by Daphne Stephanou,
Fisheries Officer A
Dept. of Fisheries
I. FISHERY BIOLOGY AND MANAGEMENT
1. Recreational use of dams
Angling in dams continued to be the main attraction and contributor to the recreational use of dams. The Cyprus Tourism Organization covered the expenses for the provision of facilities to the anglers and general public at the heavily fished dam of Xyliatos, according to the suggestions of the government technical committee for the recreational use of dams.
In 1986 2,345 yearly angling licences were issued by the Department of Fisheries and in 1987 their number increased to 3,2555. About half of them were issued for trout angling. Every year about 20,000 fingerlings of trout enrich the mountain dams for this purpose. There are indications that the experimental cage culture of trout in dams affected positively the growth of the trout which are stocked for angling.
3. Fish populations in dams
In 1986 the water quantities stored in the dams were small, especially in summer because of the draught and fish population in several dams perished.
The red swamp crayfish (Procambarus clarkii) continued to flourish in Athalassa dam and it was introduced in other two dams. The species Astacus astacus was traced in Lefkara dam. The mother stock was originally imported from Denmark ten years earlier and disappeared since then.
4. Import of new species
In late 1987 250 fingerlingsof pikeperch were imported from Hungary to establish local populations and be used for angling in Kourris dam, the largest on the island.
5. Management of dams for the production of other species
Small lowland dams were used for the production of young fish for the enrichment of dams for angling or for the production of mosquito fish, carp and goldfish which were given to the public for the control of mosquitoes and algal growth and for ornamental purposes. In addition to them about 117,200 tropical fish were imported in 1986–1987, mainly from Singapore, for ornamental purposes.
II. FISH CULTURE AND DISEASES
1. Culture of Salmonids
1.1 Experimental cage culture of trout in dams.
In late 1985–May 1986 the experimental rearing of trout was undertaken in Xyliatos dam (capacity 1.22 million tons). This resulted in the production of 2.5t of trout. In December 1986–July 1987 the experiment was intensified in order to define experimentally the “carrying capacity level” of the dam for trout production that would have no negative effects on the other uses of the water i.e. irrigation and angling. The experiment also expanded to Palaechori dam (capacity 0.62 million tons).
The experiment was highly successful. Yielding 5.5 tons from the first dam and 2.5 tons from the second. It was proved that the dams could be utilized seasonally for the production of trout In late 1987 the culture of trout in cages, on commercial basis, commenced in Xyliatos dam, after all legal formalities were overcome. The experiment expanded to the lowland of Evretou dam (capacity 25 million tons).
It is expected that cage culture of trout in dams will offer the solution for the increase of trout production in Cyprus, since the water quantities available for land-based intallations are limited.
1.2 Trout culture
Shortages of trout were seasonally very acute, as the local production did not meet the demand. The government hatchery gave to the private sector for hatching and growing 215,000(1986) and about 376,000 (1987) eyed trout eggs, alevins, fingerlings and young trout. Practically all the trout produced in the hatchery are “all female” trout.
1.3 Salmon culture
Antlantic and coho salmo were under experimental culture in the government Experimental Freshwater Fish Culture Station at Kalopanayiotis.
1.4 Sea trout culture
The seasonal (winter-spring) production of small quantities of sea trout continued in a commercial marine farm. The trout, which is actually rainbow trout fattened in brackish water, secured high prices in the local market.
2. Tilapia culture
The same farm continued the culture of hybrids of Tilapia (Tilapia aurea, T. nilotica) in brackish water. The production of Tilapia is undertaken as an interim product until the production of seabass and seabream starts.
3. Goldfish culture
A small dam is being leased to an individual for the extensive culture of goldfish for ornamental purpose. The production of goldfish at low cost in dams is expected to reduce the imports of this species.
4. Eel culture
Glass eels, imported from the U.K., were used for experimental rearing on intensive basis. The work centred mainly on weaning techniques. Weaned eels are expected to be distributed to interested individuals in addition to those used for the stocking of dams. Their experimental rearing in seawater is planned to take place soon at the new Experimental Marine Fish Culture Station at Meneou.
III. FISH AND POLLUTED WATER
The water of the dams where trout cage culture was taking place was monitored. The relevant regular sampling and water analysis refered mainly to the concentration of phosphorus, nitrogen, pH, dissolved oxygen, BOD5 and suspended solids. Also Secchi disc measurements and the water colour were recorded. The water guality remained at high levels, allowing good growth rate and food assimilation throughout the culture period.
The effluents of trout farms were monitored, as well as the water of Polemidhia dam where eutrophication occured. This is suspected to be due to the seepage of the primary treated effluents of a water treatment plant which was enhanced by transportation to the dam of high quantities of nutrients due to the autumn rains. In September, 1986, occured mass die-off of algae in the eutrophic Polemidhia dam. The eutrophic water of the dam were depleted of oxygen due to the small water quantity and the prevailing high temperatures. The water was depleted of oxygen and mass mortality of the most sensitive species occured. The problem was successfully faced with the continuous pumping of air into the dam for several days. The utilization of compressed air for the amelioration of the water quality of the dams, which is practised in several dams for water use reasons, affects positively the fish population.
Analysis of dams water were carried out in order to create an inventory of the quality of the inland waters for future use in inland waters management projects.
IV. PRODUCTION STATISTICS
|1. Rainbow trout||53t||45t|
|3. Goldfish||22,000 fish||12,000 fish|
No data exist on the quantity of fish which is produced in the dams used for angling.
V. BIBLIOGRAPHIC REFERENCES
Demetropoulos, A., 1986 Annual Report on the Department of Fisheries and the Cyprus Fisheries for the year 1984. Department of Fisheries, Nicosia, Cyprus.
Stephanou, D., 1986 The cage culture of rainbow trout (Salmo gairdneri irideus) in Xyliatos dam. Department of Fisheries, (internal report), Nicosia, Cyprus.
Demetropoulos, A., 1987 Annual Report on the Department of Fisheries and the Cyprus Fisheries for the year 1986. Department of Fisheries, Nicosia, Cyprus.
Nicosia, 16 January, 1987
Our Ref. 140/11
Our Tel. 40/3526