During the past few years aquaculture has made huge progress in nearly all areas. Production has become more stable, less susceptible to problems, and overall more reliable... at least for the most important species which make up the greater part of production volume. In the year 2010, for example, the ten most important fish species in volume terms accounted for nearly three quarters of global fish production from aquaculture. Nearly 600 species are currently produced worldwide in aquaculture, and more than half of them are fishes. In spite of this, the search goes on for new fish and seafood species that might be suitable for growing in aquaculture. The length of time required from the development of viable farming technologies to their implementation and the mass production of the new species is becoming ever shorter. Whether these species will be successful on the market does not, however, only depend on their “producibility”.
The success story of pangasius shows that – if the quality and the price are right – it often takes only a short time for a new fish species from aquaculture to enjoy international demand. But, on the other hand, it can also be seen from the example of the rapid growth and equally rapid collapse of cod farming in Norway that the market success of a farmed fish does not only depend on its biological viability but also – and at least equally – on the profitability of the production processes. And this is all the more true when a fish from aquaculture has to compete on the markets with its counterparts from fisheries. Whilst fish farmers have not only to invest substantial sums to buy fry, feed and other farming necessities but also have to bear the risk that farming entails, the fisherman can harvest the fish that Nature offers him considerably more cheaply. And this valuable experience came with the failure of cod farming. The question as to which new candidates can be expected to have realistic chances in aquaculture can thus only be answered satisfactorily if two aspects are taken into consideration. Firstly, the technological manageability of the farming processes, particularly reproduction. And secondly, the cost-revenue ratio, i.e. whether production of the given fish species will be profitable.
Another question that is of fundamental significance here is: what criteria are decisive for whether and how long a fish species can be considered to be a “candidate” for aquaculture? Is cobia (Rachycentron canadum) still to be seen as a candidate although it has been being farmed for 15 years and its production level in the meantime exceeds 40,000 t? Or barramundi (Lates calcarifer) that a lot of people see good market chances for but which still hasn’t managed a breakthrough although it has been farmed in Asia for more than four decades? The “candidate status” of a fish species for aquaculture is difficult to assess and mostly subjectively tinted because it is influenced by numerous factors. Of vital significance are the future outlook as well as the market and growth potential, and less the number of years that the species has already been farmed or the actual current production volume. Geographic aspects can also play a major role during this assessment. That is why, in spite of the unique success that tilapia has had in aquaculture almost throughout the world, this fish is still considered to be a promising “candidate” in Europe, and tilapia farming is only now being tested seriously in recirculation systems.
Particularly good chances for marine species
At present 86% of all fishes that are produced throughout the world in aquaculture are freshwater species. There are a lot of reasons, however, for believing that the future of fish production will sooner lie in marine species. Three quarters of the fishes that are produced in freshwater are, for example, cyprinoids that contribute considerably to protein supply at a regional level but are difficult to market at international level. Apart from that, the number of free inland locations that are suitable and available for aquaculture continues to fall, partially because fresh water of the necessary quality is becoming increasingly scarce in many regions. Although along numerous marine coasts there are disputes about usage rights for certain regions, in comparison with inland waters there is often the possibility to move to offshore areas. Added to this is the fact that with the exception of species such as trout and pangasius, marine fish species are often more popular than freshwater species in industrialised countries.
