Establishment and application of a population prediction model for lamprey based on gender ratio transformation

This research focuses on establishing a mathematical model to delve into the variation in gender ratios of sea lampreys (Petromyzon marinus). The aim is to comprehend their dynamic adjustments under different environmental conditions and provide decision support for fisheries management and ecological conservation. Firstly, using Analytic Hierarchy Process (AHP), we assigned weights to the influence of different resources on larval development speed, revealing the relationship between gender transformation rates, developmental speed, and environmental resources through a mathematical model. We established a mathematical model of the sex ratio adjustment process of Lampreys and an Adaptive sex variation (ASV) model, in which the ASV model was combined with Lotka-Volterra and Logistic model. By using Matlab to solve the model, two important conclusions are drawn. On one hand, sea lampreys contribute to ecosystem stability by controlling the population of other fish species, presenting a scenario conducive to overall ecological balance. On the other hand, the research illustrates a scenario where parasitic behavior leads to a drastic decline in fish populations and the collapse of the food chain, causing harm to ecosystem stability. In conclusion, the model provides a valuable strategy for fisheries management in understanding dynamic changes of sea lamprey populations under different environmental conditions.