Expert Opinion – Fishery Science

PROFESSIONALS USE COMPRESSED OXYGEN TO TRANSPORT LIVE FISH

(1) Robert Adami, Jr., Texas Parks and Wildlife Department, Natural Resource Specialist V, 4300 Waldron Rd., Corpus Christi, TX 78418, (361) 939-8745

Robert is responsible for transporting live tournament C&R redfish, speckled trout and other species to release points at various location along the Texas Gulf Coast including Sea Center Texas.

“As you know from previous Texas Gulf Coast Roundup events that you have seen, the hauling unit that is mounted on my trailer is operated with compressed oxygen. I maintain anywhere from 8-12 ppm of dissolved oxygen.”

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(2) Bill Halstead, Research Administrator, Fisheries Stock Enhancement, FWC Stock Enhancement Research Facility, 14495 Harllee Road, Port Manatee, FL 34221-9620, (941) 723-4505

“We transport fish for stocking and other purposes in live-haul tanks that we oxygenate with compressed gas [pure oxygen]. We try to maintain DO levels between 7.0 and 12.0 mg/L. We do not use mechanical aerators or agitators and we do not circulate the water in the transport cells. I have transported snook fingerlings between Texas and Florida, a trip that took approximately 24 hours, with no mortality using this method. We routinely haul redfish, snook and sea trout using this method and they all do well.”

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(3) Robert R. Vega, Manager, Texas Parks & Wildlife Department Coastal Marine Development Center.

“We transport all sizes of fish as associated with the TPWD hatchery program. We use 600 gallon fiberglass hauling tanks, and a compressed oxygen system (porous diffusing tubes). We have not used a liquid oxygen system. Optimum dissolved oxygen concentrations in our trailers range from 6 – 9 ppm depending on fish density, fish sizes, and water temperature. During long distance hauls you should also consider pH levels in conjunction with ammonia (metabolic waste products).”

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(4) Greg Vermeer, MS, Associate Research Scientist, Aquatic Animal Health, Florida Fish and Wildlife Conservation Commission, 14495 Harllee Road, Port Manatee, FL 34221-9620, (941) 723-4505, FAX: (941) 723-4507, SunCom: 516-0603/

“Avoiding anaerobic metabolism as much as possible and getting rid of oxygen debt as quickly as possible is certainly in the best interest of the fish. However, given the severity and rapid sequence of stressors (angling fatigue and injury, high temperature, live well crowding, transport, etc.) I don’t see any measures that you could take, short of actually eliminating some of the stressors, that will make much difference. Stressors that are not separated by at least three days are additive.”

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(5) Russell Miget, Ph.D., Texas Parks and Wildlife Department.

“I would agree with others you have talked with that DO concentrations of at least 100% be maintained in live hauling systems for shrimp. These animals are stressed as it is and adding the additional burden of low DO should be avoided. Fortunately this can be easily accomplished using compressed oxygen. What I have most often found with both live shrimp haulers as well as live bait dealers is that they feel as though vigorous agitation of the water (usually via spray bars) will maintain sufficient oxygen in the system. Depending on the design of the system, the biomass of animals, as well as the volume this approach to aeration ranges from mediocre to poor. The most efficient, and cost effective method to maintain saturation is to use compressed oxygen . Hope this helps.”

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(6) Ken Kurzawski, Inland Fisheries Division, Texas Parks and Wildlife Department.

“The best guidelines I know of were developed by Gene Gilliland, a researcher and bass tournament angler with the Oklahoma Dept. of Wildlife and Fisheries.

When transporting lunkers from the Share Lunker program, we almost always are transporting just one fish. Also, the program runs from October 1 through April 30, so hot water temperatures are not a factor. Our equipment will maintain dissolved oxygen levels at close to 100% saturation for the water temperatures that we encounter when hauling lunkers; probably 8 to 9 ppm at around 65 to 70 degrees.”

“Of course, the best way for reducing mortality of bass caught in warm weather is not to subject them to being held in livewells. Getting an accurate length and immediately releasing the fish will insure the highest survival.”

