long term change

in communities in greater than 15% of the area of any constituent community listed in

Table 4.

Supporting evidence and confidence in conclusions

There are various levels of supporting evidence and therefore confidence for conclusions

on the effects of activities on the conservation objectives for each qualifying interest

(Table 7). The degree of confidence with respect to findings of significant or no significant

effects is categorised as high, medium or low and can be interpreted as follows:

Overlap of community and cumulative pressures

Disturbance?

No community change

Community change

Persistentchange?

No Yes

15% of habitat area affected?

15%

31

Table 7. Level of confidence, based on supporting evidence, in relation to significance of

effects and the implication for management decisions.

Level of

confidence

Supporting

evidence

Implication in relation to significance

Where effects are found to

be significant (>15% of any

community type is

persistently disturbed

Where effects are found to be

insignificant (

32

Table 8. Spatial overlap between likely disturbing activities and habitats of conservation

interest (Habitat key provided in Table 4).

ID Species Status Area (Ha) Community Type (refer to Table 4 for

community details)

1 2 3 4 5

Approximate area (ha) of community type 554 3555 875 235 800

T06/300A Clams Licensed 12.37 12.37

T06/315A Clams Licensed 10.09 3.1 6.99

T06/302A Mussels Licensed 14.33 14.33



T06/301B Mussels Licensed 8.56 0.75 7.81

T06/351A Mussels Application 41.96 41.95


T06/340B Mussels Application 17.40 17.4

T06/307B Mussels Application 3.86 3.86

T06/311A Mussels Application 3.78 0.31 3.47

T06/307C Mussels Application 4.34 4.34



T06/305A Mussels Application 16.00 6.24 9.76



T06/016D Mussels Application 0.49 0.49



Subtidal mussel relay area (FO) 124 123.83

Intertidal mussel seed relay area (FO) 103 0.34 103.18

Seed Fishery Area var 29

Total relevant aquaculture and fishery area (ha) 11.5 462.82 19.36 0 29

Total proportion of habitat occupied by

potentially disturbing shellfish aquaculture and

fishery (%)

2.1 13.0 2.2 - 3.6

33

Assessment of sub-tidal fishing for seed mussel

Natura Impact Statement for this activity

Fishing for seed mussel in the sub-tidal waters of outer Castlemaine Harbour

reduces the extent and biomass of the seed mussel bed and may change the biota in

the area (Table 5).

Assessment

- The proposed seed dredging operation is distributed in various areas of sub-tidal

habitat identified in the community distribution map (Figure 3) as Mixed sediment

community complex. In 2010 the seed area was 29 hectares within the SAC;

however, no seed fishing took place inside a qualifying interest habitat (1130 or

1140).

- The area of overlap in 2010 was 29/800 hectares of mixed sediment community

complex (within the SAC) or 3.6%.

- The area of overlap with the potential seed areas within the SAC (295ha, based

upon 2009 and 2010 coverage and local consultation - See fisheries plan Annex

1) with;

o Habitat 1140 (Mudflats and sandflats not covered by seawater at low tide)

is zero (0),

o Habitat 1130 (Estuaries) by 120ha/5696ha which is approximately 2% of this

habitat type (120ha of 295ha total potential seed area is within the boundary

of habitat 1130 (Estuaries)). Potential seed fishery area of 120ha within

588ha of mixed sediment community complex within the Habitat Estuary

constitutes approximately 20% of this category.

o Mixed sediment community complex within the SAC is 295ha/800ha which

is approximately 37% of this community type within the SAC.

- The annual exploitation of the seed mussel constitutes disturbance as a principal

characterising species is reduced.

- Seed mussel beds in this area are ephemeral and unstable. The mussel bed and

underlying sediment is prone to turn over and wash out by winter storms and by

starfish predation. This is a characteristic of seed mussel beds throughout

Europe (Dare et al. 2004). In Castlemaine, seed mussel beds occur in different

locations each year on sand, mud, shingle and stones and show no distinct

substrate preference. Removal of seed mussel by dredging therefore occurs

against a background of dynamic natural change that occurs on an annual basis

34

in this habitat. It is considered that likely effects on the resident biological

communities that might arise through smothering or changes in suspended

sediment loading will not be significant against the natural dynamics of the site.

