. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 356 DISCOVERY REPORTS The division of the catch into age groups may now be examined. Following the attainment of sexual maturity whales are considered to give birth normally at recurrent intervals of two years. Each two-year period is occupied in gestation (eleven and a half months) and lactation (six months) after which is a resting period when the activity of the reproductive organs subsides until the onset of the next sexual season. Each age group should therefore consist of ovulating, pregna
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 356 DISCOVERY REPORTS The division of the catch into age groups may now be examined. Following the attainment of sexual maturity whales are considered to give birth normally at recurrent intervals of two years. Each two-year period is occupied in gestation (eleven and a half months) and lactation (six months) after which is a resting period when the activity of the reproductive organs subsides until the onset of the next sexual season. Each age group should therefore consist of ovulating, pregnant, lactating and resting whales covering the two-year period. It should be capable, moreover, of further analysis into. OCT IMMATURE — -O-- NOV DEC JAN SEXUALLY MATURE — FEB MAR APR PHYSICALLY MATURE Fig. i. Fin whales, females. Numbers of immature, sexually mature but not physically mature, and physically mature whales in five complete seasons at South Georgia. a one-year grouping, the lactating and resting whales being a year older than those ovulating or pregnant. At South Georgia, however, ovulating whales are rare and it has been shown that breeding is, in all likelihood, restricted to northern waters. Ovulation does occur exceptionally in the south but this does not necessarily involve copulation, and may indeed be due to some pathological condition of the individual whale. Omitting ovulation, then, the grouping of the South Georgia catch is limited to the pregnant and lactating and resting whales, of which the full analysis for five seasons is shown in Table Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Institute of Oceanographic Sciences (Great Britain); National Institute of Oceanography of Great Britain; Great Britain. Colonial Office. Discovery Committee. London ; New York : Cambridge
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