Interim report of the HELCOM CORESET project

168
10. Spatial considerations
Baltic-wide, all rivers of wild or mixed salmon populations. Salmon migrates widely and hence is a part of
the Baltic food web all over the basin.
11. Temporal considerations
Smolt production and survival may vary annually depending on fi shing effort and annual conditions at
sea. Indicators describing a specifi c year become available by the end of May 2012.
12. Current monitoring
Estimates produced frequently by national research institutes and compiled by ICES working group
WGBAST. Smolt survival and smolt production are basically ready for operational use. WGBAST may
further develop the number of salmon rivers as an indicators, as well as can consider ways of combining
the second and the third indicator; the outcome of this work is expected to be operational by 2013.
13. Proposed or perceived target setting approach with a short justifi cation.
GES boundary is based on a %-level which allows sustainable exploitation of the stock. The HELCOM
proposal for the salmon potential smolt production capacity (PSPC) is 80%. The GES boundary for this
indicator could be based on this approach, but requires further development.
4.9. Sea trout parr densities of sea trout rivers vs. their
theoretical potential densities, and the quality of the
spawning habitats
1. Working team
Author: Atso Romakkaniemi on the basis of work in ICES WGBAST
2. Name of candidate indicator
Trout parr densities of sea trout rivers vs. their theoretical
potential densities, and the quality of the
spawning habitats
3. Unit of the candidate indicator
% (proportion of parr density reached) and an
index for classifi cation of spawning habitats
4. Description of proposed indicator
Sea trout (Salmo trutta) is a big predatory species in the Baltic Sea marine ecosystem. Its abundance is
affected by fi shing and the condition of the spawning rivers. Many of the spawning rivers have been
dammed to produce hydroelectricity and the spawning grounds have in many rivers degraded due to
migration obstacles and increased siltation and eutrophication (forestry, agriculture).
This indicator is a combination of two parameters. The fi rst one follows the realized parr densities of
trout in rivers as a percentage of the estimated, theoretical maximum densities. This parameter serves
as an overall response to the quality of the spawning grounds and the adjacent sea and the fi shing pressures.
The second parameter estimates the quality of the spawning habitat in the spawning rivers. This
latter parameter is still under the development.
The data for the indicators is compiled by national research institutes and the indicators would be calculated
in the ICES WGBAST. WGBAST is further developing both indicators. The fi rst indicator it is
expected to be operational by 2012/2013 and the latter one by 2013/2014.
5. Functional group or habitat type
Anadromous fi sh
6. Policy relevance
Descriptor 1: Criterion 1.1 – Species distribution
Criterion 1.2 – Species abundance
Criterion 1.5 – Habitat extent
BSAP Ecological objective “Thriving communities of plants and animals” (Nature conservation)