Comprehensive suitability assessment of fish habitat by integrating mechanism model and bayesian network model

Abstract

The Fish Habitat Comprehensive Suitability (FHCS) indicator plays a pivotal role in evaluating fish spawning and egg hatching behavior. Assessments of fish spawning and egg hatching suitability have traditionally relied on deterministic outcomes from single- or multi-factor hydrological designs. However, considering the uncertainty of riverine environments, the FHCS and its components, including the fish spawning weighted suitability area (WUA) and the potential number of eggs hatching (Negg), should be viewed as random variables that follow specific probability distributions. To address this, an FHCS assessment method combining a mechanism model with a Bayesian network (BN) model was developed to evaluate the FHCS of four major Chinese carps (FMCCs) in the Xunjiang River, China. The mechanism model provided foundational data essential for constructing the BN. The BN model was then employed to determine the values of key factors, such as Weighted Usable Area (WUA) and egg viability (Negg), which were subsequently used to calculate the FHCS of the study area. The results of the study were obtained using the mean of the 94 % confidence intervals of the BN model parameters. The results showed that the suitable spawning period for FMCCs at the Dongta spawning ground was 68 days in 2022, compared to just 7 days in 2023. The suitable hatching period for eggs was 65 days in 2022 and only 7 days in 2023. The FHCS assessment for the study area revealed that the period of fish habitat suitability was 57 days in 2022. However, due to the brief duration of favorable flow conditions in 2023, there were no overlapping time intervals suitable for both spawning and hatching. This underscores the critical role of comprehensive suitability assessments for fish spawning and egg hatching, offering more precise and scientifically grounded tools for fish conservation.