Thornfish Research Articles

Diversification, Organoleptic and Chemical Quality Characteristics of Processed Products Based on Thorn Fish (Hexanematichthys sagor) Smoke

Diversification, Organoleptic and Chemical Quality Characteristics of Processed Products Based on Thorn Fish (Hexanematichthys sagor) Smoke

Faktor Kondisi dan Hubungan Panjang Berat Ikan Duri (Hexanematichthys sagor)

This study aims to determine the condition factors and the relationship between the length and weight of thorn fish in the waters of the Barumun River, Labuhanbatu, North Sumatra. The method used is the sampling method. The results showed that the total number of samples obtained during the study was 41 fish with a total length of thorn fish that was 20.8 cm - 25.1 cm and the average length of fish caught was 23.41 cm. Meanwhile, the weight of thorn fish is 72 g to 126 g, and the average fish weight is 106.2 g. In conclusion, the growth pattern of thorn fish in the Barumun Labuhanbatu River, North Sumatra, is a negative allometric. The condition factors in thorn fish indicate that the Barumun River environment supports the growth of thorn fish and has a balanced status.
 Keywords: Condition Factor, Hexanmatichthys sagor, Length Weight

Thorn fish Terapon jarbua (Forskål) predation on juvenile white shrimp Penaeus indicus H. Milne Edwards and brown shrimp Metapenaeus monoceros (Fabricius): the effect of turbidity, prey density, substrate type and pneumatophore density

A series of laboratory experiments was conducted at Inhaca Island Marine Biological Station, Mozambique, in order to assess the separate effects of turbidity, prey density, substrate type, pneumatophore density, and the combined effects of turbidity with the latter three, on rate of predation by the thorn fish Terapon jarbua (Forskål, 1775) on white shrimp Penaeus indicus and brown shrimp Metapenaeus monoceros. Significant interactions between turbidity and the other three factors on shrimp predation for both prey species were detected. Regardless of prey density, increasing turbidity decreased predation on P. indicus, but not on M. monoceros, for which increasing densities reduced the protective effect of turbidity. Increasing prey density increased predation on P. indicus in clear water, and increased predation on M. monoceros in low and high, but not in intermediate turbidity or clear water. The presence of a substrate suitable for burying decreased predation on M. monoceros in clear water, but not in the turbidity levels used. In clear water, solely sandy-shell substrate afforded protection to P. indicus, while in turbid water, no substrate offered significant protection and muddy substrate even increased prey vulnerability to fish probably as a result of increased preys' locomotor activity. Raising pneumatophores density seems to lower the protective value of turbidity for both species. In clear water, only low and high structure density provided a deterrent effect on predation on P. indicus; in turbid water, intermediate and higher structure density increased predation. Increasing structural complexity reduced predation on M. monoceros linearly in clear water; but in low turbid water it increased. In high turbid waters, the increase was only significant in intermediate pneumatophore density. High structural complexities impair the pursuing capacity of fish and thus decreased predation rates. The results indicate that the effective provision of shelter of different habitats depends not only on the various environmental parameters analysed, but also on the way they interact and on the behaviour of prey and predator as well.