Document 1 Proposal for imo ballast Water Management Convention a-4 Target Species selection criteria

2Definitions and abbreviations

All definitions used in this document correspond to those of IMO (2004, 2007). Other definitions are given below:

Term	Abbreviation (if any)	Definition
Non-indigenous species	NIS	Species, subspecies or lower taxa introduced outside of their natural range (past or present) and outside of their natural dispersal potential. This includes any part, gamete or propagule of such species that might survive and subsequently reproduce. Their presence in the given region is due to intentional or unintentional introduction resulting from human activities. Natural shifts in distribution ranges (e.g. due to climate change or dispersal by ocean currents) do not qualify a species as a NIS. However, secondary introductions of NIS from the area(s) of their first arrival could occur without human involvement due to spread by natural means.
Cryptogenic species	CS	Species of unknown origin which cannot be ascribed as being native or non-indigenous. Such species also can demonstrate harmful characteristics and should be included in assessments.
Invasive alien species	IAS	a subset of established NIS, which have spread, are spreading or have demonstrated their potential to spread elsewhere and have an adverse effect on one or more of the following: biological diversity, ecosystem function, socio-economic values or human health in invaded regions (Olenin et al. 2010).
Harmful aquatic organisms and pathogens	HAOP	aquatic organisms or pathogens which, if introduced into the sea including estuaries, or into fresh water courses, may create hazards to the environment, human health, property or resources, impair biological diversity or interfere with other legitimate uses of such areas (IMO 2004).
Large Marine Ecosystem	LME	Extensive areas of ocean space of 200,000 km^2 or more, characterized by distinct hydrographic regimes, submarine topography, productivity, and trophically dependent populations, adjacent to the continents in coastal waters where primary productivity is generally higher than in open ocean areas. Additional large aquatic regions, not covered by the LME system (NOAA, 2015), such as Caspian Sea or the Laurentian Great Lakes of North America, may be included to complete the geographical coverage.
Primary introduction		The primary introduction is the first arrival of a NIS or CS to a recipient region (e.g. port) within the LME.
Secondary introduction		Subsequent spread after primary introduction of a NIS/CS to other recipient regions within or outside the LME.
Established species		A NIS or CS known to form a reproducing population in a wild.
Pest		Harmful organisms living in places where they are unwanted and have a detectable environmental and/or economic impact or impact on human health. Pests may be native, non-native or cryptogenic species.
Target species	TS	Species identified for a specific port, State or biogeographic region by a Party according to the Target species criteria indicating that they have a potential for an unacceptable risk to impair human health, property, resources, the environment and/or social-cultural values.

3Biological invasions in the Baltic Sea

Harmful aquatic organisms and pathogens may be both of native and non-native origin. Native pest species usually are well known and measures to control their spread and/or mitigate their impacts are available. On the contrary, the harmfulness of newly introduced NIS or CS is difficult to predict, therefore the precautionary principle is applied, aiming at the prevention of primary introduction and secondary spread of such species.

The total number of recorded NIS and CS is 245 in the North Sea and 118 in the Baltic (AquaNIS 2015). The North Sea and Baltic Sea share large number of common NIS and CS: 58% (69 species) recorded in the Baltic Sea are known also from the North Sea (Ojaveer et al., in prep.). However, the number of species which first appeared in the North Sea (i.e. primary introductions) that were later recorded in the Baltic Sea is twice as great as that in the opposite pathway (41 versus 20, while 8 species appeared to have arrived in both seas at about the same time). The time lag between primary introduction to one regional sea and its subsequent secondary spread to another takes from five to fifty years (AquaNIS 2015). This depends on the species life form (planktonic or benthic), biological traits, environmental tolerance limits and the availability of pathways for spread. The secondary spread within the Baltic Sea varies from 30 to 480 km/year (Leppäkoski and Olenin 2000). Secondary spread is due to natural dispersal of organisms which may also be facilitated by human-associated mechanisms, including ballast water. In the Baltic Sea, 66 species are known to form viable populations and should be considered to be established (please note that in the current work, we consider three species of Marenzelleria as Marenzelleria spp., and therefore have 64 taxa listed in Table 1 under Section 6.1). A large proportion of the species (about 54 %) have a very limited distribution being currently established in one or two countries/country areas while 12% (8) of the established species are widespread and are established in at least 9 countries/country areas (Ojaveer et al., in prep.).

The level of certainty (direct evidence, very likely, possibly, unknown) in affiliating the responsible pathway for a given invasion requires special attention. It appears that only in 9% of cases of the Baltic Sea invasions (47 invasion events) we know the invasion pathway with the highest confidence, i.e., there is a direct evidence. In 15% cases, the pathway could be assigned with relatively high confidence (very likely), while in the majority of cases (60%) we only know possible pathways (Ojaveer et al., in prep.).