CONTENTS 



Introduction page 199 



Species of whalebone whales 201 



External characters and specific identity 201 



Size range 204 



Weight 205 



Yield of oil 208 



Food in the Antarctic and in warmer waters 209 



Parasites and diseases 213 



Breeding, growth and age 216 



The mean length at sexual maturity 216 



The reproductive organs 219 



Persistence of the corpora lutea of the ovaries 220 



Breeding 221 



Growth to sexual maturity 224 



The determination of age 225 



Statistics of catches 227 



Southern whaling centres 228 



Migrations and distribution 236 



Humpbacks 237 



Blue and Fin whales 249 



Relative abundance of the different species 260 



Sex ratio 266 



Seasonal changes in the local composition of the stock 269 



The monthly species ratio 270 



The monthly sex ratio 272 



Monthly average lengths and percentage of immature whales . . . 274 



The monthly percentage of pregnant females 277 



The stock of whales 278 



Evidence of the depletion of the stock 278 



Relative depletion of the different species 281 



Prospects of estimating the absolute magnitude of the stock . . . 282 



The effect on the stock of whaling at different times and in different places 284 



Species and classes of whales 285 



Whaling in different regions 286 



Whaling in different months 291 



A note on sanctuaries 292 



The reduction of whaling during the war 293 



Summary 293 



Appendix. Common names of whalebone whales 297 



References 298 



