Wylye Grayling Long - Term Study Stephen Gregory, Richard Cove, Anton Ibbotson

Biosketch : Stephen D. Gregory Education: BSc Zoology (University of Swansea) MSc Ecology (University of Oxford) PhD Ecology & Statistics (University of Paris) Projects: Foraging behaviour of Lesser horseshoe bats, Swansea Food competition between native & black rats, Galapagos Demographic consequences of sociality in animals Effects of climate and habitat change on Orangutan , Borneo Current: Drivers of salmon population dynamics, UK and France Grayling population dynamics on the Wylye, UK

Anton Ibbotson

Wylye Grayling Long - Term Study begins! Anton Ibbotson

Me!

Wylye Grayling Long - Term Study

Wylye Grayling LTS: longest grayling dataset 1996 2013: 18 years!

1996 2013: 18 years! 9760+ records from 8463 individual grayling Length Scales Wylye Grayling LTS: longest grayling dataset

1996 2013: 18 years! 9760+ records from 8463 individual grayling Length Scales River flow Stockton Park Norton Bavant Wylye Grayling LTS: longest grayling dataset

Wylye Grayling LTS: i ndividual - based data Individual marks

Individual marks Wylye Grayling LTS: i ndividual - based data

Individual marks Wylye Grayling LTS: i ndividual - based data

Long data sets needed to study changes in fish population size and their causes

Salmonid ~ similar needs to salmon & trout Grayling: an indicator of river health Ibbotson, A ., Cove, R . et al. (2001) A Review of Grayling Ecology, Status and Management Practice; Recommendations for Future Management in England and Wales. Environment Agency.

Salmonid ~ similar needs to salmon & trout Most sensitive to environmental change: Temperature ( oC ) Salmon Trout Grayling Lower 0 6 0 4 0 4 Optimum 6 20 4 19 4 18 Upper 20 34 19 30 18 25 Grayling: an indicator of river health Ibbotson, A ., Cove, R . et al. (2001) A Review of Grayling Ecology, Status and Management Practice; Recommendations for Future Management in England and Wales. Environment Agency.

Grayling: an indicator of river health Salmonid ~ similar needs to salmon & trout Most sensitive to environmental change: Most sensitive reproductive strategy Temperature ( oC ) Salmon Trout Grayling Lower 0 6 0 4 0 4 Optimum 20 34 19 30 18 25 Upper 6 20 4 19 4 18 Ibbotson, A ., Cove, R . et al. (2001) A Review of Grayling Ecology, Status and Management Practice; Recommendations for Future Management in England and Wales. Environment Agency.

Grayling reproduction: a risky strategy

Grayling reproduction: a risky strategy Spawn in April May: weather dependent Riley, W. D. & Pawson , M. G. (2010) Habitat use by Thymallus thymallus in a chalk stream and implications for habitat management Fisheries Management and Ecology, 17, 544 - 553.

Grayling reproduction: a risky strategy Spawn in April May: weather dependent Eggs shallow in redd: Salmon Trout Grayling Depth (cm) 10 15 10 15 0 5 Riley, W. D. & Pawson , M. G. ( 2010) Habitat use by Thymallus thymallus in a chalk stream and implications for habitat management Fisheries Management and Ecology, 17, 544 - 553.

Average redd characteristics Measure River Pollon River Suran Mean bottom velocity 37.2 cm/s 33.7 cm/s Selected depth 10 40 cm 20 30 cm Sempeski , P. and Gaudin , P. (1995), Habitat selection by grayling I . Spawning habitats. Journal of Fish Biology, 47: 256 265 .

Grayling reproduction: a risky strategy Spawn in April May: weather dependent Eggs shallow in redd: Salmon Trout Grayling Depth (cm) 10 15 10 15 0 5 Riley, W. D. & Pawson , M. G. (2010) Habitat use by Thymallus thymallus in a chalk stream and implications for habitat management Fisheries Management and Ecology, 17, 544 - 553.

UK flooding

UK flooding 4 of 5 UK wettest recorded years since 2000 (2000 [1], 2012 [2], 2008 [4], 2002 [5]) UK Met Office: http://www.metoffice.gov.uk /

UK flooding 4 of 5 UK wettest recorded years since 2000 (2000 [1], 2012 [2], 2008 [4], 2002 [5]) January 2014 = England's wettest in c .250 years UK Met Office: http://www.metoffice.gov.uk /

UK flooding 4 of 5 UK wettest recorded years since 2000 (2000 [1], 2012 [2], 2008 [4], 2002 [5]) January 2014 = England's wettest in c .250 years High rainfall - > High river flows UK Met Office: http://www.metoffice.gov.uk /

Wylye January 2014 © Salisbury & District Angling Club

Frome

Frome: 2012

Questions

Questions How might flooding affect grayling populations? Shared patterns in flow and grayling counts?

Wylye average daily flow (m3/s)

Grayling population: dynamics all ages

Grayling population dynamics: all ages

Grayling population dynamics: all ages

Grayling population dynamics: all ages

Grayling population: the separate ages

Grayling population: dynamics 0+ only

Grayling population dynamics: 0+ only

Grayling population dynamics: 0+ only

Grayling population dynamics: 0+ only

April 2000 1999 2000 125 - > 26 = 80 % decrease in 0+

Grayling population dynamics: 0+ only

Grayling population dynamics: 0+ only

April 2012 2011 2012 118 - > 7 = 94% decrease in 0+

observations Patterns: not cause and effect Needs closer examination, e.g., 2005, 2007 Based on counts, not population estimates Alternative factors: Temperature Habitat loss etc

Length: poor 0+ growth 2013?

Length: poor 0+ growth 2013?

Questions How might flooding affect grayling populations ? Shared patterns in flow and grayling counts? How might flooding affect grayling in the future? Forecast from observed population patterns

Procedure: population 1. Use observed data to calculate age - specific: Death rate Birth rate

Procedure: population 1. Use observed data to calculate age - specific: Death rate Birth rate 2. Competition for food among 0 + individuals

Procedure: matrix population model 1. Use observed data to calculate age - specific: Mortalities Fecundities 2. Competition for food among 0 + individuals 3. Calculate projection

Procedure: matrix population model 1. Use observed data to calculate age - specific: Mortalities Fecundities 2. Competition for food among 0 + individuals 3. Calculate projection 4. Forecast future population changes

Population forecast without floods

Population forecast with floods

Population forecast with floods

What does this mean? Floods could cause population decline Juvenile ( 0+) fish will be most affected Sensitivity analysis of model parameters: Identify information gaps Guide additional data collection

What can be done? Consider management options Habitat alterations Woody debris Test possible implications of management Catchment - based water management Extend investigation to other species?

Next steps Compare effects of flow to other factors: river temperature etc Grayling population & climate change Individual analyses

Thank you

Condition factor

18 yrs in length c. 10,000 records of c. 8500 individuals Accompanying environmental data: flow and some temperature Long - term studies needed to study effects of environment on population Environmental change is gradual Extreme events can be very influential but also quite rare Grayling is an excellent study species 18 year study / 4 year generation time = 4.5 generations Exotherm = more susceptible to temp. changes (sometimes caused by flow changes) Risky reproduction strategy Effects of environmental variables on grayling population dynamics Simulation experiment based on expert values Comparison of statistical models including different effects Alternative hypotheses Changes in populations of other fish / organisms Habitat changes Generalising the investigations to other species, e.g., trout