, annex 5.1 fish and shellfish technical baseline report...innogy ukrwe | triton knoll electrical...

RWE Innogy UK | Triton Knoll Electrical System, Onshore Crossing Schedule

Volume 4, Annex 5.1 Fish and Shellfish Technical Baseline Report

Triton Knoll Electrical System

Environmental Statement, April 2015.

Application Document 6.2.4.5.1

Pursuant to: APFP Reg. 5(2)(a)

1

RWE Innogy UK | Triton Knoll Electrical System, Fish and Shellfish Ecology Baseline

Triton Knoll Electrical System

Environmental Statement

Volume 4: Annex 5.1 Fish and Shellfish

Baseline

April 2015

Drafted By: RWE Innogy UK Approved By: Date of Approval Revision A

Triton Knoll Offshore Wind Farm Ltd Auckland House Great Western Way Swindon Wiltshire, SN5 8ZT

T +44 (0)845 720 090 F +44 (0)845 720 050 I www.rweinnogy.com

www.rweinnogy.com/tritonknoll [email protected]

Triton Knoll Offshore Wind Farm Limited Copyright © 2015 RWE Innogy UK Ltd All pre-existing rights reserved.

Liability In preparation of this document Triton Knoll Offshore Wind Farm Limited (TKOWFL), a joint venture between RWE Innogy UK (RWE) and Statkraft UK, subconsultants working on behalf of TKOWFL, have made reasonable efforts to ensure that the content is accurate, up to date and complete for the purpose for which it was prepared. Neither TKOWFL nor their subcontractors make any warranty as to the accuracy or completeness of material supplied. Other than any liability on TKOWFL or their subcontractors detailed in the contracts between the parties for this work neither TKOWFL or their subcontractors shall have any liability for any loss, damage, injury, claim, expense, cost or other consequence arising as a result of use or reliance upon any information contained in or omitted from this document. Any persons intending to use this document should satisfy themselves as to its applicability for their intended purpose. Where appropriate, the user of this document has the obligation to employ safe working practices for any activities referred to and to adopt specific practices appropriate to local conditions.

Triton Knoll Offshore Wind Farm Limited have been awarded EU TEN-E funding to support the development of the Triton Knoll Offshore Wind Farm Electrical System located in both UK Territorial waters and the UK’s Exclusive Economic Zone. The funding which is to be matched will support a number of surveys, engineering reports, and environmental impact assessment studies for the Triton Knoll Electrical System. The studies will form part of the formal documentation that will accompany the Development Consent Order which will be submitted to the Planning Inspectorate. The sum of €1,159,559 has been granted and the process to reclaim this funding is ongoing.

Kim Gauld-Clark

28/03/15

FISH AND

SHELLFISH

ECOLOGY

TECHNICAL

BASELINE

REPORT

JUNE 2014 TRITON KNOLL ELECTRICAL SYSTEM

ENVIRONMENTAL STATEMENT

Client

Client approval Gill Moore Date 28/03/2015

GoBe Consultants Ltd

Prepared by Dr Lauren Kirkland Date 18/06/14

Authorised by Sean Leake Date 19/06/2014

Signed

June 2014 1 Fish & Shellfish Ecology Technical Baseline Report

CONTENTS

1. Introduction ..................................................................................................................... 1

1.1. Background .............................................................................................................. 1

1.2. Study area ................................................................................................................ 1

2. Data Sources .................................................................................................................... 3

2.1. Overview .................................................................................................................. 3

2.2. Site-specific Triton Knoll Electrical System surveys ................................................. 3

2.3. Triton Knoll Offshore Wind Farm Environmental Impact Assessment .................... 3

2.4. Additional sources of information ........................................................................... 4

2.5. Data limitations ........................................................................................................ 5

3. Baseline Conditions .......................................................................................................... 6

3.1. Introduction ............................................................................................................. 6

3.2. Diversity, distribution and abundance ..................................................................... 6

3.3. Species of conservation importance ........................................................................ 9

3.4. Spawning and nursery areas .................................................................................. 10

3.5. Sandeel and herring spawning ............................................................................... 15

3.6. Potential herring and sandeel spawning habitat ................................................... 15

3.7. TKOWF site-specific surveys .................................................................................. 23

4. Conclusions .................................................................................................................... 25

5. References ..................................................................................................................... 26

HERRING AND SANDEEL SPAWNING APPENDIX A

SHELLFISH APPENDIX B


LIST OF FIGURES

Figure 1: Location of study area and fish and shellfish surveys ............................................... 2

Figure 2: Spawning and nursery grounds for herring, sprat, cod and whiting in the vicinity of

the Triton Knoll Electrical System .......................................................................................... 12

Figure 3: Spawning and nursery grounds for sandeel, sole, plaice and lemon sole in the

vicinity of the Triton Knoll Electrical System .......................................................................... 13

Figure 4: Spawning and nursery grounds for anglerfish, spurdog, mackerel and thornback

ray in the vicinity of the Triton Knoll Electrical System ......................................................... 14

Figure 5: Atlantic herring preferred and marginal habitat types ........................................... 18

Figure 6: Atlantic herring heat map of habitat potential ....................................................... 19

Figure 7: Sandeel preferred and marginal habitat types ....................................................... 21

Figure 8: Sandeel heat map of habitat potential ................................................................... 22

Figure 9: Sediment sediments across the study area ............................................................ 24


1. Introduction

1.1. Background

1.1.1. This report provides a contemporary and comprehensive review of data on fish and

shellfish ecology within the study area defined for the Triton Knoll Offshore Wind

Farm Electrical System project (referred to hereafter as the ‘Electrical System’ or

the ‘development’). The report has been prepared as part of the Evidence Plan1 and

the information compiled here forms the baseline characterisation upon which the

impact assessment will be based. Details on the proposed development will be

found in Volume 2, Chapter 1: Project Description.

1.1.2. As described in the Scoping Report for this development (RWE, 2014), previous

agreement has been reached with the Marine Management Organisation (MMO)

and their advisors that sufficient evidence on fish and shellfish ecology is available

from existing survey data to underpin the EIA, therefore no further characterisation

surveys are required at this pre-application stage. The MMO noted during

consultation that a systematic collation and overview of the existing evidence is

required to form the basis of the fish and shellfish ecology baseline and this report

has been written to fulfil this requirement. This report provides the technical

baseline for fish (both pelagic and demersal, including elasmobranch species) and

shellfish (molluscs and crustaceans) ecology within the Triton Knoll Electrical System

site and in the wider surrounding area.

1.1.3. The commercial exploitation of the fish and shellfish resource in and around the

Triton Knoll Electrical System site is described in Annex 8.1 and within Volume 2,

Chapter 8.

1.2. Study area

1.2.1. As fish are predominantly mobile, the study area for the proposed development is

relatively broad, with an approximate extent between the mouth of the Humber

estuary and the northern coast of Norfolk, in the southern North Sea. The limits of

the study area are presented in Figure 1:.

1 This is intended to be a working document that will be developed by the parties involved on an on-

going basis through the development of the EIA and up until the point of application (or until it is considered otherwise complete).


Figure 1: Location of study area and fish and shellfish surveys


1.2.2. The offshore study area for the development includes the TKOWF array area as well

as the more linear corridor (referred to henceforth as the export cable corridor)

beyond the array boundary up to mean high water spring (MHWS) mark. The study

area also includes a buffer area of 5km extending from the export cable corridor as

depicted in Figure 1. Whilst the export cable has subsequently been reduced from

2km to 1.1km, the buffer represents the maximum dispersion distance and provides

a maximum zone of secondary impacts from the cable installation works that may

arise during the construction of the Triton Knoll Electrical System. Reference to the

TKOWF ES suggests that the maximum adverse scenario arising from foundation

and inter-array cabling installation is 5km (RWE, 2011). As noted above the fish and

shellfish interest within the array area has previously been documented (see

TKOWF ES Volume 2, Chapter 4, Fish and Shellfish Resources), while the importance

of the corridor has not, until now, received such detailed analysis. Hence the

following sections focus on combining the work conducted for the TKOWF array

area with data falling within the export cable corridor study area.

2. Data Sources

2.1. Overview

2.1.1. Baseline characterisation data on fish and shellfish resources were gathered

through a desktop study combining the site specific TKOWF survey data with other

regional datasets.

2.2. Site-specific Triton Knoll Electrical System surveys

2.2.1. Site-specific geotechnical surveys were undertaken in 2010 and 2012 along the

Triton Knoll Electrical System cable route (Gardline, 2010; Osiris, 2013). Cone

Penetration Tests (CPT) and vibrocores were subject to Particle Size Distribution

(PSD) classification and the main characteristics of the surficial seabed sediments

were described in the Physical Environment Baseline Assessment (Annex 6.1).

