Remember meForgot password?
    Log in with Twitter

article imageOp-Ed: The aftermath of a cetacean drive reveals true stress of capture

By Elizabeth Batt     Nov 15, 2012 in Environment
Taiji - A recent drive in Taiji, Japan, drove a pod of 18 Risso's dolphins into the cove. Two were kept for captivity, 14 were killed, and two young -- one still showing birth folds, were dumped back at sea. Without maternal support, the act was a death sentence.
The dolphin drives that occur for six months out of the year in Taiji, Japan, are brutal on the mammals driven to their deaths. But few rarely consider the aftermath of the drives themselves nor the effect on those marine mammals that are released.
Most bang for their buck
In a recent report called "The Quota Problem" posted by Sea Shepherd Cove Guardian -- Nicole McLachlan, McLachlan described why Taiji fishermen elected to release a few chosen marine mammals. Far from being an act of mercy by the fishermen she said, the release had everything to do with maintaining quotas and getting the most bang for their buck:
Only the largest and most profitable dolphins will be selected for slaughter, while the smaller adults, sub-adults and calves with less meat (therefore, less $$) are released with a high risk that they may not survive themselves.
The true cost of a single marine mammal drive where survivors are dumped back out to sea, can wipe out entire pods suggests McLachlan. She then describes seeing the skeleton of a pilot whale that was released from the cove after a slaughter in recent weeks. "Its body" she said, "had washed up on a beach near the ‘Promontory’, nearby the cove, and had largely rotted away -- leaving its bones exposed."
Because this whale was released, its incidental death McLachlan adds, is "not incorporated into what they write down in their daily inventories after work." Meaning the Japanese Fisheries agency who relies on numbers recorded by prefecture, would not consider this pilot whale's death as part of the quota. [See "Small Cetacean Research" at the bottom of the page on Drive Fisheries at].
Studies into the effect on cetaceans driven in and captured in nets
Of course there are no studies that exist into the effects on surviving cetaceans that are released post catch in Taiji. But there are studies into the effects on dolphin caught as incidental bycatch by commercial fisheries in tuna nets. It is a vastly similar process that can be applied to all cetacean captures.
Both of these studies were undertaken by the National Marine Fisheries Service or NMFS.
The first was undertaken in 1999 and 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 clearer:
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 the capture, confinement and isolation, cetaceans suffer terribly, both psychologically and physically. Even when released, the scars that remain and the damage endured, can kill.
This leads us to a third issue as yet unmentioned, but very much in contention with wild cetacean capture.
NMFS is currently considering a permit application by Georgia Aquarium to import 18 wild-caught belugas from Russia. The agency in considering the permit, must decide whether the capture of these belugas was humane and in accordance with the Marine Mammal Protection Act (MMPA).
Like the dolphins in Taiji and the cetaceans captured as bycatch, these beluga whales had to be separated from their pod and driven into shallow water to be netted and captured. They no doubt endured the same psychological and physical distress detailed by both of the NMFS studies featured above.
Given that NMFS' own scientists obviously comprehend the consequences and effects of driving, capturing and netting wild marine mammals, if the agency grants this permit to Georgia Aquarium, wouldn't they be openly defying their own logic?
A Taiji update
Tonight another pod of Risso's dolphins were driven into Taiji's cove. The drive lasted almost six hours as dolphins fought to escape the drive boats. Once netted in the cove, two dolphins were selected for captivity and the remaining adults were slaughtered.
Once again, two small juveniles were unceremoniously dumped back out at sea. Too small to qualify for quota, their chance of survival minus their pod, their mothers, and the stress of capture, is virtually zero.
This opinion article was written by an independent writer. The opinions and views expressed herein are those of the author and are not necessarily intended to reflect those of
More about taiji japan, taiji dolphin drives, stresses of the dolphin drives, the cove movie, dolphin slaughter
More news from
Latest News
Top News