Adapting to and mitigating the effects of climate change
This article was features in Eurofish Magazine 6 2021
Compared to 2019, production in the Turkish aquaculture sector increased 13% to 421 thousand tonnes in 2020 according to the Turkish Statistical Institute.
Inland water aquaculture is overwhelmingly dominated by the cultivation of salmonids, mainly rainbow trout, which account for 30% of total (both marine and inland) farmed fish production. Marine aquaculture is represented primarily by seabass (35%) and seabream (26%). In 2020, there was a huge increase (90%) in the production of a sea-raised rainbow trout to over 18,000 tonnes. Taken together, these three species (rainbow trout, seabass, seabream) accounted for 96% of Turkish farmed fish production (freshwater and marine) in 2020, a picture that has not really changed since the 80s when production from fish farming first made it into government statistics.
Marine farmed fish production is twice that of farmed freshwater fish
However, in the second half of the 80s marine farmed fish output comprehensively overtook that from freshwater. Today it is more than double thanks to developments in feed and cage technologies and the push by the government to site marine cages offshore, where they do not conflict with other activities closer to the coast, and where there is more space to expand. The inland aquaculture sector is more fragmented than the marine farming industry—where there are some 430 companies producing fish in the sea, there are almost 1,700 companies operating in inland waters, according to Altug Atalay and Özerdem Maltas in an article in Marine Aquaculture in Turkey*.
Seabass and seabream are native to the Mediterranean and companies in Turkey (and other Mediterranean countries) have largely solved the obstacles that arose in the 80s when the cultivation of these two species started in earnest. Understanding the biology of the fish, developing feeding protocols, and establishing hatcheries with broodstock to produce eggs and larvae went side by side with the evolution of farming technologies contributing to a steady expansion in production over the last three and a half decades. In 2021 Turkish companies put some 550m juveniles into cages and next year they expect that number to increase to 600m. At least one company is also exporting part of the production from its hatchery. Cages for seabass and seabream are found in the Aegean and the Mediterranean, while in the Black Sea seabass and rainbow trout are on-grown. The cages are placed at least 1,100 m from the coast in water that is a minimum of 30 m in depth. These regulations were introduced in 2007 and, although the industry grumbled at the time at the additional expense, it has led to the accumulation of knowledge and expertise in offshore cage building, mooring technology, and other infrastructure that Turkey now exports to countries in the region.
Earthen pond production falls victim to the exchange rate
For both species, seabass and seabream, broodstock is either cultivated in hatcheries or collected from the wild. Spawning is typically induced using photo-thermo manipulation. The eggs are collected, hatched and the larvae grown in recirculation systems with algae in the water. The larvae are fed on rotifer and artemia. Sometimes in the case of seabass, only artemia is used. At the weaning stage they receive both particulate and live feed and following weaning the juveniles are moved to on-growing units within the hatchery where they are fed on extruded feeds until they reach 5-7 g. From the hatchery they are introduced into sea cages or earthen ponds for grow out to market size. This can take up to 20 months depending on the target weight, on the weight of the juveniles when introduced into the sea cages, on the month of introduction, and on whether the cages are in the north or south Aegean or the Mediterranean. The earthen ponds that are also used for the cultivation of seabass and seabream are all located along the south Aegean coast. The water for the ponds is pumped from the ground and is at a constant temperature around the year. Production from earthen ponds is dominated by family-owned companies cultivating modest amounts of fish, usually 30-50 tonnes. This production is, however, valued more highly than fish raised in cages as it is considered to be closer to wild fish in appearance, taste and texture, and commands a premium in price. But the production is a fraction of the volumes produced in sea cages, according to Osman Özden and his co-authors* and is likely to have fallen in the last couple of years as many of the 150-odd producers have stopped their activities due to the increase in dollar-denominated costs.
