Optimal time of year and fishing methods for controlling exotic fishes in Longluan Lake, Taiwan

Abstract

Aim: This study aimed to identify the optimal time and fishing methods for removing exotic fishes, including striped snakehead (Channa striata), marble goby (Oxyeleotris marmorata), tilapia (Oreochromis spp.), three-spot gourami (Trichopodus trichopterus), and predatory carp (Chanodichthys erythropterus), from Longluan Lake, which is located in Kenting National Park in Taiwan. Methodology: The selected fishing methods included lure fishing, longline fishing, and fyke netting. A total of 2,284 individuals were collected over 12 removal events in Longluan Lake from 2017 to 2019. Among the collected fish, 1,640 fish represented exotic species, and 644 fish represented native species. Results: Among the collected fish, 1,640 fish represented exotic species, and 644 fish represented native species. Based on the results of this study, we suggest that the optimal time for managing exotic fishes is from April to June, when is the period representing lower water levels in Longluan Lake. For removing specific exotic fish in Longluan Lake, employing lure fishing in natural habitat is effective for C. striata and Oreochromis spp., utilizing fyke netting in natural habitat is workable for T. trichopterus and C. erythropterus, and operating fyke netting in artificial habitat is useful for O. marmorata. Interpretation: The habitat preferences and sampling efficiency of gears vary among exotic fishes, however, a combination of applying lure fishing and fyke netting in both habitat types will achieve the greatest advantage for controlling exotic fishes in the Longluan Lake.