engleski

Range expansion of the signal crayfish (Pacifastacus leniusculus) in a recently invaded region in Croatia and potential for its control

The signal crayfish, Pacifastacus leniusculus has recently been introduced to the Korana River, a karstic river in the central part of Croatia, where it presents an alarming threat to its native crayfish diversity. In this study, we explored the dynamics of range expansion of the signal crayfish in the Korana River and developed an individual-based model (IBM) to explore different options for management of its populations. In 3 years, the invasive range of the signal crayfish increased 2.5 times, while dispersal rate was similar in both upstream and downstream direction. At former invasion fronts crayfish abundance increased 5 times and was translated into significant reduction of signal crayfish size (total length) in these populations. The IBM was based on the species basic life history and simulated multiyear population dynamics. We explored management scenarios for periods of 10 years that differed in catch per unit effort (CPUE), trapping period and frequency. Considering a catch effort of 10% of all individuals in the population > 60 mm, model simulations suggested that the most effective management option would be to harvest one week per month each year of the 10 year period. This would drive the population to 5% of the baseline, i.e. non-harvested abundances. The next best alternative is to harvest every year for a limited number of months (June – November). Both of these findings are conditional on a constant CPUE. We also discuss model results with a varying CPUE, and highlight the applicability of population models in invasive species management.

population model; management scenario; invasive crayfish

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