590 



Fishery Bulletin 100(3) 



pinfish. Similarly, Hansen (1970) found that annuli on 

 scales are generally formed once a year, in April. 



The maximum age of pinfish determined in this study 

 was 7 years, which exceeded the maximum age of 2 years 

 reported by Hansen (1970). The difference in maximum 

 age is probably due to Hansen's inadequate sampling of 

 the entire size range of pinfish in Pensacola Bay — he col- 

 lected pinfish at only two stations using a single, selective 

 trawl. In addition, Hansen's use of scales as the primary 

 aging structure may have contributed to the underesti- 

 mate of the maximum age of pinfish (Beamish and Mc- 

 Farlane, 1987). In contrast, pinfish collected in this study 

 were sampled from numerous locations in Tampa Bay and 

 adjacent Gulf waters with multiple types of gears that had 

 various mesh sizes, and otoliths, which are more reliable 

 aging structures than scales (Beamish and McFarlane, 

 1987), were used for age determination. Coincidentally, 

 Caldwell (1957) projected from the growth rates of age-1 

 pinfish that a 328-mm-SL pinfish may have been as old as 

 7 years; my results provide direct evidence that supports 

 his estimate. 



Reproduction, sex ratios, and maturity 



The monthly changes in GSIs show that pinfish are late- 

 autumn to early-spring spawners in Tampa Bay and 

 adjacent Gulf of Mexico waters; this conclusion was also 

 reported by Darcy (1985) and Cody and Bortone (1992). 

 Pinfish spawning is suspected to occur in offshore oceanic 

 waters (Hansen, 1970; Darcy, 1985); however, the high 

 GSIs of pinfish collected in Tampa Bay and the occurrences 

 of several of these pinfish with late-developing gonads in 

 waters about 3-6 km into the bay during October-Decem- 

 ber suggest that some spawning activity may occur in this 

 estuary. This is not surprising because most studies that 

 have examined gonadal activity in pinfish have used sam- 

 ples only from offshore waters (Franks et al., 1972; Stott 

 et al., 1980, 1981), did not use gear with various mesh 

 sizes to adequately sample the entire size range of pinfish 

 found in estuaries (Caldwell, 1957; Hansen, 1970), or did 

 not compare data on an estuary-offshore basis (Cody and 

 Bortone, 1992). 



*- 1994 



o 1995 



▼- 1996 



^ - 1997 



10 15 20 



Depth (m) 



210 ^ 



180 

 £ 150 • 



120  



90 • 



60 



B 



282 



115 



T 



42 



6-10 11-15 16-20 21-25 26-30 



Depth range (m) 



Figure 7 



Plots of (A) cumulative catch versus depth by year and (B) 

 size frequency of pinfish by depth range from the baitfish 

 trawl survey, 1994-97. In B, the lower and upper dots rep- 

 resent the 5"^ and 95"^ percentiles of the length distribu- 

 tion, the whiskers represent the 10"^ and 90'*' percentiles, 

 the box represents the 25"' and 75"' percentiles, and the 

 horizontal line represents the median length. 



Length-weight relationships 



The length-weight relationships were affected by gonadal 

 maturation. During the September-February period, go- 

 nad weight of both sexes increased, which resulted in a 

 standard-length to total-body-weight relationship that was 

 higher than it was in March-August period. Differences in 

 predicted total weight at length were 2-8% between the 

 September-February and March-August periods and 

 illustrate the effect of maturation on these relationships. 

 The slopes of the length-weight relationships from both 

 periods (3.03-3.11) were higher than the slopes of length 

 on weight relationships (2.91 and 2.90, respectively) de- 

 veloped by Caldwell (1957) and Cameron (1969). 



