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A leucistic axolotl in captivity
Credit: By Mutantrainbow (Own work) [Public domain], via Wikimedia Commons

An axolotl in captivityBy th1098 (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia CommonsThis week, I caught a post in DNews by Danny Clemens titled Meet the Mexican Walking Fish, an Animal on the Brink and I recalled hearing about this creature years ago.

They have the unique ability to regenerate their limbs and even major internal organs. In fact, they've been studied by scientists and researchers all over the world for decades.

Axolotls are the most studied salamander model for several reasons:

  1. They can be bred multiple times a year in labs.
  2. Their care has been well-documented and perfected. Since axolotls do not undergo metamorphosis, they are easier to care for since they remain in water.
  3. Their eggs are relatively large and are clear. Embryogenesis can be observed without the use of a microscope. It's even possible for scientists and researchers to perform surgery on embryos for various investigations.
Over 3 yrs old axolotl and younger axolotls
Credit: By Orizatriz (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Why We Need More Than Captive-Bred Axolotls

I've read this countless times in regards to several species of creatures: we cannot rely on captive breeding as a means to maintain healthy populations. The reasons include:

Interbreeding which causes a loss of generic diversity and increases the chances of hereditary and other defects.

  • Captive bred axolotls lose their affinity for their natural habitat with each generation.
  • Most captive axolotls hardly resemble their wild counterparts (especially leucistic or albino types).
  • Any captive breeding program should incorporate wild axolotls to give offspring the greatest chance of survival in the wild.
Axolotl
Credit: Mike Bowler (mbowler on flickr) CC-by-2.0

Axolotl Populations in the Wild are Dwindling Fast

In a fascinating article by Jolene Creighton published in From Quarks to Quasars, I discovered how dire the situation has become for the axolotl (Ambystoma mexicanum) which the IUCN Red List has now classified as critically endangered.

  • Between 2005 and 2009, there was a 90 percent decline in the axolotl population.
  • In 2013, researchers went looking for them in Mexico's Lake Xochimilco and after four months they found none.
  • In February 2014, two axolotls were discovered in the wild (but not captured).

In September 2014, Mark Stevenson of the Associated Press wrote Axolotl, Mexico's 'Water Monster,' May Have Disappeared which confirmed the following:

"The Mexican Academy of Sciences said in a statement that a 1998 survey found an average of 6,000 axolotls per square kilometer, a figure that dropped to 1,000 in a 2003 study, and 100 in a 2008 survey."

And apparently, researchers even built axolotl 'shelters' in Xochimilco, Mexico City to help these precious creatures. I expand on this further along.

Axolotl (Ambystoma mexicanum), au Musée d'Histoire Naturelle de Lille
Credit: By Vassil (Own work) [CC0], via Wikimedia Commons / Public Domain

Major Threats to the Axolotl (Ambystoma mexicanum)

According to the IUCN Red List, the major threats to this unique and important species include:

  • The drying up of the canal system and lakes in their natural habitat (Xochimilco and Chalco Lake, Mexico).
  • Human encroachment and pollution of the canal system and lakes. Increased tourist activity is poorly regulated and adds further pollution (Zambrano, 2006).
  • Introduced species of fish (tilapia and carp) have greatly increased which has also impacted axolotls through competition for food and predation.
  • Diseases, most likely spread by invasive species and as a result of poor water quality, have negatively impacted axolotl populations. Apparently, high levels of bacterial contamination poses a serious threat to them too.

But perhaps the most shocking reason: axolotls are captured for food and medicinal purposes. And sadly, this illegal trade targets axolotls that are less than one year old. This problem becomes even more detrimental to their future generations in the wild since axolotls reach sexual maturity at approximately one and a half years of age.

In the past, axolotls were also sought after for the international pet trade. Yet now, it is believed that those being sold in the international trade are of captive origin. 

Why Humans are Killing Axolotls

According to a post by Amy Majchrzak at University of Michigan's Animal Diversity Web, axolotls have been occasionally consumed (substituted for fish), and are "prepared by either roasting or boiling and the tail is eaten with vinegar or cayenne pepper."

In The Zoological Society of London's EDGE: Amphibian Species Information page, it states: 

"In pre-Hispanic Mexico (i.e. prior to the Spanish conquest and suppression of the Aztecs), the axolotl was considered to be a delicacy and was said to taste like an eel. Its fat was used as a medicine similar to cod liver oil."

Même le petit escargot du premier plan a fini dans l'estomac vorace de mon axolotlBy The original uploader was Valk at French Wikipedia [CC BY-SA 1.0 (http://creativecommons.org/licenses/by-sa/1.0)], via Wikimedia CommonsMore recently, I discovered in a February 2015 Al Jazeera America report by Diana Ferrero that there is demand for wild axolotls because of the belief they have medicinal powers (such as a cure for breathing problems). The black market tempts poor fishermen:

"Buyers come and tell me, ‘I need 20 axolotls.’ Sure, I can get you that," said Roberto Altamirano, a fisherman who revealed that "a buyer, typically a foreigner, would give him nearly $300 for each axolotl caught in the wild, enough to feed him and his family for two months."

And sadly, in Ferrero's article, Altamirano explained, "Many fishermen are willing to steal axolotls from breeding centers because it’s too hard to find them in the wild these days."

Last year, The Citizen reported that National Autonomous University of Mexico (UNAM) scientists and The University of Kent are trying to keep wild populations of axolotls alive and breeding.

A research team has set up "plants to purify the water and a few cages where the axolotl can live and reproduce without stress," according to Ferrero's report. Biologist Armando Tovar explained, "Here they have to swim, hunt and fight for food, so they’re healthier and stronger than the animals who live in a tank or in a lab."

Up next, I found out that axolotls can hold their breath for a year. The following video was uploaded on June 15th, 2011 by The State Journal-Register. Ed Zalisko, Chief Health Professions Advisor, Ph.D., at Washington State University tells us more about this amazing ability that some axolotls exhibit.

Yet I couldn't help but wonder, looking at all those tanks (their confined water homes) if this "ability" is more of a "stress" reaction to being in a captive environment? I mean, floating atop the water (in the wild) would likely carry these creatures downstream to a larger waterway.

Axolotl Salamanders Continue to Intrigue Researchers

Lastly, More About the Axolotl (aka The Water Monster)

Published on June 12th, 2013 by Epic Wildlife

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