Length-weight Relationships of Four Commercially Important Fish Species in Indonesia

Length-frequencies and length-weight relationships of the four economically important fish species Encrasicholina heteroloba (Rüppel 1837), E. punctifer Fowler 1938, Katsuwonus pelamis (Linnaeus 1758) and Rastrelliger kanagurta (Cuvier 1816) were analysed to assess the condition of the respective stocks. Length-frequency data were analysed to estimate the theoretical maximum size of fish in a stock (L∞) and the coefficient K, indicating how fast fish reach that size. A power model approach was used with length and weight data to estimate the condition factor a and allometry coefficient b. The two anchovy species (Encrasicholina) showed similar values with = 9.45 cm, K = 1.10 year-1, a = 0.00672 and b = 2.919 for E. heteroloba and L∞ = 10.78 cm, K = 1.00 year-1, a = 0.01031 and b = 2.871 for E. punctifer. For both species, the allometry coefficient was below 3, implying allometric growth. The estimated parameters for the skipjack tuna K. pelamis and the Indian mackerel R. kanagurta were L∞= 72.32 cm, K = 0.38, a = 0.0395 and b = 2.766 and L∞= 27.83 cm, K = 0.92, a = 0.00556 and b = 3.216, respectively. All data were collected in Pasir Kendang, Padang, West-Sumatra in 1993 and 1994.