Theses and Dissertations


Title: Development of a Windows based software application to simulate fish population dynamics and evaluate length and bag limits

Name: Slipke, J.W.

Degree: PhD

Chair: Michael J. Maceina

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 2003

Pages: 130

Keywords: Windows based software application,simulate fish population dynamics,evaluate length and bag limits,Fisheries Analyses and Simulation Tools (FAST)

Abstract:

I created the Fisheries Analyses and Simulation Tools (FAST) program to provide fisheries biologists with a modern software program that can be used to simulate fish population dynamics for research, management, and education. While potential uses of the FAST application are numerous, the program was primarily developed to aid the evaluation of length and bag limit regulations.The FAST application was used to explore fishery responses to minimum length limit regulations for largemouth bass in Lake Walter F. George,Alabama-Georgia. Simulation modeling was used to show why a 406-mm minimum length limit imposed in 1992 had not met its objective of increasing the abundance largemouth bass > 406 by the late 1990s. Simulation modeling predicted that reducing the length limit to 356 mm in 2000 would result in 60% more largemouth bass recruiting to the legally-harvestable fishery. Model predictions were verified with empirical data collected in 2001-2002.Simulation modeling and multiple linear regression analysis were used to investigate the relative statistical importance of study duration and fishery characteristics to detect population responses to minimum length limit regulations. The duration of the evaluation period was the most influential factor, followed by recruitment variability, the magnitude of increase in the minimum length limit, and the conditional fishing mortality rate. Based on this analysis, it may be difficult to adequately assess minimum length limit regulations when they are applied to fish populations characterized by highly variable recruitment, particularly when they are evaluated for a short period of time. Simulation modeling and spawning potential ratios (SPR) were used to identify fishing conditions that were associated with a decline and subsequent recovery of the Upper Mississippi River commercial fishery for channel catfish Ictalurus punctatus. A critical minimum SPR of 10% was identified that could serve as a biological reference point in the management of this highly exploited fishery. SPR increased from 3 - 12% at the 330 mm limit to 1O - 20% at the 381 mm limit, and corresponded well to the nearly four-fold increase in age-0 channel catfish abundance.

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