Role of lunar phases, rainfall, and wind in predicting Hilsa shad (Tenualosa ilisha) catch in the northern Bay of Bengal

Abstract

Hilsa (Tenualosa ilisha) is an important commercial fish in India. This study investigates relationships among Hilsa catch per unit effort (CPUE) and the corresponding lunar phase, rainfall variability, wind vector, and month in the northern Bay of Bengal. Hilsa catch during the monsoon season of three consecutive years (2013–2015) was analyzed by using a Generalized Least Square model with lunar phase and monsoon months (June–September) as categorical variables and wind direction as circular variable. Significantly higher Hilsa catch was observed during the waning crescent and waxing gibbous lunar phases and during easterly winds. There was no significant effect of wind velocity. Daily rainfall was significantly correlated with Hilsa migration toward the estuary. Among the four monsoon months, September exhibited the most positive significant correlation with the Hilsa CPUE. Model predicted CPUE underestimated the actual CPUE in 2016 by 20%.

Daily Patterns of River Herring (Alosa spp.) Spawning Migrations: Environmental Drivers and Variation among Coastal Streams in Massachusetts

“…The horizontal dotted lines indicate the ordinal location of the easternmost extent of Cape Cod (i.e., the division between northern and southern streams). 506 movements (e.g., Keefer et al 2008;Bizzotto et al 2009;Snook et al 2016;Berdahl et al 2017;Giri et al 2019). Across 12 stream systems in Massachusetts, water temperature was found to be the most common predictor of daily river herring movement during spawning migrations.…”

“…Environmental conditions can have varying effects on the timing of anadromous fish migrations, making the primary drivers of within‐system movements difficult to identify over different time scales. Indeed, in the literature there has been much debate on whether temperature or flow is the master variable affecting anadromous fish movements (e.g., Keefer et al 2008; Bizzotto et al 2009; Snook et al 2016; Berdahl et al 2017; Giri et al 2019). Across 12 stream systems in Massachusetts, water temperature was found to be the most common predictor of daily river herring movement during spawning migrations.…”

“…Among different anadromous fish species, temperature, river flow, lunar cycle (which also corresponds with tidal cycle), and the relative abundance of conspecifics have varying influences on daily movement patterns (Leggett 1977; for recent examples, see Keefer et al 2008;Bizzotto et al 2009;Snook et al 2016;Berdahl et al 2017;Giri et al 2019). In some cases, daily fluctuations in run strength occur without obvious environmental triggers 502 (Berdahl et al 2017).…”

Role of tide and lunar phases on the migration pattern of juvenile Hilsa shad (Tenualosa ilisha) within a meso‐macrotidal estuary

“…In the northern Bay of Bengal off the West Bengal coast, Giri et al . (2019) studied the effect of the lunar phase on the daily catch of Hilsa shad. However, that study was based on the behavioural activity of adult Hilsa shad.…”

“…peak spawning activity of the Hilsa shad was observed to coincide with the full moon(Ahsan et al, 2014) Giri et al (2019). reported the significant role of two lunar phases, waning crescent and waxing gibbous, on the catch of adult Hilsa shad and their movement in the northern Bay of Bengal and Hooghly estuary.…”