The multi-species competition model of Bali sardinella and fringescale sardinella in Pati Regency, Indonesia

Pelagic fish commodity is a leading marine fishery commodity in Pati Regency including fringescale sardinella fish (Sardinella fimbriata) and Bali sardinella fish (S. lemuru). Both types of fish are plankton eaters. Therefore, it is suspected that there is a multi-species relationship (competition) between Bali sardinella and fringescale sardinella. This study aims to develop the multi-species model (especially the competition model) of Bali sardinella and fringescale sardinella in Pati Regency. Time series data from 2008 to 2017 related to fisheries production and fishing effort data were used in this study. Furthermore, in-depth interviews with key stakeholders and field observation at Bajomulyo fishing port were conducted. The results of this study prove that there is a competition, biological interaction, between Bali sardinella and fringescale sardinella. The production function of Bali sardinella is influenced by the amount of purse seine (as the fishing effort) and the production of fringescale sardinella. The production function of fringescale sardinella is influenced by the number of purse seine (as the fishing effort) and the production of Bali sardinella. The optimal effort for Bali sardinella production is 191 units of purse seine and the optimal effort for fringescale sardinella production is 176 units of purse seine. The management of Bali sardinella and fringescale sardinella resources for capture fisheries cannot be separated. Several possible policies can be used to control the exploitation of Bali sardinella and fringescale sardinella resources, including minimum size, protection of spawning grounds, protection of nursery grounds, close season, quotas, and taxes