Model Results - The assessment model provides reasonable fits to the adult abundance index (Figures 2-3). However, the fit to the juvenile abundance index (Figure 4) is consistently overestimated in later years of the time-series. The juvenile index suggests a considerable decline over the latter half of the time-series examined. The assessment model tracks this decline, but underestimates its magnitude suggesting additional processes aren’t captured by the assessment model (e.g. temporal, spatial, and/or environmental; see Research and Data Needs Section). The catchability coefficient is estimated as qn=0.0048 in this assessment. Annual exploitable (adult) biomass estimates range from 15 to 92 million pounds (Table 10, Figure 5). The 2017 exploitable biomass estimate is 25 million pounds. Exploitable biomass levels generally decline after 1990, where previous years estimates were rarely below 40 million pounds. Increases in exploitation during the 1990s coincide with this decline (Figure 6). A large population response is evident in the years following the passages of Hurricane Katrina and Rita which caused a substantial reduction in the directed effort and supporting infrastructure of the Louisiana commercial blue crab fleet. These storms also provided optimum environmental conditions for settlement of megalopae and young crabs into Louisiana estuaries via storm surge and likely enhanced recruitment. Juvenile abundance estimates range from 152 to 574 million individuals (Table 10, Figure 5) and exhibit a considerable decline over the latter half of the time-series examined. The eight most recent juvenile abundance estimates are the lowest on record with the exception of the 1976 estimate. The 2017 juvenile abundance estimate (152 million individuals) is the lowest on record. Additionally, in the two most recent decades only two juvenile abundance estimates are above the time-series average and in the most recent decade no estimates are above the time-series average (Figure 7). It’s important to point out here the consequence of this decline on management reference point estimation. Because equilibrium conditions (i.e., average recruitment) are assumed in reference point estimation, management benchmarks will generally be biased when below average conditions persist for extended time periods. Annual instantaneous fishing mortality estimates range from 0.07-0.92, with peaks in exploitation occurring in 2002, 2012 and 2014 (Table 10, Figure 8). Trends in fishing mortality estimates, 1999-2016, are generally consistent with fishing effort (i.e., trap fisher trips) derived from the LDWF Trip Ticket Program (Figure 8). A large reduction in fishing mortality/effort was observed in the years following the passages of Hurricane Katrina and Rita. Fishing effort is not used in the assessment model but is presented here to validate trends in fishing mortality. However, the number of trap fisher trips may not be a suitable measure of fishing effort (specifically for catch per unit effort data) if the number of traps fished per trip increases (or decreases) through time and should be considered with caution. No discernable relationship is observed between exploitable biomass and subsequent recruitment. However, the most recent half decade of data pairs are all below the juvenile abundance time-series average and are some of the lowest adult biomasses observed (Figure 9). - Stock Status - The history of the Louisiana blue crab stock relative to the reference points described above is illustrated in Figures 11 and 12. Fishing mortality rates exceeding Flimit (or ratios of F/Flimit>1.0) indicate overfishing; stock biomasses below SSBlimit (or ratios of SSB/SSBlimit<1.0) indicate an overfished condition. - Overfishing Status - The 2016 estimate of F/Flimit is 0.82, suggesting the stock is not currently experiencing overfishing. However, the 2014, 2015, and 2016 fishing mortality rate estimates are past their target and the 2014 value was very close to the overfishing threshold. These estimates should be considered from a precautionary viewpoint given the upward trend in fishing mortality coupled with the decrease in exploitable biomass observed in the most recent decade. Again, the overfishing reference point estimate in this assessment (i.e., the Flimit) is calculated assuming equilibrium conditions and maybe overestimated given the below average recruitment observed in the past 20 years. Estimates of fishing mortality are not available for the terminal year of the assessment. - Overfished Status - The 2017 estimate of SSB/SSBlimit is 1.36, suggesting the stock is currently not in an overfished condition. The stock was considered overfished, however, in 1995, 2013, and 2015.