7UV . I \ 



THE AGE OF FIN WHALES AT PHYSICAL 



MATURITY 



WITH A NOTE ON 

 MULTIPLE OVULATIONS 



By J. F. G. Wheeler, m.sc. 



(Plate V, text-figs. 1-5) 



INTRODUCTION 



THE determination of age in whales is a question of much scientific interest and 

 economic importance. Hitherto, both in our own work on Blue and Fin whales 

 (1929) and in that undertaken by others (Hinton, 1925 ; Risting, 1928), the only ground 

 of comparison between individual whales or groups of whales has been that of length. 

 At South Georgia and elsewhere anatomical investigations have shown that whales 

 become sexually mature at lengths which for each species vary within comparatively 

 narrow limits, and the mean values have been used in determining the state of maturity 

 in other whales in which the anatomy could not be studied. There is a possibility, how- 

 ever, that the mean lengths at sexual maturity are not the same in all areas: and, when 

 mature whales are under consideration, average lengths may be very misleading if age 

 is in any way implied. 



The enormous size normal to most of the species produces an impression of great 

 age. It is indeed a not unnatural inference that the larger the animal the longer it must 

 live to grow to that size. An estimated length of life of more than a thousand years for 

 whales of the larger species, attributed to Cuvier, is mentioned by Dewhurst (1834, 

 p. 45). The statement appears in a supplement to the Cetacea in a translation of Cuvier 's 

 Regne Animal (iSzj), and is apparently due to the translator. Camper (1820), while not 

 committing himself on the subject of age, suggested that as the whales then being caught 

 were not as large as those first taken in the fishery 200 years before, they were not being 

 allowed time to grow to their full size. The idea of a long life and of a relation between 

 grov^fth phases and the span of life appears in G. F. Cuvier's work (1836): " . . .la duree 

 de leur vie qui doit etre considerable, si Ton en juge par analogic avec celle des autres 

 animaux a mamelles, toujours proportionnelles a celle de la croissance qui est propor- 

 tionnelle elle-meme a celle de la taille". Probably much the same opinion was under- 

 stood if not expressed when the only data concerning whales were obtained from 

 occasional stranded specimens and the reports of whales seen or captured at sea. 



