120 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



series of 32 presuniablv spent adult specimens 

 (161.0-261.8 mm.) taken at Silver Bay station 

 1393 on October 26 (table 1). 



PLACE OF SPAWNING 



From aU evidence, P. alius is a very secretive 

 and sedentary species unlikely to undertake major 

 spawning migrations, if it moves at all. The 

 adults seemingly spawn where they spend their 

 mature life, in waters of about 60 fathoms or less 

 (table 1), rarely to 1 10 fathoms. Collections from 

 the Gill show that the larvae are pelagic. Al- 

 though sampling was conducted from near the 

 shore out into the appro.ximate axis of the Stream 

 (Anderson, Gehringer, and Cohen, 1956), most 

 of the larvae were taken westward of the Gulf 

 Stream (fig. 6) over depths of less than 100 

 fathoms, mostly 20-30 fathoms (table 1). Like- 

 wise specimens dip-netted in southern latitudes 

 (below Cape Hatteras) were taken to the shore- 

 ward, except for those taken nearer the middle of 

 the Gulf Stream in higher latitudes south of Cape 

 Hatteras and one taken on the eastern side of the 

 Stream northwest of Grand Bahama Island (table 

 1 ; fig. 6). The latter individual could have been 

 spawned along the western edge of the Bahama 

 Islands, or even in the northern Antilles, and 

 reached its point of capture, despite its small size 

 (2.2 mm.), in the fast flow of the Gulf Stream in 

 this region (Leipper, 1954). The larvae taken 

 in the main Stream off the Carolinas (table 1 ; 

 fig. 6) from farther offshore could have had a 

 similar origin, or could have originated in inshore 

 continental waters and been transported much 

 farther offshore after spending several days in the 

 vagaries of the flow. Prejuveniles taken well 

 offshore north of Cape Hatteras presumably could 

 have had either a southern inshore continental 

 origin or one in the West Indies or Bahanuxs. 



MORPHOLOGY 



Detailed descriptions of morphological features 

 not discussed in this paper niay be found in 

 Jordan and Evermann (1896: p. 1239), Smith 

 (1907: p. 285), Hildebrand and Schroeder (1928: 

 p. 254), and Morrison (1890: p. 163). 



Larvae of other Priacanthidae were taken in 

 Gill tows, and series of these {Pria.catithus) were 

 distinguished from Pseudopriacanthus alfus. Lar- 

 val P. alius (see figs. 8-10 and descriptions of 

 larvae in following section) could be distinguished 



from larval Priacanthus of comparable size by 

 the presence of heavy pigment on the dorsal aspect 

 of the brain and on the dorsal surface of the gut, 

 a series of many small dark spots on the ventral 

 midline as opposed to series of only a few spots 

 (less than 10 at the smallest sizes) on Priacanthus, 

 pigmented gill arches at certain sizes, and by 

 shorter preopercular spines (half the length of 

 those in Priacanthus). 



As with most marine fishes having truly pelagic 

 larvae distributed by ocean currents (a phenom- 

 enon which permits free exchange of genes), 

 Pseudoprlacanthus alius exhibits no measurable or 

 significant geographical variation, but apparently 

 is constant throughout its range. As a partial 

 exception, the 108.3-mm. specimen from the Virgin 

 Islands (table 1 ; appencUx table A-1), representing 

 a population so placed geographically that it 

 receives little or no gene influence from other areas, 

 exhibited characters which fell within the range of 

 meristic values for the species, but approached the 

 extremes of several specimens (low gill-raker count 

 of 6-1-17; high lateral-hne scale count of 37; high 

 vertical scale-row count of 41; and a high pec- 

 toral-ray count of 19 left and 18 right). In body 

 proportions it appeared normal. 



MERISTIC CHARACTERS 



Counts were recorded only on prejuveniles, 

 juveniles, and adults. As, by my definition, the 

 full complements of all fin rays are not formed in 

 larvae, the numbei-s of spines and soft-rays were 

 not recorded for larvae. The progression of 

 development, however, is discussed under each 

 character — scale, fin-ray, and gill-raker formation 

 was very rapid, once initiated. The smallest 

 specimen for which counts were recorded and 

 included in the tables was 8.2 mm. It was con- 

 sidered tlie earliest prejuvenile. The next smaller 

 specimen available, 6.6 mm., although complete 

 in complement of other fin-rays, did not have a 

 full com])lement of secondary caudal rays. This 

 specimen was considered the largest larva of the 

 study. The point of division between larvae and 

 prejuveniles, by my definition, lies between 6.6 

 and 8.2mm. 



Fin and Fin-Ray Development 



Parts of the rays of many fins of critical-sized 

 specimens were missing. Therefore, the terms 

 "at least" and "about" are used in the following 



