Lowerre-Barbieri et al.: Age and growth of Cynoscion regalis 



653 



The complex spatial and temporal distribution of 

 weakfish may also affect estimates of seasonal 

 growth. Growth of temperate-water fish usually fol- 

 lows the seasonal cycle; it is faster in summer and 

 slower in winter (Moreau, 1987). Juvenile weakfish 

 have been shown to grow rapidly during June-Sep- 

 tember (Mercer, 1985). However, mean size at age 

 for Chesapeake Bay weakfish ages 3-6, was smaller 

 in fall-caught than in spring-caught fish (Nesbit, 

 1954, the present study). Thus, it may be difficult to 

 follow seasonal growth patterns in Chesapeake Bay 

 commercial catches. 



Historic trends in maximum size and age 



The population structure of Chesapeake Bay weak- 

 fish has dramatically fluctuated since the 1920's. 

 Hildebrand and Schroeder ( 1928) reported that most 

 fish in Chesapeake Bay commercial catches weighed 

 from 0.5 lb to 3 lb (0.23 kg to 1.36 kg) and that 6-10 

 lb fish (2.72-4.54 kg) were not uncommon. By the 

 1950's, however, Massmann (1963) reported that 

 most fish were about 0.25 lb (0.11 kg) and few 

 weighed more than 2 lb (0.91 kg). Massmann ( 1963) 

 concluded that the uniformity in size structure from 



Figure 1 1 



Commercial landings of weakfish, Cynoscion regalis, coastwide (hatched bars) 

 and in Chesapeake Bay (black bars), 1925-89, with maximum reported sizes and 

 ages (in years) for periods of high and low landings. Taken from: "Nesbit ( 1954), 

 Terlmutter et al. (1956), Taylor (1916), ^reported in Seagraves (1981), 

 'Massmann ( 1963), IVlerriner ( 1973 ), ^Shepherd ( 1988), ''Villoso ( 1989), 'present 

 study, ^Hawkins (1988). 



1954 to 1958 indicated that there were no large fluc- 

 tuations in year-class abundance; rather, he sug- 

 gested that the weakfish population had stabilized 

 at a low level of abundance. In 1970, however, the 

 maximum size and number of large fish began to 

 increase, peaking in 1980. Although the maximum 

 size and number of large fish have declined recently, 

 the current maximum size of 875 mm TL and maxi- 

 mum age of 12 remain well above those for the 1950's 

 and 1960's (445 mm TL and age 5) (Massmann, 1963; 

 Joseph, 1972). 



Similar historic changes in maximum size and age 

 have been reported over much of the weakfish range, 

 with higher maximum ages and sizes during periods 

 of higher landings and presumed abundance (Fig. 

 11). During the high landings of 1925-45, the maxi- 

 mum size was 865 mm TL (Nesbit, 1954), and maxi- 

 mum age was 8 (Perlmutter et al., 1956). However, 

 during the 1950's and 1960's when landings were low, 

 maximum size decreased to 760 mm TL and the 

 maximum reported age was 6 years (Perlmutter et 

 al., 1956). In the 1970's and 1980's, maximum size 

 and age increased to 960 mm TL (Villoso, 1989) and 

 12 years (Shepherd, 1988), concurrent with increased 

 weakfish landings. Because all previous ages were 

 based on scales, the historic pattern of higher maxi- 

 mum ages during periods of higher 

 landings are probably valid, even 

 though actual ages may have been 

 underestimated. 



Citation data indicate an abrupt 

 increase in maximum size and 

 abundance of large weakfish in 

 Delaware Bay in 1970 and in 

 Chesapeake Bay in 1971. Maxi- 

 mum size rose steadily from 1970 

 to 1979 and then remained rela- 

 tively constant until 1989 in both 

 areas. Abundance of increasingly 

 large fish (Fig. 10) also rose until 

 1980 in Chesapeake Bay and 1989 

 in Delaware Bay. Although these 

 data have no estimates of effort 

 associated with them, the general 

 pattern appears accurate. Greater 

 effort might increase the number 

 of rare, large individuals being 

 caught even if their abundance 

 remained constant, but it would 

 not be expected to cause such a 

 dramatic change in the numbers 

 and size of large fish being caught 

 (i.e. in Chesapeake Bay no fish 

 >3.5 kg TW from 1958 to 1969 to 

 more than 1,000 fish >5 kg TW in 



