FISHERY BULLETIN: VOL. 84, NO. 3 



Maximum Size and Age, 

 Life Span, and Mortality Rate 



Netuma barba is a long lived, slow growing species 

 with a low mortality rate. Specimens as long as the 

 theoretical mean length (638 mm) are frequently 

 captured. The largest catfish observed was a 980 

 mm female 36 yr old. Netuma barba life span was 

 estimated to be 23.1 yr and its mortality rate was 

 0.13. I assumed that the estimate of M (natural 

 mortality) is accurate, since Netuma barba reveals 

 a long life span, a capacity to avoid predation 

 through the defense represented by its hard dorsal 

 and pectoral spines and a parent-juvenile care 

 behavior (Reis in press). Pauly (1980) suggested that 

 species with low mortality rates are related to high 

 Loo values and to low growth coefficients. These 

 characteristics combined with the fact that Netuma 

 barba has a low fecundity (Reis in press) define the 

 species as /f- strategists (Gunderson 1980). 



ACKNOWLEDGMENTS 



I am greatly indebted to J. P. Castello for his 

 assistance and valuable suggestions and to the staff 

 of Fisheries Biology Laboratory, Department of 

 Oceanography, Fundacao Universidade do Rio 

 Grande. 



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