The Successful Restoration of the Humpback Whales Population

In the 1950’s and 1960’s Humpback Whales were highly endangered and followed by near extinction due to hunting on these species. However in the past 25 years Humpback Whales have shown a significant comeback. The growth rate is seen as very high and finally the reproduction rate is rising towards the theoretical reproduction limit of the species. These species migrate every year a vast amount of kilometres which is approximately 5000km (Bruce, Albright, Sheehan & Blewitt, 2014). Every year they return to the same feeding ground and breeding grounds where they take their calves with them. The calves are born in warm sheltered waters in the winter breeding grounds. During a calf's first southern migration, the mother is the primary provider of food and protection, as well as teaching (Mann et al., 200).

Humpback whales exhibit high levels of maternally directed philopatry and the foraging success of an individual may depend on its exposure to a variety of foraging habitats as a calf (Weinrich, 1998). Studies already conducted found that examining habitat preferences of mother-calf pairs in humpback whale breeding grounds worldwide have shown that mother-calf pairs prefer shallow, calm waters (Bruce, Albright, Sheehan & Blewitt, 2014). Staying close to the shoreline while migrating or resting in protected embayment’s or coastal waters (Ersts and Rosenbaum, 2003, Rasmussen et al., 2007). They specifically distribute themselves a certain way by depth, with mothers and calves showing a strong preference for shallower water compared to all other pod types (Ersts & Rosenbaum, 2003).

In the research conducted it states that 95% of mother-calf pairs sighted, were within 7 km of the shore and 20% of those pairs were found within 1 km of the shore, a statistically significant percentage in comparison to other group types (adult or sub-adult competitive groups). Whales showed behavioural changes when tourist vessels are in close distance of the animals however still complying to the whale-watching regulations. Long term impact of having whale watching vessels in presences of whales is still unknown (Stamation et al., 2010).

In another study in a breeding ground off the coast of the Santa Elena Peninsula in south-central Ecuador, Félix and Botero-Acosta (2011) found that the majority of humpback whale groups sighted within a 9 km radius of the peninsula tip were in water less than 50 m depth. Mother-calf pairs exhibited significant preference for shallower depths relative to other group types, with escorted pairs found at mid-depths.