2.3. Triton Knoll Offshore Wind Farm Environmental Impact Assessment

2.3.1. Surveys commissioned by TKOWFL for the consented TKOWF (including stations

within or near the Triton Knoll Electrical System study area) including the following:

Ten seasonal demersal otter trawl surveys using a 9 m trawl with a 90 mm cod end were carried out during November 2008, February 2009 and May 2009;

Three sets of bi-monthly potting surveys during April 2009, June 2009 and August 2009, with up to 40 pots sampled at each sampling site during each of the surveys;


An epibenthic 2 m beam trawl survey undertaken during September/October 2008 as part of the benthic ecology characterisation study (Volume 3: Annex E of the TKOWF ES). Although not designed to specifically sample for fish, data collected from inshore areas were sampled as these may be important nursery/spawning habitats for fish and shellfish found in the Greater Wash area. This survey provided further characterisation of the demersal fish communities in the TKOWF study area, particularly with respect to smaller species and juvenile fish that may have been missed using the otter trawl technique; and

A herring Clupea harengus larvae survey conducted 12th to 14th October 2009 (coinciding with the anticipated peak spawning period) which collected 32 samples throughout the Triton Knoll site and up to 20 km from the project boundary. A second herring larvae survey undertaken on 4th and 5th October 2010. This survey was able to focus more specifically on the potential impact areas based on the results of the site-specific modelling study.

2.3.2. The site specific TKOWF herring larvae data were supplemented with existing data

from the International Herring Larvae Survey (IHLS) conducted throughout the

North Sea during the same time period as the TKOWF herring larvae surveys (Rohlf

and Groger, 2009) and compared to long time-series data provided by IHLS surveys

of the area over the preceding 10 years.

2.4. Additional sources of information

2.4.1. A number of surveys have been conducted as part of other studies that sampled

station within (or close to) to Triton Knoll Electrical System study area. Most notably

these include the surveys conducted for the Lynn, Inner Dowsing and Lincs offshore

wind farms. These surveys commenced in the summer (early August) of 2004 and

proceeded into the summer (early June) of 2005. Surveys included the use of the

following methods:

Otter trawling;

Commercial 6m shrimp beam trawling;

Epibenthic 2m scientific beam trawling;

Longlining using an 100 hook rig; and

Potting (crab and lobster parlour pots).

2.4.2. All of the Lynn, Inner Dowsing and Lincs surveys were undertaken from licensed

commercial fishing vessels. The gear used for otter trawling, shrimp surveys, potting

and longlining was the same as that employed during commercial fishing activities.

Gear used was the same throughout each survey to ensure directly comparable

results. All trawl lines were aligned with the dominant tidal current flow (N-S), while

longlines were deployed across this (E-W). Sample locations for the Lynn, Inner


Dowsing and Lincs surveys are shown in Figure 1:, alongside the Humber Marine

Aggregate Regional Environmental Characterisation (MAREA) (HADA, 2012) data

points that have contributed to the regional understanding of the fish and shellfish

ecology.

2.4.3. Additional data sources used in this report also included:

Distribution of Spawning and Nursery Grounds as defined in Coull et al. (1998) (Fisheries Sensitivity Maps in British Waters) and in Ellis et al. (2010) (Mapping spawning and nursery areas of species to be considered in Marine Protected Areas (Marine Conservation Zones);

Humber Aggregate Dredging Association (HADA) (2012). Marine Aggregate

Regional Environmental Assessment of the Humber and Outer Wash Region;

Rogers, S.I., Millner, R.S., and Mead, T.A. (1998). The distribution and

abundance of young fish on the east and south coast of England (1981 to

1997). Cefas Science Series Technical Report Number 108;

Eastern IFCA, (2010). Annual Research Report 2010; and

Rogers, S. and Stocks, R. (2001). Strategic Environmental Assessment - SEA2

Technical Report 003 - Fish and Fisheries.

2.5. Data limitations

2.5.1. The description of spawning and nursery grounds provided in this report is primarily

based on the information presented in Ellis et al. (2012) and Coull et al. (1998). The

limitations of these sources of information should, however, be recognised. These

publications provide an indication of the general location of spawning and nursery

grounds. They do not define precise boundaries of spawning and nursery grounds,

particularly in the context of the relatively small footprint of the Triton Knoll

Electrical System. Similarly, the spawning times given in these publications

represent the maximum duration of spawning on a species/stock basis. In some

cases, the duration of spawning may be much more contracted, on a site specific

basis, than reported in Ellis et al. (2012) and Coull et al. (1998). Therefore, where

available, additional research publications have also been reviewed to provide site

specific information.

2.5.2. Mobile species, such as fish, exhibit varying spatial and temporal patterns. All the

wind farm project site specific surveys were undertaken to provide a semi-seasonal

description of the fish and shellfish. It should be noted, however, that the data

collected during these surveys represent snapshots of the fish and shellfish


assemblage at the time of sampling and the fish and shellfish assemblages may vary

considerably both seasonally and annually.

2.5.3. It is important to note that although the data used in the characterisation of the fish

and shellfish baseline conditions span a long time period, with some sources

published over a decade ago, the information presented represents a long-term

dataset. Accordingly, this allows for a detailed overview of the characteristic fish

and shellfish species in the study area. The diversity and abundance of many

species, particularly demersal fish species, is linked to habitat types, which have

remained relatively constant in the study area, indicating no major shift in the fish

and shellfish communities over the time period of the data used in this report.

3. Baseline Conditions

3.1. Introduction

3.1.1. Extensive information on the fish and shellfish communities in the area around the

proposed development (i.e. between the Wash and the Humber) was compiled for

the TKOWF ES (Volume 2, Chapter 4). This included data obtained both from

extensive desk-based searches and from baseline surveys: ES Annexes E (benthic

survey including beam trawls), F1 (herring spawning), F2, (shellfish) and F3 (otter

trawling); a summary of these sources is provided below. This adds to an extensive

knowledge of the area based on other developments in the Greater Wash, such as

other offshore wind farms and areas licensed for aggregate extraction.

3.2. Diversity, distribution and abundance

3.2.1. Long-term surveys of small fish in the inshore area were conducted annually, during

the month of September, by Cefas from 1981-1997 (Rogers et al., 1998), and

included inshore waters between the Humber and the Wash, encompassing the

landfall of the proposed development. The following species were found to have a

high occurrence (i.e. stations where recorded/total stations sampled = >40%):

Whiting (Merlangius merlangus);

Nilsson’s pipefish (Syngnathus rostellatus);

Dragonets (Callionymidae);

Sand gobies (Pomatoschistus minutus);

Dab (Limanda limanda);

Plaice (Pleuronectes platessa);

Dover sole (Solea solea);

Pogge (Agonus cataphractus); and

Sea snails (Liparis spp.).


3.2.2. Additional species recorded in inshore waters in the vicinity of the landfall included

the following:

Thornback (Raja clavata) and spotted (R. montagui) rays;

Gadoids (cod Gadus morhua);

Bib (Trisopterus luscus);

Five-bearded (Ciliata mustela) and four-bearded (Enchelyopus cimbrius) rocklings;

Stickleback (Gasterosteus aculeatus);

Sandeel (Ammodytidae);

Lesser weever (Echiichthys vipera);

Viviparous blenny (Zoarces viviparus);

Butterfish (Pholis gunnellus);

Solenette (Buglossidium luteum);

Flounder (Platichthys flesus);

Brill (Scophthalmus rhombus);

Turbot (Scophthalmus maximus);

Scaldfish (Arnoglossus laterna);

Gurnards (tub Chelidonichthys lucerna and grey Eutrigla gurnardus);

Bull rout (Myoxocephalus scorpius); and

Sea scorpion (Taurulus bubalis).

