author(s)
Mustafa Sharmila

abstract
Marine turtles are long-lived, migratory species whose life cycles depend on large-scale oceanographic conditions. Climate change is altering sea surface temperatures, ocean currents, and resource distributions, which can drive changes in migration timing, routes, and foraging grounds. This study focuses on the Visakhapatnam coastal region of the Bay of Bengal, an important migratory corridor and foraging zone for marine turtles along the east coast of India. We present a longitudinal analysis (2008–2022) of satellite-telemetry data from 128 individuals across three species (Green Turtle Chelonia mydas, Loggerhead Caretta caretta, and Leatherback Dermochelys coriacea) tagged and monitored in the Visakhapatnam coastal area. Using Argos/GPS telemetry, kernel utilization distributions, and mixed-effects models, we quantify shifts in migration phenology and route latitudes and relate these to trends in local sea surface temperature (SST) and chlorophyll-a concentrations. We find statistically significant poleward shifts in mean migration latitude (0.28° lat/decade; p<0.01) and earlier departures from nesting beaches (mean 6.4 days earlier per decade). Our results indicate that climate-driven oceanographic changes in the Bay of Bengal are already reshaping marine turtle migrations, with implications for conservation planning and management in the Visakhapatnam coastal zone.