But which marine fish species could be produced in aquaculture at all and could thus justifiably be considered as potential candidates? One very interesting species group for aquaculture is surely the breams of the Sparidae family. In addition to gilthead seabream (Sparus aurata), whose total production in the Mediterranean region amounts to nearly 150,000 t there are also other Sparidae species that are suitable for farming. Of the approximately 110 species in this family Sparus hasta, Diplodus puntazzo, Pagellus erythrinus, Dentex dentex, Acanthopagrus schlegelii and A. latus are farmed throughout the world on a more or less regular basis. Total production of all Sparidae species exceeded 260,000 t in 2010. A problem that is involved in the farming of most species is not only producing the necessary fry but also marketing. A lot of consumers probably find it hard to distinguish between the individual species and thus to accept the price differences that result from the varying degrees of difficulty that are involved in farming them
Although, as already mentioned, barramundi (“Asian seabass“) is no longer really a candidate for aquaculture it is still considered to be a rising star, for outside of Asia people have only recently begun to take notice of this fish. According to the FAO it is currently produced in about 20 countries and total production amounted to nearly 66,000 t in 2010. The major producing countries are Taiwan (23,000 t), Malaysia (20,000 t), Thailand (13,500 t) and Indonesia (5,700 t), and Australia also produces a noteworthy volume of 3,200 t. What makes barramundi so attractive for aquaculture is its salt tolerance and fast growth rate. As a diadromous, migratory fish it can be farmed in either freshwater or seawater. During its first years, in particular, barramundi grows very fast. It takes only 18 months to grow from a fingerling to a fish weighing 3 kg. And that is just the right size for cutting attractive fillets. The fishes are also produced in portion sizes of 400 to 600 g, however. All of this goes to explain why interest in this fish has remained at a high level. In Vietnam and China attempts have been made for several years and with growing success to develop their own breeds; In the USA a barramundi farm in Massachusetts has gone into operation, and in India barramundi is said to be being farmed on the coast in mariculture. In order to ensure supply of sufficient fry a hatchery was opened in Sirkazhi (Tamil Nadu) in the year 2000. There have been repeated attempts to farm barramundi in Europe, too. In The Netherlands an Australian company tried to set up a franchise system for the production of this fish. A British experiment for producing barramundi in a 1,200 t recirculation system came to a halt after just a relatively short time. In Poland barramundi have been farmed successfully for over 10 years, however, with annual production amounting to around 100 t.
The bottleneck in barramundi farming is the production of fry. Eggs are introduced to the hatcheries five to six times a year. Rearing them is still relatively expensive because the larvae have to be fed on live feed, mostly enriched Artemia nauplii. Individual hatcheries have succeeded, however, in substituting at least part of the live feed with formulated feed. Growth is then said to be not only faster but also more homogeneous. Uniform sizes are particularly important where young fishes are concerned, since this helps prevent cannibalism.
Fry are often the decisive bottleneck
Another promising option for aquaculture would seem to be some groupers of the Serranidae family, which comprises about 450 species. (“Grouper” is the name under which about half of them are traded.) In spite of their relatively high price they are very popular and are intensively fished… in many places so strongly that already 70% of stocks are considered to be overfished. Of course, this makes these fishes even more attractive for aquaculture because their production promises high profits. At present about 15 grouper species are farmed worldwide, mostly the species of the genus Epinephelus. Production volume rose strongly during the last decade. According to FAO statistics 9,410 t were produced in 2000 but this figures had risen to nearly 80,000 t by 2010. In spite of such high growth rates grouper farming still seems to have growth potential left. According to estimates 15 to 20% of all the grouper eaten worldwide currently come from farms.
The biggest obstacle is supply of fry. Although some species can already be hatched most of the fry still come from the wild (capture based aquaculture). It is estimated that about 60 million young groupers are caught annually for stocking the farms. The hatcheries supply hardly more than 1 to 2 million young fishes, even in good years. In spite of some successes hatching grouper is still rather a game of chance. A lot of grouper species change sex during their lives. As a rule the fishes are first female and then at a later age change to male. Maturity and spawning are influenced by internal and external factors (e.g. hormone level, the tides, temperature, moon phases) of which many are still unknown and which are difficult to simulate in the hatcheries. Another difficulty is feed, because the tiny larvae accept only dust-fine live feed at first. Taiwan has probably progressed farthest with hatching grouper: two thirds of the fry used for grouper farming there are already said to come from hatcheries.
Another worthwhile candidate for aquaculture would be the sablefish (Anoplopoma fimbria), also called black cod. This is one of the most commercially valuable fish species in the North Pacific. The most important market for this fish is Japan where the white, fat-rich, very tasty flesh is particularly popular in sushi and sashimi restaurants. In the past there have been several attempts to produce sablefish in aquaculture but so far none of them have proved really successful, due on the one hand to financial and biological problems and on the other hand to protests and disputes with fishermen who fear for the loss of a lucrative source of income. Research institutions in British Columbia have been working on the possibilities of producing sablefish in aquaculture for over 30 years and have during this time been able to solve a lot of the technological problems involved in the fish’s farming. Because wild catches have been falling in recent years the state authorities Fisheries and Oceans have declared sablefish to be a “priority candidate” for commercial production.
