K.Seyhan, Energyonline #1, 2009

Transcription

1 THE EFFECTS OF HABITAT RESTORATION AND HYDROELECTRİC DAMS ON THE SALMON (SALMO TRUTTA LABRAX) POPULATION OF THE SMALL STREAMS IN THE EASTERN BLACK SEA REGION OF TURKEY K. SEYHAN, E. MAZLUM, D. TURAN, S. ENGİN, G. DALGIÇ, H. İMAMOĞLU Be received Salmon is called the king of the fishes in the world. It's been told that the scientific name is given by Julius Caesar, who heard something about a fish which had the ability of jumping up rapids. That's why he named the fish Salmo (the jumper). Black Sea Trout, Salmo trutto labrax are born in fresh water; in small streams, and then migrate out into the Black Sea to feed. During their migration into the streams to spawn they are subject to sport by anglers, fisherman and man-made hindrances as well as construction of hydroelectric power generation and feasibility studies conducted in the Eastern Black Sea region of Turkey. A classic example of the mass destruction of a population of salmon recently caused by man-made hindrances occurred on the Çağlayan and Fırtına Streams in the Eastern Black Sea, Turkey where no detailed information is available in most cases. In this report, therefore, a detail account is to be given on the life history of Salmo trutto labrax in the Eastern Black Sea and problems that labrax faced and recommendations to overcome will be highlighted. Key words: stream, ecotypes, marine, fario, spawning period, migration. INTRODUCTION Black Sea Trout, Salmo trutta labrax is an endemic species inhabiting in the small streams of the Eastern Black Sea of Turkey, from Giresun, a small province, to the Georgian border. They are, as well known, an anadromus species and migrate into the streams for spawning in the spring, starting in March and lasting until May (Edwards D.J.and Doroshov S., 989; Anon., 2). The detail studies on S.t.labrax in this area back about -5 years and mainly focused on bioecological characteristics (Anon., 2; İmamoglu H., Baysal A. and Kutrup B., 999). Recently a fair investigation has resulted that there is no a genetically difference among S. Trutta labrax populations of different small streams in the South East Black Sea (Anon., 2), but two ecotypes: marine and fario. During their migration, up and down streams, they face a number of man made obstacles resulting serious reduction in this endemic trout populations in the area.

2 THE LIFE HISTORY OF THE LABRAX IN THE BLACK SEA Growth There are two ecotypes in the area; Marine and Fario. The growth and length-weight relationship are provided in figure. L & W relationship of Salmo trutta labrax Black Sea Trout growth in different habitats 7 Weight (g) 8 6 Marine ecoype Fario ecotype Marine ecotype Fario ecotype Age (years) Fig.,a. Length and weight relationship of Salmo trutta labrax in the Eastern Black Sea of Turkey. Note that there is not much difference in terms of length-weight relations between two ecotypes. Fig.,b. Growth curves for two ecotypes of Black Sea Trout. Fario ecotypes shows a significant different growth than that of marine once in the area (both graphs taken from Anon, 2). Maturity Sexual maturity of Black Sea Trout, fario ecotype,2 Sexual maturity of marine ecotype Black Sea Trout,2,8 % maturity,8,6,4 % maturity,6,4,2, , ,2 Fig. 2. Sexual maturity of two different ecotypes in the Black Sea Trout populations. Note that Lengths at which 5 % of trout are mature in two ecotypes, fario and marine, are approx. 5 and 47 cm respectively, and differ significantly (taken from Anon, 2). 2

