The Adriatic Sea has emerged as a marine area increasingly in the international focus, far beyond the confines of its natural and political boundaries. The end of the first decade of the 2000s may be a good occasion to review recent developments and challenges of the Adriatic Sea, many of which concern its specific sub-regional features.
1. The Adriatic Sea as a distinct marine sub-region
Formed as a narrow gulf deeply incised into the European mainland, the semi-enclosed Adriatic Sea has been a trade and transport route since antiquity. Due to its strategic position, the Adriatic Sea is now re-emerging as an arena of high geostrategic importance in the changing geopolitical picture of Eurasia. Although it is a part of the wider Mediterranean region, the Adriatic Sea – connected to the rest of the Mediterranean only by the Strait of Otranto – has its own specific features, and is for many reasons rightly considered a marine sub-region in its own right.
This is confirmed by both hydrographical and political definitions. As to the hydrographical definition of the Adriatic Sea as a sub-division of the eastern Mediterranean Sea basin, see the 1953 Limits of Oceans and Seas
by the International Hydrographic Organization. Regarding legal and policy instruments, the 2008 EU Marine Strategy Framework Directive 
identifies four marine regions where European marine waters extend, the Mediterranean Sea being one of those; furthermore, the Strategy sub-divides the Mediterranean, as a marine region, into four areas or sub-regions, with the Adriatic Sea as one such distinct marine sub-region.
2. Regional and sub-regional approaches in the Mediterranean
The distinction between regional and sub-regional approaches relates to the question of whether issues and options for responses are the same throughout the entire Mediterranean. Several examples can illustrate the need for distinct sub-regional approaches in the Adriatic Sea – always within the overall framework of general law of the sea and international law commitments undertaken.
For instance, as to commercial shipping, the Mediterranean (the sea where some 30 per cent of global maritime trade transits) is characterised by two major patterns: one is transit only, while the other involves calling at a port in some Mediterranean country. In the Adriatic Sea, due to its geography, there is no maritime through transit, so all commercial traffic there calls at some Adriatic port. An important share of that traffic (crude oil in particular) is then further transported on-land to mid-European countries, several of them land-locked. In such a situation, the reliance on port state jurisdiction on arrival may be of considerable importance – a feature that requires enhanced sub-regional cooperation and coordination.
This is further related to the need for coordinated proposals on the global level, such as in the International Maritime Organization (IMO). It is evident that some seas are in a rather special position as to ballast water management. Within the Mediterranean, the Adriatic Sea is a clear case, being too shallow and too narrow to be able to comply viably with the requirements of the Ballast Water Convention 
for the designation of ballast water exchange zones.
Or we can take the example of sub-regional cooperation on initiatives such as the proclamation of a Particularly Sensitive Sea Area (PSSA). While it may be difficult to argue for, or to see usefulness of, PSSA as a management tool at the all-Mediterranean level, such a measure could be highly appropriate in more compact marine sub-regions.
The Adriatic Sea is a marine area where a combination of specific sub-regional measures and application of generally agreed-upon rules of the law of the sea could provide responses to many challenges of marine safety, environmental and resource management. However, in the course of the past decade it has become evident that such challenges persist, whereas the adoption of measures for dealing with them remains difficult in the current Adriatic Sea setting.
3. The Adriatic Sea: a ‘local’ picture
Prior to 1991, there were only three coastal states on the Adriatic Sea north of the Strait of Otranto: Albania, Italy and Yugoslavia.
Today there are six, as Bosnia and Herzegovina, Croatia, Montenegro and Slovenia emerged after the dissolution of the former Yugoslavia.
Whereas land borders between the former Yugoslav federal republics have been recognized as state borders, the territorial sea in Yugoslavia was never delimited between the various republics. Following the emergence of four new Adriatic coastal states, legally binding agreements to resolve the issues of maritime delimitation have not yet been achieved. The positions of some of those coasts are but one indication of the complex and generally troubled past of the region, where boundaries have been subject to the vagaries of history.
