Statement on Physiological Effects on Dolphins Due to Chase and Capture by the Tuna Industry
Albert C. Myrick, Jr., PhD.
Retired Cetacean Physiologist,
National Marine Fisheries Service
Nina Young of the Center for Marine Conservation (CMC) submitted testimony on Feb. 29, 1996, to the House Fisheries, Wildlife, and Oceans Subcommittee, that was sharply critical of my (with other colleagues) dolphin stress research reports. I strongly contend that the CMC testimony apparently was hastily prepared without full understanding of stress physiology and without careful study of the peer reviewed and published accounts of the researches, much of which has been available in the scientific literature for up to eight years, that CMC has tried, only now, to discredit. I was not aware of CMC's testimony until late in March of this year.
In the sciences, it is an obligation or at least a professional courtesy to notify "errant" authors in advance of the criticisms of their published work, to permit them an opportunity to consider the offered arguments, and to correct errors or retract statements. CMC did not do so. It is also a professional requirement that responsible criticism to scientific reports be screened by a formal scientific review process to minimize unfounded and irresponsible argumentation by critics without the necessary qualifications to judge the evidence in question. CMC did not do so.
Finally, the legitimate forum for serious critical arguments concerning published reports is in the scientific media, for two reasons:
Because of this, the CMC testimony is a particularly excellent example of criticism that is irresponsible, illegitimate, and unprofessional. It has misrepresented the evidence by the use of reporting errors, omissions, and misstatements as well as cavalier disposition of important pieces of research reports; it has chosen a non-scientific forum in which to attack the preponderance of published Eastern Tropical Pacific (ETP) dolphin-stress literature, waiting until now to criticize some of the peer-reviewed reports that have existed for many years; and it has failed to invite my timely rebuttal arguments for fair consideration.
All of these "dirty tricks" CMC has used to persuade a preoccupied audience that the evidence for fishery stress of dolphins is weak and that stress factors are unworthy of serious consideration during these hearings.
For those of us who are sensitive to the hundreds of thousands of dolphin lives that already have been lost to the needs of profit, impatience, and expediency and those that still hang in the balance, it is alarming that an otherwise well-regarded coalition, that is the CMC and its allies, would try to make such an important issue disappear by these transparent and disingenuous tactics. It is understandable that CMC's political agenda may need to disagree with conclusions reached in documented reports that now form much of the specific literature. But to argue, as CMC has done, that published evidence of fishery stress in the dolphins, that they have agreed to view as trivial and uncompelling, equates to an absence of such stress and such evidence, is as dangerous to the hearing process as it is unconscionable.
This is especially true when so little is known about the population abundance and dynamics of the ETP dolphins. In the murkiness of our poor understanding of causal relationships of fishery and dolphins, the possible implications of the legitimate reports whose diverse lines of evidence point so consistently to dolphin stress by perturbation from the persistent fishery are too important to future evaluations of ETP dolphin population recovery to be argued away and ignored.
Putting aside the scientific evidence for a moment, from the circumstantial information about the fishery alone, it seems reasonable to expect the methods and persistence of dolphin fishing will generate unavoidable stressors that kill and impair function of the dolphins it exploits. It seems obvious for example that the chase of dolphins by a purse seiner, its three to six speedboats, and commonly its helicopter would cause substantial stress to the animals. It is conducted at sustained high speeds, usually lasting 20 to 40 minutes.
The purpose of the chase is to scare, exhaust, and otherwise force the dolphins to submit to maximum control over the school by the fisher. Numbered among the many aversive factors of the chase are continuous and unavoidable noise; turbulence; intimidation of close pursuit; forced, prolonged strenuous exercise; and threatened oxygen deprivation for excited and panting animals surfacing to breathe. These should be expected to easily cause substantial stress in most of the animals and very serious stress in the more vulnerable animals.
We humans can only try to imagine what the full effects of such a chase must be on even experienced dolphins that have survived previous chases and sets. However, little reflection should be required, except by the most prideful and obdurate skeptics among us, to conclude that these conditions are very unlike those (to paraphrase the words of CMC) of the natural "rigorous marine environment" under which the dolphins evolved and for which they "are adapted."
If one realizes that 35 years of dolphin fishing is obviously an insufficiently long evolutionary period for these dolphin populations to become fully "adapted to cope with many...[of these very extreme sorts of]...human-related stressors," the CMC arguments seem ludicrous. In my presentations of dolphin-stress research to college and civic groups, I am often asked why we find it necessary to uncover evidence of stress in dolphin fishing and its resulting mortality, when good common sense tells us that they are seriously stressed and probably many die from it.
To dramatize what may be not an entirely dissimilar "common-sense" scenario for humans, we might consider a hypothetical example of forced chasing of a mixed group of unwilling people to run on foot, for half-an-hour, over an unavoidable course through scattered areas devoid of oxygen for short distances. The humans are driven by fear of injury or death to run ahead of armored vehicles. These tanks are moving at unrelenting speeds of 12 to 15 miles per hour, detonating small explosive charges near, and maneuvering close to would-be stragglers and escapees to keep the terrified and tiring herd together. The vehicles are studded with intimidating prods or projections and programmed to force the human herd into a confining structure, which itself is forebodingly cramped and unstable and subject to collapse at any moment.
We might now consider a few of the more disturbing questions that might quite obviously arise from this hypothetical scenario. How many of this human herd of newborns, young, adults, and elderly males and females of various physical conditions and susceptibilities might become casualties of fear, strain, exhaustion, or physiological malfunction before the elapsed half-hour? Would all such casualties survive long enough to enter the confining structure?
