Evolution and recent trends of Indian oil sardine research: A review

The Indian oil sardine (Sardinella longiceps, hereafter IOS) has a unique position in terms of its economic value. In the last decade, IOS has contributed about 15–20% to India's total marine fish landings. However, recently, a sharp decline has been observed in the annual landing of the resource, and it is on the verge of collapsing due to climatic and anthropogenic perturbations. Various researchers have observed a cyclic pattern of wide annual fluctuation for IOS. This review revealed a long history of IOS research dating back to 1924. To mine the information regarding past research on IOS, bibliometric analysis has been carried out to understand the growth of literature, research area focuses, and research requirements. This study highlights a noticeable shift in research focus regarding IOS. While earlier investigations centered primarily on the physiology and biochemical properties of sardine and sardine oil, contemporary research emphasizes oceanographic parameters in relation to the IOS life cycle. The evolution of research efforts now extends beyond taxonomic classification, encompassing ecological, fisheries, and environmental aspects. The study underscores an increasing awareness of the multifaceted challenges posed by climate change and anthropogenic activities, which have prompted a transition toward interdisciplinary research approaches aimed at IOS conservation. A notable gap identified in this study is the lack of comprehensive analyses on IOS habitat suitability, particularly under dynamic oceanographic conditions and environmental indicators critical for predicting IOS availability. Additionally, the study points to the potential application of advanced predictive modeling techniques, including regression-based models such as Generalized Linear Models (GLM) and Generalized Additive Models (GAM), as well as machine learning approaches like Boosted Regression Trees (BRT) and Random Forest (RF), to predict IOS abundance and distribution effectively.