Private investors in Canada have repeatedly tried to push sablefish farming ahead. In 2003 a commercial hatchery was set up to improve technology for rearing this fish. The survival rate of eggs and larvae fluctuates strongly from batch to batch, and spinal disorders occur frequently in the fishes. Although such fishes can survive under aquaculture conditions they are hardly marketable. There are also still numerous problems with hatching but overall it has been possible to improve the process noticeably. Troutlodge Marine already raised several year classes in their hatchery on Hood Canal (Brinnon, Washington) and they now offer sablefish fry almost on a routine basis. The centre of sablefish farming is currently still in British Columbia, however. With the farms in Jervis Inlet and on the west coast of Vancouver Island the potential of this fish species is still by no means exhausted, however.
Different regions demand different species
There are also great hopes in about 20 species of the Trachinotus genus which are traded under the name pompano or jack. These fishes are in high demand in North America and Asia on account of their excellent meat quality. Catches from the fishery fluctuate very strongly, but tending towards a downward trend, so that wild catches alone can hardly satisfy demand anymore. This makes the chances rise that pompano farming could be commercially lucrative. The production of Florida pompano (Trachinotus carolinus) would probably be particularly lucrative since this fish is traded at very attractive prices in the USA. Florida pompano fillets cost 35 US$ per kilogram on average. Although attempts have been made again and again since the 1960s and 70s to produce this fish in aquaculture the necessary technology in still in its infancy. The main problems are the poor growth of the species above 200 g, difficult and expensive feeding, and a low survival rate. These problems make it difficult to grow Florida pompanos to sizes over 450 g as they are desired by the market. Trachinotus carolinus is already produced in individual cases but production volume is low and fluctuates very strongly. Perhaps it would be better to grow the fish not in net cages in the open sea but in enclosed recirculation systems. Experiments have already shown that juveniles can grow from 20 g to 450 g in four to five months and to 700 g in eight months – and with a good survival rate of around 95%.
Production of a further Trachinotus species, T. blochii, whose natural territory extends along the whole of the East African coast from the Red Sea to South Africa, has advanced much further. This Trachinotus species is farmed under the name “Golden Pompano” in considerable quantities particularly in China (Region Xiamen). Mortality problems and health problems in the early phases of the fishes’ lives have presumably been overcome for the production volume has shot up. Whereas in 2006 production amounted to only a few hundred tonnes, one year later it was more than 15,000 t and in 2010 more than 24,000 t were produced. Interest in this fish which is offered on the market practically all the year round in sizes from 400 to 1,200 g is growing in other Asian countries, too, particularly in Malaysia, India and Singapore.
In a lot of countries, and particularly in the Mediterranean region, meagre (Argyrosomus regius) which is also called croaker or corbina is extremely popular. The meat of this fish which can produce easily audible drumming and croaking noises with its swim bladder is very tasty and highly desirable so that the annual catches from the fishery which are often under 5,000 t cannot satisfy demand. Like nearly all fish species that grow to a relatively large size – meagre can reach a length of 2 m and a weight of 75 kg – the fishes grow very fast during the first months of their lives, something which is of course a positive feature for aquaculture. A drawback, on the other hand, is the fact that these fishes are predators, eating above all herring, sardines and other school fish, and thus requiring protein-rich feed in aquaculture, too. The high market value of the larger fishes over 2 kg in particular compensates for the high production costs, however, particularly since meagre is otherwise not a demanding fish and grows well at temperatures of between 16 and 20 °C. In countries like France or Spain meagre have been produced for years in varying quantities. Up to 2007 annual production amounted to around just a few hundred tonnes but rose in 2008 and 2009 to about 4,000 t. Based on this level it then more than tripled to 14,634 t just one year later in 2010. What is amazing is not only the explosive growth in volume but also the country that was behind this production: Egypt, which has for years been considered the biggest fish farming nation in Africa. The FAO statistics named Egypt’s production of meagre in 2008 for the first time at slightly more than 2,000 t, and then in 2010 at 12,246 t.
Another meagre species is produced in South Australia: Japanese meagre or suzuki (Argyrosomus japonicus) The main buyer is the USA where the white flesh of this fish which is rich in Omega 3 fatty acids is seen as a reasonably priced alternative for the expensive Chilean seabass (Dissostichus eleginoides). Suzuki costs only half the price of Chilean seabass.