3 Spawning Period Spawning period for fario ecotype starts in September, but intensively takes place from October to November. However marine ecotype spawns mainly in November, in other words their spawning period lasts less than that of fario ecotype in the area. Fecundity is also estimated as about 25 eggs per kg fish for both fario and marine ecotype. Migration Fario ecotype migrates only up and down in the streams depending on the water temperature and food availability. When the temperature drops down to below in winter they migrate to down. They are even occasionally caught in estuary as well. Marine ecotype however starts migrating into the sea in March-June when they are between 8-25 cm depending on if they become smolt in spring or autumn. They tend to stay at sea -3 years. When they become sexually mature they start going upwards into the streams again in spring. PROBLEMS The streams in the area are rich in O 2 content and have been clean up to now. Therefore this area is the home for Salmo trutta labrax, Black Sea trout. It is very important not for economic considerations but is important from the ecological point of view. The area is also very preferred for the eco-tourism. On the other hand, it should be noted that this has not received attention enough by all means therefore have faced a number of serious problems affecting wild life in the marine and freshwater ecosystem. Labrax populations have 2 main problems to overcome: Fishing: Although fishing in the fresh water by all means in all seasons is prohibited in the area, fishing pressure on the stocks have never been ended, end even over fishing is in due. Local people are very fancy to catch them using gill net in the estuary since trout catchability is very high especially during their migration into the streams. Even dynamite is also used illegally. In the streams however, net and special designed pinter for trout fishing have been in use. River betterment works: This area face flood resulting human life as well, therefore their catchment area needs to be improved. This has been the case for Çağlayan and Fırtına streams, forgetting migration pattern of the Black Sea Trout, the construction had been in progress for all the year unfortunately. The figure shows different views from Caglayan and elsewhere. This construction works have not let the Black Sea Trout migrate into the streams and vise-versa since the construction has been in progress for more than 5 years. Pollution: although pollution is on small scale for the time being, a great danger is ahead if housing sewer system is not established properly for the all villages in the stream basins in the area. A high way construction on the Eastern Black Sea coast has also been in progress and for the needs raised in the area rocks and sands in the streams are removed and brought into the sea to make a road. Last but not least treat for the salmon populations is feasibility studies and construction of the hydroelectricity power generation in progress. 3

4 a b Fig. 3,a. Cağlayan streams with just after flooding (b) a b Fig. 4,a. A Scottish river having a dam together with a water pathway letting Scottish salmon migrate up and dawn; Fig. 4, b. Çağlayan after betterment works completed CONCLUSION AND RECOMMENDATIONS Environmental consideration should be in priority for fresh water as well as for sea to save the wild life all apart from trout populations in the area. Just a little known about migration and homing of Black Sea Trout, special attention should be paid to outline migration pattern of especially marine ecotype. Dam constructions for the electricity in mind look a major treat for the Black Sea Trout if necessary measurements are not taken into the consideration. All streams in the area are subject to over fishing. It is clear that prevention measures taken sometime don t work properly, therefore local fisherman and people should be informed adequately and more serious measures should be taken afterwards. More importantly culturing possibilities of Salmo trutta labrax should be more intensively studied and plantation into the streams should be in priority as well. 4

5 REFERENCES Edwards D.J.and Doroshov,S., 989, Appraisal of sturgeon and sea trout fisheries and proposals for a rehabilitation programme, FAO-Turkey Tech.Coop. Programme, FAO W/T7449 Rome, 38 p. Anon., 2, Bioecological characteristics and culture of Black Sea Trout, Salmo trutta labrax, Research project, grant no:tagem/haysud/98/2//7,. TC Tarım ve Köyişleri Bakanlığı, Trabzon Merkez Su Ürünleri Araştırma Enstitüsü Müdürlüğü yayınları. 8 p.(in Turkish, English abstract provided). İmamoglu, H., Baysal, A.and Kutrup B., 999. Ikizdere ve Kollarinda yaşayan Salmo trutta labrax ın bazı büyüme özelliklerinin belirlenmesi. KTÜ Fen Edebiyat Fakültesi yayınları (Turkish). Kadir SEYHAN, Karadeniz Technical University, Faculty of Marine Sciences, Çamburnu-Trabzon, Evren MAZLUM, Rize University, Faculty of Fisheries, Davut TURAN, Rize University, Faculty of Fisheries, Semih ENGİN, Rize University, Faculty of Fisheries, Göktuğ DALGIÇ, Rize University, Faculty of Fisheries, Hasan İMAMOĞLU, Rize University, Vocational School, Dept. of Fisheries and Aquaculture 5