marine surveys (fisheries), UVCs & Ascension Island

Question 1

Sea Fisheries Committees

(SFCs)

Answer 1

• originally 11 SFCs with Isles of Scilly joining in the 1970s
• only in England & Wales
• managing out to 3nm from 1983 baselines
• in 2000 – national budget of £5.2m
• powers conferred from Sea Fish Regulation Act 1967
• officers very often ex police/navy or ex fishermen
• v entrenched in simplistic management measures
• little requirement to consider other issues

Question 2

env act in 1995 changed SFCs…

Answer 2

• had to consider impacts to wider env in any decision making
• requirements of Council Directive 92/43/EC (Habitats Directive) became apparent with set up of Natura 2000 (N2K) network of sites
• Countryside & Rights of Way Act 2000 (CRoW)
• evidence appropriate management in place in designated sites, especially where specific permissions given

Question 3

Marine & Coastal Access Act 2009 – Sec. 153

Answer 3

1. authority for an IFC district must manage the exploitation of sea fisheries resources in that district.
2. In performing its duty under subsection (1), the authority for an IFC district must…

• seek to ensure that exploitation of sea fisheries resources is carried out in a sustainable way,
• seek to balance social & economic benefits of exploiting the sea fisheries resources of the district with the need to protect the marine env from, (or promote its recovery from), effects of such exploitation,
• take any other steps which in authority’s opinion are necessary / expedient for purpose of making a contribution to achievement of sustainable development, and
• seek to balance different needs of persons engaged in exploitation of sea fisheries resources in the district

Question 4

marine environmental surveys

Answer 4

• What is question that needs an answer?
• What info is required to be able to answer the question & how detailed does it need to be?
• What equipment is needed to gather the necessary information?
• What is the survey method?
• How will the data need to be presented?

Question 5

marine environmental survey considerations

Answer 5

• What sampling units are needed?
• What replication is required?
• Spatial scale?
• Representivity?
• How to ensure bias is removed / limited?
• What level of positional accuracy is required?
• What time is available is carry out the data collection and analysis?

Question 6

Marine environmental survey - techniques

Answer 6

Broadscale techniques:

• Single beam echo sounder – basic bathymetry
• Multibeam Echosounder (MBES) – detailed bathymetry
• Sidescan sonar – seabed texture and substrate differentiation

Remote imaging techniques:

• Drop frame camera
• Towed cameras
• ROV – remotely operated vehicle
• BRUV – baited remote underwear video

Direct techniques:

• Benthic grabs – Van Veen, Day, Hamon, Shipek
• Diver
• Dredges
• Trawls
• Traps
• Nets

Question 7

Whitsand and Looe Bay MCZ

Answer 7

• 1 of 4 priority sites
• initial proposal for total prohibition of bottom towed gear - against officer advice
• sidescan sonar used to image seabed
• 4 survey lines
• survey verified reef location (potential PSF & A. dohrnii habitat)
• Whitsand & Looe Bay Marine Conservation Zone (Fishing Restrictions) Byelaw 2018 came into effect Feb 2019

Question 8

DDV Work: Eddystone Project

DDV = drop down video

Answer 8

• Only SAC (special areas conservation) with zoned access to BTG (bottom towed gear)
• Collaborative 6 year project with
  MCS & University of Exeter
• Currently funded by Princess Yachts
  International
• Sampling using DDV across 3 survey
  boxes; 1 treatment & 2 control
  boxes
• Continuing to collect data beyond
  the project

Question 9

Assessing new fishery activity

Answer 9

• Wrasse (type of fish)
• initial project in 2016
• fishery dependant catch sampling
• independent work (e.g. mark & recapture studies)
• byelaw
• analysing statistical returns

Question 10

IFCA

Answer 10

Inshore Fisheries and Conservation Authority

Question 11

how can we mop and map benthic (seabed) habitats, sp, and communities ?

Answer 11

achieved using range of technologies that operate at different spatial scales and resolutions

Question 12

Underwater Visual Census (UVC)

Answer 12

quantitative surveys based on direct diver
observations of marine species % habitats

Question 13

adv of UVCs

Answer 13

• can generate fine-scale data on abundance & diversity of marine species / habitats
• low-tech & can be implemented with minimal equipment & training (suitable for citizen science)

Question 14

What things do we need to consider & record to generate usable & reliable abundance & diversity data from a UVC?

