McBride and McKown: Consequences of dispersal to temperate estuaries for Caranx hippos 



529 



subtropical latitudes and its propagTiles, once dispersed to 

 temperate latitudes, are known to migrate south within 

 the same year. This species is successful largely because 

 it spawns early in the year in the subtropics and juve- 

 niles enter temperate estuaries at a time when their prin- 

 cipal prey is becoming available (Juanes et al., 1994). 

 Direct evidence of a successful autumn migration by 

 young-of-the-year P. saltatrix is available from recaptures 

 of tagged individuals and size-frequency analyses (Lund 

 and Maltezos, 1970; McBride et al, 1993). This "spring- 

 spawned" cohort of P. saltatrix was more abundant than 

 other intraspecific cohorts in the western North Atlantic 

 during the 1980s and early 1990s (Chiarella and Conover, 

 1990; McBride et al., 1993), and this species repeats 

 this life-history pattern in several oceanographic systems 

 worldwide (Juanes et al., 1996). 



The effects of this transport process, from the Carolinian 

 province to the Virginian province, is known for few other 

 species and these examples suggest a different fate for 

 these species than for P. saltatrix. Moss (1973) concluded 

 that the "sluggish" swimming ability and the critical ther- 

 mal minimum of 8.7°C for planehead filefish, Monocan- 

 thus hispidus. prevented individuals of this species from 

 surviving once they had been dispersed to temperate lati- 

 tudes. Hare and Cowen (1991) observed a wrasse, Xync/;- 

 tys novacula, settling on the continental shelf at temperate 

 latitudes, but successive cruises could not find survivors 

 from the initially observed cohort. And McBride and Able 

 (1998) reported on the annual appearance of butterfly- 

 fishes iChaetodon spp.) at temperate latitudes, but field 

 collections and laboratory experiments led them to con- 

 clude that none of these individuals survived through their 

 first winter Sinclair (1988) would categorize these unfor- 

 tunate individuals as "vagrants" from, as opposed to "mem- 

 bers" of a population. 



Although the ecological information about these tropi- 

 cal forms as they occur in temperate waters is limited, the 

 common paradigm is that "[the] Gulf Stream has a pro- 

 found effect upon the distribution of shore animals in the 

 western Atlantic . . . many tropical forms are left stranded 

 along the inhospitable shores of northeastern North Amer- 

 ica." (Briggs, 1996; p. 238). We believe that Briggs's conclu- 

 sion can be applied to most of these species; nonetheless, 

 juveniles of several "southern" species grow and survive 

 well at temperate latitudes during the summer and, based 

 on their size by autumn and their general mobility, may 

 migrate successfully back to subtropical latitudes before 

 winter (see also Hare and Cowen, 1993). We propose that 

 at least one other species is capable of following a disper- 

 sal-migration pattern that links the temperate and sub- 

 tropical latitudes during its first year The crevalle jack, 

 Caranx hippos (Linnaeus), is a migratory, coastal species 

 that is distributed worldwide at subtropical and tropical 

 latitudes (Briggs, 1960; Kwei, 1978; Grosslein and Azarov- 

 itz. 1982). In the western North Atlantic, it occurs pri- 

 marily in the southeastern United States and the Gulf of 

 Mexico (U.S. Department of Commerce, 1986), and spawn- 

 ing is known to occur only in the subtropical Straits of Flor- 

 ida (Berry, 1959; Fahay, 1975) and in the tropical Caribbean 

 Sea (Montolio, 1978). Young-of-the-year (YOY) C. hippos 



occur in subtropical estuaries of the south Atlantic states, 

 and they use these habitats as nurseries before presum- 

 ably migrating offshore in autumn (Berry, 1959). However, 

 YOY C. hippos are also reported from many temperate 

 estuaries north of Cape Hatteras (McBride'). Despite the 

 broad geographic distribution of YOY C. hippos, little is 

 known about their early life history at any latitude. From 

 archived museum collections, recent field collections, and 

 the literature, we assembled data about C. hippos in both 

 southern and northern estuaries and postulate on the sig- 

 nificance of dispersal of YOY C. hippos across two biogeo- 

 graphic provinces. 



Materials and methods 



Archival collections were examined at the New York State 

 Museum, the American Museum of Natural History, and 

 the Academy of Natural Sciences of Philadelphia, and col- 

 lection dates, locations, and sizes of C. hippos from coastal 

 habitats of New York and New Jersey were recorded (mate- 

 rial examined is listed in McBrideM. Similar data for C. 

 hippos in subtropical estuaries (from Cape Hatteras, North 

 Carolina, to Cape Sable, Florida) were taken from Berry 

 (1959). Densities and size data from samples collected in 

 Great South Bay (New York) and southern New Jersey 

 embayments during 1987 and 1988 were also examined 

 (see McBride and Conover [1991] for seine-survey design; 

 weir-sample data from Rountree et al.^). Fish densities in 

 these other estuaries and from the published literature 

 were calculated as 



CPUE = iCatch per unit of effort 

 [number offish per seine haul] ) 



for the period May-October unless stated otherwise. Field 

 sampling (described below) of temperate coastal habitats 

 was also completed, and abundance, habitats, seasonality, 

 and sizes of C. hippos were examined. Unless noted oth- 

 erwise, fish size is reported to the nearest cm fork length 

 (FL). A Gompertz model was used to model growth: 



FL = L, exp(-exp{-G|DOy - XJ}), 



where FL = fork length in mm; 



L^ = asymptotic length; 



G = instantaneous rate of growth at age Xg; 



DOY = day of the year, and 



Xq = inflection point of the curve. 



McBride, R. S. 1995. Perennial occurrence and fast growth 

 rates by crevalle jacks (Carangidae: Caranx hippos) in the 

 Hudson River estuary. In Final reports of the Tibor T. Polgar 

 Fellowship Program, 1994 (E. A. Blair and J. R. Waldman, eds.), 

 p. VI1-VI29. Hudson River Foundation, New York, NY. 

 Rountree, R. A., K.J. Smith, and K.W.Abie. 1992. Length fre- 

 quency data for fishes and turtles from polyhaline subtidal and 

 intertidal marsh creeks in southern New Jersey. Institute of 

 Marine and Coastal Science (IMCSl report 92-34, Rutgers, the 

 State Univ. of New Jersey, New Brunswick, NJ, 08903, 165 p. 