The grow-out stage for the fish culminates typically when the fish reaches a size of 400-600 g though often a small proportion of the production is grown to large fish of 1,000 g and over. The fish produced in cages is almost entirely intended for overseas markets, primarily in the EU, but also the US, Asia, and the Middle East. The product is exported fresh or frozen as whole round fish, gutted, or as fillets. Some companies have been experimenting with value-added products, such as fresh or frozen ready meals or ready-to-cook meals. The focus on export markets has shielded these companies from the depreciation in the Turkish lira over the last years which has caused the lira price of dollar-denominated raw materials to shoot up. The small companies that produce in earthen ponds supply their fish to the domestic market and so earn in Turkish lira, while costs, primarily feed, are in dollars. This mismatch has caused many of them to cease operating.
Production of alternate species has generally not taken off
While the seabass and seabream story started in the mid-80s and has since grown to become a hugely successful industry, attempts to diversify production have largely foundered. Research has been carried out on many species including common dentex, red porgy, bluespotted seabream, shi drum, sharpsnout seabream, white seabream, turbot, meagre, and tuna, but apart from the last two, commercial production of other species was 221 tonnes in total in 2019 and 27 tonnes in 2020 according to the Turkish Statistical Institute. Reasons for the lack of success vary from technical problems growing the fish to the lack of market acceptance. Ihsan Bozan, the vice chairman of Kilic, the biggest producer of farmed fish in Turkey, says that his company’s attempts to breed bluefin tuna from eggs succeeded until the fish reached some 10 kg at which point they perished. The company finally scrapped the project because it was hugely expensive. The tuna fry were being fed on seabass and seabream fry which was unsustainable without more progress than was made. Another project was to cultivate greater amberjack, but this too the company shelved after five or six years because despite producing the eggs each year growing them to viable juveniles proved impossible. Another species Kilic produces is the olive flounder, but the volumes are so small that the production is likely to be sacrificed next year to make way for an adaptation unit for seabass and seabream juveniles.
Turkish output of meagre, on the other hand, increased by 120% to almost 7,500 tonnes, while production of tuna, which is taken from the wild and then fattened for about six months, went up 86% to 4,300 tonnes. Even species that are now successful such as meagre have taken several years to get there. The challenge with meagre was that it was unknown among consumers so a market for the fish had to be created. One species that has shown a lot of promise over the last years is rainbow trout that is first grown on land and then introduced into cages in the Black Sea for the final grow-out. Companies use different strategies when growing the fish, some grow the fish to 200-600 g before growing them further either in cages in a dam lake or cages in the Black Sea. Other companies grow the fish to 500-1,000 g in a dam lake and then place the fish in the Black Sea where they grow to 4-5 kg or even 5-6 kg. The fish are introduced into the sea in October and stay there for six to nine months. In July the Black Sea water starts getting too warm so the fish must all be harvested. The product has found favour on the Japanese and Russian markets and its success there has encouraged producers to invest in processing facilities, where the fish can be made into value-added products such as fillets, steaks, portions, and even smoked products, for export to the EU.
Climate change impacts are becoming all too obvious
The Turkish aquaculture sector has been growing steadily over the years, but any growth strategy today must consider the impact of climate change and implement adaptation and mitigation measures if the sector is to continue to thrive and prosper. The industry is already starting to notice the implications. In Kahramanmaras, where Kilic produces trout in a dam lake, the water gets a little warmer each year, says Ihsan Bozan. In five years I am not sure we will be able to produce trout there any longer. Altug Atalay, Director General for Fisheries and Aquaculture in the Ministry of Agriculture and Forestry says not only is the water getting warmer, there is also less of it. Although the country has experienced floods, it has also suffered droughts and many artificial dam lakes are running dry, he says. The FAO singles out the Mediterranean as a region where droughts are likely to be longer and more frequent. According to the organisation, at the global level, the earth’s average surface temperature has increased by more than 0.8 °C since the middle of the nineteenth century, and is now warming at a rate of more than 0.1 °C every decade. This average suggests that some parts are warming more and/or faster than this. Oceans are warming too over most of the globe a change that is especially prominent in the northern hemisphere, states an FAO report, Impacts of climate change on fisheries and aquaculture. The warming water leads to a decrease in its dissolved oxygen content which has an impact on aquatic life including farmed fish. A further impact of climate change on the oceans is the increased acidity of the water as the oceans absorb more carbon dioxide due to an increase in atmospheric concentrations of the gas.
