Nonlinear model of overfishing for the Volga sturgeon based on cognitive graph of interaction of environmental factors

A. Yu. Perevaryukha

Vestnik Samarskogo universiteta. Estestvennonaučnaâ seriâ, no. 1-2 (2016), pp. 92-106

Résumé

We have discussed the development of models of dynamics of formation of reserves juveniles from natural spawning sturgeon Acipenser gueldenstaedtii of the Caspian Sea on historical data. Working hypotheses are based on the graph conceptual scheme aimed chain links. Structuring multivariate analytical conclusions about the quality of the interaction of 12 natural and anthropogenic factors in the ecosystem of the Caspian Sea have allowed us to recharge from the general ideas of the theory on to describe the specific situation of the tragic consequences of overfishing of anadromous fish with a long lifecycle. Reducing the word was swiftly enough and not consistent with the expectations of the replenishment of stocks by artificial reproduction. Dedicated contact circuit pulse propagation cognitive digraph where arcs contains the power of influence, says an indirect strengthening of action depends on the density of mortality. Interestingly, the relationship did not have a permanent independent sign «+» or «-». Recessions manifested dramatically on both boundaries of the range of optimum number of spawning manufacturers. Perhaps the decline in the efficiency of the reproduction right of the balance associated with the migration routes overlap. It is more intense withdrawal of fish more prolific race hibernating until spring in the river. The model takes into account the additional effect of increasing variations in the pace of development of the size on the survival of migrating hatchery. The system of differential equations is investigated in an iterative discrete continuous hybrid form with alternative position of equilibrium trajectory. One of the equilibrium is unstable, and is the starting point for the degradation of reproductive activity. The proposed model of reproduction under supercritical level seizures shows subtle transition from the brink of fading fluctuation to the permanent historical perspective depletion, the way into the Red Book.

Détail

Keywords: graph models in ecology, cognitive structuring of factors, unstable population processes, interpretation of nonlinear effects, effect of fish growth rate, unstable equilibrium and cycles, interpretation of overfishing of stocks, hybrid systems.

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