Post Number: 8
|Posted on Friday, September 07, 2007 - 11:15 am: || |
In answer to Juland Al-Said’s questions regarding the alligator gar “Hal” from the Belle Isle Aquarium. The alligator gar was in the process of being relocated to Colorado’s Ocean Journey Aquarium (Landry’s Downtown Aquarium) because the Belle Isle Aquarium was permanently closed. Obviously, if an aquarium is closed and there is no staff to take care of the animal the animal must be moved to a facility where the animal will receive care.
Hal lived for 23 years at the Belle Isle Aquarium in a 2,700 gallon aquarium. There was a short period when he was anesthetized and moved to a 10,000 gallon aquarium while the 2,700 gallon tank was repaired and renovated.
Release back to the wild of a long time captive animal is normally unethical on several levels. One is that captives in a public aquarium have been potentially exposed to a host of different diseases (due to many different species, from different parts of the world being held together in one facility.) Release of such a captive back to the wild creates a disease introduction risk that can endanger many other individuals and species in their natural habitat. Secondly, long-term captives often do not habituated to wild conditions. This normally isn’t a problem for fish in general. However, Hal was at BIA for over 23 years and was most likely at least 20 to 40 years old when captured from Pas cagoula County Mississippi in 1982 making this fish quite old, somewhere between 40 and 60 years at least. Relocating an old fish is always risky to their health. The chance of a geriatric fish surviving the rigors of the wild are relatively slim especially if that fish is transported great distances and then must habituate to new food, new surroundings, predators and parasites. Logistically a release back to the wild is out of the question.
When a facility is closed and animals need to be relocated somebody has to pay the bill and expenses of that relocation. Moving large fish and aquatic animals in general can become quite expensive and technically trying. A facility must first want the animal that needs a home and then must pay for transport and all associated costs. Colorado’s Ocean Journey Aquarium (Landry’s Downtown Aquarium) was willing to do this. Moving a six foot long live fish from Michigan to Colorado is no light undertaking but they were willing to give it a try.
What went wrong? You probably will get different opinions depending on who you talk to. My professional opinion is that Landry’s sent an inexperienced crew that only did things “by the book” and did not heed my professional fish experience of over 23 years working with and transporting fish. It’s a very long story involving fish physiology but to make the long story short, in my professional opinion, and those of others I consulted with, “Hal” died from asphyxiation due to excessive oxygen in the water. Gars are obligate air breathing fishes and rely on gas exchange in their swim bladder to breathe. They rely very little on their gills since they live in turbid, backwater swamps with heavy veget ation and little oxygen in the water. However, their blood gas oxygen sensors wired to their brain are still on their gills. When their blood oxygen concentration drops, the gill sensors signal the brain and tell the fish it must surface to take a gulp of air and replenish the oxygen in the swim bladder, which then replenishes the blood supply. This signal comes from the gills of the gar. This creates a dilemma. If oxygen is introduced into the water in high concentrations then the gar’s gill sensors artificially sense excess oxygen in the blood (because the gills are bathed in oxygen rich water). The gar’s brain never gets the instruction from the gill sensors to surface and breath.&n bsp; Since the gar never surfaced to breath, in never replenishes its oxygen in the swim bladder and basically asphyxiates in oxygen rich water. This doesn’t occur in normal “gill breathing fish” because they obtain oxygen from the water, not from air like a gar does. I instructed the Landry’s crew not to over-oxygenate Hal’s water and set a regulator at a very low rate. However, once they got on the road, they threw my suggestion away and went with their “instruction manual” which was designed for obligate gill breathing fishes and cranked up the oxygen to a hearty level. Shortly after they did this the gar ceased surfacing and basically asphyxiated although it was bathed in oxygen rich water. This, in my professional opinion, is the most likely e xplanation for the gar’s demise.
Another hypothesis is possible but doesn’t fit the circumstances as well. Hal was anesthetized before transport. Initially heavily to facilitate capture and so he would not injure himself or aquarium personnel while being moved from the tank and into the truck transport tank. Once in the truck transport tank he was brought out of heavy sedation and successfully acclimated to a lighter tranquilized dose and monitored for more than an hour. During this monitoring he was oriented and successfully surfaced to breath many, many times. The Landry’s staff believes he was over anesthetized and eventually succumbed to the effects of the drug (Sandoz MS-222 or Tricaine methane sulfonate). This is possible, especially since he was very old and could have geriatric fatty liver disease which would compromise the ability to metabolize the drug or some of its metabolic by products. However, the fact that he was surfacing normally and breathing very readily tends to negate this in my mind when the truck finally left for Colorado. It wasn’t until drivers and caretakers changed shifts, and the oxygen level was cranked up, was a problem noted.
I hope this answers your questions about the Belle Isle Aquarium’s alligator gar named “Hal”. If you have any further questions feel free to contact Doug Sweet.