http://elizabethbatt.com/2014/09/the-aftermath-of-a-cetacean-drive-reveals-true-stress-of-capture/

A pilot whale desperately attempts to escape being hauled under the tarps to its death. Courtesy of Martyn Stewart. All rights reserved.

The Taiji dolphin drive season in Japan began on September 1st. This evening, a pod of pilot whales were driven into The Cove and netted off from the open ocean. Two pilot whales removed from the pod were earmarked for captivity and sequestered away to floating sea pens for training.
According to reports from Ric O’Barry’s Dolphin Project, one of the new captives appears to be ailing. A Cove Monitor reported on the official Facebook page:

Captured pilot whale does not appear to have the will to live. Three trainers appear to be keeping it up to breathe.

The dolphin drives that occur between Sept. and March every year are brutal on those mammals driven to their deaths. For those lucky enough to be released, or those held for captivity, the aftermath of the drive can prove just as fatal.
Studies into the effect on cetaceans driven in and captured in nets

No studies exist about the effects on cetaceans that survive the capture process in Taiji, but there are studies on dolphins caught as incidental bycatch by commercial fisheries in tuna nets.
Two of these studies were undertaken by the National Marine Fisheries Service or NMFS.

The first undertaken in 1999, is called ‘Stress in Mammals: The Potential Influence of Fishery-Induced Stress on Dolphins in the Eastern Tropical Pacific Ocean.’ It was authored by Barbara E. Curry and details the numerous potential consequences of the chase and capture of cetaceans. Curry writes of an underlying psychological stressor of being driven that influences:

The physiological stress response to chase and capture. For example, a dolphin’s perceptions of its ability to avoid capture or its inability to escape may play a role in the degree of physiological response to the event.

These stressors Curry adds, may also include, “Disruptions of social groups including separation of closely associated conspecifics such as cow-calf pairs” which are likely to cause physiological stress in individual dolphins.” It is “well known” Curry emphasizes, “that social relationships influence physiological function,” (Hinkle, 1974).
As a result the study shows (citing Levine 1993), “Beyond the mother-young relationship, social groups are also important in moderating responses to stressful situations for all age classes.”
In other words, the act of cetaceans being driven, captured and contained, holds long-term negative consequences for the entire pod. Even after release, there are negative effects due in part to the absolute decimation of pod structure.

“It is likely that, when released, animals suffering from capture myopathy are predisposed to predation and accident” said Curry citing Williams and Thorne’s study from 1996.
Effects of confinement and captivity
Curry’s study then elaborates on the effects of confinement and isolation in dolphins captured in tuna purse-seine fisheries. Again, a comparable situation that can be applied in all cetacean captures. Several issues raised by Curry include visible agitation and isolation and restraint stress, particularly in deep-sea dolphin species such as spinner and striped dolphin:

Although there may be differences between actual physical restraint and confinement in a relatively broad space, confinement of any form may be especially stressful for these pelagic dolphins because they are unaccustomed to encountering physical barriers of any kind in their open ocean environment.

With isolation and confinement causing psychological damage, the actual chase and drive of the dolphins also causes untold physical damage said the report:

Forced exercise during chase is a significant part of the purse-seine capture procedure for dolphins in the ETP (Eastern Tropical Pacific). Speed, distance and duration of the chase are all factors that are likely to affect the dolphins’ responses to stress.

From studies undertaken with bottlenose dolphin, Curry explained, “muscle damage resulted from experimental capture of captive bottlenose dolphins.” So it seems reasonable she says, “that muscle damage may also occur in dolphins as a result of chase and capture in the ETP fishery.”
Or in Taiji dolphin drives perhaps?
Muscle damage can result from strenuous exercise in mammals, wrote Boyd, 1982; Janssen et al., 1989; Armstrong, 1990. To which Curry adds:

During muscle disruption, muscle enzymes leak into the blood via alteration of cellular membranes and tissue damage. Increased serum plasma levels of the enzyme CK, which is known to catalyze the exchange of energy during muscle activity (Conley, 1994), is a reliable indicator of muscle tissue damage.

Called “capture myopathy”, there are four clinical syndromes associated with the condition: Capture shock, ataxic myoglobinuric, ruptured muscle, and delayed-peracute syndromes. These are indicative of many stressors said Curry, “e.g. terror, chase, capture, restraint, associated with exhaustion of the normal physiological reserves that provide energy for escape.”
It is also possible Curry explained, “that dolphins experience some degree of hyperthermia resulting from being chased and herded by speedboats.” This hyperthermia she explained, “has deleterious effects in mammals.”
Necropsy findings appear to support capture myopathy
Curry’s findings were supported by a second NMFS study in 2002. Authored again by Curry along with Daniel F. Cowan, the ‘Histopathological Assessment of Dolphins Necropsied Onboard Vessels in the ETP Tuna Fishery,’ showed that scientific tests on tissue from dolphins incidentally captured by Tuna Fisheries suggested:

That the individuals underwent a reflexive response to a perceived threat, or an alarm reaction, activating all the physiologic adaptations to diving or escape to an extreme or pathological level, resulting in widespread ischemic injury to tissues.

The study evaluation then posed the question “whether some animals can suffer similar injuries but survive to die later, after release” and “what is the fate of the myocardial injury; i.e.; is healing possible, or will survived injury inevitably be followed by scarring?”
The answer given could not have been more clear:

It appears that some will heal, and some will scar. It seems obvious that an animal with a scar has survived the injury that caused the scar. A similar question applies to the renal lesions, which if severe and extensive, may be associated with renal failure. It seems plausible that in some cases these types of injuries will cause delayed mortality.

In short, from the drive process itself to capture, confinement and isolation, cetaceans suffer terribly, both psychologically and physically. Even when released, the scars that remain and the damage endured, can kill.
Note: The Japanese Fisheries Agency relies on numbers recorded by prefecture. When released dolphins die post-capture from delayed mortality, they are not considered part of the quota. See “Small Cetacean Research” at the bottom of the page on Drive Fisheries at Ceta-Base.com.