Modeling the Responses of Alligator Gar Populations to Harvest: Implications for Meeting the Needs of a Diverse Angling Constituency

Despite increased interest in managing Alligator Gar fisheries, population responses to harvest are poorly understood.  We developed an age structured dynamic pool model in R to model the effects of various exploitation scenarios.  The base model was parameterized based on measured life history characteristics and fishery metrics for Alligator Gar in Texas; 50-year longevity, total annual mortality of 8.5%, and 3% exploitation.  Recruitment was set to mimic observed annual variation in year class strength in Texas populations where recruitment is highly correlated with flood periodicity.  Alligator Gar growth was modeled using composite length at age data (n = 344) from several Texas populations fit to a power curve (Total Length (mm) = 10.64 + 759.21*Age^0.28) representing non-asymptotic growth.  We used simulation modeling to 1) quantify the effects of various levels of exploitation on spawning stock abundance, longevity, and size structure and 2) evaluate the influence of length-based fishing regulations on population abundances and size structure of Alligator Gar populations.  Our results quantify tradeoffs between harvest and trophy potential and identify the most appropriate regulation options for particular management objectives.