Migration Characteristics of the Black Sea Trout (Salmo Trutta Labrax
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www.trjfas.org ISSN 1303-2712 Turkish Journal of Fisheries and Aquatic Sciences 11: 623-630 (2011) DOI: 10.4194/1303-2712-v11_4_17 Migration Characteristics of the Black Sea Trout (Salmo trutta labrax, Pallas, 1814) in the Eastern Black Sea Coasts and Streams Muharrem Aksungur1,*, Mustafa Zengin1, İlyas Tabak2, Nilgün Aksungur1, Ali Alkan1 1 Central Fisheries Research Instıtute, Pbox. 129, Trabzon, Turkey. 2 Directory of Food, Animal and Agriculture, Fisheries Department, Bursa, Turkey. * Corresponding Author: Tel.: +90.4623411053; Fax: +90. 462/3411152; Received 18 August 2010 E-mail: [email protected] Accepted 05 May 2011 Abstract This study was done on the main streams and coastal zone where Black Sea Trout is mainly distributed. Although fario ecotype has reproductive and alimental migration in streams, the marine ecotype migrates between freshwater and marine in certain seasons. According to the data obtained, the smolt individuals of the marine ecotype living in streams since spawn have smoltification in stream mouths in spring (March- May) and go to the sea first in their lives. Some fish have smoltification in autumn. Black Sea Trout spawner individuals pass to freshwater at a period between April and June and have egg maturation there by autumn. Their return to the sea following spawning is between November and December. The findings obtained indicate that Black Sea Trout population has been depleted due to overfishing and disruption of their habitats. As a result, a new management strategy and protection programmes are vital for the recovery of the stocks. Keywords: Black Sea trout, Salmo trutta labrax, Eastern Black Sea Region, migration characteristics (structure), ecotype. Türkiye’nin Doğu Karadeniz Kıyılarında ve Akarsularında Dağılım Gösteren Karadeniz Alabalığı (Salmo trutta labrax, PALLAS, 1814)’nın Göç Özellikleri Özet Bu çalışma Doğu Karadeniz’de; Karadeniz alabalığının (Salmo trutta labrax) yayılım gösterdiği önemli akarsularda ve kıyısal bölgede yürütülmüştür. Dere ekotipi akarsu ortamında mevsimsel olarak üreme ve beslenme göçü yapmasına karşın, deniz ekotipi tatlısu ve deniz arasında belirli mevsimde yoğunlaşan göç hareketinde bulunmaktadır. Elde edilen bulgulara göre; yumurtadan itibaren yaşamını akarsuda geçiren deniz ekotipine ait smolt bireyler, ilkbahar döneminde (mart- mayıs) akarsu ağızlarında smoltlaşmakta ve yaşamlarında ilk olarak denizel ortama geçiş yapmaktadır. Bir kısım balık ise sonbahar döneminde smoltlaşmaktadır. Karadeniz alabalığı ergin bireyleri nisan-haziran aylarında, akarsuya giriş yapmakta ve anaçların yumurta olgunlaşması sonbahar sonuna kadar tatlısu ortamında gerçekleşmektedir. Doğal ortamda üreme sonrasında tekrar denize dönüşleri, kasım-aralık ayları arasındaki bir dönemde olmaktadır. Elde edilen tüm bulgular değerlendirildiğinde, yıllardan beri Karadeniz alabalığı populasyonunun gerek aşırı avcılık, gerekse de yaşama alanlarının bozulması sonucunda yıpratıldığı ve stokların bu durumunun yeniden düzeltilmesi için yeni bir yönetim stratejisinin ve koruma programlarının hayata geçirilmesi gerektiği sonucuna varılmıştır. Anahtar Kelimeler: Karadeniz Alabalığı, Salmo trutta labrax, Doğu Karadeniz Bölgesi, göç yapısı, Ekotip. Introduction Sea populations with migratory characteristics are defined as another subspecies, Salmo trutta labrax Brown trout is a kind of salmonid with the (Slastenenko, 1956; Geldiay and Balık, 1996). ability to adapt the environmental conditions largely Behaviour differences, phenotypic, and to migrate (Okumuş et al., 2002). There are morphological, and ecological characteristics are the anadromous populations of migrating brown trout on key factors in identifying the species or subspecies of the north of 42o North Latitude (Elliot, 1994). Such brown trout populations. According to these criteria, populations are also found on the North East coasts of three different ecotypes of Salmo trutta labrax (natio Black Sea and in the streams flowing there. Migratory marina, natio fario, and natio lacustris) were found in individuals are called the Sea Trout. When they come the studies done in Turkey (Slastenenko, 1956; Tabak back for reproduction, they are two or three times or et al., 2001; Okumuş et al., 2002). more as big as the trout not migrated. Eastern Black Çelikkale et al. (1999) believe that brown trout © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey in cooperation with Japan International Cooperation Agency (JICA), Japan 624 M. Aksungur et al. / Turk. J. Fish. Aquat. Sci. 11: 623-630 (2011) is the member of ihtiyofauna in the waters of Turkey. İyidere, and Solaklı where The Black Sea trout is According to the environment and geographical heavily distributed, sampling studies were done at the region they adapt, there are stream trout, sea trout, coastal stations where these streams join the sea, and and lake trout ecotypes. According to Tortonose the study aimed to find out the migrational (1955), there is only Salmo