Shortfin mako sharks show enhanced thermoregulation abilities during deep dives｜Nagasaki University Official Website（ENGLISH）

Research

September 30, 2025

Shortfin mako sharks show enhanced thermoregulation abilities during deep dives

Summary

We show that regionally endothermic shortfin mako sharks have enhanced thermoregulatory ability with an order higher warming rate than cooling rate during repeated dives, likely optimizing foraging efficiency. This ability, only comparable to bigeye tuna and swordfish in teleosts, represents the key adaptive significance of regional endothermy in fishes.

Full text

Tunas, billfishes, and some sharks, such as white sharks and shortfin mako sharks, have an ability known as regional endothermy, which allows them to maintain body temperatures higher than the ambient water. This ability has been regarded as an adaptation to cold environments. However, its role in warm-water species such as shortfin mako sharks, bigeye tuna, and swordfish has been unclear.

In this study, we attached data loggers to shortfin mako sharks caught off southeastern Taiwan to record water temperature, body temperature, and swimming depth (Fig. 1). During repeated deep dives, the body temperatures slowly decreased in deep cold waters, and rapidly increased when they returned to warm surface waters (Fig. 2). Their warming rates were over 10 times higher than their cooling rates, only comparable to bigeye tuna and swordfish among fish species studied to date. Since deep waters contain abundant food resources, regional endothermy likely helps them stay longer in prey-rich deep waters while minimizing recovery time at the surface.

One shark showed unique thermoregulation before a deep dive (Fig. 3). After quickly warming at the surface, it stayed there even longer, raising its body temperature above the ambient water before starting a deep dive. This suggests intentional “pre-dive warming” in preparation for deep cold waters. To our knowledge, no other fish species has been reported to show similar thermoregulation.

Shortfin mako sharks showed enhanced thermoregulation abilities during repeated dives. For warm-water species like shortfin mako sharks, regional endothermy allows not only heat retention but also flexible body temperature control. Our findings help explain the success of regionally endothermic fishes as apex predators across the world’s pelagic oceans.

Figure 1. A shortfin mako shark equipped with a data logger. © Zola Chen

Figure 2. Depth, water temperature, and body temperature data recorded from the mako shark. Body temperature decreased slowly in deep cold waters and increased quickly in shallow warm waters.

Figure 3. A unique body temperature change recorded from a mako shark. After rapid warming at the surface, the shark further increased its body temperature before a dive into the deep cold water.