Severe sawfish population decline in the northern Bay of Bengal

Understanding historical and contemporary sawfish bycatch patterns is critical for informing conservation strategies in Bangladesh, where populations of Critically Endangered elasmobranchs have undergone declines. This study integrates interviews from 318 artisanal fishers to evaluate ability to identify, encounter histories, temporal and spatial catch patterns, and predictors of lifetime sawfish bycatch. All respondents reliably identified sawfish from photographs, although regional variation in local names was evident. Most fishers (93%) had observed sawfish during their careers, and 89.6% had captured at least 1, with an average of 10.5 individuals per fisher. However, 61.3% reported no encounters since 2015, with a mean of 2 sightings or captures since 2015. Temporal trends show a steep decline compared to the 1980s baseline: catches declined by 30 to 40% in the 1990s, 70 to 80% in the 2000s, 80 to 90% in the 2010s, and 95 to 98% in the 2020s. Last catch timelines (mean ± SD: = 11 ± 8.56 yr) revealed peaks between 1995 and 2010, followed by pronounced reductions. Historical catches were concentrated in the southwest, Kuakata and the Baleshwar River. Fishing months, gear type (especially setbag nets and submerged gillnets), the southwest region, and fishers’ age were significant positive predictors of lifetime catch. In contrast, higher engine power and specific gears (e.g. hilsa gillnets, unbaited bottom-set longlines) showed negative associations. Submerged gillnets accounted for most catches (p = 0.002), with the lowest rates reported from floating and hilsa gillnets (p < 0.001). Although based on informed perceptions of trends and spatial patterns rather than precise historical estimates, these findings provide the most comprehensive fisher-reported evidence to date of the drastic decline in sawfish in Bangladesh and highlight spatial, demographic, and operational factors relevant to conservation planning and bycatch mitigation.