CHAOand MUSICK: LIFE HISTORY OF JUVENILE SCIAENID FISHES 



In January 1972-74, the numbers of individual 

 sciaenid fishes were considerably reduced, except 

 for M. undulatus (Figures 3, 5). Cynoscion regalis, 

 B. chrysoura, and L. xanthurus were caught only 

 occasionally. During the winter months, resident 

 fish species were more abundant than transients, 

 especially in the upper tributaries of the York 

 River (Markle 1976). Micropogonias undulatus 

 was the most abundant sciaenid fish in the middle 

 part of the York River (Figure 5). Depth distribu- 

 tion in January 1973 (Figure 3), indicated that 

 most fish were caught in the channel. Bottom 

 temperatures of the channel stations were higher 

 than shoal stations (Figure 2), which might have 

 been the major factor causing the concentration of 

 young sciaenids in the channel. 



In April 1972-74, C. regalis, M. undulatus, and 

 L. xanthurus were caught (Figures 3, 5). Cyno- 

 scion regalis was absent in 1973 (Figure 3) but 

 sparse in 1972 and 1974 (Figure 5). Micropogonias 

 undulatus was more abundant in the upper part of 

 the river and L. xanthurus was more abundant in 

 the lower reaches (Figures 4, 5), apparently be- 

 cause the young-of-the-year L. xanthurus had just 

 entered the estuary (see section on "Distribution 

 and Size"). Depth distribution of these two species 

 (Figure 3) showed that they were more abundant 

 in shoal areas, especially M. undulatus. Bairdiella 

 chrysoura was completely absent. 



Life History and Size 



Length-frequency distributions (Figures 6-19) 

 indicate that juvenile Leiostomus xanthurus, 

 Bairdiella chrysoura, Cynoscion regalis, and Mi- 

 cropogonias undulatus enter the York River con- 

 secutively from April on, and all but M. undulatus 

 leave the York River by December. Seasonal size 

 distributions of these four species in the York 

 River will be discussed individually and compared 

 with studies from other areas. Modes I and II in 

 Figures 6 and 10 and the following discussions 

 represent young-of-the-year (mode I) and year- 

 lings (or older fishes, mode II), respectively, except 

 in M. undulatus and Figure 16, where modes I and 

 II represent young-of-the-year and mode III the 

 yearlings (or older fishes). 



Leiostomus xanthurus Lacepede — Spot 



EARLY LIFE HISTORY IN THE YORK 

 RIVER. — Young-of-the-year spot, entered the 



trawl and beach seine catches in early April and 

 most left by December (Figure 6, mode I). A few 

 smaller fish stayed in the estuary over winter. 

 Yearling spot usually entered the study area from 

 March to May and left the area in September ( Fig- 

 ure 6, mode II). The intermediate mode (between 

 modes I and II) on Figure 6, April and May 1972, 

 was not found in the 1973 and 1974 samples. This 

 may indicate late spawning in the previous year 

 (1971). The length frequencies of young spot from 

 May to July during 1972-74 were pooled and 

 grouped by river strata (Figure 7). Young-of-the- 

 year spot moved up to the confluence of the 

 Pamunkey and Mattaponi rivers (Figure 1); most 

 yearling spot stayed in the lower parts of the York 

 River. During the same periods, no differences 

 were found between the length frequency dis- 

 tributions in shoal and channel stations (Figure 8) 

 of either young-of-the-year or yearling spot. 



Spot caught in the beach seine (Figure 8) were 

 obviously smaller than those taken by trawls. Spot 

 was the most abundant sciaenid in the beach seine 

 zone (depth <1.5 m) for collections with the 

 15.25-m and 30.5-m seines. The length frequency 

 distribution of spot caught by beach seine was 

 typically unimodal; mostly young-of-the-year 

 (Figure 9). Some smaller yearlings were taken 

 occasionally (Figure 9, 1974, mode II) and indi- 

 viduals >135 mm TL were captured only with the 

 30.5-m seine (Figure 9, August and September 

 1972). 



In summary, young-of-the-year spot entered the 

 York River in April and used the estuary as a 

 nursery ground. In December, most spot left 

 though some smaller fish stayed in the estuary 

 through the winter, joining the yearlings as they 

 returned to the river in the next spring. The year- 

 lings left the estuary after an extended feeding 

 period from March to October. 



OTHER STUDIES.— Selected length frequency 

 data for spot along the Atlantic and Gulf of Mexico 

 coasts of the United States are summarized (Table 

 1 ) for comparison with the present study. Hilde- 

 brand and Schroeder (1928) and Pacheco (1957, 

 1962a) reported length frequency of spot from the 

 present study area (York River and Chesapeake 

 Bay). Across all areas (Table 1), young-of-the-year 

 spot (Group on Table 1) enter the estuarine nur- 

 sery grounds during the first half of the year. They 

 may enter estuaries as early as January (Table 1; 

 Hildebrand and Cable 1930; Springer and Wood- 

 burn 1960; Sundararaj 1960). Spot first enter the 



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