There is little information on the condition of most whale populations; humpback whales are recovering strongly.
The humpback whale is a listed threatened species which has been monitored since the 1980s. Its population is continuing to recover strongly after being decimated by whaling which stopped in the 1960s (Section 2.2.1). From an east Australian population as low as 500 animals when whaling ceased, numbers have grown consistently with an estimated annual recovery rate of between 10.5 and 12.3 per cent. 240 The population was estimated to be more than 10,000 animals in 2007240 — about half of the estimated pre-whaling population size. 240 The most recent 2010 survey provides no evidence that the rate of population growth is slowing significantly with an absolute population abundance in that year of over 14,500. 241 Dwarf minke whales visit the northern Region each winter — the only location in the world with predictable encounters with these whales. Dwarf minke whales are also reported in very low numbers further south in the Region. 242 Being a relatively cryptic species, little is known of the population status of dwarf minke whales that migrate there. The population of dwarf minke whales that interact with visitors in the Region has been conservatively estimated to be 449 in 2006, 342 in 2007 and 789 in 2008. 243 It is unknown whether this reflects actual abundance or only that part of the population that is more likely to interact. 244
Dwarf minke whales visit the Region each winter
© Matt Curnock
There is estimated to be 18 species of dolphin in the Region. They are found throughout the Region with some species solely inhabiting inshore waters and others typically being found far from the coast. There is limited information or monitoring of the status of most species. While all dolphin species are protected in the Region, the Australian snubfin and Indo-Pacific humpback dolphins are considered the highest priority for management in the Region because of their small, localised populations, exposure to high levels of human activity, and suspected population declines. 245 Recent research suggests the northern Australian population of Indo-Pacific humpback dolphin that occurs in the Region may be a distinct species. 246 This new classification would have implications for its conservation status as the population would be smaller and more confined than under its current classification. There are no overall population estimates for the Australian snubfin or Indo-Pacific humpback dolphins in the Region. 247 At a local scale, it is estimated that there are less than 100 Australian snubfin dolphins in Cleveland–Halifax Bays 248 and about 70 in Keppel Bay–Fitzroy River 249. An aggregation has also been recorded at Princess Charlotte Bay–Bathurst Bay on Cape York Peninsula 250, but there has been no population census. There have been population estimates for Indo-Pacific humpback dolphins in Cleveland Bay (50 or less) 248; the Capricorn coast (about 64); Keppel Bay (about 107); and Port Curtis (about 85) 251. Populations of this species are also known to occur south of the Region in Great Sandy Strait 252 and Moreton Bay 253. There is almost no understanding of populations of these two species elsewhere in the Region, although there have been sightings. Populations of these inshore species are likely to be in decline throughout the Region. For populations to remain stable, modelling suggests that the snubfin dolphin population in Cleveland– Halifax Bays and Keppel Bay–Fitzroy River can sustain a human-related death rate of only one animal every four years 254 and one animal every year respectively. 249 The incidental deaths of two snubfin
Two inshore dolphin species are considered at risk and likely to be in serious decline.