Humpback whale calves often exhibit very erratic and potentially risky behavior. During our research study we saw calves would swim off after dolphins, interact with researchers in the water and frequently pop up within feet of the research vessel. On occasion they breach repeatedly and end up separated from the mother and we've also seen them confuse male escorts for mothers.
There is no doubt that, although large, these calves are as naive and vulnerable as any other young offspring. We would therefore like to provide some boat handling guidelines that may help ensure the safety of these young calves during their early days in Hawaiian waters.
When transiting :
Slow Down. The youngest humpback whale calves spend almost 90% of their time traveling at or just below the surface. Surfacings often comprise just a single blow, which is extremely hard to see. Between these surfacings they frequently persist just below the surface and therefore remain very vulnerable to vessel strikes. Additionally these young calves are uncoordinated and naive - they may not yet associate engine sounds with on-coming vessels. Don’t expect a calf to respond to an oncoming vessel . Slow down, give them space and be ready for erratic changes in direction.
When whale watching :
Always approach mother and calf pairs from the mother’s side, so that the mother remains between the boat and the calf.
Be aware that surface active calves can be very disoriented. Watch for erratic changes in direction.
When maneuvering around calf groups, wait until the calf leaves the surface before moving the vessel.
Try not to disturb resting mother and calf pairs. The chance to rest undisturbed prior to migration is vital to the calf, so give resting calves lots of space, minimize vessel relocations around these resting groups and whenever possible do not approach or follow groups from directly behind as this may push them into unnecessary travel.
As the season winds down, be sure that these groups do not become the focus of extended whale watches and multiple boats - surrounding whales will almost always cause them to relocate, expending vital energy that the calf could otherwise allocate to growth, that will directly enhance it’s chances of making a successful migration north - and returning back to Hawaii in years to come