What percentage of the nursing newborns or dependent children in the herd would eventually succumb if their parental providers became casualties? How many of the surviving, more resilient members of this human herd might adapt or learn to habituate to unexpected and repeated episodes of this nature without lasting harmful effects? Would repeated trials habituate some or all of them to the aversive stimuli, or would reexposure condition them into more rapid submission, but sensitize them to a greater level of stress vulnerability? Beyond some maximum level of psychological and physical training, would it be possible that some or even many of the human herd still may not "get used to it?"
Inasmuch as these questions may apply also to dolphin schools chased by purse seiners, we only have common-sense answers without definitive experimental proof. Considering that there is almost total scientific ignorance about most of these questions for dolphins under such extreme stressor conditions, it is up to us to ask and answer the most relevant obvious question. Is it ethical or judicious to allow tuna caught with chased dolphins to be labeled "dolphin safe," when no studies have shown evidence that this is true, and when all of our common sense tells us that it is not true?
We turn, now, to the more "scientific" part of this presentation and the question of whether tuna caught with dolphins with no observable dolphin mortality should be considered "dolphin safe." This question is predicated upon at least two assumptions that are to some extent testable with current research techniques.
The first assumption is that any stress sustained by dolphins in tuna fishing causes little, if any, mortality. This would mean that any uncounted mortality before capture or after release from the net would be minimal and thus, the number of dead counted in the closed net would be very near the actual mortality. The second assumption is that persistent dolphin fishing including repeated successful and unsuccessful chases and sets do not affect the dolphins' long-term biology. Thus, their recovery would be expected if counted annual mortality is held to some small percentage of its estimated population.
Both of these assumptions recently have been called into question implicitly by results of various studies by Myrick and colleagues that have addressed different aspects of ETP dolphin biology. Although these studies have not yet provided definitive answers concerning the full extent to which ETP dolphins have been and continue to be affected, their results implicate fishery stress as being associated with dolphin dental resorption, hypocalcemia, delayed sexual maturity and reduced pregnancy rates, darkened adrenal cortices and non-entanglement mortality, and enhanced analgesic behavior in the nets. While various alternative interpretations may explain the results of each study, only a stress interpretation is consistent with the results of all of the studies. Since this is the simplest explanation of all of the data, it should be regarded as having the strongest probability of being the most accurate interpretation.
This presentation could easily provide a point-by-point explanation of the inaccuracies, misstatements, and exaggerations, fill in the omissions, correct the logic, and repair other damage to our understanding of the evidence of ETP dolphin stress caused by the irresponsible and unscholarly testimony by CMC. One example, among the litany of inaccuracies, is the suggestion by CMC that serum-calcium levels much below 9 mg/dl would not be regarded as being low (hypocalcemia) by most veterinarians and clinicians. This was followed by CMC's omission of our presented control data for many dolphin species, including Hawaiian spinner dolphins, which demonstrated average normal serum-calcium for dolphins as being near 10 mg/dl, the same as for most other normal mammals.
To discuss every point, would be tedious, time consuming, and, in my opinion, persuasive (and of further embarrassment to CMC). To do so would also suggest that the forum and methods chosen by CMC to decide the merits of the published scientific evidence are legitimate. They are not. In fact, to date there has been no letter, note, or article published in the scientific media that has disputed or refuted the results of any of evidence that I (and my colleagues) have published.
Nevertheless, some sort of general response and assurance to this audience is called for. It already exists in the form of the most recent peer-reviewed and published paper on ETP dolphin stress (Myrick and Perkins 1995). Its introduction provides a working clinical definition of the type of stress under study (i.e., distress), and reviews the arguments for stress and summarizes the evidence from past studies. It then reports the results of our study that provide what is the most important and persuasive evidence of the fishing stress effects of ETP dolphins found thus far. The full article is available to the studious.
For the purposes of this presentation and its conclusion, I will briefly discuss some of the Myrick/Perkins paper's more important points of evidence and their implications.
First, we examined the cortex of adrenal glands from male spinner and spotted dolphins found dead in purse-seine nets in sets where no entanglement and no gear contact or malfunction was observed and on which no evidence of injury (e.g., cuts, scrapes, net marks) to dolphins by entanglement or entrapment was noted. This strengthened the probability that all or most of our study dolphins did not die in the nets from suffocation drowning caused by entanglement, entrapment, or lethal gear-contact.
Second, because the color of the cortex begins to change from lipid-yellow in non-stressed mammals to lipid-depleted and blood-colored dark reddish brown in mammals under acute stress after about an hour, and the various chases, encirclement, and capture stages of the dolphins in our sample ranged between just under an hour and more than two hours, we reasoned:
While it is clear that we have much more work to do in order to test the stress hypotheses further, it should be equally clear that we do not know enough about these problems and their complexities to make action decisions that may likely place the dolphin populations in greater jeopardy. Too many dolphins have been lost in the past because we acted hastily, greedily, and in ignorance. Are we ready to permit this to happen once again?
Call your Congressperson at 202-225-3121 and tell them to reject H.R, 2823 and support H.R. 2856
Call Newt Gingrich, House Speaker at 202-225-0600 and tell him the same thing, he can stop H.R. 2823
Call the President at 202-456-1111 and tell him to withdraw his support for the dolphin-death bills S.1420/H.R. 2823.
Dr. Roger S. Payne to Members of Congress
http://www.earthisland.org/immp/myrick.html