A review of the weights of cetaceans with estimates of the growth and energy budgets of the large whales

Abstract

Published data on weights of Cetacea have been reviewed, and the body weights of all Cetacea, including foetuses, vary approximately with the cube of the body length. These weight/length relationships have been used to calculate the total biomass of whales caught in the Antarctic since 1904. Analyses of linear growth in rorquals show that different parts of the body grow at dissimilar rates, the head region growing at the fastest rate. All growth rates appear to slow down noticeably at puberty. During the first year of life the body weight of rorquals increases tenfold, the largest unit increase in the entire growth phase, and at puberty the whale appears to have attained 70-75[percent] of the total adult body weight. Analyses of migratory patterns of rorquals show that the whales arrive in the Antarctic from lower latitudes chiefly in December and January and remain there for at least three months. During this time the blubber increases in thickness, and the body weight increases by 30-50[percent], chiefly because fat is deposited in the blubber, meat and viscera. These increases are correlated with the intense feeding while in the Antarctic. Estimates of metabolic rates, growth efficiencies and energy budget have been outlined for blue and fin whales. The fat stored in the body in the Antarctic is of major importance in maintaining the whale throughout the rest of the year. Indications are that in lower latitudes, whales feed at a tenth of the rate in the Antarctic, if at all, and during the Antarctic feeding period must accumulate about 40[percent] of body weight in fat as an energy store. The enormous fat stores in pregnant females are sufficient to cover the energy cost of foetal growth and subsequently lactation for seven months.