The impact of fishing on the biological structure of the pike Esox lucius (L.) population of the Volga River avandelta

Abstract

The main area of pike habitat and fishing is the avandelta of the Volga River. Pike fishing is conducted by passive fishing gear - mainly by secrets, to a lesser extent by nets. The main part of the pike catch traditionally falls in the spring period, when it forms pre-spawning and spawning clusters. Since 2010, official pike catches have been declining in March and April, due to an increase in illegal seizures. Pike caviar, due to its high nutritional qualities and demand among the population, has a high cost, which contributes to the massive concealment of commercial catches and poaching. Over the past two decades, the biological indicators of pike in the Volga River delta have undergone changes. Based on long-term data, there was a decrease in the age range, an increase in the proportion of younger age groups, a decrease in the proportion of females in the sexual structure of the population, average age, length and weight of pike. At the same time, the size and weight indicators of the same-aged pike individuals are quite stable. The main reason for the ongoing negative changes is the purposeful high commercial withdrawal of females in the pre-breeding and spawning periods. The scale of the total pressure of illegal industrial, poaching and amateur fishing, according to expert estimates, is comparable to the amount of official catch recorded by fishing statistics. To reduce the catch of spawning females for the first time, it is recommended to increase the minimum fishing length of the pike.