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Transcript of No Slide Title · representatives of Agnatha, ‘jawless ... • Need to monitor wider habitat...
Lamprey populations in the UK & the development of a new sampling tool
for deep water habitats
Nicola Teague
Lamprey in the UK• Lamprey – among the most ancient &
curious aquatic vertebrates
• Along with hagfish are sole extant representatives of Agnatha, ‘jawless fish’
• 3 species of lamprey in the UK– Sea lamprey– River lamprey– Brook lamprey
• River and sea lamprey are anadromous, migrating through whole river lengths, estuaries & the marine environment
• Brook lamprey complete life cycle in shallow headwaters
Lamprey in the UK• All 3 species listed under Annex II of
Habitats Directive
• River lamprey additionally listed under Annex V
• A number of rivers throughout England & Wales designated as SACs for their conservation
– 18 sites for sea lamprey– 17 sites for river lamprey– 10 sites for brook lamprey
• All 3 species listed under Appendix III of the Bern Convention
• Indicator species for fish biological element of WFD
Data & Monitoring• Prior to denotation of the Habitats
Directive records of lamprey largely anecdotal
• Life in UK Rivers – a standardised quantitative ammocoete method developed
• Quadrat electric fishing in shallow marginal habitat
• Optimal & sub-optimal habitat
• 6 yearly condition assessments– Abundance (site & catchment)– Population demographic structure
(recruitment & age class)– Distribution (no decline across
catchment)
Identification• Adults
– Size– Colour– Dentition– Finshape
• Transformers– Colouration– Dentition– Oral/eye measurements
• River/brook indistinguishable at ammocoete stage
• Ammocoetes– Pigmentation– Caudal fin– Myomere counts
Conservation status• First condition assessment reporting in
2006– Riverine sea lamprey SACs – 1 considered
favourable – River Wye– Riverine river lamprey SACs - 1 considered
favourable – River Usk
• Second reporting cycle due at the end of 2012
• Currently no prediction that the status of sites will have improved
• 3 condition assessment categories considered suitable although river specific targets may be more appropriate
• Sampling technique considered successful for Lampetra spp. but varied success for Petromyzon
Sea lamprey quandary• Sea lamprey ammocoetes often not observed
or disproportionate to Lampetra & sea lamprey adults
• Continued record of sea lamprey adults at counters, traps & spawning confirms continued presence of species in UK waters
• Yorkshire Ouse, Derwent & Eden– Sea lamprey adults observed spawning
annually but no ammocoetes recorded
• Scottish National Lamprey Survey– 14,201 ammocoetes across 138 catchment
just 77 sea lamprey
• Rivers Wye & Usk– 3,111 ammocoetes across 2 catchments, 559
sea lamprey
Sea lamprey quandary• 1 : 50 ammocoetes recorded in UK identified as
sea lamprey
• Recognised in favourable condition status targets
– >0.2 m-2 vs >10 m-2 optimal habitat– 0.1 m-2 vs 2 m-2 catchment
• Evidence from US & an APEM account for a 10- 12 m Scottish Loch suggests may be missing suitable sea lamprey habitat in deeper water
• Review of lamprey ammocoete habitat preferences:
– Found wherever substrate & water current are suitable regardless of water depth
– Small streams close to water line– Larger rivers greater habitats & depths– Preferences differ between species– Highest densities in 5-7th order streams at >1m
Alternative sampling techniques• Recognised in US that a deep water sampling
technique needed
• Different techniques trialled:– Shovel or suction dredge– Towed nets– Orange-peel, petersen & anchor dredges– Lampricides– Electrified beam trawl– Manned submersible– Combination of electric fishing with a suction
pump or trawl
• Development of a new technique for UK:– Mackey/Yorkshire pattern air-lift sampler– Qualitative– Samples cover ~0.05 m2
Trial of air-lift technique
• Welsh River Dee Chester weir to u/s Farndon bridge
• 193 air-lift deep water samples over 134 sites
• 46 electric fishing marginal sites
• Collected sediment sieved & lamprey speciated, measured & enumerated
• Estimate of % sediment composition made
Results of trial• Lamprey ammocoetes recorded in 39
electric fishing sites – 1 sea lamprey
• 66 air-lift samples contained at least 1 lamprey ammocoete
• 48 sea lamprey ammocoetes across 27 samples & 10 sites
• 13 samples contained sea lamprey alone
• Sea lamprey counts ranged from 1 to 7 individuals per sample
• Lampetra spp. recorded at 53 sites ranging from 1 to 13 individuals per site
• Lampetra spp: sea lamprey ratio – 2.2:1
• All lamprey collected in good condition & returned alive
Results of trial
• Substrate where lamprey recorded dominated by silt, organic matter or fine sand
• Some ammocoetes recorded where substrate dominated by clay or pebbles
• No significant habitat difference between lamprey species
• Water depths where lamprey recorded ranged from 1.6 to 4.4 m
• Very few individuals found within tidal reach
Comparing results
• Airlift sample qualitative/semi- quantitative ~0.05 m2
• Electric fishing 1 m2 fully quantitative
• Direct comparison not currently possible
• High densities of lamprey in deeper water
• Greater ratios of sea lamprey than in marginal habitat
Population demographics• 1 EF sea lamprey age 5+ close to
metamorphosing
• Deep water sea lamprey – 0+ to 3+
• Lampetra with both techniques – 0+ to 3/4+
• Contradicts US research which suggests older 2+ individuals move into deeper water
• Flooding may displace individuals, especially smaller age classes out of shallows into deeper waters
• May reside there permanently due to river specific conditions
• Maybe sampling technique is biased
Future technique developments
• Assessing efficiency & selectivity
• Making the technique quantitative
• Sampling a larger area
• Trialling in different river systems
• Develop a better knowledge of habitat preference
• Incorporate into condition monitoring
• Develop density targets for condition assessment
Summary & conclusions• Paucity of information on UK lamprey populations
& conservation remains
• Sea lamprey are particularly poorly understood
• Need to gain further information on habitat preferences & usage to effectively conserve populations
• Need to monitor wider habitat types
• Need to monitor more frequently & have indicator sites
• Need to develop a quantitative deep water sampling technique
• Habitat may need protection
• Favourable condition targets may need updating