The Harvest Effect on Dynamics of Northern Fur Seal Population: Mathematical Modeling and Data Analysis Results

Oksana Zhdanova (), Alexey Kuzin and Efim Frisman
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Oksana Zhdanova: Institute of Automation and Control Processes, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, Russia
Alexey Kuzin: Pacific Research Fisheries Center, 690091 Vladivostok, Russia
Efim Frisman: Institute for Complex Analysis of Regional Problems, Far Eastern Branch, Russian Academy of Sciences, 679016 Birobidzhan, Russia

Mathematics, 2022, vol. 10, issue 17, 1-24

Abstract: We examine population trends in light of male harvest data considering the long-time series of population data on northern fur seals at Tyuleniy Island. To answer the question has the way males were harvested influenced the population trajectory, we analyzed the visual harem size and birth rate dynamics of the population, as well as the strategy and intensity of the harvest. We analyzed the dynamics of the sex ratio in the early (1958–1988) period to estimate parameters in the late period (1989–2013) based on the observed number of bulls and pups, while utilizing the distribution of reproductive rates obtained from pelagic sealing. Using a matrix population model for the observed part of the population (i.e., the male population), we analyzed the population growth rate associated with changes in both birth and survival rates considering the stochastic effects. Observations allow us to reject the hypothesis of nonselective harvest. Among the variety of natural and anthropogenic factors that could contribute to the decrease in the birth rate in the population, the effect of selective harvesting seems to be the most realistic.

Keywords: Callorhinus ursinus; matrix population model; harvest; conservation; growth rate (search for similar items in EconPapers)
JEL-codes: C (search for similar items in EconPapers)
Date: 2022
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