Delimitation of maritime zones of sovereign rights and jurisdiction between the countries on the eastern Adriatic Sea coast, on the one hand, and on the western coast (Italy), on the other, is largely pending – with the general exception of the continental shelf. This situation of pending maritime delimitation issues, some of which have emerged in the relatively recent past due to the emergence of new coastal states as well as a consequence of new maritime zones being proclaimed, is an important feature of the Adriatic Sea area today.
One other Adriatic Sea feature is better understood when the coastline lengths of individual countries are contrasted with their economic uses of the seas, such as maritime transport and fisheries. Natural features of the Adriatic Sea contribute to a rather peculiar situation in which the two opposite coastlines, eastern and western, are separated by a relatively narrow sea (in average 86 nautical miles in width). The total length of the entire Adriatic Sea coastline, including all islands, extends over some 8300 kilometres. However, some 7000 km of the coastline, or around 85 per cent, extends along the eastern Adriatic side. This is due to its geomorphology, characterised by a highly indented coastline and numerous islands, most of which form an archipelago that follows the general trend of the mainland coast. The length of the coastline of Croatia occupies by far the largest share: approximately 6200 km, or around 75 per cent of the entire Adriatic coastline. Italy’s Adriatic coastline, situated along the entire western coast, is significantly less indented, and has a total length of approximately 1300 km (some 15 per cent of the Adriatic coastline). The remaining part of the Adriatic coastline extends along the opposite, eastern, side and is shared between three non-EU countries: Albania (around 400 km of coastline), Montenegro (290 km), Bosnia and Herzegovina (20 km). The only other EU member state on the Adriatic Sea coast, Slovenia, has some 45 km of coastline, providing the remaining 0.5 per cent of the total length of the Adriatic coastline.
When it comes to maritime traffic and trade volume, however, the situation in many respects seems reversed, especially as regards the proportions for the eastern and western Adriatic coasts. By far the largest share of the maritime traffic and trade involves Italian ports, which annually receive around 75 to 80 per cent of the total commercial ship traffic and cargo transported. Croatia makes up around 10 per cent of the total Adriatic traffic, both in terms of number of vessels and amount of cargo, though with a tendency of growth. The remaining countries – Slovenia, Bosnia and Herzegovina (through the Croatian port of Ploče), Montenegro, and Albania – together make up the remaining 15 per cent of the traffic and 10 per cent of the cargo transported. Of their ports, the single Slovenian international commercial port of Koper stands out: it is larger than any other single port on the eastern Adriatic coast (except for the northeastern Italian port of Trieste).
The significance of this difference from the perspective of marine environmental protection and resource management can be illustrated in the context of ballast water issues. Three of the Adriatic countries – two EU members (Italy and Slovenia) and one candidate (Croatia) – all show profoundly different circumstances. Italy, with its maritime export, is the biggest generator of ballast water introduced into the Adriatic Sea, accounting for over three quarters of the annual total. Slovenia’s coastline is indeed a short one, yet this country is not a negligible contributor of ballast water, due to the maritime export volume from its single international port, Koper. Finally, Croatia has by far the longest coastline in the Adriatic Sea, yet is currently contributing far less ballast-water import, due to the still relatively low volumes of maritime export.
Also in some other economic aspects, such as fisheries, Adriatic proportions are diametrically reversed. Italy is clearly the biggest user of the Adriatic Sea; it has always been the undisputed fishing superpower there. While Italy has the dominant fishing fleet, most of the fishing grounds lie in waters closer to the Croatian island chain. The disproportion is especially obvious in bottom-trawl fishery, with the Croatian annual catch at around 5,000 tons, as against the Italian catch of some 50,000 tons. As to the other Adriatic Sea countries, their overall annual fish catches are very low.
