(II AOandMUSICK: LIFE HISTORY OF JUVENILE SCIAENII) FISHES 



Mexico waters (Welsh and Breder 19231. Later 

 spawning by a northern component of the popula- 

 tion is evidenced from the length ranges of post- 

 larvae and juvenile spot (Table 1). 



( ynoscion regain (Bloch and Schneider) — 

 Weakfish 



EARLY LIFE HISTORY IN YORK 

 RIVER. — Young-of-the-year weakfish first en- 

 tered trawl catches in July or August and virtu- 

 ally left the estuary in the winter (Figure 10, mode 

 I). Yearling weakfish returned to the river in April 

 or May and left in September or October (Figure 

 10, mode II). Larger weakfish (2 yr or older) were 

 caught only sporadically during this study be- 

 cause of gear avoidance. The length mode of small 

 weakfish in August showed a rapid increase (Fig- 

 ure 10). This increase may be due to the recruit- 

 ment of yearlings or an earlier spawned group of 

 young-of-the-year. Length frequencies for 

 weakfish ( <250 mm TL) caught from August to 

 October 1972-74, were pooled to compare dis- 

 tribution by size in the York River and its 

 tributaries (Figure 11). Smaller fishes were more 

 abundant in the Pamunkey and Mattaponi rivers 

 than in the York River proper. Yearling weakfish 

 also showed a movement upriver ( Figure 11). This 

 suggests that young weakfish entered the low sa- 

 linity nursery ground (upper portion of the York 

 River) and then moved downriver as they grew. 

 Pooled length frequency distributions revealed an 

 apparent difference between shoal and channel 

 areas of the York River (Figure 12). Yearling 

 weakfish (or larger ones) were proportionally 

 more abundant in the channel. The 15.25-m beach 

 seine catches contained no weakfish, but occasion- 

 ally the 30.5-m seine caught some young-of-the- 

 year weakfish in the summer. 



OTHER STUDIES.— Major populations of 

 weakfish are confined to the Atlantic coast of the 

 United States from New York to Georgia. Existing 

 data indicate young-of-the-year weakfish enter es- 

 tuarine or coastal catches from May to July ( Table 

 2). The smallest sizes of the weakfish in the 

 catches differ with area and may be due to gear 

 and/or time of sampling. Small fishes with less size 

 variation (about 5 mm) were taken over a longer 

 period of time in southern areas than northern 

 areas (Table 2 ). Young-of-the-year weakfish do not 

 occur in catches during winter months in northern 

 coastal areas or estuaries (Perlmutter 1956; 



Massmann et al. 1958; Thomas 1971; Markle 

 1976). Year-round catches of weakfishes from 

 North Carolina (Hildebrand and Cable 1934) and 

 Georgia (Mahood 19741 were from sounds and 

 short coastal rivers. Most of the studies suggest 

 the age-group on Table 2 was a combination of 

 young-of-the-year and yearlings. No distinct mode 

 could be identified for young-of-the-year from 

 these studies. This may be due to the multiple 

 spawning (Merriner 1973, 1976) and/or the re- 

 cruitment of the young-of-the-year from different 

 spawning populations. 



The reproductive biology of weakfish is better 

 known than other sciaenid fishes studied here. 

 Welsh and Breder (1923) described the eggs and 

 development of weakfish and noted that Delaware 

 Bay was a spawning ground for weakfish. Mer- 

 riner (1973) indicated that weakfish have an ex- 

 tended spawning season in North Carolina 

 (March- August) and are characterized by high 

 fecundity and possible multiple spawning by some 

 females. Pearson (1941) took plankton tows in 

 lower Chesapeake Bay from May to August in 

 1929 and 1930 and reported greater densities of 

 weakfish larvae (1.5-17 mm TL) in subsurface 

 tows (average 67/tow) than in surface tows (aver- 

 age 13/tow). The density of planktonic weakfish 

 decreased at those stations within Chesapeake 

 Bay, compared with sites near the bay mouth. 

 Harmic ( 1958) reported that newly hatched larval 

 weakfishes averaged 1.8 mm TL. Soon after hatch- 

 ing, the larvae became demersal and were dis- 

 persed into the nursery areas of Delaware Bay by 

 means of the "salt wedge." The smallest weak- 

 fishes taken in the bottom trawl were 6 to 10 mm 

 TL (Hildebrand and Cable 1934). The young-of- 

 the-year weakfish in York River are probably 

 progeny from adults spawning near the mouth of 

 Chesapeake Bay. Weakfish tagged and released in 

 lower Chesapeake Bay (Nesbit 1954) were later 

 recovered to the north in New York and New Jer- 

 sey, and southward in North Carolina. Nesbit 

 (1954), Perlmutter et al. (1956), and Harmic 

 (1958) cited the presence of a northern spawning 

 population in New York and northern New Jersey 

 waters and a southern spawning population from 

 New Jersey to North Carolina. Seguin (1960) 

 found that morphometric and meristic variation of 

 weakfish exists along the middle Atlantic coast 

 and suggested that three possible population seg- 

 ments may exist: a New York group, a Delaware 

 and lower Chesapeake group, and a North 

 Carolina group. Joseph (1972) questioned the 



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