Abstract:
Since the introduction of multi-day fishing boats to the Sri Lankan fishing fleet, the use of ring nets
to harvest fish resources gathered around flotsam has grown in popularity. Ring net catches
included fish species that are not commonly caught in other fishing methods such as gillnetting and
longlining. These species are found near moored or natural Fish Aggregating Devices (FADs). To
ensure the sustainable use of pelagic fish resources and develop reasonable and effective
management strategies, it is essential to comprehend the reasons behind their spatial and
temporal variability. Understanding the connections between fish spatial distribution and
environmental variables is critical for fisheries management and conservation. In this context, the
present study was carried out using remotely sensed satellite data from 2016 to 2019 on the 30-
day means of sea surface temperature (SST), chlorophyll-a (Chl-a), and water current velocity
(WCV) in the Indian Ocean to examine potential fishing grounds of Indian scad (Decapterus russelli)
and triggerfish (Canthidermis maculata), primarily caught by using ring nets. Present findings
indicate that Indian scad preferred SST, Chl-a, and WCV ranges of 27.5-29.5 °C, 0.1-0.37 mg/m3,
and 0.01-0.35 m/s, respectively. An analysis revealed that triggerfish species preferred SST ranges
of 27.5-29.1 °C, Chl-a ranges of 0.1-0.4 mg/m3, and WCV ranges of 0.055-0.25 m/s. Most of the
catches were reported within the EEZ throughout the year and, the Arabian Sea, the Bay of Bengal,
and the Southern Ocean, Sri Lanka were the primary fishing grounds for the species throughout the
months and seasons. The northeast monsoon (NEM) produced most of the catches rather than the
southwest monsoon (SWM). During the period of SWM, most catches were recorded within the
EEZ while most of the catches during the NEM period were observed in the Bay of Bengal and the
Southern Ocean, Sri Lanka. The present study concludes that environmental conditions directly
influence the fishing grounds of Indian scad and triggerfish, and Ring net fisheries are directly
impacted by the variability of oceanographic conditions. Present findings help aid in reducing
fishing costs and time spent for searching fish during fishing activities, as well as decision-making
for sustainable fisheries management.
