70 



Fishery Bulletin 100(1) 



100 

 80. 

 60 

 40 

 20 







\ Pelagic larvae & benthic luveniles (at OT5) 

 23 September 1991 



 flexion larva (n=9) 



E3 postflexion larvae (n=25) 



n benttiic luveniles (n=23) 



n n n 



Jl 



_  1   ' f 



^° -■ B Benttiic juveniles - near Beacti Haven Ridge 

 21 October 1991 ^ 



 Station 0T2(n=1 5) 

 nStationOTS (n=^3) 



40 



30- 



10. 



50-, 



40 



30 



20. 



10. 







Q Benttiic juveniles - offstiore of Beacti Haven Ridge 

 22 October 1991 



 Station C (n=29) 

 D Station E{n=13) 



H 



m 



Jun 1 Jul 1 Aug 1 Sep 1 Ocl 1 



Hatctiing date 



Figure 9 



Hatching-date distributions for larval and newly settled juvenile 

 Pnonotus carolinus collected 23 September 1991 (A) and for juve- 

 niles collected on 21 October 1991 (B) and 22 October 1991 IC). See 

 Figures 1 and 8 for locations of sampling stations. 



spp. eggs or larvae in Block Island Sound, and Able 

 and Fahay ( 1998) did not observe Prionotus larvae 

 above the continental shelf north or east of Hud- 

 son Canyon, New York. Instead there are many 

 reports of Prionotus eggs, larvae, and juveniles in 

 southern New England estuaries, specifically in 

 Long Island Sound (Wheatland, 1956; Richards, 

 1959; Williams, 1968; Richards et al., 1979) and 

 Narragansett Bay (Herman, 1963; Bourne and Go- 

 voni, 1988; Keller et al, 1999). Thus, the relative 

 importance of estuaries versus shelf habitats as 

 spawning grounds for Prionotus may vary in other 

 regions compared with our results for New Jersey. 

 Nonetheless, Prionotus spawning seasonality ap- 

 pears to follow a pattern similar to that of other 

 species with a wide latitudinal range that have a 

 shorter spawning season at higher latitudes (e.g. 

 Conover, 1992) and that spawn later in the south 

 (e.g. Barbieri et al., 1994). An important departure 

 from this general trend is that Prionotus repro- 

 ductive seasonality may vary not only with respect 

 to latitude but along an estuary-shelf gradient 

 as well. Because adults of both Prionotus species 

 enter estuaries early in the spring and migrate 

 back out to the shelf in summer (McBride and 

 Able, 1994), we postulate that spawning occurs 

 first in estuaries at a given latitude. In support 

 of this hypothesis are the collective results from 

 our study and other published reports. After the 

 summer spawning peak within estuaries such as 

 Chesapeake Bay and Long Island Sound, Priono- 

 tus spawn during August and September offshore 

 of Chesapeake Bay and New Jersey. In contrast, 

 spawning does not continue into late summer off- 

 shore of southern New England (Pearson, 1941; 

 Richards et al., 1979; Able and Fahay 1998). 



To explain this potentially novel spawning pat- 

 tern does not require any new controlling mecha- 

 nism other than that used to explain spawning 

 by other coastal fishes of the region. Temperature 

 and photoperiod are known to influence spawn- 

 ing activity in fishes (Burger, 1939) and may in- 

 fluence spawning seasonality of searobins. Water 

 temperatures offshore of the middle Atlantic sea- 

 board are known to fluctuate widely both tem- 

 porally and spatially (Colvocoresses and Musick, 

 1984) and this fluctuation affects the spawning 

 pattern of many species. For example, a simple 

 south to north progression of spawning activity 

 above the shelf is evident for Centropristis stri- 

 ata (Able et al., 1995) and Scophthalmus aquo- 

 sus (Morse and Able, 1995). For Prionotus, how- 

 ever, we propose that spawning seasonality is 

 controlled by an interaction between latitudinal 

 and estuarine gradients of temperature (i.e. earli- 

 er spawning in estuaries occurs because of earlier 

 warming of these shallow embayments). Temper- 

 ature has already been shown to affect the distri- 

 bution of Pr-ionotus adults along both latitudinal 

 and estuarine gi-adients (McBride and Able, 1994; 



