were: gafftopsail catfish ( Bagre 

 marinus), sea catfish ( Arius f elis ) , 

 croaker ( Micropogon undulatus ) , black 

 drum ( Pogonius cromis ) , flounder 

 (Cithar ichthys spp. and Parlichthys 

 spp.), mullet ( Mugil spp.), Irish 

 pompano ( Diapterus olisthostomus ) , 

 pinf ish ( Lagodon rhomboides ) , puffer 

 ( Sphoeroides testudineus ) , sheepshead 

 ( Archosargus probatocephalus) , snook 

 ( Centropomus ssp.), weakfish (Cynos- 

 cion spp.), spotted seatrout (Cynos - 

 cion nebulosus ) , whiting (Menti- 

 cirrhus americanus ) , and gray (man- 

 grove) snapper ( Lutjanus griseus ) . 



With emphasis on the St. Lucie 

 Canal discharges, species were chosen 

 from the results of the multiple re- 

 gression analyses which best fit the 

 criteria outlined in the methods 

 section. The results of those cri- 

 teria produced the following list of 

 species whose catch rates were sig- 

 nificantly affected by the St. Lucie 

 discharges and whose catch records 

 were relatively regular. 



South Fork = 

 Zone 1: 



North Fork = 

 Zone 2 : 



Bridge 



Section = 

 Zone 3: 



Inlet Section = 

 Zone 4: 



Entire Estuary: 



Gray (mangrove) 

 snapper and mullet 



Snook, sheepshead 

 and croaker 



Snook and black 

 drum 



Gafftopsail cat- 

 fish, croaker, weak- 

 fish, gray snapper 

 and black drum 



Croaker, mullet, 

 Irish pompano and 

 snook 



Regression analysis indicated 

 that there were no significant ef- 

 fects instantaneously on the catch 

 rates of any of the above species 

 (Table 2). However, after a lag of 

 one week following maximum daily 

 flow for a week, there was an in- 

 crease in the catch rate of gray 

 snapper, croaker and weakfish in the 

 inlet section. There was a lag of 

 four weeks after average St. Lucie 

 Canal discharges, resulting in an- 

 other correlation involving catch 

 rate increases in the inlet section 

 of sheepshead, gafftopsail catfish 

 and Irish pompano. As the total 

 average flow above the median St. 

 Lucie Canal discharge increased, the 

 gray snapper and black drum catch 

 rates significantly decreased in the 

 inlet section. 



While the inlet section was 

 active as a result of the discharges, 

 the snook catch rates oscillated be- 

 tween the North Fork and bridge sec- 

 tion. After a lag of two weeks fol- 

 lowing average St. Lucie Canal dis- 

 charges, the snook catch rate de- 

 creased in the North Fork; and the 

 third week it increased in the bridge 

 section; one week later it increased 

 in the North Fork; it finally showed 

 a decrease in the bridge section 

 catch rate in the fifth week. Over- 

 all, as the length of the St. Lucie 

 average flow increases, the snook 

 catch rate for the estuary increased 

 as well. 



Croaker is also affected in the 

 North Fork. After a lag of three 

 weeks following average St. Lucie 

 Canal discharges, catch rates de- 

 crease in the North Fork. After a 

 lag of four weeks following behind 

 maximum St. Lucie discharges, catch 

 rates increased in the North Fork. 



Although throughout the estuary 

 a negative correlation with the 



275 