Recoverability of all biotopes associated with seed mussel, following physical

disturbance, is high (www.marlin.ac.uk). The substratum required for settlement

of mussel and re-establishment of the mussel bed is unlikely to be significantly

altered above background levels in these dynamic high energy habitats. The

types of dredge used for dredging mussel seed beds are lighter than other

bivalve dredges and do not have a blade or teeth. At the time of fishing, the

mussel beds are elevated from the surrounding substratum and the dredge does

not penetrate the seafloor and disturbance of the sediments below the bed is not

therefore significant, again compared to natural background variability. This is

supported by evidence of repeated annual settlement of mussels in the area

although commercial seed fishing has been in operation since 1977.

- The appropriate assessment of Activity 1 is summarised in Table 9.

Conclusion

The activity may be permitted on the basis that less than 15% of any individual

community type is affected in any one year of activity and there is a medium to high

level of confidence in this conclusion based on evidence at this site and at other

sites.

Mitigation

No mitigation actions are recommended.

35

Tabl

e 9.

Con

clud

ing

App

ropr

iate

Ass

essm

ent i

n re

latio

n to

Act

ivity

1 (

Sub

-tida

l fis

hing

for

seed

mus

sel).

FC

S =

Fav

oura

ble

Con

serv

atio

n S

tatu

s

(as

mea

sure

d by

the

para

met

ers(

s) in

dica

ted.

Act

ivity

R

elev

ant

ecol

ogic

al

effe

cts

(fro

m

stat

emen

t of

AA

)

Hab

itat

affe

cted

Com

mun

ity

affe

cted

with

in

habi

tat

Att

ribu

te

Att

ribu

te

follo

win

g

prop

osed

activ

ity

Sig

nific

ance

of im

pact

Rat

iona

le

Sup

port

ing

evid

ence

Con

fiden

ce

1. S

ub-ti

dal

fishi

ng fo

r

seed

mus

sel

Red

uctio

n of

m

usse

l bed

, le

ads

to c

hang

e in

stru

ctur

e an

d fu

nctio

ning

of t

he

bent

hic

com

mun

ity

Est

uary

M

ixed

se

dim

ent

com

mun

ity

com

plex

Hab

itat a

rea

Sta

ble

(max

imum

of

2% a

ffect

ed)

Not

si

gnifi

cant

ly

dist

urbe

d

Less

than

15

% o

f any

co

nstit

uent

co

mm

unity

is

dist

urbe

d.

GIS

dat

a,

evid

ence

fro

m

prev

ious

ye

ars

fishe

ries

at

the

site

Hig

h

Com

mun

ity

dist

ribut

ion

Pot

entia

lly

alte

red

by

appr

oxim

atel

y 3-

4% in

any

on

e ye

ar.

Not

si

gnifi

cant

ly

dist

urbe

d

Hig

h

36

Assessment of Activity 2: Relaying of seed mussel on the inter-tidal sand flat

(fishery order and aquaculture license areas)


The relaying of seed mussel on the intertidal sand flat leads to change in the existing

biota and sediment (Table 5).

Assessment

Habitat directly affected:

- The habitat affected is ha in the inter-tidal areas of habitats 1140 and 1130 and

fine to muddy sand with polychaetes community complex and intertidal muddy

fines sand community complex.

- The area for intertidal relaying overlaps with;

Habitat 1140 (Mudflats and sandflats not covered by seawater at low

tide) is 244ha/4287ha which is 5.7% of this habitat type,

Habitat 1130 (Estuaries) by 244ha/5696ha which is approximately

4.28% of this habitat type

Fine to muddy sand with polychaetes community complex

244ha/3555ha which is approximately 6.8% of this community type

- Intertidal muddy fines sand community complex by 11.5ha/554h which is

approximately is 2.1% of this habitat type

- In relation to the Inch Mussel relay area; based direct estimates of mussel

coverage produced from previous fishing plans the actual area of this community

that will receive mussels will be substantially less than 92.59ha. However the

assessment considers that all of this area is suitable for use.

