This is the 15704th most frequent Russian word.
приростом
"Приростом" means "growth" or "increase" (as an instrumental case form of "прирост").
In this sentence, "приростом" is used as an instrumental case of the noun "прирост" (growth or increase). It indicates the means or result with which something was completed: separation increase.
Этот год предприятие завершило с приростом прибыли.
This year, the enterprise concluded with an increase in profit.
The word "приростом" here emphasizes the instrument or the contributing factor to the growth of the population: young individuals.
Популяция животных увеличилась благодаря приростом молодых особей.
The animal population increased due to the growth of young individuals.
Here, "приростом" identifies growth or increase as a characteristic impacting an event or action.