4. The Adriatic Sea: a broader picture
On the western Adriatic coast there is a highly industrially developed country, Italy. The eastern coastal states there are mostly less industrially developed, but several developed mid-European countries (several of which are land-locked), gravitate naturally to the Adriatic Sea. Some of them are heavily dependent on that maritime route for their energy imports: Austria, for instance, receives 75 per cent of its oil imports through Adriatic ports, and Bavaria in southern Germany a full 100 per cent.
In the foreseeable future the Adriatic region may see major changes. As to future oil transport routes, several large-scale visions clash here when it comes to projections for the next decade.
Some of the projects conceived over the past decade, on exporting Russian and Caspian oil through the Mediterranean in order to (partly, at least) by-pass the Bosporus, include the prospects of various Adriatic ports and terminals. The eastern Adriatic coast, due to its placement and natural features, is central to several such energy transport plans and projects. It is blessed with several deepwater ports, especially along the Croatian coast – and thus also closer to central Europe.
Implementation of these plans and projects would, however, also result in an important change in tanker transport of oil in the Adriatic Sea: there would be a shift from exclusively crude oil import, as today, to include export as well, should the newly conceived projects materialise. That, in turn, could aggravate issues like those related to the problem of ballast water and the risks of introducing harmful aquatic organisms to the shallow, semi-enclosed Adriatic Sea. Conservation of Adriatic Sea living resources is of high importance for the coastal countries. Moreover, maritime safety considerations and the increase of related risks for the marine environment emerge as well. In addition, plans are underway for large LNG (liquefied natural gas) import terminals in the Adriatic Sea area, to help in diversifying central European gas imports and lessen the dependence on Russia; no such terminals are in place today.
The Croatian coast, due to its placement and natural features, is central in several such energy transport plans and projects. In addition to industrial interests, also the geopolitical interests of main players on the Eurasian scene – Russia, the USA and some key EU countries – are at stake here, and should be taken into account when explaining overall Adriatic Sea developments and their future projection.
5. Marine environmental and resource management concerns
Already today, however, there are serious reasons for concern. By the early 2000s, scientific and monitoring projects had documented the troubling effects and risks of current maritime uses of the Adriatic Sea – both shipping and fishing – on the state of its living resources and the marine environment.
As to maritime transport and shipping in general, the current levels of traffic in the Adriatic Sea, apart from accident risks, give rise to various concerns for the coastal states. Particularly important here are the impacts of operational oil discharges from large ships, mainly on international shipping routes that traverse the Adriatic. For the first time, the extent and frequency of that type of pollution in the Adriatic Sea have been confirmed by analyses performed in projects using special satellite technology (satellites equipped with Synthetic Aperture Radar, SAR) – such as, from the early 2000s onwards, those of the Sensors, Radar Technologies and Cybersecurity Unit, DG Joint Research Centre of the European Commission.
Analysis of images obtained has demonstrated the occurrence of greater spill concentrations along main maritime routes, proving that such operational oil spills from ships are underway on a large scale here – despite the Special Area status of the entire Mediterranean Sea, including the Adriatic, under MARPOL Annex I, whereby the discharge of oil and oily waste is prohibited.
Another major concern relates to marine living resources and their conservation and management. Due to its specific characteristics, the Adriatic Sea contains some of the highest fish-producing areas in the Mediterranean. This is especially the case in the northern Adriatic, as well as in several other localities along the Croatian coast. However, Adriatic fish stocks have been exposed to devastating fishing practices. From the commercial perspective, the most interesting species in the Adriatic Sea are demersal (benthic, bottom-dwelling) ones. The profitability and accessibility of demersal resources, due also to the wide and mostly shallow Adriatic Sea shelf, have contributed to their depletion. At the same time, the abundance of typical prey species has increased. Especially disturbing findings were revealed in 2000/2001, based on data comparison of two research survey cruises monitoring the state of demersal fish stocks over a span of 50 years: the results of the HVAR cruise in 1948 and those of the MEDITS cruise since 1998.