- Given the nature of the impact outlined in Table 5, the activity of relaying seed

mussels onto intertidal habitats will constitute a disturbance by virtue of the fact

that the activity will likely lead to a shift in community composition. However, it

must be also noted that the data provided in Annex II that the species

composition of benthic macrofauna in sand and in sand/mud under mussel cover

in the intertidal mussel nursery area in Castlemaine Harbour is largely similar i.e.

- Based on a survey completed in April 2010 (see Annex V) existing % mussel

coverage (ie. the percentage of the sand substrate that is covered by mussel)

averages 12% and ranges from 0-43% across different plots allocated to co-op

members. The area occupied by seed mussel (as opposed to fully grown

mussel) was 4%. There are also extensive patches of adult mussel on the sand

37

flat outside of the mapped nursery area. It is unclear if this is due to natural

settlement of mussel spat or drift of spat from previous relaying activity.

- These estimates suggest that many of the plots allocated by the co-op to its

members do not receive seed mussel annually and that the physical impact of

annual seed depositions is low compared to the area of the nursery. The nursery

itself occupies a relatively small proportion of the area occupied by polychaetes

and bivalves in muddy sand

- Benthic core samples taken in the nursery area in April 2010 (see Annex II)

shows that the benthic fauna in the nursery area is low in abundance and

diversity. This is not unexpected in this brackish water area. Mussel cover has a

significant effect on the abundance and species composition of polychaetes

living in the sand underneath the mussel bed but not on bivalves or crustaceans.

The abundance of a number of deposit feeding polychaetes is reduced under

mussel and the abundance of other deposit feeding polychaetes is higher.

Habitat potentially affected:

- Sea grass on sand: The intertidal seagrass bed east of Inch is mapped annually

by the Environmental Protection Agency (EPA). The area of the bed in 2010 was

2% less than in 2009, which is within the natural range of variability (Annex IV).

- The intertidal mussel relaying site is approximately 300m distant (summary

statistics of 12 measurements of this distance indicate a mean of 290m,

standard deviation of 61m and a minimum distance of 202m from the eastern

edge of the sea grass bed (Figure 3). The footprint of the relaying activity is

larger than the allotted nursery area, however, due to dispersal of seed beyond

borders of the nursery. There is no risk of direct impact i.e. active relaying of

seed or active dredging close to or through the sea grass bed during relaying of

seed. The risk of encroachment of seed onto the seagrass bed is minimal given

the 300m buffer between the licenced area and the sea grass bed.

The appropriate assessment of Activity 2 is summarised in Table 10.

Recommendation

The activity may be permitted on the basis there is a high confidence that there will

be no significant impact on the habitat.

Mitigation


38

Table 10. Concluding Appropriate Assessment in relation to Activity 2 (Relaying of seed mussel on the intertidal sand flat).

Activity Relevant

ecological effects

(from statement

of AA)

Habitat

affected

Community

affected

within habitat

Attribute FCS

following

proposed

activity

Significance

of impact

Rationale Supporting

evidence

Confidence

2. Relaying of seed mussel on the intertidal sand flat

The existing benthic invertebrate fauna will change

1140/1130 Fine to muddy sand with polychaetes community complex; intertidal muddy fines sand community complex

Habitat area

Stable (4.3% and 5.7% for habitats 1140 and 1130, respectively)

Minor The % overlap of activity and any benthic Community is below 15%. The effects are not disturbing to the existing community

GIS, benthic data from the site in 2010

High

Community distribution

Stable (maximum 6.8% and 2.1% area altered or affected, respectively)

Minor High

Area occupied by seagrass on sand

Stable None High

39

Assessment of Activity 3: Dredging of half-grown mussel from the inter-tidal

area


Dredging of mussels from the intertidal sand flat leads to changes in the sediment

and benthic communities in this area (Table 5).

