Some Reproductive Features of Brown Trout (Salmo trutta macrostigma Dumeril, 1858) and its Larval Development under Culture Conditions

In this study, some reproductive features of wild brown trout (Salmo trutta macrostigma Dumeril, 1858) populations in Aksu, Eşen, Alara and Alakır streams in Turkey were examined and larval development was also investigated in two different culture conditions established on Eşen Stream (Trial 1) and at the Research Unit of Eğirdir Faculty of Fisheries at Süleyman Demirel University (Trial 2). The spawning time of brown trout in Aksu Stream in the second half of December was different from other localities, at the end of the January and in the first week of February. The gonadosomatic index values ranged between 17.5 and 19.8%, the mean egg diameters of females in all localities were between 3.51 and 3.78 mm (P<0.05). The incubation lasted for 370 and 390 day-degree (10.5-10.9 ºC), and the yolk-sac of the larvae was absorbed in 28 and 32 days in trials 1 and 2, respectively. The mean live weight (LW), total length (TL) and mouth widths (MW) in start-fed larvae and those with absorbed yolk-sac in both trials showed non significant differences before the 25th day of the trial. On the 25th, 50th, 75th and 100th day, the mean LW, TL and MW values of the larvae in the trial 1, however, ranged from 108.30 to 547.30 mg, 23.05 to 42.74 mm and 2441 to 3993 µm; whereas these values in trial 2 were 91.30 to 366.60 mg; 20.04 to 35.18 mm and 2123 to 3386 µm, respectively. The differences among the mean values were significant (P