Reproductive parameters of the North Atlantic right whale

Main Article Content

Scott D. Kraus
Philip K. Hamilton
Robert D. Kenney
Amy R. Knowlton
Christopher K. Slay


North Atlantic right whale reproduction was assessed for the period 1980 through 1998. At the end of this period, we estimated there were
between 299 and 437 right whales alive, including 70 mature females. Using maximum and minimum population estimates for the entire
period, mean values for gross annual reproductive rate were 0.36 and 0.49 respectively, and the mean value for calves per mature female
per year was 0.25. There is a significant decreasing trend in calves per mature female per year over the entire study period. The mean age
at first calving is 9.53 years. The mean number of cows recruited annually since 1985 is 3.8. Mean annual calving intervals have increased
significantly during the study period from 3.67 years (1980-1992) to over 5 years (1993-1998). Although the North Atlantic population is
affected by significant anthropogenic mortality, diminishing reproductive rates are probably also responsible for the plight of this

Article Details