Assessment


- The habitat affected is 244ha in the inter-tidal areas of habitats 1140 and 1130 and

fine to muddy sand with polychaetes community complex community complex and

intertidal muddy fines sand community complex.

- The area to be dredged is;

Habitat 1140 (Mudflats and sandflats not covered by seawater at low

tide) is 244ha/4287ha which is 5.7% of this habitat type,

Habitat 1130 (Estuaries) by 244ha/5696ha which is approximately

4.28% of this habitat type

Fine to muddy sand with polychaetes community complex

244ha/3555ha which is approximately 6.8% of this community type

Intertidal muddy fines sand community complex by 11.5ha/554h which is

approximately is 2.1% of this habitat type.

- The relaying of seed in the inter-tidal area leads to some changes in the species

composition of macrobenthos. The removal of mussel cover by dredging will,

presumably, lead to a reversal of those changes and a return to a species

composition representative of the community type shown in Figure 3 and as

described in Annex II for this area. The dredge essentially removes the mussel

structure and the fauna associated with it. The underlying sediment may remain

undisturbed as the mussel mud, which accumulates in the bed, detaches the

bed from the underlying substrate (Saurel et al. 2003). The typical fauna of this

underlying substrate is then re-established at a rate depending on the sediment

type and exposure. Dredging releases fine sediment, from the mussel mud, into

the water column and the dispersal plume depends on local tidal conditions

during dredging. In areas where mussels are bottom cultivated disturbance and

dispersal of the mussel mud is important in facilitating the recovery of the typical

fauna of the underlying sediment and to avoid raising the bed higher into the

40

inter-tidal zone. Typically accumulation of mussel mud is less an issue in

exposed areas.

Habitats indirectly affected:

- Seagrass on sand: Evidence (see Annex IV) indicates that dredging does not

lead to transport of fine sedimentary material from the dredge area to the

seagrass bed upshore and to the west of the dredging area and that the volume

of material required for such an effect is inconsistent with the scale of dredging

operations proposed. The area of the sea grass bed is stable and there is a

300m buffer between the dredging area and the edge of the seagrass.

The appropriate assessment of Activity 3 is summarised in Table 11.

Conclusion



Mitigation


41

Table 11. Concluding Appropriate Assessment in relation to Activity 3 (Dredging of seed mussel from the intertidal sand flats).

Activity Relevant ecological effects (from statement of AA)

Habitat affected

Community affected within habitat

FCS Parameter

FCS following proposed activity

Significance of impact Rationale

Supporting evidence Confidence

2. Dredging of seed mussel from the intertidal sand flat

Dredging effectively removes the mussel bed from the area thereby changing the existing biota in the dredged area Dredging can potentially displace fine materials onto sensitive Zostera communities west of the nursery area

1140/1130 Fine to muddy sand with polychaetes community complex; intertidal muddy fines sand community complex

Habitat area

Stable (4.3% and 5.7% for habitats 1140 and 1130, respectively)

Minor and temporary

The % overlap of activity with any benthic Community is less than 15%.

GIS High


Stable (6.8% and 2.1% area altered or affected, respectively)

Minor and temporary

High

Area occupied by seagrass on sand

Stable None High

42

Activity 4: Relaying and dredging of mussels in the sub-tidal channel of

Castlemaine Harbour


Relaying and dredging of mussels in the sub-tidal channel of Castlemaine Harbour

leads to changes in the sediments and benthic communities in the area (Table 5).

Assessment

- The areas considered under this activity are the of existing areas utilised by the

Fisheries Cooperative within the fishery order area, existing mussel aquaculture

licence areas and areas applied for the production of mussels and comprises

approximately 219ha.


o Habitat 1140 (Mudflats and sandflats not covered by seawater at low tide) is

zero (0).

o Habitat 1130 (Estuaries) by 219ha/5696ha which is approximately 3.8% of

this habitat type.

o Fine to muddy sand with polychaetes community complex 219/3555ha

which is approximately 6.1% of this community type.

