Killer whale predation on bluefin tuna: exploring the hypothesis of the endurance-exhaustion technique

Abstract

Killer whales Orcinus orca occur in the area of the Strait of Gibraltar, where they prey on migrating bluefin tuna Thunnus thynnus. In the spring, killer whales were observed to chase tuna for up to 30 min at a relatively high sustained speed (3.7 ± 0.2 m s -1 ) until they captured them. Using simple models based on previous locomotor performance data on killer whales and thunnids, we investigated the hypothesis that killer whales push tuna beyond their aerobic limits to exhaust and capture them. To test this hypothesis, the endurance of bluefin tuna was estimated from data on maximum burst and aerobic swimming available for bluefin and yellowfin tuna T. albacares. The endurance performance of killer whales was evaluated on the basis of the maximal rate of oxygen uptake during exercise (V O 2 max ). We modelled the maximum aerobic power output for a killer whale according to swimming speed using a V O 2 max ranging between 20 and 30 ml O 2 kg -1 min -1. The output of this model was compared to the observed sustained swimming speed of killer whales chasing prey over long durations. Our results support the hypothesis that killer whales may use an endurance-exhaustion technique to catch small to medium sized (up to 0.8 to 1.5 m) bluefin tuna, while larger tuna may be inaccessible to killer whales unless they use cooperative hunting techniques or benefit through depredation of fish caught on long lines, drop lines or trap nets.

Pregnancy is a drag: hydrodynamics, kinematics and performance in pre- and post-parturition bottlenose dolphins (Tursiops truncatus)

“…-1 hunting speeds used by marine-mammal eating killer whales (Ford et al, 2005), which use the endurance-exhaustion method (Guinet et al, 2007), the maximum swim performance of near-term pregnant dolphins does not afford fast enough evasive speeds to outrun the killer whales. Meanwhile, the maximum swim speed of non-pregnant dolphins (6.32ms -1 ) could afford predator avoidance when the sharks and killer whales operate at the lower end of their range of hunting speeds.…”

Swimming and diving energetics in dolphins: a stroke-by-stroke analysis for predicting the cost of flight responses in wild odontocetes

“…In particular, many odontocete cetaceans will engage in short, extraordinary bouts of high-speed performance. For example, killer whales (Orcinus orca) can maintain speeds exceeding 3.7 m s −1 when chasing tuna (Guinet et al, 2007), and short-finned pilot whales (Globicephala macrorhynchus), named the 'cheetahs of the deep sea', can sprint up to 9.0 m s −1 while chasing deep-water prey (Aguilar de Soto et al, 2008).…”

“…Locating and chasing prey (Williams et al, 2004;Guinet et al, 2007;Aguilar de Soto et al, 2008), as well as flight responses to avoid predators (Ford et al, 2005) or anthropogenic disturbance Goldbogen et al, 2013), can result in significant short-and long-term increases in swimming speed. In particular, many odontocete cetaceans will engage in short, extraordinary bouts of high-speed performance.…”

Killer whale (Orcinus orca) occurrence in Venezuelan waters, 1982-2008

“…Secchi and Vaske, 1998;Dalla Rosa and Secchi, 2007;Hernández-Milian et al, 2008). Links between tuna and billfish peak occurrence and killer whale sightings have been suggested for other areas of the Atlantic Ocean including the western North Atlantic and the Straits of Florida (Katona et al, 1988), the Bahamas Dunn et al, 2007 14 ), the Strait of Gibraltar (Guinet et al, 2007;de Stephanis et al, 2008), Brazil (Secchi and Vaske, 1998;Dalla Rosa and Secchi, 2007) and Uruguay (Passadore et al, 2008). Also, as noted by Katona et al (1988) and Passadore et al (2007), since oceanic variables affect tuna prey distribution, the timing of tuna migration is somewhat variable, which in turn may affect occurrence of the killer whale in this area.…”