Wilber: Influence of Apalachicola River flows on Callinectes sapidus 



183 



whether there was evidence that the Apalachicola 

 River affects blue crab landings on a regional basis, 

 Franklin and Wakulla landings were removed from 

 the west coast dataset. Regression analyses were 

 conducted to test whether Apalachicola flows and 

 the remaining west coast landings were significantly 

 related. 



Results 



Annual landings 



Blue crab landings varied nearly 10-fold over the 

 period of record examined in each county (Fig. 2). 

 Significant autocorrelations between consecutive 

 years were present in both Franklin (r 2 =0.19, 

 P=0.006) and Wakulla (r 2 =0.37, P=0.016) County 

 landings. Annual flow parameters did not exhibit 

 any significant autocorrelations. 



Annual Franklin County blue crab landings were 

 most highly correlated with Apalachicola River flows 

 of the previous year and these correlations were 

 positive (Table I). The growout flow with a one-year 

 time lag accounted for the greatest amount of varia- 

 tion in blue crab landings (r 2 =0.32, P<0.001; Fig. 

 3A). The regression analysis of ARIMA residuals 

 (autocorrelation in blue crab landings removed) and 

 growout flows of the previous year was also signifi- 

 cant (r 2 =0.21; P=0.004). Wakulla County landings 



ANNUAL BLUE CRAB LANDINGS 



1.5 



O.S 



0.0 



WAKULLA 

 FRANKLIN 



—i — i — i — [ — i — i — i — i — | — i — i — i — i — [ — r 

 1950 1960 1970 1980 



YEAR 



1990 



Figure 2 



Annual blue crab (Callinectes sapidus) landings for 

 Franklin (closed squares) and Wakulla (open 

 squares) Counties in millions of kilograms. 



were significantly correlated only with Apalachicola 

 flows of the previous year, with the growout flow 

 also accounting for the greatest amount of variation 

 in annual blue crab landings (r 2 =0.52, P=0.001; Fig. 

 3B). The regression analysis of ARIMA residuals 

 and growout flows one year previous was significant 

 (r 2 =0.35, P=0.02). The shorter (1973-90) data record 

 for Franklin County landings was more strongly 

 correlated with growout flows with a one-year time 

 lag (r 2 =0.49, P=0.001; Fig 3C) than was the full 39- 

 year dataset. 



Monthly and seasonal landings 



As expected, the monthly Franklin and Wakulla 

 County blue crab landings (1979-90) exhibited sig- 

 nificant autocorrelations for 1- and 12-month time 

 lags. All monthly river flow parameters (minimum, 

 mean, and maximum) also exhibited significant cor- 

 relations between successive months and with 12- 

 month lags. Correlations between monthly landings 

 and flow parameters (without any adjustments for 

 significant autocorrelations) were positive for time 

 lags of 3, 4, and 5 months. Significant negative cor- 

 relations were present for flows that lagged 2-4 

 months behind landings. Correlations that used 

 landings and flow data with the 1- and 12-month 

 autocorrelation effects removed were not significant 

 for either county. 



Peak harvests generally occurred between May 

 and September in both counties. There were also no 

 significant correlations between the seasonal (three- 



