FISHERY BULLETIN VOL 77. NO 1 



We will generally refer to bluefish <10 mm 

 standard length (SL) as larvae and those >10 mm 

 SL as juveniles. Bluefish hatch at about 3 mm SL 

 and by 10 mm SL the fin ray development is nearly 

 complete and in living specimens the body is dark 

 blue on the back and silvery on the sides, as in the 

 pelagic juvenile stage of goatfish and mullet (Nor- 

 cross et al. 1974). 



RESULTS 



H\dr<)graphiL Ffaturc!) iif 

 Middle and South Atlantic Bights 



Shelf water characterized by salinities of 

 <35%o, is divided into coastal water ( <33.6%o) and 

 shelf edge water i33.6-35.0"'iMii i Wright and Parker 

 1976). The Gulf Stream, characterized by 

 salinities "-36. 0"/oc) and/or temperatures -IS'C at 

 100 m or -IS'C at 200 m, flows generally beyond 

 the edge of the continental shelf The water mass 

 between the shelf water and Gulf Stream, called 

 the slope water, is separated from the shelf water 

 by a strong surface feature, except in midsummer, 

 called the slope front. Surface manifestations such 

 as lines of flotsam, differences in water color, and 

 choppiness of the Gulf Stream are seen on moder- 

 ately calm days. The .shelf water is sluggish and 

 influenced by short-term effects of wind, but gen- 

 erally moves south along the shore. The Gulf 

 Stream moves northward or northeastward at ve- 

 locities over 100 cm/s (Sverdrup et al. 1942). 



Eggs 



Bluefish eggs, which share features with pelagic 

 eggs of many other species, were not found in any 

 of our collections. Bluefish eggs have a smooth 

 spherical membrane, a diameter of 0.90-1.20 mm 

 averaging 1.00 mm, a pigmented yolk, a single oil 

 globule about 0.2 mm in diameter, and 

 melanophores in rows on the embryo (Deuel et al. 

 1966). Even though an egg has all of the above 

 features, it can be identified with certainty as 

 being a bluefish egg only if the oil globule is pig- 

 mented and in later development the number of 

 myomeres has become established at 24 to 28. 



Two studies have reported occurrences of 

 bluefish eggs along the east coast. Marak and Col- 

 ton (1961) listed a few of them from late May to 

 early June 1953 in 12,8°C water south of Cape 

 Cod. These data are suspect because: 1 ) identifica- 



tion was based on inadequate descriptions by 

 Agassiz and Whitman (1885) and Perlmutter 

 ( 1939); and 2) adult bluefish in spawning condition 

 are not present off southern New England until 

 later in the year when temperatures are consider- 

 ably warmer. In a second study conducted from 

 1960 to 1962 off Virginia, Norcross et al. (1974) 

 reported bluefish eggs during the period June 

 through August from near shore to the continental 

 slope. Although none occurred in our collections, 

 from the similarity in distribution of bluefish eggs 

 and larvae seen by Norcross et al. ( 1974), it seems 

 that an accurate indication of spawning location 

 can be derived from the capture of small larvae. 



Larvae 



.Scasonal-Cjfographic Distribution 



Although bluefish larvae occurred between 

 Massachusetts and Florida during every season, 

 two major geographically distinct concentrations 

 of larvae were found; one south of Chesapeake Bay 

 near the Gulf Stream in spring, and the other 

 north of Cape Hatteras over the middle of the 

 continental shelf in summer. 



During spring, bluefish larvae were taken from 

 near Cape Hatteras to Cape Canaveral, Fla. Of the 

 473 larvae taken at 25 stations during the surveys 

 of May 1966 and 1967, greatest concentrations 

 were between the offings of New River, N.C., and 

 Charleston, S.C., near the edge of the continental 

 shelf (Figure 2). In April and May 1971, we also 

 caught bluefish larvae near Cape Hatteras 

 primarily offshore near the Gulf Stream. From 

 these data, it appeared that bluefish spawned near 

 the edge of the continental shelf in the South At- 

 lantic Bight during spring. 



Bluefish dominated the neuston catches near 

 Cape Hatteras during the eight weekly cruises in 

 spring of 1972 (Table 2). They occurred on every 

 cruise and in every water type sampled. The var- 

 iability in catches between paired tows during this 

 series was too large to permit precise comparison 

 among the dates or sampling areas. However, the 

 largest catches were made in water just shoreward 

 of the Gulf Stream. Most of the specimens taken in 

 or near the Gulf Stream were between 5 and 12 

 mm SL, whereas the few taken over the shelf 

 ranged from 11 to 21 mm SL. 



The numbers of bluefish caught each week gave 

 no indication of relative abundance during spring 

 in this area, partially because weather-influenced 



216 



