Fishing Enclosure as a Simple Approach to Stimulate Spawning Success of Tenualosa ilisha (Hamilton, 1822) in Bangladesh

Abstract

The study was intended to assess the impact of fishing enclosure during the peak breeding time of hilsa, Tenualosa ilisha on its breeding success. During the last peak breeding season of hilsa (October 4-25, 2021) a comprehensive investigation was attempt to evaluate the impact of fishing enclosure by “MV Rupali Ilish” research vessel, speedboat and experimental fishing net were deployed to demeanor a rigorous investigation in and around the spawning grounds areas (about 7,000 sq km, including Moulvirchar, Monpura, Dhalchar and Kalirchar). Additionally, data were also assumed from landing stations (via terrestrial cruises) near the spawning ground areas and other hilsa prone region of Bangladesh. The percentage of spent hilsa (locally called pite) and oozing hilsa were monitored following a standard protocol. Among all the hilsa captured in and around the spawning grounds, the proportion of male and female were 16-41% and 85-97%, respectively of the total catch, suggesting a male and female sex ratio (1:2.3). The rate of breeding success in 2021 was 51.76% i.e., 51.7% hilsa successfully participated in the breeding process which was 103.52% higher than the base year (2001-02). The approximate number of fertilized eggs in 2021 was 7,86,314 kg. Increased production of hilsa eggs and jatka indicated a positive impact of twenty-two days fishing enclosure. Percentages of gravid and oozing hilsa were also found higher compared to previous years. Due to the prohibition of all types of fishing, the percentage of female hilsa in the breeding areas increased up to 83.96%. Overall, twenty-two days fishing enclosure was found very effective for successful spawning of hilsa.