Ayhan Yildirim

Age and growth properties of brown trout ( Salmo trutta L.) living in Kan Stream, upper Çoruh River, Turkey

Age and growth were analyzed for brown trout from the Stream Kan, upper Coruh River, from January 2001 to December 2001. Age varied between 0-7 years and the ratio of male to female was 1:1.05. Fork length and total weight for brown trout varied by 6.9-22.1 cm and 4.9-158.5 g for males, by 6.8-26.1 cm and 4.3-211.9 g for females, respectively. Fork length and total weight at the same age classes were not statistically significant between males and females. The highest specific growth rate occurred between age 1 and age 2 for both sexes. The von Bertalanffy equations were used to determine growth in length for both sexes and overall population separately. The growth parameters for males, females and overall population were estimated as L ∞ = 32.5 cm, K = 0.169, t 0 = −0.978, L ∞ = 36.7 cm, K = 0.139, t 0 = −1.065 and L ∞ = 35.9 cm, K = 0.147, t 0 = −1.002, respectively. Overall growth performance ( o ) suggested that difference between the growth of brown trout from Kan stream and those from some other populations was found not statistically significant.

Spatial and Seasonal Variations in Condition of Barbus plebejus escherichi in the Upper Çoruh River, Turkey

ABSTRACT Spatial and seasonal variations in somatic index (SI), condition (K), and environmental factors were investigated for Barbus plebejus escherichi from the upper Çoruh River basin from March 2000 to March 2001. Differences among values of juveniles, males, and females were not statisticaly different for K and SI. The maximum values of K and SI for adults occurred at the end of spring, whereas minimum values were observed in early summer and winter. Both K and SI of juveniles showed more stable pattern than those of adults. Condition and nutrition changed based on both gonad development and environmental factors.

Spatial and temporal variability of fish communities of the Upper Mississippi River, USA

Fish community structure, morphological characteristics, functional composition, and life history attributes in relation to three aquatic habitats, backwater shoreline (BWS), main channel borders (MCB), and side channel borders (SCB) in Pool 4 of the Upper Mississippi River System (UMRS) were assessed. Fish communities were sampled annually using standardized electrofishing techniques from 1994 to 2004. We found significant differences in community composition and abundance, and the clearest pattern was that diversity and fish community structure in BWS were different from those in both MCB and SCB. We also found morphological characteristics, functional composition, and life-history differences among the habitats, with fish communities from BWS having a number of different characteristics from both MCB and SCB. Temporal changes in fish abundance, community structure, morphological, functional and life-history attributes from each habitat may reflect both human impact and environmental factors on the Upper Mississippi River System.

Seasonal Changes in Condition and Gonadal Maturation of Brown Trout (Salmo trutta) in a Turkish Stream

ABSTRACT Condition factor and somatic index (SI) in brown trout (Salmo trutta) of the Stream Kan in northeastern Turkey varied seasonally in mature fish, with the highest values from May through September, while juvenile fish demonstrated less pronounced fluctuation in these characters. Gonadosomatic indices (GSI) for mature were highest in September for males and females, with values of 3.1 and 6.5% respectively. There was a significant p<0.05) positive correlation between GSI and K in both sexes, whereas SI correlated significantly (p<0.05) with GSI only for females. Water temperature was significantly (p<0.05) correlated with K, SI and GSI.

Life History Characteristics of Red Shiner, Cyprinella lutrensis, in the Lower Platte River, Nebraska, USA

ABSTRACT We investigated the life history characteristics of red shiner (Cyprinella lutrensis) from the lower Platte River spring of 2000 to fall of 2003. Most individuals (45.5%) were males, and the overall ratio of males to females was 1:1.74. The largest and heaviest fish were 59.0 mm fork length (FL) and 2.80 g (age 3) for females and 64.6 mm FL and 3.86 g (age 4) for males. Juveniles first appeared in June and ranged from 10.0 to 14.9 mm FL. While growth of juveniles was isometric, that of older fish was allometric. Condition factor varied seasonally with mean values for juveniles, males, and females were 1.08, 1.27, and 1.26, respectively.