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Some biological aspects of sardine Sardina pilchardus and gilt sardine Sardinella aurita in the Zadar fishery ground – similarities and differences

This paper presents a comparison between the biological aspects of sardine Sardina pilchardus and gilt sardine Sardinella aurita which belong to the same clupeid family and share the same ecological niche. The aim of this study was to determine and compare sardine (N=1219) and gilt sardine (N=2033) length and age population composition, reproduction, growth, length-weight relationship and condition from March 2004 to January 2009. Samples were obtained from the catches of inshore (Virsko more) and offshore waters (Dugi Otok) in the Zadar area. Total lengths of sardine and gilt sardine varied from 13.0 to 19.0 cm and from 10.0 to 32.5 cm, respectively. Sardine age composition varied from one to nine years, and for gilt sardine from one to sixth years. Sardine and gilt sardine growth parameters were: L∞=20.5cm, K=0.46/year, t0= -0.5 year and L∞=34.2cm, K=0.36/year, t0= -0.9 year, respectively. The spawning of sardine began in October and lasted until the end of May when gilt sardine started to spawn. Sardine and gilt sardine total fat was from 1.1% (January) to 41.1% (August), and from 1.61% (July) to 7.9% (October), respectively. The moisture content in sardine and gilt sardine varied from 60.1% to 75.2% and from 69.7% to 79.0%, respectively. The fat content in the body was in inverse relationship with moisture and reproduction cycle in both species. Sardine length-weight relationship indicated negative allometry, whereas gilt sardine showed positive allometry. The condition coefficient for sardine was slightly higher (K=0.7771 ± 0.07) than for gilt sardine (K= 0.7081 ± 0.08).

sardine; gilt sardine; length and age composition; length-weight relationship; condition; Adriatic Sea

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