The assumption of the Working Package 2 (WP2) is to build a robust background of all the available information and data on Non-Native (NN) aquatic species in the targeted countries that will be continuously updated by the outcomes derived by the WP2: an online platform and a database. The relative tasks to be fulfilled to complete the implementation of WP2 are (a) literature review and survey of main watercourses of Partner Countries, (b) interview with industry representatives and stakeholders, (c) combining the findings for producing an online platform, (d) creating an online database and (e) pilot testing together with assessments reviews. The presented summary is referred to the literature review and survey of the main watercourses of Partner Countries.

The pioneer studies on NN or Non-Indigenous species (NIS) date back to the 1970s. Since then, global research in this field has grown rapidly. Globally, the introduction of marine NIS can happen deliberately or accidentally. Available data from European Environment Agency (EEA) show that around 1 223 NIS are present in European seas, of which almost 81% (1 039) were recorded in the period 1949-2017. The trend in the introduction of NIS to the Mediterranean Sea peaked in 2000-2005, with approximately 21 new species per year. The main introduction vectors of alien species known in the Mediterranean are (i) aquaculture activities (44 species, 41%), (ii) the Suez Canal (28 species, 26%), (iii) maritime transport (17 species, 15%), (iv) fishing activities (3 species, 3%) and (v) aquaria trade (1 species 1%).

Balkan Peninsula, one of the world biodiversity hotspots, possesses the highest proportion of range-restricted endemic fish species in Europe. However, recent surveys from several Balkan countries have revealed that 15%–23% of their freshwater fish fauna is alien, with catchments, such as the Danube River and Pamvotis Lake (Greece) having ichthyofauna comprised of more than 50% and 80% of alien fishes, respectively. Until the early 1950s, introductions were primarily of North American and Asian species, while the interest for the species from Northern and Western Europe arose later. In total, 60 fish species have been introduced in the Balkan Peninsula intentionally, accidentally, or by natural dispersal. The first introductions in inland waters were documented in the 19th century in Bulgaria (two species), Croatia (one species), and Slovenia (four species). Alien species inventories constitute a fundamental first step and a critical tool for the implementation of relevant policies and the delineation of management approaches. Although management efforts/policy initiatives to tackle alien and invasive species intensified at the global and regional level, such inventories must be regularly updated and remain current since the introduction rate of new NN species globally does not appear to level off. The inclusion of alien species (or NNS) descriptors and indicators in policy instruments has created reporting obligations at national level (e.g., see Tsiamis et al., 2019) and triggered a surge of scientific activity focused on the detection, quantification, exploration, and mitigation of their impacts. Also, Citizen Science (i.e., the involvement of the public in the production of scientific data – McKinley et al., 2017) has emerged as a powerful contributor to the early detection of new alien species. Further, surveillance of established invaders (Giovos et al., 2019) and novel genetic methods are more routinely employed to clarify uncertainties concerning species identities and geographic origins (Bayha et al., 2017; Viard et al., 2019). As a result, the time lag between the first detection of a new alien species and the publication of the corresponding record has decreased in recent years, largely aided by the willingness of scientific journals to publish such biodiversity observations.

The Balkan Peninsula is bordered by the Adriatic and Ionian Seas to the west, the Mediterranean Sea to the south, and the Aegean, Marmara, and Black Seas to the east. The great biodiversity of fish species is a result of the region’s geological and paleo-climatic history and the geophysical variety of the inland water bodies. The climatic differences between the various parts of the Balkan Peninsula further contribute to these biogeographical differences.

Albania has a high level of biological diversity at the landscape, ecosystem, and species levels, especially concerning its small land area. This diversity is the result of (a) the wide range in climate, altitude, and geology in Albania; (b) its location at the intersection of two major biogeographic zones (Central Europe and the Mediterranean); (c) its location astride an important bird migration route; (d) its coastline on the Adriatic and Ionian seas; and (e) an abundance of ecologically diverse freshwater ecosystems. Albania is ecologically linked to neighbouring countries through shared ecosystems, habitats, lakes, and rivers as well as migrations of birds and marine organisms. So far, there are 20 registered marine invasive alien species (IAS). They represent different taxonomy classification such as: Rhodophyta (4 species), Chlorophyta (1 species), Phaeophyta (1 species), Spermatophyte (1 species), Annelida (1 species), Decapods (3 species), Molluscs (5 species), and Pisces (4 species). Different methodologies were used for the identifications of the NN species in Albania. Some of the identifications were made by direct sampling of the NN individuals by the researchers. In other cases, the collection of the samples was done by the fishers and the identification and description of the species from the scientists later on or through  the citizen science projects, such as “Is it Alien to you? Share it!!!” and “Local Ecological Knowledge - LEK”.

Bosnia and Herzegovina (BIH) has included almost 5,100 identified taxa, which underlines its floristic richness and places the country among the richest ones in biodiversity in Europe. This is also confirmed by the great deal of endemic and relict species, especially among the invertebrates. BiH's fauna is characterized by the occurrence of refugia and development centres, and by the most unique fauna of karst sources, mountain torrents, and canyons. Fish fauna in BIH is relatively well investigated. There are freshwater 119 fish species in total. The highest diversity is recognized within the family Cyprinidae (26 genera and 51 species) and Salmonidae (5/8). During floristic research of the area along the lower course of the Una River in the spring of 2009, 14 IAS  were recorded, which mainly spread because traditional agricultural practices had been abandoned. BiH possesses only a short shoreline and that marine science in general is not very well developed (or still needs development). 

