Growth and reproduction of chub population were investigated in Lake Yeniçağa, Bolu, Turkey. A total of 729 chub were sampled between March 2009 and July 2010. The age of sampled chub ranged from 1+ to 8+. According to the sex ratios of female and male (2.98:1.00), female was dominant in this population. For all individuals, von Bertalanffy growth parameters were L∞ = 36.88 cm, W∞ = 713.01 g, k = 0.248, t0 = -1.278 and b = 3.109. The average condition factor (CF) was 1.48. The lengths at first sexual maturity of female and male chub were 19.2 cm and 15.3 cm respectively. Reproduction period was between the months April to July, egg diameter 1.29 mm and average egg yield were determined to be 25349 unit/individual. The minimum landing size and prohibition season of fishing of chub, which was regulated by the Republic of Turkey Ministry of Food, Agriculture and Livestock were compatible with this study.

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Abstract:Epilithic algae are very important for the nutritional chain for lotic ecosystems. It is also included in the group that should be examined in order to determine biodiversity in aquatic ecosystems. For this purpose, this study has been carried out in the Yağlı, Mülk, Sırakonaklar and Koçunboğazı streams, which are located in the Coruh Basin. The streams' altitude of (1730-2350 m), depth of (13.0 -45.6 cm), water temperature of (6.20 -8.10 °C), dissolved oxygen of (8.8-9.4 mg l −1 ), pH of (6.60-8.10), nitrite of (0.009 -0.020 mg l −1 ,) and nitrate values of (0.50 -2.26 mg l −1 ,) were determined. In the study, 17 taxa belonging to the Bacillariophyta group were detected. Cymbella affinis Kütz, Encyonema minutum (Hilse) D.G. Mann, Hannaea arcus (Ehrenberg) R.M.Patrick and Ulnaria ulna (Nitzsch) Compère species were found to be distributed throughout all streams. In particular, it was determined that Hannaea arcus (Ehrenberg) R.M.Patrick species was the highest quantitatively in the Yagli stream. It was determined that the streams have an oligotrophic character in terms of water quality and epilithic algal composition.Keywords: Environment, Epilithic, Stream, Diatom, Coruh Basin Introduction:

This study aimed to determine some biological parameters such as age, growth condition factor, length-weight relationship, and sex ratio of Beysehir daces (Squalius anatolicus) sampled from Oymapınar dam lake between March 2016 and February 2017. A total of 422 Beysehir daces were sampled using 100 m long and 2,5 m depth monofilament gillnets (20, 30, 40, 50 mm mesh size) from the Oymapınar dam lake. The ages of the Beysehir daces ranged between II and VIII. The oldest age for females was VIII and VII for males. The sex composition of the sampled fish showed that 47.39 % of the samples were females and 52.61% were males. It was determined that the fork lengths of the females varied between 20.0 cm and 55.1 cm and the weights varied between 93.37 g and 2307.88 g. Von Bertalanffy growth parameters for all individuals were determined as L∞ = 60.57 cm, W∞ = 3260.79 g, k = 0.160 and t0 = -0.877 The b values of the length-weight relationship for females, males and all individuals were 3.202, 3.185 and 3.194, respectively. The average condition factor (CF) for all individuals was calculated as 1.278 ± 0.006. The findings of this study will aid in the development and implementation of longterm management plans for the Beysehir dams in this lake, as well as serve as the foundation for future research on the biological parameters of fish living in this lake.

ÖzetYeniçağa Gölü'nden Mart 2009-Temmuz 2010 tarihleri arasında örneklenen 291 kadife balığının ölüm oranları incelenmiş, stok büyüklüğünün tahminiyle stoktan en verimli şekilde faydalanılabilmesi için uygun av gücü ve ürün miktarı belirlenmiştir. Toplam ölüm katsayısı (Z) 0,55 yıl -1 , doğal ölüm katsayısı (M) 0,46 yıl -1 , balıkçılık nedeniyle olan ölümlerin katsayısı (F) 0,09 yıl -1 , stok işletme oranı (E) 0,16 yıl -1 , yaşama oranı (S) % 57,86 bulunmuştur. Yeniçağa Gölü'nden araştırma dönemi boyunca 8344 adet (4350 kg) kadife balığının avlandığı, bir av döneminde gölde 130204 adet (43317 kg) kadife balığının bulunduğu hesaplanmıştır. Bu stoktan en verimli şekilde yararlanılabilmesi için mevcut av gücünün % 203 artırılmasıyla 8793 kg ürün elde edilebileceği saptanmıştır.Anahtar kelimeler: Bolu, kadife balığı, Tinca tinca, ölüm oranları, stok tahmini, Yeniçağa Gölü. Mortality Rates and Stock Assessment of Tench (Tinca tinca L., 1758) in Lake Yenicaga (Bolu-Turkey) AbstractThe mortality rates of the 291 tench sampled from the Lake Yenicaga between March 2009 and July 2010 were investigated, by the estimation of stock size, suitable fishing effort, yield and biomass determined to utilize most efficient way. Total mortality (Z), natural mortality (M), and fishing mortality (F) coefficients, stock exploitation (E) and survival (S) rateswere calculated as Z= 0.55 year-1, M= 0.46 year-1, F= 0.09 year-1, E= 0.16 year-1, and S= 57.86%, respectively. During the research period 8344 (4350 kg) tench which were fished from Lake of Yenicaga, was calculated that in one fishing season 130204 (43317 kg) tench were found in the lake. To benefit from this stock most efficiently, by increasing the current fishing effort 203% were determined that 8793 kilos of yield could be obtained.Key words: Bolu, tench, Tinca tinca, mortality rates, stock assessment, Lake Yenicaga. GİRİŞÜlkemizde çok sayıda doğal göl, gölet ve baraj gölü bulunmasına rağmen avcılık yoluyla elde edilen içsu ürünleri 2014 yılı itibariyle 36.134 ton olarak gerçekleşmiştir (Anonim, 2015). Ticari avcılık yapılan birçok göl ve gölette aşırı avcılık söz konusu olmakla birlikte, içsulardaki istihsal alanlarında, stok tespiti yoluyla stoktan avlanılması gereken en yüksek sürdürülebilir ürün belirlenebilmekte, balık popülasyonları üzerine olan aşırı veya yetersiz avcılığın önüne geçilebilmesiyle mevcut üretim miktarı artırılabilmektedir. Balıkçılığın iyi yönetilebilmesi için, stok tahmini çalışmaları ile birlikte, yaşlılık, predasyon ve hastalık gibi nedenlerden ileri gelen doğal ölümlerin ve avcılık yoluyla stoktan ayrılan balık miktarlarının da belirlenmesi gereklidir.Ülkemizdeki ticari ve sportif balıkçılığın yapıldığı doğal göllerden biri de Yeniçağa Gölü olup birçok göçmen kuşu barındırması, çevresinin yöre halkı tarafından mesire yeri olarak kullanılması ve turba yatağı olması ile önemli bir sucul sistemdir. Göldeki