Farmed Mediterranean mussels could be the next Turkish success story

by Thomas Jensen
EM5 features Türkiye

Growing interest in mussel production

This article was featured in Eurofish Magazine 5 2023.

The aquaculture sector in Türkiye has expanded rapidly over the last two decades. According to the Turkish Statistical Institute, over two decades production increased almost 6.5 times to 515,000 tonnes in 2022. Much of this increase can be attributed to the expansion in production of the main marine species, seabass and seabream. Output of rainbow trout, the main species produced in freshwater, also grew impressively increasing 3.7 times to 145,000 tonnes.

These increases pale into insignificance, however, when compared with the growth in production of trout raised in the Black Sea. From an admittedly low base of 1,200 tonnes in 2003, production of Black Sea salmon, as it is called, exploded to 45,000 tonnes in 2022, an annual growth rate of 20%. These four finfish species dominate Turkish aquaculture production accounting for 97% of the total. Their status tends to conceal the fact that 27 finfishes, four molluscs, two crustaceans, two gastropods and four algae are cultivated in Türkiye. Following the industry’s success with farmed finfish production, the government is encouraging the production of mussels and other bivalves. The hope is that these species will become another success story for the Turkish aquaculture sector.

Advantages of farmed mussels include predictability and safety

Bivalve molluscs have been consumed throughout history thanks to their excellent taste and the valuable nutrients they offer. More recently, as foods and systems of their production are increasingly being evaluated for their environmental impact, bivalves stand out for their sustainability. In Türkiye several bivalve species are caught from the Mediterranean, the Aegean, the Sea of Marmara, and the Black Sea. The catches include clams, Mediterranean mussels, oysters, cockles, and scallops. Of these species, so far only Mediterranean mussels are farmed. Although the volumes are still small these are expected to increase as the government encourages production. In ­Türkiye wild catches of bivalves can be affected by pollution. More predictable production as well as greater consumer safety are among the reasons the government wishes to encourage farming. To increase the production of bivalves a fundamental factor is the availability of sites. In a 2020 paper1, Serpil Serdar and Sükrü Yildrim state that environmental parameters of a site, including the water quality, depth, temperature, and turbidity, presence of food, structure of the seabed, protection from waves, tides and currents, predators, and potential for fouling must all be evaluated to determine its suitability. In addition, the potential for conflicts with other users and the site’s accessibility must also be considered. Hereafter, in relation to the specifications of the site, the species and the production technology are to be determined. Finally, sales, marketing, and efficient administration are critical for a successful operation. Identifying sites is among the government’s priorities The ministry’s latest strategic plan2 for the fisheries and aquaculture sector also mentions the need to determine aquaculture sites and carrying capacities, though it cautions that there is a lack of scientific studies of potential sites as well as only limited cooperation between institutions and stakeholders. A further risk is the potential for disagreement between the different ministries involved in the approval process.


Aquaculture production in Türkiye (tonnes)

Rainbow trout144,347134,174126,101113,678
Source: Turkish Statistical Institute

But these challenges are likely to be overcome as both the government and the industry evince keen interest in developing mussel farming. In, for example, Balikesir province, which has coasts along the Sea of Marmara and the Aegean Sea, 11 mussel farms with a combined capacity of just under 16,000 tonnes a year have been sanctioned and applications for a further 16 farms are in various stages of approval. Six hatcheries for mussels are also planned. The total capacity of projects awaiting approval is over 27,000 tonnes giving a potential (if all projects are approved) total capacity of 43,000 tonnes per year in just this one province.

From left: Altug Atalay, General Director and Turgay Türkyilmaz, Deputy Director, Ministry of Agriculture and Forestry.

Mussel farms in Brittany offer a source of inspiration

At the behest of the Ministry of Agriculture and Forestry Eurofish organised last year a field trip for representatives from the Directorate of Fisheries. The representatives, Altug Atalay, Director ­General; Turgay Türkyilmaz, Deputy Director General; and Tanju Ozdemirden, Head of Aquaculture visited four shellfish farming companies in Brittany, France, where they were introduced to shellfish growing techniques, were shown harvesting and depuration operations, heard about challenges facing French shellfish farmers, learnt about legislation and regulations governing the sector, and saw how shellfish was processed, packaged, and marketed. The visit also resulted in a French consultant visiting Türkiye to advise the government on how to create the legal infrastructure to foster the industry while safeguarding consumers and the environment. This year Eurofish organises another field trip for a Turkish delegation, but this time to the Danish Shellfish Centre which is part of the National Institute of Aquatic Resources at the Technical ­University of Denmark. The delegation, which comprises representatives from the ministry and from industry, will learn about standard operating procedures along the entire mussel and oyster supply chain, diseases and their control, and regulation. The representatives will visit farms and a shellfish wholesaler for insights into production, processing, marketing, and sales of shellfish in Denmark.

