Adult southern flounder apparently migrate from 

 estuaries to the nearshore Gulf of Mexico each fall to 

 spawn. Larvae, in turn, migrate from the shallow Gulf 

 to marsh nurseries in estuaries. Occurrence of adults far 

 inland into freshwater during some months (Conner 

 and Truesdale 1972, Bryan et al. 1975) suggests that 

 the species moves extensively. 



Adults have occurred frequently over soft, muddy 

 bottoms (Hoese and Moore 1977), but large numbers 

 are also known to frequent sandy beach areas (Fox 

 and White 1969, Sabins 1973). The young appear to be 

 distributed from high-salinity waters near tidal passes 

 to low-salinity waters of irjand river deltas (Conner 

 and Truesdale 1972, Sabins and Truesdale 1974). 



In comparison with other estuarine areas along the 

 Louisiana coast, only moderate commercial catches of 

 southern flounders have been recorded in the Chenier 

 Plain area (Perret et al. 1971). The catch was largest in 

 January through April. Perry (1976) found southern 

 flounder to rank fifth in standing crop estimates (19.5 

 kg/ha or 17.1 lb/a) of fishes in the marshes of Rocke- 

 feller Wildlife Refuge. 



Although Day et al. (1973) refer to flounders as 

 ' mid carnivores ' and ' top carnivores, ' the latter is 

 more appropriate for all but the smallest size classes 

 (Gunter 1945, Knapp 1950. Reid et al. 1956, Darnell 

 1958, Fox and White 1969). Adult flounders are highly 

 predatious and are reported to consume ' large quanti- 

 ties 'of fishes, crabs, and shrimps (Knapp 1950, Darnell 

 1958, Fox and White 1969). Food habits of young 

 flounders have not been studied. Darnell (1958) sug- 

 gested that they feed mainly on small benthic inverte- 

 brates. 



The spawning habits of southern flounder are 

 poorly known. Each fall, adults concentrate in the 

 lower reaches of estuaries. This phenomenon is general- 

 ly believed to be in preparation for Gulfward spawning 

 migrations. Spawning apparently takes place in the 

 nearshore Gulf of Mexico from late autumn through 

 early spring, but mostly in November through Febru- 

 ary (Sabins 1973). Recruitment of young into inland 

 open water areas occurs mainly from December 

 through April (Sabins 1973, Tarbox 1974). Marshes of 

 either high or low salinity may serve as nurseries. 



Factors limiting the distribution or occurrence of 

 southern flounder in northern Gulf waters have re- 

 ceived little attention. In general, adults and large juve- 

 niles occur from freshwater to maximum Gulf salinities, 

 and in inland areas, appear to be rather ubiquitous with 

 respect to salinity (Perret et al. 1971). They have also 

 been collected at temperatures from 5° to 35° C (41° to 

 95° F). Spawning, however, is apparently restricted to 

 the colder months and high-salinity waters of the near- 

 shore Gulf. 



5.5.8 GULF MENHADEN (Brevoortia patronus) 



The Gulf menhaden or pogy is migratory through- 

 out much of its life cycle. Daily movements of adults 

 occur typically in the form of large surface-feeding 



schools which become the focus of a large summer fish- 

 ery (Chapoton 1970, 1972, 1973). Fishing season 

 occurs from AprU to October. 



The Gulf menhaden is a schooling species through- 

 out its life. As adults they inhabit the open Gulf of 

 Mexico. They concentrate nearshore (less than 10 fm) 

 through spring and summer and move farther offshore 

 during fall and winter (Roithmayer and Waller 1963, 

 Fore 1970, Chapoton 1973). Young-of-the-year, on 

 the other hand, are principally inhabitants of estuarine 

 waters, where they remain from 6 to 12 months after 

 hatching (Combs 1969). Interior marsh lakes and bay- 

 ous are judged to be the primary nursery habitats of 

 young Gulf menhaden (Conner and Truesdale 1972). 

 These shallow areas are slightly brackish and turbid, 

 and have soft, detritus-rich bottoms. In the Chenier 

 Plain and adjacent areas, young menhaden sometimes 

 inhabit the more inland portions of estuarine systems 

 (Gunter and Shell 1958, Herke 1966, Baldauf et al. 

 1970,Herke 1971, Arnold! 1974). 



On the basis of limited data reported by the 

 National Marine Fisheries Service menhaden juvenile- 

 monitoring program, it appears that, in some years, at 

 least, Chenier Plain estuaries may produce the highest 

 catch rates of young menhaden in the western Gulf of 

 Mexico. This may be due to the proximity of the Che- 

 nier Plain to the major spawning area, just off the Mis- 

 sissippi Delta, and to hydrographic conditions (i.e., the 

 westward-flowing longshore currents). As many as 

 133,016 juvenile menhaden were caught in a 4-minute 

 surface trawl (0.25-in bar mesh) in Calcasieu Lake marsh 

 bayous in late May (Herke 1966, 1967). Mean catch 

 per trawl sample at several stations was 49,400. Al- 

 though weirs appeared to affect the distribution of 

 some fish species in the study area, they did not seem 

 to influence menhaden. In a study of fishes at Rocke- 

 feller Wildlife Refuge, Perry (1976) reported a standing 

 crop of64.2 kg/ha (57.2 lb/a). 



Studies of food preferences or feeding behavior of 

 Gulf menhaden have not been conducted in the Chenier 

 Plain. In nearby Barataria Bay, however, Day et al. 

 (1973) referred to menhaden simply as 'herbivores,' 

 making no distinctions as to life history stages. Reintjes 

 and Pacheco (1966) stated that food was probably the 

 principal biological factor affecting the well-being of 

 menhaden in estuaries. Larval Gulf menhaden are 

 particulate-feeding carnivores, (chiefly on microcrus- 

 taceans)and juveniles are nonselective, filter-feeding 

 omnivores, chiefly on planktonic algae and micro- 

 crustaceans (Reintjes and Pacheco 1966). Adults in the 

 Gulf seem to feed on phytoplankton by filtration 

 (Reintjes and June 1961). However, Darnell (1958) 

 concluded that phytoplankton were not the primary 

 food of larger menhaden (83 to 103 mm or 3 to 4 in) 

 in the turbid waters of Lake Pontchartrain. He found 

 that suspended bacteria and material other than living 

 plants (e.g., silt, detritus, benthic microinvertebrates) 

 were the most important dietary components. In add- 

 ition, the blue-green alga Anabaena was an important 

 supplement in the diet of juveniles. 



Fore (1970) reported that the principal spawning 

 area for menhaden in Louisiana is in 'offshore areas 

 near the Mississippi River Delta.' 



259 