3.2.3. Surveys were undertaken for the Lynn, Inner Dowsing and Lincs offshore wind farms

designed to obtain baseline information regarding diversity and abundance of fish

and invertebrates (particularly commercial species) from the vicinity of the

proposed Lynn, Inner Dowsing and Lincs offshore wind farm sites, with the aim of

describing the overall community structure in the area. These surveys commenced

in the summer (early August) of 2004 and proceeded into the summer (early June)

of 2005. The results of the surveys are outlined below:

Whiting was by far the most dominant demersal fish species of commercial interest in trawl catches with the exception of the May survey, where its abundance dropped to numbers similar to other species such as thornback ray and Dover sole;

Valuable target species of local commercial fisheries (cod, Dover sole, and thornback ray) were generally caught in low numbers and catches showed a strong seasonal variation;

‘Core’ fish species widely recorded throughout the surveys were thornback ray, bib, whiting, bull rout, dragonet and dab. Other common and abundant small fish included pogge, lesser weever, and common sea snail;

Elasmobranchs (including those caught in a targeted longline survey) were represented by a number of species, although only thornback ray was recorded throughout the year; other taxa (spotted ray, smallspotted


catshark (Scyliorhinus canicula), smoothhound (Mustelus spp.) and tope (Galeorhinus galeus) were recorded less frequently with diversity and abundance highest in May and June;

Surveys for commercially important shrimp conducted between November and March showed that pink shrimp (Pandalus montagui) was the dominant shrimp species, and was widely recorded across the survey area excepting a single station very close inshore (just to the north of Skegness); at this station, brown shrimp (Crangon crangon) overwhelmingly dominated. Pink shrimp catches peaked in December and February, with brown shrimp catches peaking in early December; and

Potting surveys for crab/lobster were dominated by edible crab (Cancer pagurus); crab catches peaked in December, with lobster catches peaking in August.

3.2.4. Surveys commissioned by TKOWFL for the now consented TKOWF (including

stations within or near the Triton Knoll Electrical System study area). The results of

the surveys are outlined below:

Low species diversity with a total of 33 species of fish were recorded during the otter trawl and epibenthic beam trawl surveys, with dominance by relatively small demersal species including dab (Limanda limanda), common sole (Solea solea), bull-rout (Myoxocephalus scorpius), pogge (Agonus cataphractus), dragonet (Callionymus lyra), sea snails (Liparis spp.) and gobies (Pomatoschistus spp);

There were also subtle differences between the seasons, with winter assemblages generally distinct from those found during autumn and spring, although these differences were largely explained by the variation in abundance of the two most numerically dominant species, dab and bull-rout (dab being less abundant during the winter survey and bull-rout less abundant during the spring survey);

Common sole was one of the commercially important finfish species found in this area during the site specific surveys. Other commercially important species also recorded included cod (Gadus morhua); plaice (Pleuronectes platessa); whiting (Merlangius merlangus); and lemon sole (Microstomus kitt). Only two species of commercially important elasmobranch were recorded, both in very small numbers and as juveniles: thornback ray (Raja clavata) and blonde ray (Raja brachyura);

The four main commercially important shellfish in the area were common lobster (Homarus gammarus), edible crab (Cancer pagurus), velvet swimming crab (Necora puber) and common whelk (Buccinum undatum);

Velvet swimming crab and lobster were particularly associated with the coarser, gravelly sediments within the TKOWF array area;

Edible crab was recorded throughout the area, on all substrates, although the highest abundances of individuals were found to be associated with


gravelly substrates with greatest abundance to the west of the TKOWF array area. The shallow, sandy inshore area tended to be dominated by juveniles of this species;

The common whelk was seasonally abundant (peak numbers in April) along the sandy inshore sections of the survey area. Other species of commercial importance recorded in high numbers included pink shrimp (Pandalus spp.) and brown shrimp (Crangon crangon);

3.2.5. Bivalves of commercial interest in the area include mussels (Mytilus edulis) and

cockles (Cerastoderma edule); beds of both of these appear to be ephemeral in

nature within the region. Seed mussels are collected for sale and/or for deposition

in other areas, where they are later harvested. Consultation with the fishing

industry indicated a broad area of seed mussel fisheries off the Lincolnshire coast

from around Mablethorpe south to the mouth of the Wash, which is broadly similar

to that reported previously by HADA (2012). The Triton Knoll Electrical System study

area crosses the area of potential seed mussel beds. However, information

collected by the Eastern IFCA (Eastern IFCA, 2010) indicated that mussel fisheries

were much more limited in extent, and located outside of the Triton Knoll Electrical

System study area, approximately 5 km to the south. Further information on

principal fishing grounds for bivalves of commercial interest is outlined in the

Commercial Fisheries Technical Report (Annex 12.1).

3.3. Species of conservation importance

3.3.1. A number of species of conservation importance have been occasionally recorded in

the wider area (Greater Wash SEA area and/or Humber); predominantly in

inshore/estuarine waters. These include:

Allis shad Alosa alosa and twaite shad A. fallax; Appendix III of the Bern Convention, Annexes II and V of the EC Habitats Directive, UK BAP priority species;

River lamprey Lampetra fluviatilis and sea lamprey Peteromyzon marinus; Appendix III of the Bern Convention, Annex II of the EC Habitats Directive, UK BAP priority species;

European smelt Osmerus eperlanus; Annexes II and V of the EC Habitats Directive, UK BAP priority species;

Salmon Salmo salar and sea trout S. trutta; salmon is on Annex III of the Bern convention and freshwater populations on Annexes II and V of the EC Habitats Directive, both are UK BAP species; and

European eel Anguilla anguilla; critically endangered on the IUCN red list; UK BAP priority species.


3.3.2. None of these species listed were recorded during either the TKOWF surveys or

during previous surveys of OWFs in the Greater Wash area. It is noted, however,

that the surveys were not designed to target these migratory species.

3.3.3. Species such as cod, plaice, herring, mackerel and sole (all of which were recorded

during the TKOWF, and Lynn, Inner Dowsing and Lincs surveys and which occur

commonly in the Greater wash region) are also listed under a commercial marine

fish group UK Species Action Plan.

3.4. Spawning and nursery areas

3.4.1. Many species of fish and shellfish are known to either spawn or have nursery areas

in relatively close proximity to, or potentially overlapping with the Triton Knoll

Electrical System site (Coull et al., 1998; Ellis et al., 2012; Rogers and Stocks, 2001;

see Figures 2 - 4).

3.4.2. The key species identified within the scoping phase were herring, cod, whiting,

sandeel, lemon sole, plaice and sole.

3.4.3. Detailed information on spawning and nursery areas for fish species was considered

in the TKOWF ES (NB herring are discussed separately below). These spawning and

nursery areas are based on the best, most recent available data (Ellis et al., 2012).

3.4.4. Spawning activity is summarised below (from Ellis et al., 2012):

There are no species with ‘high intensity’ spawning in the area of the proposed development;

The species reported to have spawning activity in the area are sandeel, sole, cod, sprat, whiting and lemon sole, whose spawning distributions extend for vast areas around the eastern and southern coast of the UK; the study area forms only a small percentage of these areas; and

Only sandeel and sole spawning grounds overlap the Triton Knoll Electrical System study area, with these grounds being of low intensity spawning.

3.4.5. The only commercially important demersal spawning fish species in the area, as

established through the consultation and scoping process, are sandeel and herring.

These species are considered further in Section 5.5 and 5.6 of this report.

3.4.6. For fish nursery grounds, the only two species with ‘high intensity’ grounds in the

study area are whiting and herring. Species with low intensity nursery areas that

cross the study area (as well as widely around the UK) comprise thornback ray, cod,

plaice, Dover sole and lemon sole.


3.4.7. Shellfish spawning in the area includes shrimp and whelk (which spawn in winter),

and lobster and edible crab (summer). Data from TKOWF surveys showed that some

egg-bearing ‘berried’ lobster were present in the vicinity of the scoping boundary in

June (TKOWF ES Annex F1).


Figure 2: Spawning and nursery grounds for herring, sprat, cod and whiting in the vicinity of the Triton Knoll Electrical System


Figure 3: Spawning and nursery grounds for sandeel, sole, plaice and lemon sole in the vicinity of the Triton Knoll Electrical System


Figure 4: Spawning and nursery grounds for anglerfish, spurdog, mackerel and thornback ray in the vicinity of the Triton Knoll Electrical System

The IHLS surveys consistently identified an area of very high herring spawning

activity well to the north of the TKOWF site, immediately north of Flamborough

Head. In 2008 the IHLS recorded a maximum of 1400 larvae m-2 (of <10 mm) at the

main Bank’s herring stock spawning grounds north of Flamborough Head, compared

to just one larva m-2 south of 54° North (graticule of latitude north of the proposed

development, south of Bridlington), below which the TKOWF site lies. Similarly in

2009, the IHLS recorded a maximum of 4000 larvae m-2 in the Flamborough Head

spawning ground compared with 137 larvae m-2 south of 54° North (50% of the

latter being >10 mm).


3.5. Sandeel and herring spawning

3.5.1. The TKOWF site is located on the periphery of the Banks spawning grounds, one of

the four spawning components that make up the North Sea herring stock (alongside

Shetland/Orkney, Buchan and Downs spawning grounds). The main focus of the

Banks spawning ground is thought to lie to the north, off Flamborough Head. Low

intensity sandeel spawning takes places within the Triton Knoll Electrical System

study area, reportedly from November to February. Spawning areas for this species

off the east coast are large, extending from northern England to the English

Channel.