- Although the co-op has allocated plots to its members for the purpose of relaying

of mussels in both the intertidal area and the sub-tidal channel of inner

Castlemaine Harbour (Figure 2) the volume of mussel this area receives

depends on the quantities re-laid by each member in the intertidal area.

- The percentage of the intertidal area with mussel cover in spring of 2010

averaged 12% in areas where the half grown mussels had not been dredged for

the purpose of relaying in the sub-tidal channel. This low cover also suggests

that the volume of mussels that can be transferred from the nursery will not

cover a significant proportion of the sub-tidal channel.

- Although no survey of mussel cover was undertaken in the channel the sub-tidal

faunal survey completed in the channel in autumn 2009 indicates that mussel

cover is relatively low (see Annex III).

- Although the fauna in this estuarine channel is, as expected, low in diversity and

abundance the diversity and abundance of macrobenthos recorded was

significantly higher in samples containing mussels than in other areas (Annex

III). It is not clear if this is due to the presence of mussels or is simply a spatial

effect. Mussels, however, provide additional structural habitat for colonisation of

43

macrofauna.

- The 2009 sub-tidal survey (Annex III) shows that the fauna is dominated by

polychaetes and that the sediments are mainly fine to medium sands with

varying proportions of shell. Mussel cover appears to be low.


Conclusion



Mitigation

No mitigation measures are recommended.

44

Tabl

e 12

. Con

clud

ing

App

ropr

iate

Ass

essm

ent i

n re

latio

n to

Act

ivity

4 (r

elay

ing

and

dred

ging

of m

usse

l in

the

sub-

tidal

cha

nnel

of C

astle

mai

ne

Har

bour

).

Act

ivity

R

elev

ant

ecol

ogic

al

effe

cts

(fro

m

stat

emen

t of

AA

)

Hab

itat

affe

cted

Com

mun

ity

affe

cted

with

in

habi

tat

FCS

Par

amet

er

FCS

follo

win

g

prop

osed

activ

ity

Sig

nific

ance

of im

pact

Rat

iona

le

Sup

port

ing

evid

ence

Con

fiden

ce

4. R

elay

ing

and

dred

ging

of

mus

sel i

n th

e su

b-tid

al

chan

nel o

f C

astle

mai

ne

Har

bour

Rel

ayin

g ca

n sm

othe

r ex

istin

g fa

una

lead

ing

to

chan

ge in

co

mm

unity

st

ruct

ure

and

func

tion.

D

redg

ing

effe

ctiv

ely

rem

oves

the

mus

sel b

ed

from

the

sub-

tidal

, dis

turb

s se

dim

ents

and

le

ads

to

chan

ges

in

faun

a

1130

Fi

ne to

m

uddy

san

d w

ith

poly

chae

tes

com

mun

ity

com

plex

Hab

itat

area

S

tabl

e (3

.8%

and

0

for h

abita

ts

1130

and

11

40,

resp

ectiv

ely)

Min

or

The

% o

verla

p of

act

ivity

with

H

abita

t and

C

omm

unity

is

belo

w 1

0 an

d 15

%,

resp

ectiv

ely.

GIS

Hig

h

Com

mun

ity

dist

ribut

ion

Sta

ble

(max

imum

of

6.1

%

area

alte

red

or a

ffect

ed)

Min

or

Hig

h

45

Activity 5: Impact of intertidal oyster culture

Natura impact statement for this activity

Fishery and aquaculture effects may lead to changes in sediments and benthic

communities in the area in which they occur leading to cumulative effects on the

habitat (Table 5).

Assessment

- In Castlemaine oysters (C. gigas) are grown in licensed areas on trestles above

the seabed (Figure 1).

