Sea Surface Temperature, Depth, and Octopus (Octopus cyanea) Production in the Fishing Grounds of the Northern Alas Strait, West Nusa Tenggara, Indonesia
M. Junaidi
Study Program of Marine Science, Faculty of Agriculture, University of Mataram, Mataram City, West Nusa Tenggara Province, Indonesia.
Soraya Gigentika
*
Study Program of Marine Science, Faculty of Agriculture, University of Mataram, Mataram City, West Nusa Tenggara Province, Indonesia and Scientific Forum for Sustainable Fisheries Management (FIP2B NTB), Mataram City, West Nusa Tenggara Province, Indonesia.
Paryono
Study Program of Marine Science, Faculty of Agriculture, University of Mataram, Mataram City, West Nusa Tenggara Province, Indonesia.
Muslihuddin Aini
Scientific Forum for Sustainable Fisheries Management (FIP2B NTB), Mataram City, West Nusa Tenggara Province, Indonesia and Study Program of Fisheries Resource Utilization, Faculty of Fisheries, Gunung Rinjani University, East Lombok District, West Nusa Tenggara Province, Indonesia.
Syaeful Bachri
Department of Marine Affairs and Fisheries of West Nusa Tenggara Province, Mataram City, West Nusa Tenggara Province, Indonesia.
Misbahul Umam
Department of Marine Affairs and Fisheries of West Nusa Tenggara Province, Mataram City, West Nusa Tenggara Province, Indonesia.
*Author to whom correspondence should be addressed.
Abstract
Aims: To describe monthly sea surface temperature (SST) and depth of octopus fishing grounds in the northern Alas Strait, Indonesia, and their relationships with Octopus cyanea production and catch per unit effort (CPUE).
Study Design: Descriptive-correlational observational study.
Place and Duration of Study: Fishing grounds used by fishers from Seruni Mumbul (East Lombok) and Poto Tano (West Sumbawa) villages, West Nusa Tenggara, April–August 2025.
Methodology: Sixteen fishing grounds were identified through fisher interviews. Each landed octopus was weighed and recorded with its vessel code and date; CPUE was calculated as kg per trip. Monthly SST was derived from daily level-4 OSTIA data (0.05°) and depth from BATNAS bathymetry. Spearman and repeated measures correlation (rrm) were applied to 59 fishing ground–month pairs.
Results: Mean monthly SST ranged from 28.15 °C (August) to 29.45 °C (May), while within-month differences among fishing grounds were 0.27–0.41 °C. Production totalled 1568 kg (1400 individuals) from 499 trips, peaking in May (539 kg); 66.3% came from the Sumbawa side. Monthly CPUE was stable (3.0–3.3 kg per trip), so production followed the number of trips. SST was not significantly correlated with production (ρ = 0.21; P = .11) or CPUE (ρ = −0.04; P = .77). Within fishing grounds, production was slightly higher in warmer months (rrm = 0.31; P = .04), but not after effort standardisation (rrm = −0.06; P = .71), because trips were more frequent in warmer months (rrm = 0.36; P = .02). Depth (2.7–41.2 m) was not significantly correlated with production (ρ = −0.16; P = .57; n = 15).
Conclusion: Within the narrow SST range of one season, SST did not explain CPUE, and landed production mainly reflected fishing effort. Monitoring should record effort, including zero-catch trips, and environmental data at each fishing ground over several seasons.
Keywords: Octopus cyanea, sea surface temperature, depth, fishing ground, catch per unit effort, small-scale fisheries, Alas Strait