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Growth and condition of endemic trout Salmothymus obtusirostris in a Dalmatian river Jadro

Soft-muzzled trout (Salmothymus obtusirostris) is the endemic species in the Dalmatian division of Euro-Mediterranean sub region. Its endangered subspecies S.o. salonitana inhabits only two short rivers &#8211; the Jadro, which is the original habitat, and the Žrnovnica, where it was transferred about 25 years ago. The growth and condition of this fish during the post-spawning period in the Jadro river was studied. The specimens caught ranged from 8 to 29 cm in standard length and from 9 to 350 g in weight. The growth in standard length could be expressed by the following expression: Lt = 34.99 (1-e-0.3467 (t-0.0041)). The overall growth performance was 6.06, which is very similar to other populations of this species, indicating the reliability of the growth curve, as this parameter has minimum variance within the same species. The length - weight relationship expectedly showed negative allometric growth with a low b-value of 2, 76 (W=0.03.L2, 76 ; r=0.994 ; p<0.01) and also negative relationship between condition factor and standard length (CF=1.964&#8211; 0.023 SL ; r =-0.537 ; p<0.05). The fish from this river grew somewhat smaller in length and weight than in the other river Žrnovnica. That is probably a consequence of the fact that the river Jadro flows through very urban suburb of the Dalmatian largest city Split, where the most of the river&#8217; s bed is regulated. There is also higher fish species competition in this river. Hence, the protection of this endangered endemic species is of the utmost importance.

Salmothymus obtusirostris; Growth; Croatia

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