3.5.2. Information from Coull et al. (1998) indicate that the study area crosses herring

spawning grounds. These grounds are thought to be used in August-October (Coull

et al., 1998). However, the ES for TKOWF comprehensively reviewed herring

spawning in the area using recent data (ES Volume 3, Annex F). These site specific

herring larval surveys were conducted by TKOWFL in early October 2009 and 2010

to investigate the spawning activity in the TKOWF site and the surrounding area.

The results from the 2009 and 2010 site specific surveys suggest that the most

important and intensive spawning by the Bank’s herring stock occurs predominantly

well to the north of the TKOWF site. The data also strongly suggest that spawning is

not occurring in or close to the TKOWF site in any significant way. Furthermore,

investigation into the potential for spawning to the south of the TKOWF site was

also undertaken, through a review of the evidence generated by the Sheringham

Shoal OWF herring larvae surveys. Based on this review, it is considered that herring

do not spawn to the south of the TKOWF site in any significant quantities.

3.5.3.

3.6. Potential herring and sandeel spawning habitat

3.6.1. The Folk sediment classification (Folk, 1954) has been used to describe seabed

habitat as this is also the classification scheme used to underpin the British


Geological Survey’s (BGS’s) 1:250,000 scale seabed sediment maps. This sediment

classification has subsequently been used within the MAREA reports.

3.6.2. Using the Folk (1954) classification enables the screening of seabed areas forspatial

overlap with areas of seabed that have the potential to support herring or sandeel

spawning activity. This approach enables compatibility of herring and sandeel

potential spawning habitat environmental assessments with a range of products

(e.g. MAREAs, marine planning areas) and data sources (e.g. BGS 1:250,000 maps).

Further information on the seabed habitat classification in the study area is located

in Technical Annex 6.1 of the ES.

3.6.3. Suitable potential spawning habitat has been described in various peer review

papers, technical working group reports (ICES HAWG) and grey literature (Bowers,

1980; Rankine, 1986; Aneer, 1989; Morrison et al., 1991; Maravellias et al., 2000;

Maravellias, 2001; Mills et al., 2003; Skaret et al., 2003; Geffen, 2009; Payne, 2010;

ECA and RPS Energy, 2010a, 2010b, 2011). The review and analysis of the source

data for potential spawning habitat resulted in the development of the seabed

surficial sediment classification. The sediment classes used in the screening for

potential spawning habitat are as follows:

Preferred habitat sediment class – in the context of this methodology, these are sediment division/units which herring or sandeel favourably select as part of their spawning habitat requirements;

Marginal habitat sediment class – in the context of this methodology, these are the sediment division/units which herring or sandeel may select as part of their spawning habitat requirements. This sediment class has adequate sediment structure but is less favourable than preferred habitat; and

Unsuitable habitat sediment class – seabed sediment classes which have inadequate sediment structure to be chosen by herring or sandeel for spawning grounds.

3.6.4. Potential herring and sandeel habitat have been identified within the Humber

Region, based on sediment type, historic spawning areas and fishing fleet data (see

Reach et al., 2013 and Latto et al. 2013 for full methods for herring and sandeel,

respectively).

Potential herring spawning habitat

3.6.5. The results of the broad scale mapping process carried out as part of the Humber

Herring CIA (ERM, 2013 an Appendix to MarineSpace Ltd et al. 2013) based upon

BGS sediment data, as illustrated in Figure 5, show that the Triton Knoll Electrical

System study area overlaps with the preferred potential Atlantic herring spawning

habitat sediment class of sandy gravel and gravel and a small area of sediment class


considered to be marginal potential habitat. Figure 5: also shows areas of unsuitable

habitat (shown in white), i.e. sediment classes not considered to be preferred or

marginal spawning habitat for Atlantic herring.

3.6.6. As part of the Humber Atlantic Herring CIA (ERM, 2013 an Appendix to MarineSpace

Ltd et al. 2013), and in line with the Herring EIA Working Group methodology

(MarineSpace Ltd et al., 2013, Appendix B) a range of data were used and mapped

to try to establish potential herring habitat presence. The focus of the spatial

mapping assessments was the analysis of multiple overlaps of data layers used in

the assessment methodology and the resultant ‘heat’. In effect the greater the

number of data layer overlaps, then the higher the ‘heat’ and the associated

confidence that the area of seabed mapped has the potential to provide herring

habitat. An assessment of the confidence in the data for indicating the presence of

herring spawning habitat was also carried out. Figure 6: presents the degree of

interaction between the Triton Knoll Electrical System study area and data

indicating very high, high, medium and low ’heat’ scores for the presence of

potential Atlantic herring habitat. The Triton Knoll Electrical System study area

predominately falls within the very low to medium heat score categories, with a

small area along the offshore cable route which falls within a high heat score

category.


Figure 5: Atlantic herring preferred and marginal habitat types


Figure 6: Atlantic herring heat map of habitat potential


Potential sandeel spawning habitat


Sandeel CIA (ERM, 2013 an Appendix to MarineSpace Ltd et al. 2013) based upon

BGS sediment data, as illustrated in Figure 7, show that the Triton Knoll Electrical

System study area overlaps slightly with the preferred potential sandeel spawning

habitat sediment classes of gravelly sand, with the majority of the Triton Knoll

Electrical System overlapping with marginal habitat sediments of sandy gravel.

Figure 7 also shows areas of unsuitable habitat (shown in white), i.e. sediment

classes not considered to be preferred or marginal spawning habitat for sandeel.

3.6.8. As part of the Humber Sandeel CIA (ERM, 2013 an Appendix to MarineSpace et al.

2013), and in line with the Sandeel EIA Working Group methodology (MarineSpace

et al. 2013, Appendix B) a range of data were used and mapped to try to establish

likelihood of sandeel habitat presence. The focus of the spatial mapping

assessments was the analysis of multiple overlaps of data layers used in the

assessment methodology and the resultant ‘heat’. In effect the greater the number

of data layer overlaps, then the higher the ‘heat’ and the associated confidence that

the area of seabed mapped has the potential to support sandeels. An assessment of

the confidence in the data for indicating the presence of potential sandeel habitat

was also carried out. Figure 8 presents the degree of interaction between the Triton

Knoll Electrical System study area and data indicating very high, high, medium and

low ’heat’ scores for the presence of potential sandeel habitat. The Triton Knoll

Electrical System study area falls within the very low to low heat score category.


Figure 7: Sandeel preferred and marginal habitat types


Figure 8: Sandeel heat map of habitat potential


3.7. TKOWF site-specific surveys

3.7.1. A site-specific geotechnical survey was undertaken in 2012 along the Triton Knoll

Electrical System cable route (Osiris, 2013). Cone Penetration Tests (CPT) and

vibrocores were subject to Particle Size Distribution (PSD) classification and the

main characteristics of the surficial seabed sediments were described in the Physical

Environment Baseline Assessment (Annex 6.1). The characteristics are summarised

below and in Figure 9:

The distribution of seabed sediments across the Nearshore and Midshore Areas of the export cable corridor is complex, with sands, gravels and clays present; and

The distribution of sediments across the Offshore Area of the export cable corridor is more homogenous with silty gravelly sand and gravelly sand dominating.

3.7.2. The site-specific geotechnical surveys indicate that the preferred habitat sediments

span a much reduced proportion of the cable corridor than the broad scale mapping

suggests. The difference between the two interpretations of the potential herring

habitat suitability could be due to the very low to medium confidence in the

Humber Atlantic herring CIA data.

3.7.3. In relation to sandeel spawning, the broad scale mapping established that the Triton

Knoll Electrical System study area overlaps with primarily marginal and unsuitable

habitat sediments, with very low to low confidence in the data for the Humber

sandeel CIA data. The site-specific geotechnical surveys confirm the presence of

marginal habitat sediments along the cable corridor.


Figure 9: Sediment sediments across the study area


4. Conclusions

4.1.1. The fish and shellfish communities present within the Triton Knoll Electrical System

study area, as summarised in this technical baseline report, are typical for the wider

southern North Sea region. The characterisation studies identified the potential for

spawning and nursery grounds for sandeel, herring, sole, cod, sprat, whiting and

lemon sole to be present in the vicinity of the Triton Knoll Electrical System study

area.

4.1.2. Broad scale mapping, based on sediment data, established that the Triton Knoll

Electrical System study area overlaps with preferred, marginal and unsuitable

potential Atlantic herring spawning habitat, although site-specific geotechnical

surveys indicate that the preferred habitat sediments span a much reduced

proportion of the cable corridor than the broad scale mapping suggests. The

difference between the two interpretations of the potential herring habitat

suitability could be due to the very low to medium confidence in the Humber

Atlantic herring CIA data.

