Reproductive biology of Hilsa Shad Tenualosa ilisha (Hamilton, 1822) in Labuhanbatu waters, Northern Sumatra, Indonesia: a basis for fishing management.

Abstract

Hilsa shad Tenualosa ilisha, locally known as terebuk fish, is found in Labuhanbatu waters, Northern Sumatra, Indonesia. The population of this species has decreased significantly due to overexploitation. Despite its commercial importance, there is currently no information on the reproductive biology of this species in the region. This information is important for the development of sustainable fishing and conservation strategies. Therefore, this study aimed to examine the reproductive biology of T. ilisha in Labuhanbatu waters, Northern Sumatra, Indonesia. Observations were conducted for a year, from January to December 2019, in the Barumun River, Labuhanbatu Regency. Fish samples were caught using gill nets with three mesh sizes (2, 3, and 4 inches) operated by a boat. The samples were analyzed for sex, gonad development stage (GDS), gonadosomatic index (GSI), and fecundity. A total of 1,914 fish were recorded, including 1,428 (74.5%) males and 486 (25.4%) females. Samples with GDS III and IV were predominant among both males and females throughout the year. The highest GSI was recorded in January and March with values of 1.6% and 11.3%, respectively. The fecundity of female fish ranged from 81,450 to 245,267 eggs/fish, whereas the number of males was predominant in every month of sampling. Tenualosa ilisha spawns throughout the year, with the peak spawning season occurring from January to March. Strengthening the management implications of seasonal fishing bans during the spawning peak (January-March) may protect females.