Armstrong et al.: Age, growth, and reproduction of Lophius amencanus 



225 



the vertebrae to decrease slightly in diameter, possibly 

 the resorbtion of the outer surfaces due to starvation 

 in late winter. 



Mean lengths were back-calculated for 256 males and 

 260 females. One hundred forty-two individuals, whose 

 sex could not be determined because their gonads were 

 undifferentiated (94-239 mm TL) but who were deter- 

 mined to have one annulus, were included in the back- 

 calculations for each sex, bringing the total number 

 used in the analysis to 398 males and 402 females. 



The observed lengths were consistently higher than 

 back-calculated or von Bertalanffy lengths for indi- 

 vidual age-groups (Table 3). However, the differences 

 are within the limits of seasonal growth, so the fourth 

 criterion appears to have been fulfilled. 



Males and females had very similar lengths-at-age 

 until age 4. Above age 4, the mean lengths for females 

 were slightly greater than males, with the difference 

 becoming more pronounced with increasing age 

 (Fig. 10). 



The data suggest a difference in maximum age for 

 the two sexes. The oldest male collected was 9 years 



old. Males older than 6 were exceptionally rare. Only 

 one individual from each of the age groups 7, 8, and 

 9 was captured during the course of this study. The 

 oldest female sampled was 11 years old. Fifty females 

 greater than 6 years old were obtained. It appears that 

 the number of older males is much fewer than females, 

 indicating greater mortality of the males. 



Mean back-calculated lengths-at-age were used to 

 develop the vonBertalanffy growth equations. The 

 resulting parameters and equation for females are: 



K =0.095 



L^ = 1576 mm 



to =0.162 



Lt =1576.0 (1-e - 



0.095 (t-O. 



162))_ 



The growth equation for males was calculated using 

 three slightly different data sets. It was first calculated 

 using all the mean back-calculated lengths available. 

 The equation was then formulated after eliminating the 

 two fish in age-groups 8 and 9 from the data set and 

 finally it was calculated without age-groups 7, 8, or 9. 



