Results and confidence

The current evaluation of environmental status using coastal fish covers the period 2011-2016. The evaluation is based on time series data dating back to 1998-2008 using a 'deviation from baseline approach' or a 'trend based assessment', depending on the time series coverage. Evaluations were carried out for 21 of the total 42 'scale 3 assessment units'. Data up to 2016 was available for 20 of the assessment units. For more information on assessment units, see Assessment protocol.

Good status is achieved in most of the monitoring locations (25 out of a total of 43 locations). Within some assessment units there are different results compared to the threshold value between monitoring locations, likely reflecting differences in the local appearance of coastal fish communities. When summarizing over HELCOM assessment units, good status is achieved in 13 out 21 assessed units, indicating an overall moderate environmental status of key coastal fish species in the Baltic Sea.

There are, however, some general patterns suggesting that the status depends on the geographic area and species assessed. In more northern and eastern areas, where perch represents the key species, the status is generally good (good status is achieved in 21 out of 25 monitoring locations where perch is the key species), whereas in more southern and western units where flounder represents the key species, status is generally not so good (good status achieved in only 4 out of 18 monitoring locations where flounder is the key species).


Result table 1. Status evaluation outcome per monitoring location and assessment unit for the assessment period 2011-2016. GS = good status, nGS = not good status.

 Key coastal fish species results table 1.png

In the northernmost parts of the Baltic Sea (Bothnian Bay and The Quark), the status is generally good. In most monitoring locations the relative abundance of perch is high and stable or increasing. Only in one location (Norrbyn) is the status failing to achieve the threshold, indicating a not good status.

The relative abundances of perch are generally high and stable in the Bothnian Sea, Åland Sea and Archipelago Sea, and increasing in one area (Finnish ICES SD 29).

In the central part of the Baltic Sea (Northern Baltic Proper, Gulf of Finland, Gulf of Riga and Gotland Basin) there are differences in the status across the monitoring locations. In the more northern regions (Gulf of Finland and Northern Baltic Proper) and southern areas (Eastern part of the Gotland Basin) the threshold value is achieved, whereas one of the Gulf of Riga monitoring stations (Hiiumaa) and the Swedish locations in the Gotland Basin (Kvädöfjärden and Vinö) are generally assessed as failing the threshold.

In the Bornholm and Arkona Basins there is only data from one Swedish (Torhamn, Bornholm Basin) and one Danish (Præstø Fiord, Arkona Basin) location. The status is recognised as good in Torhamn and not good in Præstø Fiord. In the remaining assessment units and monitoring locations in Danish waters (where flounder is the key species), good status is generally not achieved, even though one location (Isefjord and Roskilde fjord) is characterized by good status. 

 

Bothnian Bay

Key coastal fish species results figure 1 BBay.png

The Quark

Key coastal fish species results figure 1 Quark.png

Bothnian Sea

Key coastal fish species results figure 1 BSea.png

Åland Sea

Key coastal fish species results figure 1 Åland.png

Archipelago Sea

Key coastal fish species results figure 1 Archipelago sea.png

Northern Baltic Sea

Key coastal fish species results figure 1 NBP.png

Gulf of Finland

Key coastal fish species results figure 1 GoF.png

Gulf of Riga

Key coastal fish species results figure 1 GoR.png

Western Gotland Basin

Key coastal fish species results figure 1 WGB.png

Eastern Gotland Basin

Key coastal fish species results figure 1 EGB.png

Bornholm Basin

Key coastal fish species results figure 1 BornholmB.png

Arkona Basin

Key coastal fish species results figure 1 ArkonaB.png

Mecklenburg Bight

Key coastal fish species results figure 1 MecklenburgBight.png

Belt Sea

Key coastal fish species results figure 1 BeltSea.png

The Sound

Key coastal fish species results figure 1 Sound.png

Kattegat

Key coastal fish species results figure 1 Kattegat.pngResults figure 1. Status evaluations are displayed per sub-basin for each monitoring location. In locations where the baseline approach is applied, the threshold value is displayed as a green and a red field and the evaluation of good status/not good status is made for each point in time. The black lines indicate the median of the evaluated period.  For assessment units where the available data only allowed for a trend based evaluation, a green line denotes a good status evaluation outcome whereas a red line denotes a not good status evaluation outcome. The trend-line indicates a significant positive (green) and negative (red) trend at p < 0.1 during 2008-2016 for the times-series in each location.

 

Confidence of the indicator status evaluation

In general, the confidence varies across assessment units, countries and monitoring programmes since, for example, the number of years for which coastal fish monitoring has been carried out varies between locations, as does the spatial coverage of monitoring within assessment units, and thus the confidence in the actual assessment. Generally, the confidence of the evaluation is higher in locations where monitoring started before 1999 and where data is available for all years during the assessment period (2011-2016), where there is good spatial coverage of monitoring and where the monitoring is fisheries independent and targeting the focal species of the assessment.

The confidence scoring followed the principles as outlined in the HELCOM integrated biodiversity assessment. Confidence was scored using four criteria with three different levels (1= high, 0.5 = intermediate, and 0 = low). The criteria used was:

Confidence in the accuracy of the estimate (ConfA). Level 1 = fisheries independent monitoring, 0.5 = fisheries dependent monitoring (commercial catch data and recreational catch registration) targeting focal species, and 0 = fisheries dependent monitoring not targeting focal species (commercial catch data for cyprinids).

Confidence in the temporal coverage of assessment (ConfT). Level 1 = data for all years during 2011-2016, 0.5 = one or two years of data missing during 2011-2016, and 0 = three or more years of data missing during 2011-2016.

Confidence in spatial representability of the assessment (ConfS). Level = 1 full coverage/several monitoring locations per assessment unit given its size, 0.5 = two or more monitoring locations per assessment unit, and 0 = one monitoring location per assessment unit.

Methodological confidence (ConfM). For coastal fish all assessment units reach level 1 since all monitoring programs included in the assessment are described in the coastal fish monitoring guidelines .

 

Results table 2. Confidence in the status assessment according to the criteria developed within HELCOM for the integrated biodiversity assessment. 

Key coastal fish species results table 2.png


In general, the confidence in the accuracy of the assessment (ConfA) is high in majority of the assessment units. It is somewhat lower in the units depending on fisheries dependent monitoring in Finland and Denmark. The confidence in the temporal coverage (ConfT) is high in all areas except for the Latvian, Lithuanian and Danish areas due to missing data in one or more of the years in the assessment period. The confidence in spatial representability (ConfS) is highest in the Finnish and Danish areas where there is full coverage of sampling in the assessment units. It is poorer in all other countries where fisheries independent monitoring is carried out with a few monitoring locations per assessment unit.

 

Key coastal fish species results figure 2.pngResults figure 2. Maps of confidence of the current assessment. See Results table 2 for details.

 

The confidence concept as developed for the purposes of the integrated biodiversity assessment is not fully applicable to coastal fish as further assessment of the precision in data and the congruence in status across monitoring locations within assessment units would provide additional information that is needed.