Yearly trend in the proportion of pregnant animals among mature female Antarctic minke whales in the JARPA and JARPAII period

This paper is a revised version of SC/F14/J9 presented to the JARPAII Review Workshop. The discussion of the paper was modified to take into consideration some recommendations from the Review Workshop. The proportion of pregnant animals among mature females (PPF) in Antarctic minke whales was examined from samples collected during 1987/88-2004/05 JARPA and 2005/06-2010/11 JARPAII surveys. Analysis was conducted for two biological stocks which were separated at 165oE. The PPF of both stocks appeared stable at around 0.9 and when data from all years were combined, the PPF was 0.932 for I-stock and 0.904 for P-stock. Linear regression analysis showed no significant yearly trend in either stock during the JARPAII period. From logistic regression analysis, no significant trend was detected during the JARPAII period but a significant increasing trend was detected for P-stock during the JARPA and all period. This latter result was influenced by just two lower PPF values in the 1990/91 and 1994/95 seasons. Although a high PPF was observed throughout the survey period, monitoring of PPF is important to detect possible change in nutritional condition and reproduction which affect sustainable management of these whale stocks.