4.1.3. In relation to sandeel spawning, the broad scale mapping established that the Triton

Knoll Electrical System study area overlaps with primarily marginal and unsuitable

habitat sediments, with very low to low confidence in the data for the Humber

sandeel CIA data. The site-specific geotechnical surveys confirm the presence of

marginal habitat sediments along the cable corridor.


5. References

Aneer G., 1989. Herring (Clupea harengus L.) spawning and spawning ground

characteristics in the Baltic Sea. Fisheries Research, 8, 169–195.

Bowers A.B., 1980. Characteristics of herring (Clupea harengus) spawning grounds.

ICES CM 1980/H:13

Coull, K.A., Johnstone, R. and Rogers, S.I. (1998). Fisheries Sensitivity Maps in British

Waters. Published and Distributed by UKOOA Ltd, Aberdeen, 63 pp.

East Channel Association and RPS Energy (ECA and RPS), 2010a. East English

Channel Herring Spawning Potential Assessment. Volume 1, Issue 1 (Rev 1).

East Channel Association and RPS Energy (ECA and RPS), 2010b. East English

Channel Herring Spawning Potential Assessment (2009 Update). Volume 1, Issue 2

(Rev 1).

East Channel Association and RPS Energy (ECA and RPS), 2011. East English Channel

Herring Spawning Assessment. Volume 1, Issue 3.

Eastern IFCA, (2010). Annual Research Report 2010. 230 pp.

Ellis, J.R., Milligan, S.P., Readdy, L., Taylor, N. and Brown, M.J. (2012). Spawning and

nursery grounds of selected fish species in UK waters. Cefas Scientific Series

Technical Report 147. Available at:

http://www.cefas.defra.gov.uk/publications/techrep/TechRep147.pdf

Folk R.L. (1954). The distinction between grain size and mineral composition in

sedimentary rock nomenclature. Journal of Geology, 62 (4): pp. 344‐359.

Geffen A.J., 2009. Advances in herring biology: from simple to complex, coping with

plasticity and adaptability. ICES Journal of Marine Science, 66, 1688‐1695.

Humber Aggregate Dredging Association (HADA) (2012). Marine Aggregate Regional

Environmental Assessment of the Humber and Outer Wash Region. Volume I:

Chapters 1-6. Issued May 2012.

Latto P. L., Reach I.S., Alexander D., Armstrong S., Backstrom J., Beagley E., Murphy

K., Piper R. and Seiderer L.J. (2013). Screening Spatial Interactions between Marine

Aggregate Application Areas and Sandeel Habitat. A Method Statement produced

for the British Marine Aggregates Producers Association.


MarineSpace Ltd, ABPmer Ltd, ERM Ltd, Fugro EMU Ltd and Marine Ecological

Surveys Ltd (2013). Environmental Effect Pathways between Marine Aggregate

Application Areas and Atlantic Herring Potential Spawning Habitat: Regional

Cumulative Impact Assessments. Version 1.0. A report for the British Marine

Aggregates Producers Association.

Maravelias C.D., Reid D.G., and Swartzman G., 2000. Seabed substrate, water depth

and zooplankton as determinants of the prespawning spatial aggregation of North

Atlantic herring. Marine Ecology Progress Series, 195, 249–259.

Maravelias C.D., 2001. Habitat associations of Atlantic herring in the Shetland area:

influence of spatial scale and geographic segmentation. Fisheries Oceanography, 10,

259–267.



Application Areas and Sandeel Habitat: Regional Cumulative Impact Assessments.

Version 1.0. A report for the British Marine Aggregates Producers Association.

Mills C., Eastwood P.D. and Rogers S.I., 2003. Herring spawning grounds in the

eastern English Channel. CEFAS (FB‐ECOS) Working Paper – Herring Spawning

Grounds in the Eastern English Channel. Pp 9.

Morrison J.A., Napier I.R., and Gamble J.C., 1991. Mass mortality of herring eggs

associated with a sedimentary diatom bloom. ICES Journal of Marine Science, 48,

237‐245.

Payne M.R., 2010. Mind the gaps: a state‐space model for analysing the dynamics of

North Sea herring spawning components. ICES Journal of Marine Science, 67, 1939–

1947.

The Planning Inspectorate (PINS) (2014). Scoping Opinion: Proposed Triton Knoll

Electrical System. Issued May 2014.

Rankine P.W., 1986. Herring spawning grounds around the Scottish coast. ICES CM

1986/H:15

Reach I.S., Latto P., Alexander D., Armstrong S., Backstrom J., Beagley E., Murphy K.,

Piper R. And Seiderer L.J. (2013). Screening Spatial Interactions between Marine

Aggregate Application Areas and Atlantic Herring Potential Spawning Areas. A

Method Statement produced for the British Marine Aggregates Producers

Association.


Rogers, S. and Stocks, R. (2001). Strategic Environmental Assessment - SEA2

Technical Report 003 - Fish and Fisheries.

Rogers, S.I., Millner, R.S., and Mead, T.A. (1998). The distribution and abundance of

young fish on the east and south coast of England (1981 to 1997). Cefas Science

Series Technical Report Number 108.

Rohlf, N. and Groger, J. (2009) Report of the Herring Larvae Surveys in the North Sea

in 2008/2009. Working Draft. International Council for the Exploration of the Sea,

WD HAWG 2009, 11pp

Skaret G., Nottestad L., Ferno A., Johannessen A. and Axelsen B.E., 2003. Spawning

of herring: day or night, today or tomorrow? Aquatic Living Resources, 16, 299‐306.

Triton Knoll Offshore Wind Farm Limited (TKOWFL) (2014). Triton Knoll Offshore

Wind Farm Electrical System Environmental Impact Assessment Scoping Report.

Submitted March 2014.

HERRING AND

SANDEEL

SPAWNING

APPENDIX A FISH AND SHELLFISH ECOLOGY

TECHNICAL BASELINE REPORT

JULY 2014 TRITON KNOLL ELECTRICAL SYSTEM


Client

Client approval Date




Signed

July 2014 1 Fish & Shellfish Ecology Technical Baseline Report

CONTENTS

1. Introduction ..................................................................................................................... 3

1.1. Purpose of Appendix ................................................................................................ 3

2. Herring larval surveys ....................................................................................................... 3

2.1. International Herring Larval Survey (IHLS) ............................................................... 3

2.2. Triton Knoll Offshore Wind Farm herring larvae survey .......................................... 7

2.3. Conclusions .............................................................................................................. 8

3. Potential herring and sandeel spawning habitat ............................................................. 8

3.1. Datasets used in the assessment ............................................................................. 8

3.2. Caveats and limitations of the data used ................................................................ 9

3.3. Interpretation of preferred habitat and confidence heat maps ............................ 10

3.4. Comparison of site specific geophysical surveys and the CIA preferred habitats

maps 11

4. References ..................................................................................................................... 16


LIST OF FIGURES

Figure 1: North Sea herring - Abundance of larvae <10 mm (n/m2) in the Orkney/Shetland,

Buchan and Central North Sea area (16 – 30 September 2013, maximum = 12,800 n/m2)

(Source: ICES HAWG Report, 2014). ....................................................................................... 4

Figure 2: Peak abundance of North Sea herring larvae in the central North Sea subarea

from 2007 – 2012 (Source: IHLS, 2014) ................................................................................... 6

Figure 3: Regional sediment and seabed type along the offshore export cable corridor .. 13

Figure 4: Comparison of site-specific geophysical survey data and the CIA preferred

herring spawning habitat data .............................................................................................. 14

Figure 5: Comparison of site-specific geophysical survey data and the CIA preferred

sandeel spawning habitat data ............................................................................................. 15


1. Introduction

1.1. Purpose of Appendix

1.1.1. The purpose of this appendix is to provide additional information to supplement the

detail provided in the Fish and Shellfish Ecology Technical Baseline Report

pertaining to herring and sandeel spawning. This addendum relates specifically to

the comments received from the Marine Management Organisation (MMO) and

their scientific advisers (CEFAS), and Natural England (NE) regarding International

Herring Larvae Surveys (IHLS) and potential herring and sandeel spawning habitat.

2. Herring larval surveys

2.1. International Herring Larval Survey (IHLS)

2.1.1. The International Council for the Exploration of the Sea (ICES) programme of herring

larval surveys in the North Sea and adjacent areas has been in operation since 1967.

The main purpose of this programme is to provide quantitative estimates of herring

larval abundance, which are used as a relative index of changes of the herring

spawning‐stock biomass in the assessment.

