1. Freshwater fish Classification Tools
Alistair Duguid 6

2. FCS2 Summary I Basic approach similar to Ireland, and England/Wales
Uses Bayesian-based modelling of variables (environmental, spatial and pressure) to predict:
Prevalence (the probability that a species is present) and average abundance of each species at each site.
Total observed count then compared to expectations at that site, under reference conditions
Models expected distribution using a Zero-inflated negative binomial distribution

3. A rare fish species

4. A locally abundant species

5. Prevalent
and abundant

6. FCS2 input data
Scottish model can use one-run or multiple pass electrofishing data
Based on salmonids only (disturbance sensitive and data widely available)
Covariates initially chosen on the basis of expected importance
e.g. distance to sea, geology, presence of barriers, spatial location, NH4, P
Then fitted approximately to assess whether they provide significant predictive power for further inclusion
Use significant variables to fit final regression model with MCMC

7. Pressure variables FCS2 uses pressure variables
Environmental covariates which are likely to be caused by anthropogenic pressure
Chosen based on expert opinion
Set reference values for these from national or EU guidelines (e.g. REFCOND)
Add these into the calibration model to predict fish abundance AT REFERENCE CONDITION at each site

8. EQR calculation EQR= “ecological quality ratio”
Value from 0= lifeless, to 1= pristine
For FCS2 calculated from probability of catching the observed number (or fewer) fish, at the specific site, under reference conditions
FCS2 provides EQRs at several different levels:
for each species in a survey
joint EQRs across surveys at a single site
combined EQRs from several sites in a waterbody

9. Setting class boundaries
Involves using artificial datasets to assess the EQR’s for catches which match ideal class conditions (taken from WFD normative definitions)
Then choose the boundary values which give maximum separation between these
CLASS
Species present
Abundance
High
All expected species present.
(Salmon and trout present)
At expected abundance
Good
>80% expected abundance
Moderate
55% of expected species present
(Salmon or trout present)
>55% of expected abundance
Poor
30% of expected species present
(at least one year class present)
>30% of expected abundance

11. Classification and regulation of fish barriers Alistair Duguid Fishery Trust Workshops November 20176

12. Background
SEPA has included fish barriers directly in WFD classification since 2008
Allows fish pressures to be captured without necessarily having electrofishing data
Important in identifying fish- specific pressures in 1st RBMP
Aims to identify and account for the most important and clear cut issues
Major cause of waterbody downgrades
Key priority for restoration
“One-out-all-out” principle of classification
A “passing” fish barrier result doesn’t over-ride other downgrades e.g. from electrofishing
Photos: Colin Bull,
Stirling University

13. Fish barrier classification
Classification standards developed by UKTAG
Interpreted for Scotland in the SG Classification Directions
These define “Severe loss” as being “more than 80 % of fish that would otherwise be able to move upstream to, or downstream from, the river or part concerned”.
Changes between 1st and 2nd RBMP
Incorporating standardised barrier assessment criteria (WFD111) into “80% rule”
Specific inclusion of all migratory species- 80% apply to any one species, although suggest electrofishing evidence also necessary for eels and lamprey
Minor changes to use river length rather than catchment area
High status
Good status
Moderate status
Poor status
Severe loss of fish access to less than 1 % of catchment area
Severe loss of fish access to less than 5 % of catchment area
Severe loss of fish access to less than 20 % of catchment area
Severe loss of fish access to greater than 20 % of catchment area

14. Barrier classification- key points
SEPA currently hold information on ~ 3700 barriers
~1330 imp waterfalls
~1760 artificial passable barriers
~580 artificial impassable barriers
Data from a mixture of sources
New records are sense checked by SEPA fish ecologists
Older records have not been re-assessed unless SEPA have received data suggesting original assessment wrong
SEPA have prioritised new surveys :
To find natural limits to migration above key impassable weirs
In areas where waterfalls and weirs marked on OS maps
In urban areas where barriers are likely

15. Fish barriers as pressures
For River Basin Planning, impacts (i.e. results of less than good status) require an explanatory pressure
The pressure is then used to set objectives for action
Barriers can be used to explain failing fish ecology results upstream
Both impassable or passable barriers can be considered if supported by evidence
Examples might include:
Inadequate fish passes on large hydro dams
Cumulative impacts of several passable but difficult weirs
Process requires fish ecology classification as starting point
Electrofishing, possibly adults in future?

16. Fish barriers as pressures
Assigning pressures based on weight of evidence
Requires confidence in the impact and the link to pressure
Type of information considered
Evidence of impact
How many sites assessed?
Which species affected?
What classification result?
What level of change compared to downstream population?
Impact on adult or smolt numbers?
Type of barrier
Likely severity to different species
E.g. Key dimensions, WFD111 assessment
Existing mitigation measures
Conformance with good practice guidelines
Possible alternative explanations

17. Thanks for listening!