Able et al • Paralichthys denatus early life history 



the available evidence, we conclude that at least a 

 portion of the P. dentatus do this in New Jersey 

 estuaries. It is clear that at sizes larger than approx- 

 imately 11 mm SL, they become scarce in continental 

 shelf plankton collections (Fig. 3) and that they can be 

 collected in New Jersey inlets, usually at sizes of 11-14 

 mm TL. In addition, the larger juveniles have been 

 collected, at least from power plant screens, with some 

 regularity (Fig. 4). In some years larger YOY (240-300 

 mm) are clearly represented in recreational catches in 

 New Jersey estuaries (Festa 1979). Despite this pat- 

 tern, it is not always easy to collect small juvenile 

 P. dentatus in New Jersey estuaries. As we pointed out 

 earlier, the collections of small juveniles (30-50 mm, 

 Fig. 4) occurred in a single year (1975) but not in subse- 

 quent years (1976-80). In addition, small juveniles are 

 rarely encountered in the winter (January- April), 

 following recruitment to the estuary (Fig. 4). Limited 

 data might lead to the assumption that YOY P. den- 

 tatus could not survive winter temperatures in New 

 Jersey inshore waters. Johns et al. (1981) indicate that 

 larval P. dentatus fail to develop past yolksac absorp- 

 tion when reared at temperatures below 5°C. Estu- 

 arine temperatures in New Jersey regularly drop to 

 several degrees below this level in winter (Rutgers 

 Univ., Mar. Field Stn., Tuckerton, NJ 08067, unpub- 

 lished data). Thus, if transforming individuals suffer 

 the same mortality as the yolksac larvae, individuals 

 that have moved into the estuaries may not survive 

 winter. Also, several studies indicate that P. dentatus 

 in Chesapeake Bay may succumb to infections of the 

 hemoflagellate Trypanoplasma hullocki at low tem- 

 peratures (Burreson and Zwerner 1982, 1984; Sypek 

 and Burreson 1983). Effective immune response to the 

 parasite was not noted in natural infections below 10°C 

 (Sypek and Burreson 1983). This parasite occurs in 

 New Jersey waters (G. Burreson, Va. Inst. Mar. Sci., 

 Gloucester Pt., VA 23062, pers. commun. July 1987), 

 but its effect on New Jersey populations of P. dentatus 

 is unknown. 



Some authors have assumed that because of the 

 perceived paucity of YOY in New Jersey and other 

 estuaries in the northeastern United States, the impor- 

 tant nurseries for P. dentatus occur in Virginia and 

 North Carolina (see Rogers and Van Den Avyle 1983 

 for review). We find the evidence to support this con- 

 clusion ambiguous and in some cases contradictory. 

 First, the evidence for abundant juvenile P. dentatus 

 is based primarily on studies in South Atlantic Bight 

 estuaries that no doubt support P. dentatus nurseries 

 (Tagatz and Dudley 1961, Miller and Jorgenson 1969, 

 Burns 1974, Powell 1974, Cain and Dean 1976, 

 Bozeman and Dean 1980). However, some of these data 

 sources (Weinstein 1979, Weinstein et al. 1980) also 

 include southern flounder P. lethostigma and gulf 



flounder P. albigutta. but the patterns observed are 

 considered characteristic of P. dentatus (see Rogers 

 and Van Den Avyle 1983). Second, there is evidence 

 that estuaries in the northern Mid-Atlantic Bight do 

 provide nurseries for juvenile P. dentatus (Grosslein 

 and Azarovitz 1982). This has been substantiated for 

 Connecticut (Pearcy and Richards 1962), Long Island 

 (Poole 1961), New Jersey (Table 1 and this study), 

 Delaware Bay (this study), and coastal Delaware 

 (Pacheco and Grant 1973). That nurseries occur in 

 these areas would certainly be consistent with the ex- 

 tensive spawning and larval development that occur 

 in the northern Mid-Atlantic Bight (Smith 1973 and this 

 study), especially considering the lack of evidence for 

 larval transport or advection from this area. Third, the 

 habitats utilized by small juvenile flounder may be 

 difficult to sample. There is evidence that juvenile 

 P. dentatus use eelgi-ass beds in North Carolina (Adams 

 1976), Chesapeake Bay (Orth and Heck 1980, Wein- 

 stein and Brooks 1983) and New Jersey (senior author's 

 pers. observ.). Sampling flatfishes in these structural- 

 ly complex habitats with conventional gears (trawls, 

 seines) is inefficient and difficult. 



To our knowledge, no one has presented data to con- 

 firm or deny the possibility that P. dentatus uses the 

 continental shelf as a nursery area. Certainly spawn- 

 ing in the Mid-Atlantic Bight and on Georges Bank 

 occurs great distances from estuaries (Fig. 2). Perhaps 

 many of the larvae undergo transformation, descend 

 to the bottom over the continental shelf, and then move 

 into estuarine areas at a variety of sizes, beginning with 

 early transforming individuals. This could help explain 

 the relative scarcity of small juveniles and the large 

 numbers of YOY (150-320 mm) that appear during 

 summer (Fig. 4). These YOY occur in the recreational 

 fishery in New Jersey in some years (Festa 1979). A 

 continental shelf nursery area is more tenable in the 

 northern Mid-Atlantic Bight, given the broad continen- 

 tal shelf (~ 150 km) relative to the narrow shelf (~ 50 

 km) off North Carolina. We know of no adequate 

 continental-shelf sampling progi-am, using appropriate 

 collecting gear, to support or refute this possibility, but 

 suggest it should be vigorously tested. 



The growth of YOY P. dentatus in New Jersey 

 estuaries appears to be very fast, with individuals 

 reaching 160-320 mm 1 year after spawning (October, 

 Fig. 4). An almost identical growth rate has been found 

 in Long Island estuaries (Poole 1961), where length fre- 

 quencies reported for July, August, and September are 

 similar to those from New Jersey (Fig. 4). Additional- 

 ly, the modal sizes of males (25.1 cm) and females 

 (27.1 cm) of YOY reported from Long Island (Poole 

 1961) and those for both sexes from New Jersey (Fig. 4) 

 are similar to the modes of YOY captured in fall over 

 the continental shelf (Fig. 5). Assuming little or no 