2.1.2. The total area covered by the IHLS surveys is divided into subareas corresponding to

the main spawning groups. Sampling in each subarea is timed to coincide with the

historical peak hatching periods. The subarea of relevance to the Triton Knoll

Electrical System is the central North Sea (CNS) subarea, where IHLS surveys are

undertaken annually to coincide with the peak hatching period between 1st

September and 30th October.

2.1.3. The ICES Herring Assessment Working Group (HAWG) 2014 (ICES, 2014) report

presents herring larvae data collected during surveys in September 2013. The report

states that the estimate for the CNS area was very small in 2012, but has increased

considerably in 2013. Figure 1 shows the abundance of herring larvae in the CNS

subarea, using the most recent IHLS data from the surveys undertaken in

September 2013. The survey data clearly shows the ‘core’ spawning grounds at

Flamborough Head in the CNS area.


Figure 1: North Sea herring - Abundance of larvae <10 mm (n/m2) in the Orkney/Shetland, Buchan and Central North Sea area (16 – 30 September 2013, maximum = 12,800 n/m2) (Source: ICES HAWG Report, 2014).


2.1.4. The most southerly annual IHLS sampling stations for the CNS region occur within

10 km of the Triton Knoll development site, although it should be noted that the

IHLS sampling south of 54°N (where the Triton Knoll site is located) varies from year

to year. The IHLS sampling strategy prioritises areas which are presumed to have

higher densities of larvae over areas which are likely to have lower densities (ICES,

2008) and the reduced sampling effort south of 54°N (Figure 1) suggests that this

area is historically less important for the CNS herring stock.

2.1.5. Figure 2 shows the results of annual IHLS surveys for the CNS over a six year period

from 2007 – 2012. These data show that there is year to year geographic variation

in the main herring spawning area in this part of the North Sea but also confirms

that spawning over this period has been primarily focussed to the north of

Flamborough Head. In years within which the larval density is at a peak within these

years there appears to be an expansion of the spatial distribution of herring larvae

whereas there is an apparent contraction within years where the core larval stock is

comparatively low. These data suggest that the most significant herring spawning

does not usually occur south of Flamborough Head. It is noted that the IHLS

sampling south of 54°N (closer to the TKOWF site) varies from year to year and it is

therefore possible that some degree of sampling bias may account for this trend.

2.1.6. The higher abundances recorded in the vicinity of the TKOWF site during the 2009-

2011 IHLS surveys are likely to represent a southerly extension of the periphery of

the Flamborough Head spawning area, with the core of the spawning area

remaining to the north and east of Flamborough Head. This geographic variability in

spawning activity is typical for herring, a species whose spawning behaviour

(including spawning location) is known to be modulated by environmental variables,

such as sea surface temperature (Maravelias, 2001).

2.1.7. The apparent temporal trend within the 2007-2013 survey IHLS data sets is that the

limited spawning activity recorded somewhat further south (in the vicinity of the

TKOWF site) is representative of a peak year expansion of larval density and that

the Greater Wash region is more likely to represent the periphery of the main

Flamborough Head spawning area recorded during IHLS surveys. It is noted that

IHLS surveys are not conducted extensively to the south however and therefore,

due to historic records of herring spawning within the region, consideration is given

to site specific surveys and potential spawning habitat.


Figure 2: Peak abundance of North Sea herring larvae in the central North Sea subarea from 2007 – 2012 (Source: IHLS, 2014)


2.2. Triton Knoll Offshore Wind Farm herring larvae survey

2.2.1. To inform the assessment of the potential impacts on herring spawning and the

proposed Triton Knoll Offshore Wind Farm (TKOWF) development, site-specific

herring larvae surveys were conducted in 2009 and 2010 to determine whether or

not herring spawning grounds (as represented by the high abundances of small

herring larvae) were present within and in the vicinity of the TKOWF site and to put

the site into the wider context of the Flamborough Head spawning grounds through

comparison to the long time series IHLS data sets. The results of these surveys were

used to inform the characterisation of herring spawning grounds for the purposes of

the TKOWF Environmental Impact Assessment (EIA) (TKOWFL, 2011).

2.2.2. The sampling technique used was the same as that used by the IHLS (using a Gulf

high-speed plankton sampler), although at a sampling density greater than that

used for the IHLS. Both of the site-specific surveys were conducted during the first

two weeks of October to coincide with the main spawning period for herring in this

region of the North Sea. The IHLS in 2009 and 2010 were undertaken in the last two

weeks of September, reflecting the slightly earlier spawning period to the north of

Triton Knoll.

2.2.3. The site-specific surveys showed that, although herring larvae were recorded within

the survey area, the abundances were considerably lower than the abundances

usually recorded at the Flamborough Head spawning grounds. At one site

approximately 10 km to the north of Triton Knoll, there was evidence of some

limited spawning (i.e. higher abundances of small larvae, >10 mm) during the 2010

survey, though this was considered to have been at the periphery of the main

Flamborough Head spawning grounds. The larvae recorded during the site-specific

surveys were lacking any yolk sacs, indicating that they were more than 10 days old

and therefore would have drifted to the survey area from spawning grounds further

afield during that period.

2.2.4. The results of the IHLS (from 2001/02 to 2010/11 surveys) clearly showed

consistently high herring larval abundances (thousands of larvae <10 mm m-2)

recorded off the coast of Flamborough Head and further north (over 80 km to the

north of the development site). The TKOWF Environmental Statement (ES)

concluded that the site-specific herring larvae surveys were single event surveys

and therefore spatial and temporal variation in environmental variables and year to

year location of herring spawning grounds mean that it is important to interpret the

data in the context of other background information and data sources. In this case,

when considered in combination with the broadscale, long time series data of the

IHLS, the TKOWF ES concluded that the results provided a strong indication that the


TKOWF area was not close to any of the significant or consistently used spawning

grounds for herring in the region.

2.2.5. It is important to note that the herring survey results presented in the Triton Knoll

Environmental Statement give a “snap shot” description of the distribution and

abundance of herring spawning in the area. The surveys do not cover the whole

spawning period for the whole area and therefore cannot define the spatial and

temporal distribution of spawning herring.

2.2.6. The combining of the site-specific survey data with IHLS data has some limitations

and the comparability due to sampling season is a potential area of uncertainty

within the dataset. The data are considered to be representative of larval density

within the area and complementary to that of the IHLS.

2.3. Conclusions

2.3.1. Spawning grounds in the North Sea have been regularly sampled during the IHLS,

conducted by ICES, since the 1970s and one spawning ground immediately north of

Flamborough Head (approximately 80 km northeast of the development site) has

been shown to be a regular, reliable (though with some natural annual variability)

spawning ground for herring. Althoughs the periphery of the Flamborough Head

spawning grounds occasionally extends south of 54°N, no further spawning grounds

have been consistently identified south of Flamborough Head (54°N) during the

IHLS.

2.3.2. In addition to the larval surveys conducted by IHLS and TKOWF, a regional

description of the sediment type allows for consideration of the potential spawning

habitat present within the Triton Knoll Electrical System study area. The following

sections describe the potential spawning habitat.

3. Potential herring and sandeel spawning habitat

3.1. Datasets used in the assessment

3.1.1. Further to the methodology outlined in the Fish and Shellfish Technical Baseline

Report (Section 3.6) in relation to the broad scale mapping process as carried out as

part of the Humber Herring and Sandeel Cumulative Impact Assessments (CIA)

(ERM, 2013 an Appendix to MarineSpace Ltd et al. 2013), the following spatial

datasets were considered in the confidence assessment to inform the location of

potential spawning grounds for herring and sandeel:

Seabed sediment Folk classification: British Geological Survey (BGS);


Seabed sediment Folk classification: Marine Aggregate Regional Environmental Assessment (MAREA);

Seabed sediment Folk classification: Regional Environmental Characterisations (RECs);

Fishing Fleet: Vessel Monitoring System (VMS);

Fishing Grounds: Eastern Sea Fisheries Joint Committee (ESFJC);

Spawning Grounds: Coull et al. (1998); and

Spawning Grounds (Herring only): International Herring Larvae Surveys (IHLS).

