While showing a cactus book to my then six years old son we were admiring a beautiful picture on the cover showing a field with a large magnificent group of Echinocactus grusonii, the Golden Barrel Cactus, in the picture shining in the afternoon for as long as you could see. As I had been telling my son about all the illegal collecting and habitat destruction taking place, he was astonished by the beauty of the field and asked me in awe “Can you still see that nowadays??” I must say that deeply moved me, particularly when with shame I had to tell him that unfortunately the field had been destroyed for the construction of the large Zimapán dam and the species was at least critically endangered, with no such fields existing anymore. Nevertheless, he could still enjoy the beauty of the plant in captivity.
During the IV international congress of the Goodeid Working Group last November that took place in the city of Morelia, one of the six presentations were versed on the captive conservation of Goodeid fishes. It was titled “The role of the North American branch of the GWG in the conservation of the Goodeids” and was presented by Dr. John Lyons. Captive conservation is a complex matter and the points highlighted in the presentation are so important for those persons involved in fish conservation that I think worth to be brought up in this editorial. I have personally got to very similar conclusions and adopted them over the years.
Dr. Lyons explained the integration by a group of experts of a list of Goodeid populations that are threatened and are suggested as a focus for captive conservation. These unities represent either full species or populations, which due to their uniqueness and the level of threat they face, deserve high priority in conservation efforts. The species are labeled “Evolutionary Significant Units”, listing 87 populations. This is quite a significant number for a family of about 40 different species, giving a clear indication of both the genetic richness and the level of endangerment of the family. Some of the populations listed are extinct in the wild and all face severe threats and may disappear from nature in the coming years, some will inevitably.
One of the conclusions of the talk is that before starting a conservation effort, it is important to select the targets of the efforts with care.
Another important aspect when preserving a species is to understand that the minimum number of individuals to be kept to prevent loss of genetic diversity is around 300 specimens. While understandably this may be too many for most aquarists with restricted quarters, it should serve as a criterion to select fewer species of which to keep a larger number of individuals. A way to help in keeping the integrity of the genetic pool of a population is to exchange individuals with other persons or institutions keeping the same population. Very important is evidence that there is the certainty that the population of exchange is the same as the one kept or the stock would be ruined by hybridization.
Very important is to avoid selecting for fry with attractive or desirable characteristics, but instead to maintain all phenotypes in a population, preventing with this the loss of variability and a rapid departure from the natural form. We must understand that the moment that we place a fish in an artificial environment, it starts to drift away from its natural form. This is due to the different environmental parameters like the weather of seasonal effects, lack of competition, lack of predators, lack of preferred prey for which the species has evolved over the years, and many other factors. Additionally, aquatic environments are formed by a community of species that have achieved a delicate balance over millions of years of evolution and not just by a single species. We should not aggravate this with artificial selection.
Another important point is if possible to keep more than one aquarium with the same species, so the risk of losing the stock by disease or any other disastrous event is diluted. Not keeping two closely related populations is another important practice as any error would also cause hybridization.
Given these arguments you may understandably think that captive populations are not a very good substitution for conservation in situ, and you are right, but unfortunately, conservation in situ is in most cases with Goodeids close to impossible to achieve, and hence this is probably one of the best current solutions that we have.
A suggestion by Dr. Lyons is for the GWG to maintain a list of persons committed to keeping certain Goodeid populations. I believe this is a very important point as allows evaluating the level of safety each population has and facilitate the interchange of individuals. Understandably some people may prefer to remain anonymous for a variety of reasons and this modality of course could be incorporated into a registration system.
My opinion concerning this last point is that the registration of a population may serve even more than to interchange individuals and to keep a register. People tend to get discouraged over the years without any feedback and the registration of a population may serve both as a reminder of the commitment as well as a motivational reason to continue the long-term effort. Conservation, to be useful, is not a one-year commitment, but a long-term one. In this regard, the BAP (Breeding Award Programs) many aquarium clubs offer to act in the counter sense of conservation as many people prefer to quickly exchange a species they keep so they can breed another species and get more points.
One comment by Dr. Arcadio Valdés came after the conference about the need to get rid of deformed or unfit specimens in a captive population. This is another problem. We have seen that long-term captive populations of some species, particularly when inbreeding has been extensive, likely fix some deformities which are expressed in a large number of individuals.
We have at least one clear potential example of this. The original population of Skiffia francesae collected by Dr. Robert Miller around 1967 in the Teuchitlán River in Jalisco, which happens to be the last collection recorded for this population, was placed by Dr. Miller in the skillful hands of James Langhammer in the United States, then curator of the Belle Isle Aquarium. It is because of him that we still have the original population, which has been kept over the years by many aquarists at least in the United States, Europe, and Mexico. However, probably the reduced number of initial fish caused what is known as the founder effect. Among other problems, the founder effect likely caused that a great number of the Skiffia francesae that are kept in captivity nowadays exhibit a condition where they swim sideways. So if the size of the population allows it, it is probably best to get rid of specimens that show a flawed condition.
As you may conclude, conservation is a labor of conviction and love, as the reward obtained for the efforts will only be the long-term enjoyment of the nowadays available forms of life, so much affected by human activities. It may be far the time when the conditions of the original habitats can be somehow reestablished to the point where some of the original inhabitants can be reintroduced, not before acclimation processes that allow them to better survive.
When destroying a habitat, many times likely with morally valid reasons as to get the resources to feed families, but many other times based on greed and ignorance, we are not damaging nature after all. Life forms constantly evolve and new forms will eventually recolonize the lost habitats, and the diversity of life we destroy will eventually return to earth. What we do as humans destroying habitats and species is damaging ourselves, as we lose the source of enjoyment, knowledge, and beauty that nature offers to us, and we unrightfully take this decision for our future generations, that won’t have the chance to enjoy it and will rightfully blame us.
© Copyright 2014 Juan Miguel Artigas Azas, all rights reserved
Artigas Azas, Juan Miguel. (12月 01, 2014). "Goodeid conservation guidelines". Freshwater Fishes of Mexico. 检索 2月 21, 2024, 从: https://mexfish.info/section.php?id=4&lang=cn.