532 



Fishery Bulletin 98(3) 



E 



1.5 



1.0- 



0-5 



° Various published studies 

 • This study (NY & NJ) 



6> 



O.O-Hia-S-!- 



27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 

 Latitude ("N) 



Figure 3 



Densities (arithmetic mean number of fish caught per seine 

 haul 1 of young-of-the-year Caranx hippos by sampHng latitude 

 (Rhode Island to Florida). Data were limited to seines from 

 10- to 90-m long, set during May-October and calculated per 

 year if a study was conducted for multiple years. Data were 

 taken from the following surveys (open circles), listed here 

 by decreasing latitude (with seine length): Hoff and Ibara, 

 1977 (12 m); Briggs and O'Connor, 1971 (91 m); Briggs, 1975 

 (91 m); Ecological Analysts, Inc. 1981. Ecological studies at 

 Oyster Creek Nuclear Generating Station. Feb. 1981 EA Report 

 JCP91I3 Progress Report. September 1979-August 1980, pre- 

 pared for Jersey Central Power and Light Company, Appendix 

 D, E, unpaginated (46 ml; Marcellus, 1972 (11 m); Thomas, D. 

 L., and C. B. Milstein 1973. Ecological studies in the bays and 

 other waterways near Little Egg Inlet and in the ocean in the 



vicinity of the proposed site for the Atlantic generating sta- 

 tion, NJ. Progress Report for January-December, 1972, vol. I: 

 Fishes and volume II: Appendices, Ichthyological Associates, 

 Inc. Absecon, NJ, 1065 p. ( 76 m): Thomas, D. L., C. B. Milstein, 

 T R. Tatham, R. C. Bieder, D. J. Danila, H. K. Hoff, D. P. Swie- 

 cicki, R. F Smith, G. J. Miller, J. J. Gift, and M. C. Wyllie. 1975. 

 Ecological studies in the bays and other waterways near Little 

 Egg Inlet and in the ocean in the vicinity of the proposed site 

 for the Atlantic generating station, NJ. Progress Report for 

 January-December, 1974. Volume I: Fishes, 490 p. Ichthyologi- 

 cal Associates, Inc. Absecon, NJ. (76 m); de Sylva, D. P., F. A. 

 Kalber, and C. N. Shuster 1962. Fishes and ecological condi- 

 tions in the shore zone of the Delaware River Estuary, with 

 notes on other species collected in deeper water. University 

 of Delaware Marine Laboratory. Information Series Publica- 

 tion 5. Technical Report to Delaware Board of Game and Fish 

 Commissioners under Dingell-Johnson Federal Aid in Fish 

 and Wildlife Restoration. Delaware Project F-13-R-1-2-3, 150 

 p. Contact senior Richard McBride (senior author) for data 

 of this report (18 m): Richards and Castagna, 1970 (12 m); 

 Tagatz and Dudley 1961 (21 m): Ogburn et al., 1988 (15 ml; 

 Anderson et al., 1977 (20 m); Miller, G. L., and S. C. Jorgen- 

 son. 1969. Seasonal abundance and length frequency distribu- 

 tion of some marine fishes in coastal Georgia, 103 p. U. S. Fish 

 Wildl. Ser Data Rep. 35. Washington, D.C. (on two microfische) 

 (21 m); Gilmore, 1988 (62 m); Schooley, 1977 (12 m); Peters, 

 1984 (9 m): Futch and Dwinell, 1977 (15 m); and Gunter and 

 Hall, 1963 (15 m). Data from the present study, restricted 

 to the years 1987 and 1988, are shown separately (filled cir- 

 cles) and include two southern New Jersey locales and Haver- 

 straw. Jamaica, and Great South bays. New York (30 and 61 m 

 seine nets). There was no significant relationship among the 

 data (Spearman correlation coefficent, r^=0.24, »=40; P=0.14). 



higher, as would be expected for a "subtropical" species, 

 than densities of those propagules transported to temperate 

 estuaries. Not all CPLTE values we examine in our study 

 were directly comparable because of potential differences 

 in deployment procedures, sampling habitats, and range of 

 seine sizes. We hope that others will report more data for such 

 comparative purposes in the future. We are also unaware 

 of comparative data for tropical regions to determine if this 

 species is more abundant in a more central portion of its 

 latitudinal range. Young-of-the-year C. hippos abundance is 

 generally low compared with other estuarine finfishes from 

 Massachusetts to Florida (e.g. Ay\'azian et al.. 1992;Tremain 

 and Adams, 1995; Able et al., 1996). and we conclude that 

 this species is uncommon throughout this range. 



Having found juvenile C. hippos in reasonable densities 

 in temperate estuaries, we also observed them to occupy 

 habitats similar to those of juvenile C. hippos in subtropical 

 estuaries. In both temperate and subtropical regions, juve- 

 niles of this species appear to use estuaries as nurseries (see 

 also Berry, 1959; Kwei, 1978). We observed individuals as 

 far upstream as the freshwater interface (about 1 ppt). at 

 about rkm 90-100 in the Hudson River during July-October 

 (Cooper et al., 1988; Geoghegan et al., 1992). Several others 

 have reported YOY C. hippos in oligohaline habitats (Chris- 

 tensen, 1965; Tagatz, 1968; Smith, 1985; Beebe and Savidge, 

 1988) but none in fresh water The presence of C. hippos 



within the Hudson River was associated with warm temper- 

 atures; this species occurred in similarly warm temperatures 

 in subtropical estuaries ( 18-33°C: Tagatz and Dudley, 1961; 

 Christensen, 1965; Tagatz, 1968). The concentration offish 

 in and near Haverstraw Bay is probably due to this region's 

 broad width and shallow bathymetry, which slows water- 

 flow rates and responds rapidly to solar radiation (Cooper 

 et al., 1988). In addition, three power plants that release 

 heated effluent are located near Haverstraw Bay (Cooper 

 et al., 1988). Temperature eventually becomes a very impor- 

 tant parameter affecting YOY C. hippos distribution, and 

 cold temperatures have been implicated in several cases of 

 ovei-wintering mortality for C. hippos. We know of no exper- 

 imental study to document the lower lethal temperature 

 for this species, but Bean ( 1903) noted that C. hippos could 

 overwinter in aquarium conditions above 10°C, and Hoff 

 (1971) observed dead C. hippos in waters colder than 9°C, 

 whereas conspecifics in a downstream portion of the same 

 Massachusetts river survived in waters above 9°C. Water 

 temperatures fall below 10°C for at least the 4-mo. period 

 of December-April near Haverstraw Bay and above the con- 

 tinental shelf of the middle Atlantic states (Cooper et al., 

 1988; Mountain and Holzwarth, 1989); therefore there is no 

 suitable overwintering habitat for C. hippos north of Cape 

 Hatteras. Yet although the predictability of the seasonal 

 cycle may be an important determinant of a species' latitu- 



