Biologycal aspect of Indian Scad (Decapterus russelli) (Ruppell,1830) caugth in Bali and Madura Straits, and Southern waters of East Java, Indonesia

Abstract

The way to determine whether the Indian scad (D. russelli) comes from the same stock or not, is using estimation morphology and biology. The kinship of D. russelli in the three waters is not too close, and it has a very distant kinship with D. macarellus and D. kurroides. D. russelli and D. macrosoma in Bali Strait and South Java is close. The results of the analysis show that two of five components of the characteristic morphometric factor of D. russelli in the three waters have a character differential percentage of 37.73% and similarity of 62.27%. The growth rate obtained (L∞) from Bali Strait is 26,16 cm FL, the growth rate coefficient (K) is 0,63 per year, and (t0) is -0,20 years length maturity (Lm) male 13,9 cm FL and female 16,1 FL. The type of foods that is found are 12 phylums. The growth rate obtained (L∞) from Southern Waters of East Java of 28,28 cm FL, the growth rate coefficient (K) is 0,83 per year, and (t0) is -0,18 year, length maturity (Lm) male 15,3 cm FL female 16,7 cm FL. Type of foods that is found are 6 phylums. The growth rate obtained in Madura strait has an asymptotic length (Loo) 24,63 cm FL ; K 0,63 per year and t0 -0,27 year. Indian scad is a carnivore with the main food is Zooplankton (61%). using the morphological and biological approach, it is found that the D. russelli caught in the three waters come from a different stock.