Lamprey populations in the UK & the development of a new sampling tool for deep water habitats. Nicola Teague

Transcription

1 Lamprey populations in the UK & the development of a new sampling tool for deep water habitats Nicola Teague

2 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

3 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

4 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)

5 Identification Adults Size Colour Dentition Finshape Transformers Colouration Dentition Oral/eye measurements River/brook indistinguishable at ammocoete stage Ammocoetes Pigmentation Caudal fin Myomere counts

6 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

7 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

8 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 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 5-7 th order streams at >1m

9 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 m 2

10 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

11 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

12 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

13 Comparing results Airlift sample qualitative/semiquantitative ~0.05 m 2 Electric fishing 1 m 2 fully quantitative Direct comparison not currently possible High densities of lamprey in deeper water Greater ratios of sea lamprey than in marginal habitat

14 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

15 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

16 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