Using Proportional Stock Density and Relative Stock Density As Management Tools for Spotted Seatrout in Mississippi

We explored the use of proportional stock density (PSD) and relative stock density indices (RSD) to quantify the length-frequency distribution of Mississippi’s Spotted Seatrout stock. We assigned five length categories: Stock (S), Quality (Q), Preferred (P), Memorable (M), and Trophy (T) based on the all-tackle world record Spotted Seatrout. Values of PSD and RSD were estimated using data collected by gillnet surveys from 2006 to 2013. Annual PSD values ranged from 33% to 50%, RSD-P values ranged from 7% to 23%, RSD-M values ranged from 0% to 0.9%, and RSD-T values were 0% in all years except 2008. Inter-annual variation was estimated using a resampling analysis. The results of this study indicate that there was no inter-annual variation among PSD and RSD values from 2006 through 2013. Based on the analyses, the Mississippi Spotted Seatrout stock, of “Stock” length or greater, is comprised of mostly individuals of “Quality” and “Preferred” lengths with very little of the stock composed of “Memorable” and “Trophy” length individuals. We recommend the use of PSD and RSD as additional assessment tools because they are easily calculated, use data that are readily available, and provide information on the stock length-composition.