The duties of this section include the mass production of single cell algae, rotifers, artemia nauplii and enriched artemia metanauplii.
The facilities of this section have not change since the previous season with two exceptions: a. carbon dioxide was introduced in the air line feeding the big bags to increase production and b. the pneumatic control of the seawater heating system was replaced by a more affordable electronic regulation.
All the algal strains obtained during the 1993–4 season from different sources are presently kept alive in the hatchery and routinely duplicated at the level of test tube. When required, they are supplied to Institutions and privates. In this way the hatchery is working as a small algoteca at disposition to any Turkish counterpart.
In the present season, two algal species have been selected for mass culture due to their higher level of DHA: Nannochloropsis oculata (strain number: CCAP 849/1) and Isochrysis sp., Tahitian strain (strain number: CCAP 927/14). Both species performed well at mass production level. Some growing data concerning the biggest rearing volumes (350-1 bags) are reported in Annex 9. All cultures were found contaminated by bacteria, but they did not apparently affect growth. During the present season, no ciliate outbreak occurred. FAO Ankara kindly provided new strains of both species fom CCAP, Scotland.
A total amount of 144,4 m3 of algal culture was produced (Annex 9), dawn of 31% over the production of the season 1993–4. Since the production of seabream fingerlings, the only fish for which algae are produced, should result at least twice larger than in 1993–4, the management of the section is clearly going in the right direction of reducing production costs.
Toward the end of the production cycle, many mass cultures (bags and big bags) of Isochrysis crashed. The reason should probably be found in the new Sodium Nitrate used at that time, a commercial grade fertilizer employed in agriculture. After the introduction of a purer form of this nutrient, the problem disappeared.
Production protocol and culture medium were the same ones of the previous year with the exception of the main duties of the section head, here presented (Annex 10).
Also in this unit no change was made on the production system adopted the previous season.
Of the two rotifer strains available at the hatchery, only the small size strain was utilized for mass production, the other one (big size strain) being kept at test tube level.
Since mass cultured rotifers feed on baker's yeast only, the day before harvest yeast distribution is replaced by the enrichment diet Protein Selco (produced by INVE, Belgium) in order to improve the feeding quality of the rotifer for larval fish. The better suited DHA Protein Selco for its high content of docosahexenoic acid was not yet available in Turkey and its use is recommended for the next season.
At the date of February 25th a total amount of 203,2 billion rotifers was produced, 25.6% down last year output (Annex 11). However the quantity of rotifers actually delivered to seabream larvae (55,7 billion) was ⅔ higher than 1993–4 season. An overall better use of the subsection and a reduction in production costs is also due to the great reduction in the amount of discharged rotifers.
Average daily densities of rotifer reared in 3-m3 fiberglass tanks are listed in Annex 11 and compared with 1993–4 production. The difference of density at 5th and 6th day are probably due to the 24-hours delay in supply Protein Selco (a booster of rotifer fertility) to some tanks during the present season.
As in the previous season, no particular problem was found in the mass production of rotifers and no ciliate outbreaks occurred.
The instructions provided by the consultant the previous year (duty rota system, daily working schedule, tank daily counting, tank daily handling, rotifer vessel inventory, oxygen day and night monitoring, weekly consumption of expendable materials and cleaning procedures) have been followed in detail during the present season and are not reported here.
For this unit too no change concerning both protocol and rearing facilities has been introduced since last year.
Three different cysts have been used: Artemia AS (very small nauplii with high content of HUFA) for the first artemia feeding of seabream larvae, Artemia Bass Starter for the first feeding of seabass larvae, Artemia EPAC to produce enriched metanauplii. All cysts are manufactured by INVE, Belgium.
EPAC nauplii received a 24-hour enrichment before being fed to the larvae. Enrichment medium was Super Selco produced by INVE, Belgium. The more fitting DHA Super Selco was not yet available in Turkey and its use is recommended for the next season.
The daily leftover of nauplii and metanauplii, if any, was stocked in plastic bags and frozen. They represent a useful emergency food in case of failure of routinary production of artemia.
A complete outline of artemia production is not available since production was still going on at the time the consultant left. Results and average number of nauplii per gram of cyst up to the date of February 25th are quoted in Annex 12. The average number of nauplii per gram of cyst looks closer to what declared by the manufacturer, if compared with the 1993–4 results, thank to a greater experience in handling these productcs.
Average survival rate of metanauplii after 24-hours enrichment was a good 89.1% (Annex 12).
A total amount of 1.36 billion AF nauplii, 3.75 billion of BE nauplii and 6.82 billion metanauplii have been produced so far.
The instructions given last year (production of nauplii and enriched metanauplii, daily programme, daily working programme, daily inventory and weekly consumption of expendable materials) remain unchanged except for the form concerning the daily planning, whose improved new version is reproduced here (Annex 13).
The expendable materials consumed during the present season are listed in Annex 14, together with the foreseen needs for the next season (1995–6).
At its peak production the section was staffed by 12 people, organized as follow: one head, three workers for the algal subsection, five workers for the rotifer subsection and three workers for the artemia subsection. Seven workers were recruited on a temporary basis as soo as the different units started production (Annex 22).
Such a large staff is mainly due to cover the rota system (Saturday and Sunday) in absence of facilities for overtime.
