Longevity and Mortality Rates of Fish in Nature 163 



species. Most of these fall somewhere near the lines for one or 

 other of the first four groups, with the sturgeon in the top 

 right-hand section of the diagram having the highest values 

 of both Tjj^ax ^^d ^ooj ^^^ ^ cluster of the small and short- 

 lived species near the origin (see enlarged panel). The only 



50 - 



40 



O' '-^ ' ' ' ' /SALMONOIDEI 



O lO 20 30 40 bO / 



PLtURONECTOIDEI 



3CO 



Fig. 5. Relation between maximum age (Tmax) and asymptotic length (Loo) in 

 various species not included in Fig. 4 (from Table I). The lines are those for the 



four groups shown in Fig. 4. 



species which, from the data we have examined so far, appear 

 to be exceptional are the Thunniformes — with their large size 

 and relatively short life they occupy a position similar to that 

 of the true salmon — and possibly the Rays (e.g. Dasyatis 

 akajei; Yokota, 1951), but age determination is difficult in the 



