Changes in abundance and distribution of humpback whales Megaptera novaeangliae in Hervey Bay Marine Park, Australia, based on aerial surveys conducted in 1992 and 2004

Aerial surveys were conducted throughout Hervey Bay Marine Park between August and October 1992 and 2004 to determine changes in abundance and distribution of the Eastern Australia humpback whale population in this area. Due to concerns about possible effects of boat traffic on whale distributions associated with a growing whale watching industry, the number and location of vessels were also recorded during these surveys. Throughout the 1992 season, 17 flights were conducted and a total of 41.93 surveys hours were completed, recording 186 pods, and a total of 320 animals. In addition, 392 boats were spotted in the area. During 2004, 10 flights took place with a total of 23.56 survey hours, 203 pods were sighted and a total 388 animals were recorded. In addition 216 boats were spotted in the study area.Results suggested an overall increase in the density of whale sightings from 1992 to 2004. By comparing total numbers for both years normalized to the number of survey hours, it can be seen that the total number of pods and the total number of individuals both increased. In 1992, with 7 more flights and an extra 10 hours on survey, the total number of pods and the total number of whales observed were less than in 2004. The composition of the pods showed a variation throughout both seasons consistent with a known distinctive temporal segregation of humpback whales on their annual migration. The percentage of calves was higher in 2004 than in 1992 consistent with the overall recovery of the eastern Australia population.Boat traffic did not show an effect on whale distributions in either year of the study. However this work provides a baseline for continuing to monitor boat traffic and whale distributions to help ensure that the east Australia whale population will continue to recover together with a sustainable growing whale watching industry