Proceedings of the Third World Fisheries Congress: Feeding the World with Fish in the Next Millenium—The Balance between Production and Environment

Population Genetic Structure of Indian Mackerel Rastrelliger kanagurta (Perciformes: Scombridae) in the Coastal Waters of Brunei

Zohrah Haji Sulaiman


Fish species diversity is known to increase toward the equator along a north–south axis. It is high in the tropical equatorial Indo-Pacific region, including parts of the South China Sea, the Sulu Sea, and the Sulawesi Sea around Borneo and beyond. However, as fish diversity increases, individual species abundance decreases. A total of 241 species from 81 families of marine fishes can be found in Brunei waters—an estimated total fish resource of 20,000 metric tons (Department of Fisheries 1993).

Unlike its neighbors in Borneo, Brunei Darussalam has a short 130-km stretch of coastline and a fishery limited to 38,600 km 2 (Loo et al. 1987). Fish consumption in Brunei is expected to increase to 9,334 metric tons in 2000 (Woo et al. 1987). At present, Brunei fish production is sustainable; however, the habitual consumption of specific fish types (e.g., Indian mackerel Rastrelliger kanagurta) poses a conservation concern because it may lead to an eventual decline in abundance and the loss of genetic diversity. The estimated stock of Indian mackerel, a popular food in Brunei, is 240 metric tons, and the current catch is about 9% of total landings (Department of Fisheries 1993).

To understand the genetic diversity of mackerels in Brunei waters, the genetic population structure was inferred from allozyme electrophoresis at three sites (Figure 1). These results can be used to formulate plans for the sustainable management of fish resources in Brunei Darussalam.