Over 900 non-indigenous species – be that fish, molluscs such as mussels, or crustaceans such as prawns – have been spotted in the Mediterranean Sea, and almost 300 in the Black Sea.

Rapa whelk is one of them. But what is it exactly, and why should we learn about it?

Here are five things to know about rapa whelk:

1. Commonly known as rapa whelk, Rapana venosa is a sea snail or a whelk, originally from the western Pacific.

© Istanbul University/GFCM 

Rapa whelk feeds on molluscs – oysters, scallops, clams and mussels – and it can travel over large distances in search of food. When not scavenging, it buries itself into the soft sediment of the sea.

It first showed up in the Black Sea in 1946, in Novorossiysk Bay (Russia), where it is thought to have been transported through a process called biofouling – the accumulation of microorganisms, plants, algae or small animals on surfaces where they are not wanted, such as ship and submarine hulls.

Over the following decades, the rapa whelk population continued to prosper in the Black Sea thanks to its high fecundity and tolerance to salinity, pollution and lack of oxygen. Its predatory nature, a lack of competition and natural predators and an abundance of potential prey have further helped rapa whelk take root in the Black Sea.

2. The arrival of the non-indigenous whelk has led to steep declines in the populations of several native species in the Black Sea.

 ©SUMAE/GFCM 

Commercial species such as oysters, scallops, clams and mussels in the Black Sea have suffered from the establishment of rapa whelk in the local ecosystem.

But while the rapa whelk was initially viewed as an unwelcome invader, it’s now exported globally and brings in multimillion dollar revenues for the countries bordering the Black Sea, providing livelihoods for thousands of fishers in the region.

3. Rapa whelk is the most harvested non-indigenous invasive species by Black Sea countries.

©Istanbul University/GFCM 

It is the first non-indigenous invasive species in the Black Sea to gain prominent commercial status, and since the 1980s, it has been exported to several countries in Asia.

Recent assessments by the General Fisheries Commission for the Mediterranean (GFCM) of the Food and Agriculture Organization of the United Nations (FAO) have revealed that the rapa whelk is in fact now in a state of possible overexploitation, moving away from the maximum sustainable yield.

4. Non-indigenous species such as rapa whelk can reshape an entire ecosystem, and we can no longer stop the inevitable changes they bring. What we can do is quantify and study them, and based on this knowledge, forge a pathway to manage their presence in the future.

©NEA/GFCM

In a bid to better understand the spread, impacts and use of rapa whelk as a fishery resource, the GFCM made rapa whelk one of its priority species in the Black Sea.

In 2018, with funding from the European Union, the GFCM established a regional research programme for rapa whelk fisheries.

As part of the programme, and under the framework of the GFCM BlackSea4Fish project, Bulgaria, Georgia, Romania, Turkey and Ukraine joined forces to perform a comprehensive experimental beam trawl survey.

A trial survey was conducted in July 2019 with a Turkish vessel. Then, to ensure that comparable results could be obtained elsewhere, a common survey protocol was established.

Next, in 2020 and 2021, six different vessels surveyed a total of 1 018 Black Sea locations using the same sampling protocol. 

The survey’s estimation of the rapa whelk population will ensure that there is a solid base of information to support decision-making, put in place a common management plan, underpin the necessary policy and legislative measures, and raise awareness among stakeholders.

©NIMRD/GFCM

"Rapa whelk is a very distinctive case that illustrates how the 2018 Sofia Ministerial Declaration and the 2030 GFCM Strategy can turn a non-indigenous species into a profitable fisheries and marketing opportunity, with remarkable potential to support the socio-economic fabric of the Black Sea coastal communities, decent income for fishers and blue jobs for its processing industry,” said Valerie Lainé, Head of the European Union Delegation to the GFCM, Head of Unit Fisheries Management in Mediterranean and Black Sea, Directorate General for Maritime Affairs and Fisheries, European Commission.

“Fisheries knowledge and research are fundamental to shape a stable and sustainable future for rapa whelk fisheries. Now, all our efforts to manage this stock will be based on the successful outcomes and scientific knowledge gained from the first ever regional research plan on rapa whelk in the Black Sea, implemented within the BlackSea4Fish project with the constructive contribution of the Black Sea states. The European Union strongly supported this research plan – a novelty for this region, promoting a blue opportunity for the Black Sea,’" she added.

5. There is a need to forge a common regional approach to ensure that rapa whelk is managed in a sustainable way – striking a balance between the commercial fishing of this species and the protection of other species in the Black Sea.

As part of efforts to achieve this, the GFCM and its partners are holding an SSF Forum workshop on 9 May 2022. This was preceded and will be fed by in-country in-person stakeholder consultations carried out within the framework of the BlackSea4Fish project and the rapa whelk research programme.

The in-country consultations and the SSF Forum workshop bring together fishery management authorities, fishers, researchers, inspectors, representatives of the processing industry, exporters, representatives of non-governmental organizations, consumers and any other interested parties.

The focus of these activities is on identifying rapa whelk management measures adopted by countries in the Black Sea as part of the GFCM-led research programme on rapa whelk in the region.

The in-country consultations kicked off in Turkey (Trabzon, 29 March 2022), followed by Romania (Constanta, 19 April 2022) and Bulgaria (Varna, 28 April 2022). Culminating in a regional online meeting on 9 May 2022, which coincides with Europe Day, the SSF Forum – about 100 participants – will evaluate the results of the consultations, and identify and discuss the best management measures for rapa whelk in the region.

“The SSF Forum workshop and the research programme are great examples of regional cooperation, with countries joining forces with the help of the GFCM and the European Union so that rapa whelk can be effectively managed in the Black Sea,” said Hüseyin Özbilgin, BlackSea4Fish Project Coordinator at the GFCM Technical Unit for the Black Sea, based in Bulgaria.

A big thank you to our partners in each country: the Bulgarian Institute of Fish resources, the Georgian National Environment Agency, the Romanian National Institute for Marine Research and Development “Grigore Antipa”, the Turkish Central Fisheries Research Institute (SUMAE), the Istanbul University Fisheries Faculty, the Ukrainian team of experts; and the European Union for its financial contribution.