Aquaculture could suffer in myriad ways from warming waters
In Turkey small scale fish farmers such as those farming seabass and seabream in earthen ponds, or small producers of rainbow trout in rivers, or seabass in the Black Sea are among those likely to be most affected by climate change. Limited capacity to invest in adaptation measures, such as aerators, when the oxygen content of the water falls, makes them particularly vulnerable. Climate change is also expected to lead to changes in the availability and trade of products from aquaculture and fisheries which could have consequences for producers everywhere. The potential short-term impacts of climate change on aquaculture could include the consequences of extreme events such as storms, droughts, floods, diseases, or harmful algal blooms, which reduce yields and increase costs. In the long term reduced precipitation, warmer water, ocean acidification, and hypoxic zones will force policy and technical adaptations in the sector. Halit Filiz, dean of the Faculty of Fisheries at Mugla Sitki Kocman University, notes another impact of increasing water temperatures. This is the spread of invasive species which can do a lot of damage to native flora and fauna. In an ongoing project run by the department of marine and inland waters science and technology, awareness about invasive species is being increased among the public. His faculty is in discussions with Kilic to develop a project to study the effects of climate change on aquaculture. Hijran Yavuzcan Yıldız and M. Binhan Ganioğlu* point to an increase in temperature, decline in rainfall, increasing periods of drought, elevation in sea levels, and saltwater intrusion as some of the changes that will affect the Turkish aquaculture sector. Higher water temperatures can affect growth and reproduction rates of fish and have a detrimental impact on eggs, larvae, and juveniles. It can also have an impact on disease outbreaks and on the relationship between pathogens, the fish, and the water they inhabit. The current level of knowledge, however, makes it difficult to predict how climate change will affect pathogens and disease occurrence in aquaculture. On the other hand, warmer water may increase fish growth rates, as well as open up new areas for aquaculture. It may increase phytoplankton production and biodiversity which could prove beneficial for the culture of bivalves.
Official responses to climate change are encouraging, but are they enough?
In Turkey the natural water temperature differences between the Black Sea, the Aegean, and the Mediterranean allow the marine aquaculture sector to optimise the distribution of species, says Mr Atalay, which partly explains the growth in marine aquaculture production despite climate change The recent outbreak of mucilage in the Sea of Marmara and last year’s undersized anchovy in the Black Sea, which led to an unprecedented ban on fishing in the middle of the season, he also links to warming waters. The government is responding to these developments. Apart from the immediate relief that small scale fishers in the Sea of Marmara received because of the mucilage, a new national ministry for environment and climate change has been constituted, and workshops and seminars on climate related issues are being held to discuss cross-ministerial plans of action and to create awareness of the threats posed by climate change. The government is also encouraging fishers and farmers to switch to renewable forms of energy and is subsidising the switch to more energy efficient equipment. It is also working to raise awareness among fish farmers about feeds that have lower environmental impacts and a smaller carbon footprint. The use of recirculation aquaculture systems is being encouraged to reduce water consumption and Mr Atalay expects that over the next decade more and more companies will switch to these systems attracted by the water saving and by the ability to precisely control all the parameters affecting the growth and well-being of the fish.
Private companies too are starting to implement measures that will reduce their carbon footprint. The use of renewable energy and batteries instead of fossil fuels and a greater degree of recycling are among the changes some have introduced. As Mr Bozan from Kilic says, international certification agencies and also banks need us to demonstrate what we are doing for the environment, so we have a vested interest in making our operations more sustainable.