The comparison revealed major negative changes in the composition and distribution of demersal fish resources, clearly indicating their overexploitation. Some species, such as rays, have been especially affected by the intensity of trawl fishery and were disappearing; moreover, various indicators of the poor state of, in particular, demersal Adriatic fish stocks have been documented. Exploitation pressure has not been proportional to the productivity of many important species and stocks, resulting in a key problem for the sustainability of the Adriatic Sea fisheries.
Despite serious concerns for the sustainability of Adriatic Sea fisheries as well as frequent incidents of illegal oil spills from vessels, most of the Adriatic Sea remained under the legal status of the high seas until recently.
6. Extending sovereign rights and jurisdiction: a recent Adriatic Sea development
A key measure under international law, as codified by the United Nations Convention on the Law of the Sea, 
is the Exclusive Economic Zone (EEZ). However, although such maritime zones have been introduced in most of the world’s seas, none of the Adriatic Sea coastal states had proclaimed an EEZ (or a maritime zone based on it) prior to 2003. In October 2003, Croatia was first to declare an ‘Environmental and Fisheries Protection Zone’ in the Adriatic Sea, based on the EEZ regime.
However, criticism was forthcoming from neighbouring EU member states, Italy and Slovenia, channelled also through various EU bodies, including the European Commission. This carried significant weight politically, since Croatia has been an applicant, and thereafter a candidate for EU membership – and the issue of the proclaimed Zone has gradually been placed in the context of the progress in Croatia’s EU accession process. Eventually, after several revisions of the initial decision, Croatia was, as of March 2008, persuaded to discontinue application of the Zone to the EU countries, until a solution ‘in the EU spirit’ could be found.
Maritime delimitation issues and claims by Italy and Slovenia figured prominently on that agenda.
In October 2005 and January 2006, through its internal legislation Slovenia unilaterally proclaimed a maritime zone of sovereign rights and jurisdiction in the Adriatic Sea.
Although labelled as an ‘ecological’ zone, this is rather a political claim, and not a marine environmental or resource management measure based on international law. The proclaimed zone extends in parallel to the Croatian coast of western Istrian peninsula. Also the continental shelf that Slovenia claims to have in that area is not
a natural prolongation of its own land territory, but rather of the land territory of Croatia in front of its western Istrian coast. So far, there have been no official or public reactions from other EU member states or any EU body to Slovenia’s evidently excessive maritime claim, although that claim is clearly in violation of the Law of the Sea Convention. No state except Croatia has publicly protested. The Slovenian ‘ecological zone’, while a paper tiger only, remains formally in effect under its national legislation.
In February 2006, Italy adopted a law on the establishment of an ‘ecological protection zone’. 
Within the zone, Italy is to exercise its jurisdiction in the area of protection and conservation of the marine environment, including the archaeological and historic heritage. The Law, however, does not
apply to fishing activities. Moreover, the Law only authorizes the establishment of an ecological protection zone, pending a decree of the President of Republic. This is related to achieving delimitation agreements with the ‘states involved’, i.e., those whose territory is adjacent to or facing Italian territory.
In effect, and as the result so far, status quo
has been maintained regarding coastal state jurisdiction in the Adriatic Sea. No progress was made regarding management and conservation measures for the heavily depleted Adriatic fish stocks. Quite the contrary, the same harmful fishing practices continued without any legal possibility of control by the coastal state. Due to political considerations, advances in measures to combat marine pollution were also limited – even though frequent incidents of illegal oil spills had been proven by research projects conducted under the auspices of the European Commission itself.
In addition to the right of any coastal state that can lawfully proclaim an EEZ to apply that regime in accordance with the Law of the Sea Convention, some core principles of the law of the sea have been under testing in the Adriatic Sea. Most importantly, that includes the basic axiom that the land dominates the sea in determining maritime areas under sovereignty and the sovereign rights of coastal states.
