We investigate the migratory behaviour of juvenile loggerhead sea turtle (Caretta caretta) hatchlings within a region of the North Atlantic Gyre. To do so, we develop and compare an individual based (IB) model and a partial differential equation (PDE) model, specifically an advection-diffusion equation derived from a position-jump process. We compare their behaviour and show that they yield similar results, but that there are still some differences between the two. Using the IB model we assess survival probabilities of hatchlings in recent years (2016-2023), revealing that survival rates are statistically significantly (𝑝-value = 2.62 ⋅ 10^−6) not constant over time in this region. However, there could be global events that influence the survival probability, as years 2019 and 2023 have a large deviation in survival probability.