- The activity overlaps predominantly with Fine to muddy sand with polychaetes

community complex (Table 4, Figure 4).

- Oyster farming typically has a moderate and localised (usually under the

footprint of the culture activity) effect on inter-tidal benthos (Bouchet and Sauriau

2008; Forrest et al. 2009). Due to baffling effects and high density of suspension

feeders this may lead to an increase in organic and silt composition. Although

such effects can be significant in large (hectares) cultivated areas (Nugues et al.

2008) given the scale of cultivation in Castlemaine the effects are deemed to be

minor and localised. The conclusion is further supported by the fact that

predominant substrate type in the culture area is sand (indicating some degree

of flushing) and the communities are tolerant of organic loading. The

characterising species described (e.g. Pygospio elegans and Eteone longa) are

dominated by Group III species from Borja et al. (2000). These species are

tolerant to excess organic enrichment which will stimulate population growth.

The tidal range in Castlemaine is relatively high (3.9m on Spring tides and 1.8m

on Neap tides). This allied with the strong tidal streams experienced indicated

that water movement is high in the harbour which results in a high proportion of

sandy sediments in the harbour. These conditions will serve to reduce the risk of

accumulations of organic matter beneath the cage systems.

- Spawning of non-native oyster (C. gigas) poses a potential risk to the ecology of

Castlemaine Harbour. No significant spawning has been observed (2008 and

2009 benthic surveys) and there are no accumulations of naturally spawned C.

gigas in the area. In addition, the extensive use of triploid oyster within the area

46

also serves to reduce the risk of spawning in this area.

- Access to the licensed oyster sites is by boat from Cromane Point (Position 4

Figure 2), the Sideover (along east side of the point Position 5 Figure 2), Douglas

(Position 9 Figure 2) and Tullig Pier (Position 8 Figure 2) (BIM personal

communication). Oyster culture sites are visited sporadically during the culture

period in order to thin and grade oysters and rotate bags. Each site would be visited

on a bi-weekly basis and the level of foot traffic would therefore be considered very

light. Tyler-Walters and Arnold (2008) conclude that in communities found in the

intertidal sediments (muddy-sand), similar to those found in Castlemaine, would

have low sensitivity to the light foot traffic experienced at the oyster culture sites.


Conclusion

- The general conclusion is that the activity of culturing oysters in bags on trestles in

the intertidal areas in Castlemaine Harbour SAC is not a disturbance on intertidal

mudflat and sand flat habitats (1140) as well as estuarine (1130) habitats.

Mitigation


47

Table 13. Concluding Appropriate Assessment in relation to Activity 5 (Intertidal Oyster Culture).

Activity

Relevant ecological effects (from statement of AA)

Habitat affected


Attribute

Attribute following proposed activity



5. Intertidal oyster culture using bags and trestles

The effects caused by structures can lead to increased sedimentation in low energy areas. Concentration of filter feeder can lead to production of pseudofaeces which may accumulate on seafloor beneath structures and cause changes in faunal composition.

1140/1130 Fine to muddy fine sand with polychaetes community complex

Community composition

Stable Not significantly disturbed

The dominant community type identified is such that the effects of oyster culture at the level proposed are likely to be localised and will not significantly alter the community constituents.

Community data, sedimentary data, hydrodynamic information and published literature.

High

48

Activity 6: Impact of intertidal clam culture

Natura impact statement for this activity

Seeding and dredging of clams from the intertidal sand flat leads to changes in the

sediment and benthic communities in this area (Table 5).

Assessment



o Habitat 1140 (Mudflats and sandflats not covered by seawater at low tide)

is 22.5ha/4287ha which is 0.4% of this habitat type,

o Habitat 1130 (Estuaries) by 22.5ha/5696ha which is approximately 0.3% of

this habitat type

o Intertidal sand with Nephtys cirrosa by 19.4ha/875ha which is approximately

2.2% of this community type (Figures 13).

o Fine to muddy sand with polychaetes community complex by 3.1ha/3555ha

which is approximately 0.1% of this community type.