The need to conserve the marine resources and prevent environmental degradation of the Adriatic Sea speaks strongly in favour of the adoption and implementation of all measures available, including an EEZ. There is, however, no more than international law to support this line of action. Powerful economic and political interests, both on the Adriatic regional and the broader Eurasian strategic level, seem to favour maintaining status quo
in the overall picture of Adriatic Sea jurisdiction.
7. Pending joint initiatives: the example of an Adriatic Sea PSSA
Due to its special features and the slow exchange of water with the rest of the Mediterranean through the Strait of Otranto, the Adriatic is a particularly sensitive sea, highly vulnerable to marine pollution. PSSA, as a concept of balancing the apparently local and regional/sub-regional environmental protection interests with the global interests of international shipping and industry may prove to be a feasible and useful avenue for the Adriatic Sea.
When seen in relation to the emerging context of regionalisation of the ‘European seas’, which seems an important underlying element of the new EU Marine Strategy Directive, the relevance of an Adriatic Sea PSSA is further enhanced. While the Marine Strategy is directly applicable only to the EU member states and marine waters covered by their sovereignty or jurisdiction, member states are required within each marine region or sub-region to make every effort to coordinate their actions with third countries. An ability to cooperate on a PSSA may prove a key test-case for the Adriatic countries – EU members, candidates, or aspirants alike – towards meaningful implementation of an otherwise broad EU Marine Strategy, on a specific and needed goal of Adriatic marine environment protection and sustainable development. An Adriatic PSSA could be an important first step in that direction.
So far, however, the matter remains pending. In the spring of 2006, Croatia invited the other Adriatic coastal states to cooperate towards a proposal for an Adriatic Sea PSSA to be submitted to the IMO, and has distributed a draft study for the Adriatic Sea PSSA, prepared with the assistance of the Fridtjof Nansen Institute in Oslo in cooperation with several Croatian scientific institutions. A Joint Expert Group, with the participation of Albania, Bosnia and Herzegovina, Croatia, Italy, Montenegro and Slovenia, has been formed and several meetings have been held. The Group made good progress at its first three meetings in 2006 and 2007; since then, however, it seems as a stalemate on some issues has hampered the conclusion of the work and submission of the Adriatic Sea PSSA proposal to the IMO.
8. The Adriatic Sea dilemma: a persistent challenge
There exist great regional imbalances, even diametrically opposed situations, among the coastal states – as illustrated by the share, position and various features of coastline of Adriatic Sea countries, on the one hand, and the extent of their maritime uses of the Adriatic Sea, on the other. As a result, while some overall interests in the Adriatic Sea remain shared, other, more specific ones, are poles apart.
Moreover, the pressing need for sound environmental protection and improved resource management and conservation in the Adriatic Sea remains hampered by a plethora of delimitation disputes and emerging maritime boundary issues. That is of little help to the Adriatic Sea states currently facing major challenges as to the sustainability of marine resources – and where possible impacts by the expansion of international shipping and fishing in one specific Adriatic area may spill over to another, potentially affecting the entire region.
All the Adriatic Sea countries share one important, lasting feature: they are all coastal states here, with a multitude of important activities and considerations. Various measures will need to be put in place, to enable sustainable resource utilization and rational management, and durable marine environmental protection in the Adriatic Sea.
The Adriatic Sea region will inevitably need to be oriented towards cooperation in approaches to matters of joint concern, such as marine environmental protection and resource conservation and management – yet where all the participants can retain certain profoundly different features as their dominant. In that situation, to strike the right balance between the national regulation sphere, which can take into account each country’s peculiarities and rights under international law, on the one hand, and regional/sub-regional cooperation based on commonality, on the other, is likely to remain the key challenge for the Adriatic countries in the next decade. In responding to that challenge, the Adriatic countries should remain within the framework of general rules of international law and global agreements to which they are parties, in order both to facilitate long-term stability in mutual relations and to arrive at solutions acceptable to third states.