Answer 14

• standardised effort
  -> UVC surveys generally involve swimming a transect of fixed, known length & counting numbers of individuals of diff sp observed in a “belt” of fixed width centred on transect
• observer error
  -> individ surveyors vary in skill at identifying sp & in abundance estimates, which needs to be recorded, measured, or standardised (e.g. same surveyors, paired / ‘buddy’ transects)
• detectability
  -> not all sp are equally detectable (camouflage, crypsis, diver avoidance)
  -> often separate transects for mid-water & cryptic/benthic sp & invertebrates to account for variation in detectability
  -> env conditions (e.g. turbidity, sea state) can also affect detectability and need to be recorded (UVC not possible in
  some env)
• habitat
  -> quadrat surveys often carried out in parallel with UVC to quantify sessile benthic fauna & flora (e.g. corals, seagrass) & habitat type (e.g. substrate, rugosity).

Question 15

photo quadrats

Answer 15

• method involves placing a fixed area quadrat on randomly / systematically selected locations on seabed …
• & photographing them at high resolution
• creates permanent visual record for later (re)analysis

Question 16

how is photo quadrat data analysed?

Answer 16

1. Sp annotation
   -> presence/absence
   -> sp richness
   -> relative abundance of macrofauna (where individual organisms can be identified)
2. Grid cell counts
   -> classify cells based on dominant cover
   -> used for percent cover of different benthos
   -> can be hard to work out what is ‘dominant’ in some cells
3. Point counts
   -> ID sp / substrate types at randomly generated points
   -> used for percent cover.
   -> only subset of points needs to be analysed (but assumes that number of points sampled is large enough to be representative)
4. Image segmentation
   -> semi-automated classification of image into areas of consistent pixel colour which can
   then be identified & measured
   -> fast BUT tends to only work well in high quality images with distinctly coloured patches

increasing work on incorporating artificial intelligence & machine learning into photo quadrat analysis

Question 17

how is photo quadrat used?

Answer 17

• monitoring change
• quantifying ‘blue carbon’
• deep water habitat surveys
• classifying & mapping ecological communities & habitats
• studying sp-habitat associations

Question 18

CASE STUDY - Mapping benthic habitats and endemic fish distributions at Ascension Island

Answer 18

• Ascension Island: remote volcanic island located in central tropical Atlantic
• home to 1 of world’s largest marine protected areas, designated in 2019
• terrestrial habitats of island consist predominantly of arid, sparsely vegetated, volcanic landscapes
• BUT coastal waters that surround island team with life!!
• owing to Ascension’s remoteness, fish diversity is low BUT abundance is high

Question 19

more on Ascension Island

Answer 19

• endemic sub-littoral fish sp:
  -> Marmalade razorfish (Xyrichthys blanchardi)
  -> Resplendent angelfish (Centropyge resplendens)
  -> Ascension hawkfish (Amblycirrhitus earnshawi)
  -> Ascension goby (Priolepis ascensionis)
• Island has no reef-forming stony corals, BUT there are soft & encrusting corals that colonise rocky reefs
  -> diverse range of encrusting sponges also occur on rocky reefs
• Intense grazing by fishes & urchins (particularly hyper-abundant black triggerfish) also suppresses growth of upright macroalgae (seaweeds)
  -> where macro-algae does occur, it’s generally limited to low-growing turf
• Sub-littoral habitats are dominated floristically by crustose coralline red algae (Lithothamnia spp.) which are resistant to grazing and are the main biogenic habitat creators
• flat expanses of coarse sand & grave adjacent to reefs

Question 20

coralline algae on Ascension Island

Answer 20

• Sub-littoral habitats are dominated floristically by crustose coralline red algae (Lithothamnia spp.) which are resistant to grazing and are the main biogenic habitat creators
• Coralline algae can be reef-forming, encrusting, or form beds of unattached nodules known as rhodoliths (maerl)
• Like many calcifying organisms, these sp are potentially vulnerable to ocean acidification

Question 21

a UVC was carried out on Ascension Island…

Answer 21

… in order to map near-shore benthic habitats & communities

• surveys consisted of 50 m transect swum by pair of divers…
• 1 counting benthic (bottom) associated fish & other counting pelagic (mid-
  water) sp in 2m belt centred on transect
• 3rd diver followed behind deploying photo-quadrats at 2m intervals along transect line