Habitat modelling of escolar fish (Lepidocybium flavobrunneum, Smith 1843) in the southwestern Indian Ocean using remote sensing data

Abstract

Escolar (Lepidocybium flavobrunneum) belongs to Gempylidae family, is a top predator species that plays a crucial role in the marine ecosystem. However, limited information is available regarding their spatial-temporal variations in habitat, while habitat suitability index (HSI) modelling has been widely used in recent years for conservation, fisheries, and ecology. We compared an Arithmetic Mean Model (AMM) and a Geometric Mean Model (GMM) to gain insights into their habitat distribution. Fishery data were collected from the southwestern Indian Ocean between 2010 and 2014. Ten oceanographic remote sensing data sets were compiled, and four of them were selected based on their higher R 2 values obtained from Generalized Additive Model (GAM), Boosted Regression Trees (BRT), and Random Forest (RF) analyses for constructing the model combination. Meanwhile, Suitability Index (SI) curves were employed to determine the habitat suitability range for escolar. Environmental parameters were combined using a step-wise approach and applied for both AMM and GMM. The models were evaluated based on the Lowest Akaike Information Criterion (AIC) value. Eventually, AMM was chosen over GMM with the AIC value was 28.49 and 31.25, respectively. The selected model combination of AMM was Sea Surface Height (SSH), Oxygen (O), and Sea Surface Temperature (SST) meaning these parameters influenced the distribution of escolar. The SI curve of the chosen model indicated the habitat range for each parameter as follows: SSH (0.61–0.69 m), O (222–230 mmol m−3), and SST (18.7–21.1°C). The most suitable habitat for escolar was observed within the coordinates 36 ºS-30 ºS and 28 ºE-36 ºE. Thus, this method is demonstrated in a case study where just presence data are provided and the incorporation of remote sensing environmental factors is gathered. This result could help improve escolar fishery management in the southwestern Indian Ocean.