: Information included in this text draws on previous studies by the author, to which readers interested in further discussion are referred, in particular, as to the proclamation of Adriatic Sea maritime zones and certain delimitation issues: Davor Vidas, ‘The UN Convention on the Law of the Sea, the European Union and the Rule of Law: What is Going on in the Adriatic Sea?’, International Journal of Marine and Coastal Law, Vol. 24, No. 1, 2009, pp. 1–66; and, regarding the PSSA initiative in the Adriatic Sea: Davor Vidas, ‘Particularly Sensitive Sea Areas: The Need for Regional Cooperation in the Adriatic Sea’, in Katarina Ott (ed.), Croatian Accession to the European Union: The Challenges of Participation (Zagreb, Institute of Public Finance/Friedrich Ebert Stiftung, 2006), pp. 347–380.
- Directive 2008/56/EC of the European Parliament and of the Council, of 17 June 2008, establishing a framework for community action in the field of marine environmental policy, Official Journal of the European Union, L 164, 25 June 2008, p. 19.
- International Convention for the Control and Management of Ships' Ballast Water and Sediments, 2004. IMO doc. BWM/CONF/36.
- Another Mediterranean EU country, Greece, is partly oriented on the broader Adriatic-Ionian Sea area, with its coasts and islands close to the Otranto.
- See especially: European Commission, DG Joint Research Centre, Atlante dell’inquinamento da idrocarburi nel mare Adriatico (Luxembourg, European Communities, 2005), p. 10. According to that report, 257 oil spills from ships were detected in the Adriatic Sea (area north of latitude 39° N) in 1999; 263 spills in 2000; 184 in 2001; and 244 spills in 2002. A special campaign for the Adriatic Sea during only two-and-a-half summer months in 2004 (16 July–30 September) revealed 77 possible oil spills there; see ibid., pp. 9–10 and 49–53.
- See S. Jukić-Peladić, N. Vrgoč, S. Krstulović-Sifner, C. Piccinetti, G. Piccinetti-Manfrin, G. Marano and N. Ungaro, ‘Long-term changes in demersal resources of the Adriatic Sea: comparison between two trawl surveys carried out in 1948 and 1998’, Fisheries Research, Vol. 53, No. 1, 2001, pp. 95–104.
- The United Nations Convention on the Law of the Sea, UN doc. A/CONF.62/122, text in United Nations Treaty Series, Vol. 1833, p. 3.
- Decision on the Extension of Jurisdiction of the Republic of Croatia in the Adriatic Sea, adopted by the Croatian Parliament, Sabor, on 3 October 2003 and, published in Narodne novine (Official Gazette), No. 157, of 6 October 2003; English translation in Law of the Sea Bulletin, No. 53, 2004, pp. 68–69.
- Decision on Modifying the Decision on the Extension of the Jurisdiction of the Republic of Croatia in the Adriatic Sea, adopted by the Croatian Parliament on 13 March 2008 and published in Narodne Novine (Official Gazette), No. 31, 2008.
- Act on the Proclamation of the Ecological Protection Zone and on the Continental Shelf, adopted by the Slovenian Parliament, Državni zbor, on 4 October 2005 and published in Uradni list (Official Gazette), No. 93, 2005. English translation in Law of the Sea Bulletin, No. 60, 2006, pp. 56–57; that translation, however, does not contain the word ‘proclamation’ in the title of the Act, which is otherwise contained in the title of the Act in its original Slovenian-language version: ‘Zakon o razglasitvi’ (Act on the Proclamation). See also the Decree on the Determination of the Fisheries Sea Area, passed by the Government of Slovenia on 5 January 2006, and published in Uradni list (Official Gazette), No. 2, 2006.
- Law 61 on the Establishment of an Ecological Protection Zone Beyond the Outer Limit of the Territorial Sea, adopted on 8 February 2006 and published in Gazzetta Ufficiale della Republica Italiana (Official Gazette of the Italian Republic), No. 52, of 3 March 2006; English translation as provided by Italy in Law of the Sea Bulletin, No. 61, 2006, p. 98.