Sperm Whale's chronicles

Habitats: “Where to find”

Sperm whales (Physeter macrocephalus) are one of the easiest cetaceans to recognise at sea [1]. They can be spotted from distance because of two main reasons: the angled blow, typical of this species (Figs. 1, 2) [1] and their flukes, which are lifted up right before they dive (Fig. 3) [1].

Figure 1: The asymmetrical blowhole far to the left on the head of a Sperm Whale.

Figure 2: Sperm whale exhibits the forward-angled blow typical of the species.

Figure 3: Sperm whale lifting the fluke before the dive.

P. macrocephalus inhabit all oceans and seas of the planet (Fig. 4), but high densities are frequently found in edges of banks and continental shelves, canyon waters [1] and productive areas [6]. They are usually seen offshore (depths >1km) [6], but can also be seen near of coast, where the continental slope is narrow and the water is deep [1].

Figure 4: Sperm whales range. Source: NOAA

Figure 4: Sperm whales range. Source: NOAA

Sperm whales have different distributions for each sex [6]. Adult males can often be found in high latitudes [1], even bordering ice [6]. Males’ movements across the oceans led to a high genetic uniformity of sperm whales’ populations [1]. Females and calves usually remain in the same area (~ 1000 km wide) for at least a decade [1]. However, Whitehead (2003) believes that the areas occupied by females are just a subset of the waters where males are regularly found [6]. The knowledge of male movement is limited: their movement is mapped by female model, but covering a bigger area of ocean or with frequent returns to smaller habitats [6]. But male movement is way more complex than that of females, including patterns for breeding and feeding [6].

The differences in distribution are also seen in depths, the most striking feature of sperms’ habitats [6]. Females usually don’t go to continental shelf waters, but it is not a rule of males, which have been seen in waters as shallow as 200 m [6].

Sperms generally dive down to 300-800 m for 30-45 min, but eventually, they can go down to 1,000-2,000 m and stay under water for well over an hour [6]. Calves and sexually immature individuals do not dive for too long or too deep [6]. Calves are often found near of surface, where they wait for the adults.

There is little evidence for migration between sperm whales. Some seasonal hypotheses are not consistent or well observed [6]. However, movement patterns have a main role in the understanding of population dynamics and behaviour [6].

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