Identifying key drivers of extinction for Chitala populations: data-driven insights from an intraguild predation model using a Bayesian framework

The fish species N. chitala is a freshwater fish that is widely distributed in African and Asian countries, including India, Pakistan, Bangladesh, Sri Lanka, Nepal, Thailand, and Indonesia. This species has been categorized as endangered (EN) in the Conservation Assessment and Management Plan. The study aims to investigate the cause of the species’ decline in their natural habitat. Using mathematical models supported by empirical data analysis, we explore the interaction of the species with other tropic levels and discover important parameters that may be attributed to the rapid decline. Based on the literature, we considered an intraguild predation (IGP) system consisting of three species, namely Chitala (IG predator), Mugil (IG prey), and shrimp (resource). Two variants of IGP models governed by three coupled differential equations are considered for data modeling purposes. Chitala depends only on Mugil and shrimp in one model. An alternative food source is available to Chitala in the second model. The models are estimated using the Bayesian modeling framework. Posterior estimates of the parameters for each model were obtained using the Gibbs algorithm, and the reversible-jump Markov chain Monte Carlo method has been utilized for posterior model inference. Our findings suggest that the primary reason for the decline in Chitala is due to the reduced nutritional gain from the Mugil and reduced predation efficiency in acquiring shrimp as a food source in the unavailability of Mugil. This study may be useful to develop management strategies for Chitala conservation by emphasizing the regeneration of Mugil populations.