Within the EU, an area where bivalve molluscs are harvested is classified A, B, or C depending on the level of E. coli detected in 100 g of mussel meat. A indicates the least and C the most contamination. This classification determines the kind of treatment the product must undergo before it can be marketed for human consumption. Turkish legislation in this area is aligned with that of the EU and this system of classification is also used there. Class A areas must be sampled at least 10 times a year and 80% of samples may not have more than 230 E. coli/100g and no sample may exceed 700 E. coli/100g. If these criteria are met the shellfish may be harvested for direct human consumption. In the case of Class B, a minimum of eight samples are required each year of which nine tenths may not exceed 4,600 E. coli/100g and none may exceed 46,000 E. coli/100g. To be released for human consumption the shellfish must be depurated in an approved facility; or they can be relayed for at least a month in a Class A relaying area; or they can be cooked using an approved treatment process. A Class C area must be sampled at least eight times a year and no sample may exceed 46,000 E. coli/100 g. Shellfish can be marketed for human consumption if they are relayed for a period of two months in a Class B area followed by treatment in an approved depuration facility; or if they are relayed for two months in a Class A area; or if they are cooked using an approved treatment process. Shellfish from areas with contamination levels consistently exceeding 46,000 E-coli/100 g may not be harvested. During depuration the shellfish are held in tanks with clean natural or artificial sea water for the period necessary to bring the contamination down to acceptable limits.

Alternative sources of ingredients for carnivorous fish feeds are being studied

Another species that is produced in Türkiye is Atlantic bluefin tuna. This high value fish is fattened or farmed as production involves catching young fish in the wild and feeding them for a period after which they are harvested. This activity started in 2002 with three companies and today five firms are involved in this business. According to Prof. Deniz Coban from the Department of Aquaculture Engineering at Adnan Menderes University in Aydin, fattening refers to when fish of 30 kg and above are kept in captivity in sea cages for 3-7 months, while farming signifies fish of 8-30 kg maintained for around two years. Full-cycle production of tuna has been accomplished in Japan and recently at the Spanish Oceanographic Institute. Turkish attempts to close the tuna cycle have met with some success at the experimental level. At Kilic, the biggest producer of farmed fish in Türkiye, researchers managed to keep the tuna fry viable until 10 g after which they perished. The young fish were fed on seabass and seabream fry which made it too expensive to continue the trials. Prof. Coban suggests that breeding of bluefin tuna (as well as other species, that are under threat) should be the subject of a collaboration between research bodies, the private sector, and government institutions. In this connection he attended a meeting to discuss a fisheries and fish farming strategic plan for 2024 to 2028, where aquaculture-related issues included new production areas, new ­species, and farm management technologies. The results of the meeting will soon be announced by the authorities. An issue facing the fish farming industry concerns the feeds used for the main farmed finfish species. Seabass, seabream, trout, meagre, and Black Sea salmon are all carnivorous demanding a certain fraction of fishmeal and fish oil in their diet. As catches of the forage fish used in the production of these two ingredients fluctuate, and because of economic, environmental, and social concerns associated with reduction fisheries, researchers in academia and the industry are experimenting with alternatives including insect-, microalgae-, and plant-based products. At the aquaculture and fisheries department, Prof. Coban and Dr Mehmet Güler are conducting trials with the US Grain Council to study the impact of feeds containing alternate ingredients on the FCR and wellbeing of fish.

Climate change is close to the top of the aquaculture industry’s agenda

Finding more sustainable ways of feeding carnivorous fish is among the initiatives the aquaculture industry is taking to reduce its impact on the environment. Warming waters, lower dissolved oxygen levels, droughts, floods, and other extreme weather events have provoked concern in the industry. Özerdem Maltas, Vice President of the Central Union of Aquaculture Producers, a union of regional associations, says that climate change and how to deal with it are the most important issues to be discussed at union meetings. One strategy the union has been following is to try and convince the government not to issue further permits for flow-through systems (typically used for trout farming), but to encourage farmers to switch to recirculation aquaculture systems to save water. A completely closed system is very expensive but given the right incentives the farmers could start with a semi-closed system, feels Mr Maltas, which would be a step in the right direction. We also encourage fish producers to balance their fish production with algae and mussel cultivation to offset the nutrients released by the fish farming, he adds. Some producers are also adding renewable energy from solar panels, wind, and water to partly replace the conventional sort, prices of which have shot up because of the war in Ukraine. Altug Atalay, General Director for Fisheries and Aquaculture says that the ministry is considering postponing the start of the fishing season from September to October or even November as a response to the warming water. With regards to the inland aquaculture and fisheries sector the general directorate is closely monitoring the situation. In one dam lake, for example, where the water level is decreasing, we have stopped fishing and are trying to divert additional water to the dam since the water is used also for agriculture. We must take the interests of fishers, fish farmers, and crop farmers into account, says Dr Atalay.

Farmed fish producers should add more value to their products

The hostilities have had consequences for the aquaculture sector because fish exports to Russia have grown rapidly over the four years to 2022 making it one of the most important destinations for Turkish farmed fish. The war has reduced purchasing power in Russia making Turkish products more expensive, says Altug Atalay, General Director for Fisheries and Aquaculture who expects to see a drop in Turkish seafood exports to Russia in 2023. Much of what the sector exports is whole round or gutted fish either fresh or frozen and Mr Atalay would like to see greater value added to the raw fish by, for example, processing it into fillets, steaks, or other products that would allow the producers to earn more per unit weight. He is convinced that value rather than volume is the way forward for the Turkish aquaculture sector.

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