- The environmental issues that can arise particularly in relation to the culture of

clams relate primarily to the intrusive harvesting techniques. Harvesting can

cause changes to the sediment and non-target benthic organisms, changes that

can take up to 4 and 12 months respectively to recover in extreme cases. Plots

covered by meshes in sandy silt substrates can lead to localized sedimentation

and an increase in the organic content of the sediment. Generally the effects

soon disappear once netting is removed.

- Access to the sites is from Position 0 in Figure 2. A single route is used to the

sites.

Habitats indirectly affected: None

- The appropriate assessment of Activity 6 is summarised in Table 14

Conclusion

The activity licensed may be permitted on the basis there is a high confidence that

there will be no significant lasting impact on the habitat types encountered.

49

Mitigation


50

Table 14. Concluding Appropriate Assessment in relation to Activity 6 (Intertidal culture of clams in Castlemaine Harbour).

Activity

Relevant ecological effects (from statement of AA)

Habitat affected


FCS Parameter

FCS following proposed activity



6. Intertidal culture of clams

Preparation of beds and relaying of seed can dominate existing fauna leading to change in community structure. Dredging effectively removes the infauna and disturbs sediments and leads to changes in fauna

1130/1140 Intertidal sand with Nephtys cirrosa ; Fine to muddy sand with polychaetes community complex

Habitat area

Stable (nominal overlap of 0.3% of 1130 and 0.4% of 1140)

Minor The % overlap of activity with Habitat and Community is below 10 and 15% respectively.

GIS

High


Stable (2.21% and 0.1% overlap, respectively)

Minor High

51

Activity 7: Predator control, winkle picking, discharges

- The predator control programme seeks to reduce the populations of shore crab

which predate on seed mussel. Shore crab populations are productive and the

capacity to control the population using the scale of control described in the

management plan is limited. The control relies on behavioural attraction of the

crabs to baited pots. The fishing technique is highly selective and benign on non-

target fauna and on the physical environment. The creation of a seed mussel

bed on the inter-tidal area is likely to increase the productivity of mobile epifauna

such as shore crab through provision of refuges for postlarvae and juvenile crab

and a food source for crab. The predator control balances this by removing a

proportion of the crab biomass.

- Periwinkles (Littorina littorea) are picked in the intertidal area by an unknown

number of operators. Periwinkle is not a typical species of intertidal sand and

mud flats. The significance of this activity in relation to habitat area, structure and

function is deemed to be insignificant.

- Summary of Total Discharges (excluding wastewater treatment plants) in

relevant catchment area relating to Designated Shellfish Area (taken from S.I.

268 of 2006 European Communities (Quality of Shellfish Waters) Regulations.

Regulation 6, Cromane, Co Kerry).

! "

# $

% $


Conclusion

The activities may be permitted on the basis there is a high confidence that there will

be no significant lasting impact on the habitat types encountered.

Mitigation


52

Table 15. Concluding Appropriate Assessment in relation to Activity 7.

Activity Relevant

ecological

effects (from

statement of

AA)

Habitat

affected

Community

affected

within

habitat

FCS

Parameter

FCS

following

proposed

activity

Significance

of impact


evidence

Confidence

7. In

combination,

picking of

periwinkles

and predator

control and

discharges

Predator control,

other fish

removals and

discharges may

alter the species

composition at

the site and the

structure and

functioning of

communities

1140/1130 Various Habitat

area

Stable Minor These activities

have local

effects and do

not significantly

alter the range

or area of the

benthic

community

Expert

judgement

and

inference

from other

studies

Moderate

Habitat

structure

and

function

Stable Minor Moderate

53

Assessment of the effects of shellfish production and in combination effects

on the Conservation Objectives for Otter, Salmon and Lamprey

Statement for AA

As the shellfish production activities within the SAC spatially overlap with Otter (Lutra

lutra), Salmon (Salmo salar) and Lamprey these activities may have negative effects

on the abundance and distribution of populations of these species.