3.2. Caveats and limitations of the data used

3.2.1. The data used in the broad scale mapping process carried out as part of the Humber

Herring and Sandeel Cumulative Impact Assessments (CIA) (ERM, 2013 an Appendix

to MarineSpace Ltd et al. 2013), has to be considered alongside the following caveat

statements:

The International Herring Larval survey (IHLS) was greater in extent and duration in the past. Now, due to sharp reduction in ship time and number of participating nations, the survey now only samples peak spawning locations and at around the peak spawning. While the Downs component is surveyed three times (covering the whole hatching period), all others areas are in general covered only once a year, and most often during the same time period, hence peaks timings can be missed. This pattern is persistent for most of the last 20 years. It is obvious that these gaps must result in larger levels of uncertainty when calculating larvae abundance indices for the North Sea (ICES 2012). It is important to note that in areas where the IHLS survey was not undertaken is not indicative of no spawning;

Herring larvae remain close to the seabed during the yolk-sac phase. The IHLS only samples down to 5 m above the seabed, and for this reason, yolk-sac and smaller larvae are not sampled effectively, as the towed plankton samplers used for the surveys are not deployed close enough to the seabed;

For the purposes of the CIA assessment, preferred habitat for both herring and sandeel is based on substrate classification alone. It must be noted that there are other factors, i.e. for herring: raised seabed features, good oxygenation plus other factors, are involved in establishing a ground as suitable for spawning. As a consequence not all areas described as preferred habitat will be suitable for spawning;

It is also important to note that some historic herring spawning grounds which currently have very little or no spawning activity can be re-colonised (subsequent seabed recovery from impacts and ability to support spawning activity over time) (ICES, 2012);

Heat maps generated from overall data confidences are not necessarily indicative of spawning areas. Higher confidence levels indicate that more layers of data are available for that area and do not relay any information


about data contents. Hence should not be assumed to be directly related to spawning activity.

It is acknowledged that the methodology in the CIA report (ERM, 2013 an Appendix to MarineSpace Ltd et al. 2013) will be subject to periodic review, and subsequent revised versions may be released as the scientific understanding of Atlantic Herring spawning habitat preferences advances, and/or when new data become available.

Vessel monitoring systems are used in commercial fishing to allow fisheries regulatory organizations to monitor the position, time at a position, and course and speed of fishing vessels. From January 2005 all UK fishing vessels over 15 metres in overall length were required to have installed on board a satellite tracking device. Since January 2012 vessels greater than or equal to 12 m have a requirement to install these systems.

3.3. Interpretation of preferred habitat and confidence heat maps


Sandeel CIA (ERM, 2013 an Appendix to MarineSpace Ltd et al. 2013) based upon

BGS sediment data, as illustrated in Figure 5 and 7 of the Fish and Shellfish

Technical Baseline Report (for herring and sandeel, respectively), show the overlap

of the Triton Knoll Electrical System study area with preferred and marginal

potential spawning habitat. Areas of the seabed shown in white represent either

seabed sediment classes which have inadequate structure to be chosen by herring

or sandeel for spawning grounds, or areas where sediment data is not available.

3.3.2. The heat map approach (as shown in Figures 6 and 8 of the Fish and Shellfish

Technical Baseline Report, for herring and sandeel, respectively) adopted in terms

of confidence levels indicates varying degrees of likelihood that an area will be

suitable for spawning or will contain spawning beds.

3.3.3. These heat maps, generated from overall confidences, are not necessarily indicative

of spawning areas; rather, higher confidences indicate that more layers of data

were available for that particular area (irrespective of data content). It should not

be assumed to be directly related to spawning activity. The data outlined in Section

3.1 of this document have been used to create the herring and sandeel heat maps,

as shown in Figures 6 and 8 of the Fish and Shellfish Technical Baseline Report, for

herring and sandeel, respectively.

3.3.4. The confidence ‘heat’ map for Atlantic herring potential spawning habitat (Figure 6

of the Fish and Shellfish Technical Baseline Report) shows that the regions of

highest confidence are those areas of seabed where IHLS data positively identify

Atlantic herring spawning. This is most notable in the northern part of the region,

inshore along the Holderness coast. Analysis of the TKOWF Atlantic herring larvae


survey data (TKOWFL, 2011) extends the coverage of IHLS data across the Humber

region and provides confidence that the extent of the data reflects actual

distribution of larvae, mitigating a lack of ICES IHLS sampling south of Spurn Point

(ICES, 2012) i.e. the extent of the larvae is not limited by ICES IHLS data gaps.

3.3.5. The confidence ‘heat’ map for sandeel herring potential spawning habitat (Figure 8

of the Fish and Shellfish Technical Baseline Report) shows that the regions of

highest confidence are those areas of seabed where the preferable habitat

sediments overlaps with the Coull et al. (1998) sandeel spawning layer. This is most

notable in the northern part of the region, and across the Dogger Bank. A smaller

region of high confidence is associated with the Silver Pit, a bathymetric low (tunnel

valley) in the centre of the MAREA area.

3.4. Comparison of site specific geophysical surveys and the CIA preferred habitats

maps

3.4.1. Figure 3 illustrates the interpreted geophysical survey data (Gardline, 2010 and

Osiris, 2012) across the export cable corridor and wider array area. It also illustrates

the point data collected during a number of surveys that has been used to

characterise the REC and MAREA regions. The site specific TKOWF sediment data

formed part of the MAREA characterisation and has been developed further within

the figure through the illustration of the vibrocore survey data. The combination of

site specific survey sediment data and geophysical survey data give a high

confidence in the characterisation of seabed sediment conditions and therefore in

the characterisation of herring and sandeel potential spawning habitat within the

cable area.

3.4.2. Further to the figures presented in Section 3.6 and 3.7 of the Fish and Shellfish

Technical Baseline Report, Figures 4 and 5 below show a direct comparison

between the characterisation of the seabed sediments from the site-specific

geotechnical surveys along the Triton Knoll Electrical System cable route, and the

interpretation of the preferred spawning habitat maps that were incorporated into

the broad scale mapping process carried out as part of the Humber Sandeel CIA

(ERM, 2013 an Appendix to MarineSpace Ltd et al. 2013) based upon BGS sediment

data.

3.4.3. In relation to potential herring spawning habitat, Figure 4 indicates areas of

preferred herring habitat sediments (sandy gravel) along parts of the Triton Knoll

Electrical System cable route in both the geophysical surveys and the corresponding

BGS sediment data, although it was found to a lesser extent in the site-specific

geotechnical surveys. The BGS data highlights an area of marginal herring habitat


sediments along a section of the cable route landward of the fan area. This area of

marginal sediments was not found in the site-specific geophysical surveys.

3.4.4. In relation to potential sandeel spawning habitat, Figure 5 indicates similar areas of

marginal sandeel habitat sediments along the central section of the Triton Knoll

Electrical System cable route, from both the site-specific geophysical surveys and

from the BGS data. Preferred sandeel habitat sediments are shown in the results

from both the site-specific and BGS data, although these sediments do not fall in

corresponding areas along the cable route.


Figure 3: Regional sediment and seabed type along the offshore export cable corridor


Figure 4: Comparison of site-specific geophysical survey data and the CIA preferred herring spawning habitat data


Figure 5: Comparison of site-specific geophysical survey data and the CIA preferred sandeel spawning habitat data


4. References

Coull, K.A., Johnstone, R. and Rogers, S.I. (1998). Fisheries Sensitivity Maps in British

Waters. Published and Distributed by UKOOA Ltd, Aberdeen, 63 pp.

ICES (2008) Manual for the International Herring Larvae Surveys South of 62' North.

International Council for the Exploration of the Sea, Annex 7: Working Documents

to PGHERS, 27pp.

ICES (2012). Report of the Herring Assessment Working Group for the Area South of

62ºN (HAWG), 13-22 March 2012, ICES HQ, Copenhagen, Denmark. ICES CM

2012/ACOM:06. 835 pp.

ICES (2014). Report of the Herring Assessment Working Group for the Area South of

62ºN (HAWG), 11-20 March 2014, ICES HQ, Copenhagen, Denmark. ICES CM

2014/ACOM:06. 1257 pp.

Maravelias C.D., 2001. Habitat associations of Atlantic herring in the Shetland area:

influence of spatial scale and geographic segmentation. Fisheries Oceanography, 10,

259–267.



Application Areas and Atlantic Herring Potential Spawning Habitat: Regional

Cumulative Impact Assessments. Version 1.0. A report for the British Marine

Aggregates Producers Association.



Application Areas and Sandeel Habitat: Regional Cumulative Impact Assessments.

Version 1.0. A report for the British Marine Aggregates Producers Association.

Triton Knoll Offshore Wind Farm Limited (2011). Environmental Statement Volume

3 (Annex F). F1: Herring Larvae Survey Report.