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(7) Todd Engeling, Program Director, A.E. Wood Fish Hatchery, Texas Parks and Wildlife Department, Inland Fisheries.

“Dissolved oxygen should be at least at saturation levels, which is dependent on temperature and altitude. Some examples follow: 75 degrees F at sea level saturation is 8.7 ppm at 2000 ft. It is 7.8 ppm at 83 degrees F at sea level saturation is 7.8 ppm at 2000 ft is 7.3 ppm. A good rule of thumb is to haul one pound of fish /gallon of water, but if you are going to exceed that be sure to keep the dissolved oxygen above saturation (10-15 ppm) and the water temperature below 72 F.”

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(8) David Campbell, Program Director, TP&W Trophy Largemouth Bass Program (The Lunker Program), Texas Parks and Wildlife Department.

“Yes, we do use compressed oxygen during tranporting. The problem I have is the super saturation in the summer time, with a closed tank and oxygen going in with only one fish. An agitator is used if necessary to maintain a workable level of one or two parts within saturation. Here at the Center, air and not oxygen, is injected into the holding tanks along with water which maintains a saturation level.”

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(9) Norm P. Heil, Project Leader, U.S. Fish and Wildlife Service, Warm Springs Fish Health Center.

“Things to consider when hauling Bass under tournament conditions: ie, small space, large fish:

Optimum DO, 7-8 ppm for extended periods. The ideal hauling rule of thumb is one pound of fish to every gallon water to reduce stress for long periods.”

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(10) Dennis P. Lee, Senior Fisheries Biologist, Fisheries Programs Branch, California Department of Fish and Game.

“When transporting fish, we generally bubble oxygen (O2) into the transport water with a diffuser, the dissolved oxygen level is at saturation for existing water temperature and elevation Transporters used to move or haul live black bass are equipped with compressed oxygen tanks and regulators to bubble oxygen through one or two bottom mounted diffusers.

It is sometimes difficult, however, to keep levels above 5 ppm when water temperatures exceed 75 F. by simple aeration. However, if you bubble oxygen into the water, it should be no problem.”

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(11) Chris Martin, Senior Fisheries Biologist, Georgia Resources Division, Fisheries Management Section.

“We use compressed welding oxygen to supply oxygen in our fish hauling tanks. We shoot for 10 parts per million dissolved oxygen.”

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(12) Mark McElroy, District Vll Inland Fisheries Supervisor, Louisiana Department of Wildlife and Fisheries.

“Compressed Oxygen always. Often, we are transporting a lot of fish and to reduce the stress we want as much oxygen in the water as we can get.”

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(13) Nick Nichols, Alabama Division of Wildlife and Freshwater Fisheries, Marion State Fish Hatchery.

“Usually whenever we are transporting fish, winter or summer, our aeration equipment in our transport tanks will maintain the dissolved oxygen concentrations at levels approaching saturation levels. Aeration is primarily used to lower the dissolved carbon dioxide sense the dissolved oxygen concentration is controlled with compressed oxygen. At 90 degrees F, dissolved oxygen levels may be around 7 ppm. , the mechanical aeration is primarily used to remove CO2 from the water. We also like to have it as a backup in case we have a problem with the O2 system.

We generally avoid transporting fish in mid to late summer though for the following reasons.

Warmer water holds less oxygen in solution in warm water while the fish’s respiration and metabolic rate is higher. Also in warmer weather, bacteria densities in water are much higher, though this is somewhat offset by the fish’s immune response being higher as well. The main reason that we haul fewer fish in summer months is that when we harvest ponds in hot weather the fish are more likely to be stressed during harvest.”

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(14) Bob Wattendorf, Fisheries Marketing & Special Projects, Florida Fish and Wildlife Conservation Commission.

“Our hatchery uses compressed oxygen. We strive to keep it above 7ppm, 6 is normally adequate much less than that and there will be some stress. 6-8 ppm is very adequate provided you keep the fish at close to or even a few degrees cooler than the water temperature they were taken from (not the surface temperature but the temp at the depth the fish were holding).”