trutta in the waters of characteristics of the Black Sea trout and its marine - Anatolia. There are the subspecies of Salmo trutta fario transition periods (Figure 1). labrax in the streams flowing to the Black Sea and At stream sampling studies, two different sizes Salmo trutta caspius in the Aras flowing to the (5 and 6.5 m. in diameter) and mesh sizes (17 and 22 Caspian Sea. mm) of casting net and electrofishing (Auseng brand Although sea trout (Salmo trutta labrax) is IG.00 Baujahr 11/84 type back portable shocker) were accepted as a subspecies of brown trout, it is probably used which can create 300-600-800 volt direct current an opportunist ecotype. It is only seen in the waters of performing better especially in small streams and side Eastern Black Sea Region. A similar ecotype is found streams. The sampling study was done by using cast- in the streams and on the coasts of Northern Europe net on the main streams and shocker on the side (Ireland, Scotland, Norway, Sweden). Unlike the streams. Fish traps were used to do the sampling Salmon, the Sea trout does not have true better in the migration periods of the fish. The number smoltification, and it moves to inshore brackish water of drift gillnet used and the approximate areas of the after it reaches a certain size (some 20-60 g) under field work, when the shocker was used, were recorded favourable conditions. However, unlike the salmon, it to identify the migration and fish movements in the does not wait until the general maturity and, when streams. necessary, it passes to freshwater frequently. As this In marine sampling studies, different types of local trout is specific to the Black Sea, it may not be coastal extension nets were used, eight of which were as sensitive as rainbow trout and salmon to 100-meter-long un-tangle net of 28 and 40 mm mesh temperatures above 22°C (Çelikkale et al., 1999). size, and two of which were 100-meter-long tangle In conclusion, this trout in the northeast part of net of 17 and 28 mm mesh size. Coastal extension our country can be called as “Black Sea trout” to nets upright to the coast were used in the area indicate its adaptation region and origin. However, it between Çağlayan and Kapistra rivers. Tangle nets is morphologically the same species as the trout in were placed in so called brackish water to close the Europe (Lelek, 1980; Chernitskii, 1988; Radchenko stream mouth completely for full detection of the and Aleyev, 1997; Solomon, 2000; Nikandrov and entry into the stream, and field works were longer in Shindavina, 2007; Vassilev and Trichkova, 2007). these periods. Fish were transferred to the laboratory in a chilled container, then measured (total length) to Materials and Methods the nearest millimeter. Fish measuring boards and sticks were used for the measurement of This study was done in the Eastern Black Sea morphometric characters. Weight measurements were and the region between Trabzon and Artvin, Turkey done with 0.01 g precision electronic scales after on the main streams of Kapistre, Çağlayan, Fırtına, draining the water and mucosal secretion of the fish Kapistre River B L A C K S E A Çağlayan River Fırtına River Rize Trabzon İyidere River Solaklı River Kaçkar Mountain N 3932 m Uzungöl 0 5 10 15 km Figure 1. Study area in the North-east Turkey Region. M. Aksungur et al. / Turk. J. Fish. Aquat. Sci. 11: 623-630 (2011) 625 with a dry cloth or blotter. As there are no other seasonal migration in freshwater. The larvae coming distinguishing features in the samples, morphometric out of the nests close to the upstream and in side and meristic studies, the individuals which had streams spend their first feeding period in these areas smoltification and lost their spots by turning silver but move to other places afterwards due to water were accepted as marine ecotypes (Chernitskiy, 1988; temperature, food abundance, and instinctual drive. Tabak et al., 2001; Okumuş et al., 2002). Age was All members of the Black Sea trout are believed to determined using the otoliths. Whether there was have the same behaviour patterns prior to some change in body fat and protein amounts of the smoltification as there are not any clear differences fish during their migration periods was sought to be between the ecotypes before smoltification. found out with the analysis of the samples caught at As to the findings, the members of fario ecotype different environments. mostly move along the coast and in a region 5 km inside the coast in winter (54.9%) and spring months (66.7%), and sampling was done during this period in Results the plump area of the marine water and stream water. In general, many animals need to migrate for That water temperature at coast is about 8°C in winter such reasons as the desire for proximity to feeding but 2 to 6°C in the higher parts, and the region of environment and natural habitat (summer and 1500-2000 m high is under snow are the factors wintering migrations) and suitable environment for affecting nutritional status and, thus, fish movement in rivers. The water temperature increases to 20 or reproduction.