[ AQUACULTURE ]
Barramundi from aquaculture is already part of the standard range in numerous Thai supermarkets. There, the species is mostly known as seabass or white snapper.
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 www.eurofishmagazine.com
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 Eurofish Magazine 3/ 2013
This issue covers Romania and reviews the ESE in Brussels. The Aquaculture section looks at new candidate species.