​Thresholds and Status evaluation

The threshold values for the indicator are defined as the annual average volume of oil introduced to each sub-basin during the selected reference period (Thresholds table 1). The reference period selected for the modern baseline in this indicator is 2008-2013, during which the estimated volume from spills have been at a historically low level (Thresholds figure 1).


Thresholds table 1. Threshold values expressed as volume of oil per sub-basin.

Sub-basinAnnual average of total spills during reference period 2008-2013 [m³]
Bothnian Bay0,1135
The Quark0,0007
Bothnian Sea0,1863
Åland Sea0,1363
Gulf of Finland5,2447
Northern Baltic Proper14,3056
Gulf of Riga0,0124
Western Gotland Basin0,2304
Eastern Gotland Basin1,8503
Gdansk Basin0,1038
Bornholm Basin2,8667
Arkona Basin7,6978
Bay of Mecklenburg0,4070
Kiel Bay0,1575
The Sound0,1121
Great Belt0,4215


Oil spills thresholds figure 1.bmp

Thresholds figure 1. The estimated volume of oil from detected oil spills and the number of observations and flight hours between 1989 and 2016. The red square identifies the reference period used to determine the threshold value.


It is important to note, that the HELCOM Contracting Parties have committed to the goal of 'No illegal oil spills detected through annual aerial surveillance activities' in the Baltic Sea Action Plan (BSAP), in line with the 1992 Helsinki Convention, and that this goal is aligned with the requirements of MARPOL Annex I. This goal is still to be strived for, and is not substituted by the threshold values used to evaluate this indicator. The threshold values of this core indicator has been derived for the purpose of evaluating the status of the marine environment, and exceeding the target is considered as having a harmful effect on the environment. However, reaching the level of zero spills must still be strived for in the long-term.