Stock Assessment of Arius maculatus (Thurnberg, 1792) (Ariidae, Siluriformes) in Panguil Bay, Northwestern Mindanao

Abstract

Arius maculatus, commonly known as spotted catfish and locally known as Tambangongo, has a great potential as an aquaculture species, but there is very limited information known for the stocks in Panguil Bay. This study aimed to assess the wild stocks of A.maculatus, and make an inventory of the fishing boat and gears in two stations in Panguil Bay, namely: Tangub, Misamis Occidental and Baroy, Lanao del Norte. Length frequencies were analyzed to provide estimates of growth, mortality, exploitation ratio, and recruitment pulse of A. maculatus in the bay. A total of 589 boats (324 motorized boats and 265 non-motorized boats) were recorded from the sites. There were 473 units of 15 types of fishing gear used in the sites and 6 types of these were only used in catching A. maculatus. A total of 3,259 specimens were collected for 12 months from the sites. The aquatic habitat of A. maculatus from the two sites was characterized by a pH range of 7.9-8.1, temperature of 28.5-29.1°C, salinity of 13.31-15.9 ppt, dissolved oxygen levels of 4.0-5.41 ppm, and total suspended solid values of 0.1-0.6 g/L. Reproductive biology analysis indicates that eggs start to mature from October to December, then spawning starts from January to March, and the fish fry recruitment starts in April and May. A. maculatus can grow up to 98.95 cm with an asymptotic length of 98.86 cm (K value = 0.35) equivalent to asymptotic weigth of 8,750 g. Mortality Z = 0.99, with natural mortality M = 0.67 and fishing mortality F = 0.33. This study revealed that A. maculatus in Panguil Bay is not over-exploited since the exploitation rate (E = 0.33) is minimal and large individuals can still be collected from the field.