Montenegro is characterized by high genetic, species, and ecosystem biodiversity. The main characteristic of the biodiversity of Montenegro is the high concentration of different species and ecosystems in a limited area. Specific investigations and monitoring of NN species in Montenegro have not been conducted. Present records of NN species originated from various projects and monitoring programs, including national and international surveys. In recent years, the application of LEK was conducted in the framework of the FAO AdriaMed and BALMAS projects which allowed to set transnational collaborations among researchers of Adriatic countries. LEK of fishers has been investigated to gain alternative information on species presence, while qualitative and quantitative indices of species abundance have been performed in parallel by the scientists. These projects have recorded the presence of six species of macroalgae, one species of sponges, 11 species of molluscs, three species of arthropods, two worms, one bryozoan, one ascidia, and 12 new fish species. Regarding freshwater ecosystems, a compilation of bibliographical records of introduced fish species is presented in Piria et al. (2018), where 16 fish species have been identified in the Montenegrin region as species that represent NN species in this country.

Managing IAS is one of the biggest challenges for terrestrial, freshwater, and marine native biodiversity conservation. Invasive species have been reported as the second most common cause of species extinctions, while their ecological impacts can propagate along the food web. These impacts can affect the function of, socio-economy and health of an ecosystem, and cause severe loss of ecosystem services. Their management is crucial for biodiversity conservation and human wellbeing. In several cases, the application of such strategies has led to many successful eradications. In the marine environment, high environmental connectivity through the water medium fosters the dispersal of species, rendering efforts to control biological invasions more challenging. Eradication of marine invasive species has been achieved in rare cases characterized by early detection and rapid response in restricted areas. In case of established populations of invasive species, eradication is unlikely, and the management is aiming  to reduce their populations to levels that exert lower impacts considered as acceptable. A comprehensive approach to invasive species management should be considered: the expected impacts of these species on native ecosystems, the available technical intervention options, their expected likelihood of success and their cost, the risks associated with management, and the extent of public support and stakeholder support for the proposed interventions. The range of most marine invasive species has mainly been represented by 12 model species, distinguished by differences in their dispersion capacity (low vs. high), their distribution in the area under management (localized vs. non-localized), and their taxonomic identity (macrophyte, invertebrate, or fish). None of the management actions was considered ideal (fully applicable) to control any of the 12 model species. However evidence shows that managing marine invasive species is more likely to succeed when the species are detected early and authorities' response is rapid.

In Albania, limited data are present actually in a literature review, mainly due to the limited research on several groups, especially invertebrates, and on aquatic habitats (both marine and freshwater). Most of the data related to the IAS has been gathered sporadically, through  general studies focusing on several groups of flora and fauna. Though little has been done by the institutions, there are several international conventions and agreements ratified by Albania that also involve NN or IAS. The main research institutions that may relate to the NN and IAS in Albania are the Agricultural University of Tirana, the University of Tirana (and other Universities in the districts), the Food Safety and Veterinary Institute, and the Institute of Public Health.

Database of Aquatic NNS identified in Albania, the national language name, pathways and vectors together with the corresponding published literature 

Bosnia and Herzegovina still does not have a developed program for monitoring invasive species, as well as there is no law that regulates the monitoring, control, and reduction of the negative impact of invasive species. Strategy and Action Plan for the Protection of Biological Diversity of Bosnia and Herzegovina 2015-2020 states the country’s obligation to work on the control of invasive species. According to this strategy, allochthonous animal species have arrived onto the territory of BIH directly by human impact, for breeding and production, or indirectly by different activities. Besides, the problem of invasive aquatic species in BIH is also described in the Strategic Study on the Environmental Impact of the Water Management Plan for the Sava River Ties in the Federation of Bosnia and Herzegovina. Currently, there is an ongoing project entitled “Sava TIES - Preserving Sava River Basin Habitats through Transnational Management of Invasive Alien Species'' deals with the identification and control of invasive species within the Una National Park. The Sava TIES project will address these challenges and develop a strategic framework for cross-sectoral, transnational management, control, and eradication of IAS in the Sava River basin. This will be the first-ever attempt to tackle this demanding issue on a transnational corridor level in the region, while bringing benefits to the greatest Danube region and beyond through the gained experience.

In Montenegro, there is no specific monitoring program focused only on NN and IAS. Data on those species are collected through various national and international projects, monitoring and surveys, but no specific monitoring is conducted. In Montenegro, there is no developed program for monitoring invasive species. Regulation EU No. 1143/2014 has been implemented in Montenegrin legislative framework through Law on Alien and Invasive Alien Species of Plants, Animals, and Fungi. This law regulates the manner of preventing the introduction and spread of foreign and invasive alien species of plants, animals, and fungi, to mitigate and minimize the harmful impact on biodiversity, ecosystem services, and/or human health.