EXPERT Tâ—?PIC
cobia, is holding back the opportunity but effort is going into research and development. Farmed cobia has several characteristics that lead to a consistent promising market, including freshness and high-quality flesh being a good source of health-promoting omega 3 fatty acids. To establish a niche market, it requires demand for a specific product, and more importantly a consistent supply of high quality product. Aquaculture exhibits the benefits of controlling the production cycle to meet consumer demands in terms of forecasting production and consistency in size and quality of the final product. In this context, farmed cobia is a potential candidate for a niche market; however, it is important to highlight the necessity of industry support and sustained marketing effort. Whilst the increasing demand for fresh seafood and marine fish is expected to continue into the future in Brazil, there is still much to be done regarding feeds and farming techniques. LuĂs AndrĂŠ Sampaio from Universidade Federal do Rio Grande is involved in a current study on the performance of juvenile cobia reared in low salinities (three and six percent), with or without alkalinity correction in a RAS. He is presenting at WA2015 in Jeju and will highlight that the survival rate was 100 percent at all treatments, but growth parameters (final weight, weight gain, SRG and feed intake) decreased significantly at salinities of six and three percent when compared with the control. Results suggest that cobia has a limited euryhaline capacity, but they can be reared in low salinity (three and six percent) for six weeks with no mortality. However, when reared in three percent salinity, juvenile cobia can benefit from alkalinity supplementation and the higher pH associated with this, in order to sustain better growth than those reared in the low alkalinity treatment.
Australia
2
In Australia, cobia (previously known as black kingfish) are not often seen in the fish markets but are a prized species for tropical recreational fishermen. They generally can be encountered near reefs and other structures from south-western West Australia, around the north of the country and as far south as the central coast of New South Wales. In the wild they can grow to well over 45-50 kg and are strong fighters. Information was filtering through to Australia from various studies on the species. The information was exciting. The news was that cobia was a very fast growing species - the maximum age recorded for a 1.6m, 50kg+ cobia in the Gulf of Mexico was only 11 years of age. Juveniles grew to more than 60cm in their first year, and fish a metre long were only around three years old. Females matured in their second year when around 80 to 90cm, while male fish often matured in their first year. Scientists discovered that cobia spawned between April and September in the northern hemisphere (that region's spring and summer) and in Australia the spawning period occurred September to June. The size at first maturity for 50 percent of male and female cobia in Australia was 78cm, again at about two years of age. Additionally, cobia produce excessive numbers of eggs. Scientists working in the Gulf of Mexico highlighted that individual cobia spawned a number of times throughout the season. Evidence was that the fish spawned as often as once every five to 12 days. It was not unusual to see larger fish spawning up to 1.5 million eggs per batch, but the average 'batch fecundity' of cobia in Australia was shown to be
40 | INTERNATIONAL AQUAFEED | May-June 2015