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