SHELLFISH

APPENDIX B FISH AND SHELLFISH ECOLOGY

TECHNICAL BASELINE REPORT

JULY 2014 TRITON KNOLL ELECTRICAL SYSTEM


Client

Client approval Date




Signed


CONTENTS

1. Introduction ..................................................................................................................... 3

1.1. Purpose of Addendum ............................................................................................. 3

2. Brown Shrimp................................................................................................................... 3

2.1. Offshore wind farm surveys ..................................................................................... 3

2.2. Triton Knoll Electrical System Commercial Fisheries Technical Baseline Report ..... 3

3. Brown crab and lobster .................................................................................................... 7

3.1. Offshore wind farm surveys ..................................................................................... 7

3.2. Triton Knoll Electrical System Commercial Fisheries Technical Baseline Report ..... 7

4. References ..................................................................................................................... 11


LIST OF FIGURES

Figure 1 Surveillance Sightings of UK Vessels in the Regional Study Area (All Fishing

Methods, 2008 to 2012) (Source: MMO, 2013 & BMM, 2014) ............................................... 5

Figure 2: Beam trawling fishing grounds (brown and pink shrimp) for UK registered fishing

vessels (Source: EIFCA, 2012 & PMSL, 2014) ........................................................................... 6

Figure 3: Key shellfish (potting) fishing grounds for the Bridlington fleet (Source: Holderness

Fishing Industry Group, 2013) .................................................................................................. 9

Figure 4: Key shellfish (potting) fishing grounds for the Lincolnshire and North Norfolk

based fleets (Source: Consultation, 2014) ............................................................................. 10


1. Introduction

1.1. Purpose of Appendix

1.1.1. The purpose of this appendix is to provide additional information to supplement the

detail provided in the Fish and Shellfish Ecology Technical Baseline Report (Annex

5.1) pertaining to shellfish. Specifically the addendum address comments received

from the Marine Management Organisation (MMO) their scientific advisers CEFAS,

and Natural England (NE) regarding the distribution of brown shrimp (Crangon

crangon), brown crab (Cancer pagurus) and lobster (Homarus gammarus).

2. Brown Shrimp

2.1. Offshore wind farm surveys

2.1.1. The Triton Knoll Offshore Wind Farm surveys (TKOWFL, 2011) recorded high

numbers of the commercially important pink shrimp (Pandalus spp.) and brown

shrimp (Crangon crangon). The surveys recorded the highest abundances of brown

shrimp generally to the south of the TWOWF site, associated with the more sandy

substrates in this area, in line with the habitat preferences for the species. This is

also in line with the findings reported in the Environmental Statement for the Race

Bank offshore wind farm, located to the south of Triton Knoll, which also recorded

high abundances of brown shrimp in this area (Centrica Energy, 2009).

2.1.2. Surveys commissioned for the Lynn, Inner Dowsing and Lincs offshore wind farms

for commercially important shrimp were conducted between November 2004 and

March 2005. The surveys concluded that pink shrimp was the dominant shrimp

species, and was widely recorded across the survey area excepting a single station

very close inshore (just to the north of Skegness). At this station, brown shrimp

overwhelmingly dominated. Pink shrimp catches peaked in December and February,

with brown shrimp catches peaking in early December (AMEC, 2007).

2.2. Triton Knoll Electrical System Commercial Fisheries Technical Baseline Report

The Triton Knoll Electrical System Commercial Fisheries Technical Baseline Report

(Annex 12.1) highlights the importance of the brown shrimp fishery in the Wash

area, stating that brown shrimp is the “mainstay of the fishery at present”.

2.2.1. The key fishing grounds identified in the vicinity of the Triton Knoll Electrical System

are shown in Figure 1 (regional surveillance data) and Figure 2, compiled using data

derived from consultation with local fishermen in 2012 (Boston and Kings Lynn) and


updated during consultation in 2014 (Kings Lynn). The key fishing grounds are also

overlaid on extents of the brown and pink shrimp fishery provided by the EIFCA.

2.2.2. The data combined from the EIFCA and consultation with local fishermen, as shown

in Figure 2, highlight the importance of the coastal margins to brown shrimp and, as

a consequence, beam trawling activity within the region.

2.2.3. Further detail on the commercial fishing of brown shrimp in the vicinity of the

Triton Knoll Electrical System can be found in the Triton Knoll Electrical System

Commercial Fisheries Technical Baseline Report (Annex 8.1; Application Document

6.2.4.8.1).


Figure 1 Surveillance Sightings of UK Vessels in the Regional Study Area (All Fishing Methods, 2008 to 2012) (Source: MMO, 2013 & BMM, 2014)


Figure 2: Beam trawling fishing grounds (brown and pink shrimp) for UK registered fishing vessels (Source: EIFCA, 2012 & PMSL, 2014)


3. Brown crab and lobster

3.1. Offshore wind farm surveys

3.1.1. The TKOWF surveys (TKOWFL, 2011) found common lobster and brown crab, with

lobster particularly associated with the coarser, gravelly sediments within the

TKOWF array area. Brown crab were recorded throughout the area, on all

substrates, although the highest abundances of individuals were found to be

associated with gravelly substrates with greatest abundance to the west of the

TKOWF array area. The shallow, sandy inshore area tended to be dominated by

juveniles of this species.

3.1.2. The majority of the individuals recorded in the TKOWF survey area were male.

Previous tagging studies (Jessop et al., 2007, MAFF, 1966) and recent larval studies

(Eaton et al., 2003) showed that mature females make significant northward

migrations along the Yorkshire coast to spawn while males are relatively sedentary,

seldom displaying significant migrations. The sex data from the TKOWF survey may

reflect this pattern, with males permanently resident in this region and females

potentially migrating further offshore to spawn. However, the results may also be

an artefact of the fact that berried females bury themselves and do not feed in the

period around October and November. They are therefore unlikely to enter baited

pots (Jessop et al., 2007) and this may have been reflected in the TKOWF survey

data.

3.1.3. Potting surveys from crab and lobster were undertaken for the Lynn, Inner Dowsing

and Lincs offshore wind farms between November 2004 and March 2005. Catches

in the surveys were dominated by brown crab with peak catches in December, with

lobster catches peaking in August.

3.2. Triton Knoll Electrical System Commercial Fisheries Technical Baseline Report

3.2.1. The Triton Knoll Electrical System Commercial Fisheries Technical Baseline Report

(Annex 12.1) in reporting the results of detailed site specific consultation

demonstrates that within the inshore area of the Triton Knoll Electrical System, the

principal fishing method is potting for a range of shellfish species, mainly brown

crab, velvet crab and lobster.

3.2.2. ICES rectangle 36F0, directly north of the export cable corridor, records the highest

landings values for the crab and lobster fishery in the UK, with lobster being the

highest value species caught, followed by edible crab. The potting fleet targeting

the Triton Knoll Electrical System study area primarily originate from Bridlington,

Lincolnshire and North Norfolk.


3.2.3. The principal shellfish fishing grounds for the Bridlington fleet are given in Figure 3

and show that the key grounds encompass a considerable part of the offshore

turbine array. This is expected as the Bridlington fleet fishing into the Wash consist

of vessels greater than 12m in length and as a consequence they have a greater

capacity to fish for longer periods and in a range of weathers not suitable for

smaller ‘day’ boats.

3.2.4. The main shellfish fishing grounds utilised by the Lincolnshire and North Norfolk

fleets are given in Figure 3 and show key grounds such as the Inner Dowsing, Race

Bank and Docking Shoal, the North Norfolk coastal margins, the western part of the

offshore turbine array and the Lynn Deeps area of the deep water channel.

3.2.5. Further detail on the commercial fishing of brown crab and lobster in the vicinity of

the Triton Knoll Electrical System can be found in the Triton Knoll Electrical System

Commercial Fisheries Technical Baseline Report (Annex 12.1).


Figure 3: Key shellfish (potting) fishing grounds for the Bridlington fleet (Source: Holderness Fishing Industry Group, 2013)


Figure 4: Key shellfish (potting) fishing grounds for the Lincolnshire and North Norfolk based fleets (Source: Consultation, 2014)


4. References

AMEC (2007). Lynn Offshore Wind Farm. Environmental Statement.

Centrica Energy (2009). Race Bank Offshore Wind Farm. Environmental Statement.

Eaton, D.R., Brown, J., Addison, J.T., Milligan, S.P. and Fernand, L.J. (2003). Edible

Crab (Cancer pagurus) Larvae Surveys off the East Coast of England: Implications for

Stock Structure. Fisheries Research 65:191-199.

Jessop, R.W., Woo, J.R. & Torrice, L. (2007). Eastern Sea Fisheries Joint Committee

Research Report. Eastern Sea Fisheries Joint Committee, 259pp.

MAFF (1966). The Norfolk Crab Fishery. Ministry of Agriculture, Fisheries and Food,

Laboratory Leaflet No. 12, 27pp.

Triton Knoll Offshore Wind Farm Limited (2011). Environmental Statement Volume

3 (Annex F). F2: Shellfish Potting Surveys (May 2011).