Otter (Lutra lutra)

- The proposed activity will not lead to any modification of the following attributes

for otter

o Extent of terrestrial habitat,

o Extent of marine habitat or

o Extent of freshwater habitat.

o The activity involves net input rather than extraction of fish biomass so that

no negative impact on the essential food base (fish biomass) is expected

- The number of couching sites and holts or, therefore, the distribution, will not be

directly affected by mussel production activity

- National surveys of otter in Ireland in 2006 found that 75% of sites surveyed in

the south west of Ireland showed signs of otter occupancy. There are no specific

data on otter population size in Castlemaine although they are present

throughout the area.

- Shellfish production activities are unlikely to pose any risk to otter populations

through entrapment or direct physical injury.

- Disturbance associated with vessel and foot traffic could potentially affect the

distribution of otters at the site. However, as shown below for bird populations,

the level of disturbance is likely to be very low.

- The crab control programme associated with the inter-tidal mussel area uses

baited pots that could attract otters. The risk of entrapment is low because of the

specific design of the crab gear which uses small hard-eye rather than soft-eye

54

entrances. The latter could pose more risk to otters that may try and enter the

pot through the eye.

Salmon (Salmo salar)

- Salmon populations run into the Rivers Laune and Maine which flow into

Castlemaine Harbour. Numbers of adult salmon returning to the River Laune

increased between 2004 and 2007. Scientific advice from the Stating Scientific

Committee on Wild Salmon Stocks 2010 indicated a surplus over and above the

conservation limit required to enable optimum levels of spawning. In the Maine

there was no estimated surplus.

- Shellfish production activities do not pose any risk to the following salmon

attributes

o Distribution (in freshwater)

o Fry abundance (freshwater)

o Population size of spawners (fish will not be impeded or captured by the

proposed activity)

o Smolt abundance (out migrating smolts will not be impeded or captured by

the proposed activity)

o Water quality (freshwater)

Sea Lamprey (Petromyzon marinus) and River Lamprey (Lampetra fluviatilis)

- There are no specific data on populations of Sea Lamprey or River Lamprey in

Castlemaine

- The proposed activity will not have any effect on sea lamprey and river lamprey

attributes

o Extent of anadromy (% of river accessible)

o Access to spawning (freshwater)

o Availability of juvenile habitat (freshwater 3rd order channels)

o Spawning beds (freshwater)

o Juvenile density (freshwater

o Population structure of juveniles (freshwater)

o Extent of spawning bed habitat (freshwater)

- The appropriate assessment in relation to effects on otter, salmon and lamprey

is summarised in Table 16.

.

55

Table 16. Concluding Appropriate Assessment in relation to effects of all activities on salmon, otter and lamprey.

Activity Relevant

ecological

effects (from

statement of AA)

Species

affected

Attributes Attribute

following

proposed

activity

Significance

of impact


evidence

Confidence

All activities Activities may

affect the

abundance and

distribution of the

species

concerned

Salmon,

Otter,

Lamprey

All No

change

None No spatial

overlap with

attributes or no

direct or indirect

impact envisaged

GIS

High

Section 7 - Appropriate Assessment: Special Protection Area

Assessment of the effects of fisheries and aquaculture production on

Conservation Objective 1 (waterbirds) for the SPA

Introduction

This section provides an Appropriate Assessment of the potential impacts of existing and

proposed aquaculture activities on the conservation status of waterbird populations of

special conservation interest in the Castlemaine Harbour SPA (site code 004029). One bird

species (Chough), listed as a SCI, is not included in this assessment because the

screening assessment concluded that there is not any spatial overlap between the

activities being assessed and the distribution of this species.

Conservation Objective 1

Conservation Objective 1 for the Castlemaine Harbour Special Protection Area is defined

as follows: -

To maintain the favourable conservation co

Castlemaine Appropriate Assessment

Documents

Transcript of Castlemaine Appropriate Assessment