Warm Springs National Fish Hatchery
Southeast Region

 

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Warm Springs NFH's Alligator Gar Research Accomplishments

 

2005

  • Provided assistance for the first time to Pvt. John Allen NFH staff with spawning, culture, and research efforts.
  • Began development of spawning procedures (including stripping eggs from females and collecting sperm from males to optimize the cross ratio of 5 males to 1 female).
  • Began development of culture techniques for rearing early life stages at the hatchery.

 

2005 – Research

  • Collected sperm samples for a cryopreservation study. The study focuses on developing freezing techniques for alligator gar sperm.
  • Frozen sperm samples were placed in a repository for future studies.

 

2006

  • Provided assistance to Pvt. John Allen NFH staff with broodfish collection, spawning, culture, and research efforts.
  • Spawned three females and eight males at Pvt. John Allen NFH. First successful strip spawning of alligator gar produced 251,600 eggs. Over 140,000 fry produced at Pvt. John Allen NFH.
  • Fry was distributed to several federal and state agencies along the Mississippi River.
  • Culture techniques were evaluated and additional protocols were developed at Warm Springs to raise alligator gar in earthen ponds. Natural forage was also produced for the larval and young of year alligator gar.
  • Approximately 15,000 fry were received from the spawning at Pvt. John Allen NFH and 10,000 were stocked into ponds. This first year trial yielded a very low survival with returns ranging from 4 to 8%. Bird predation more likely was the biggest contributor to the low numbers but high predation amongst themselves is also a factor.
  • 96 fish (averaging 12.66 inches, 0.34 lbs.) were coded wire-tagged and distributed to the Hatchie River in Tennessee in July 2006.

 

2006 – Research

  • Collected additional sperm samples for a cryopreservation study. The study focuses on developing freezing techniques for alligator gar sperm.
  • Frozen sperm samples were placed in a repository for future studies.

 

2007

  • Provided assistance to Pvt. John Allen NFH staff with broodfish collection from St. Catherine’s Creek NWR, spawning, culture, and research efforts.
  • Spawned four females and three males at Pvt. John Allen NFH. The strip spawning of alligator gar produced over 224,000 eggs. Fry was distributed to several federal and state agencies along the Mississippi River.
  • Due to anti-escapement issues, the hatchery staff developed trials and protocols to raise alligator gar intensively by utilizing several 8-foot long tanks, several circular tanks, raceways in the holding house and the lake sturgeon building, and a 20’ raceway in Pond # 41. Raising the gar in ponds was not attempted this year.
  • Pond culture techniques were refined to produce and concentrate natural forage (including fathead minnows) for feeding larval and young of year alligator gar.
  • Approximately 10,000 fry (344.8 grams) were received from the spawning at Pvt. John Allen NFH and were stocked into the raceways and tanks. Over a seven week period from mid-May to early-July the gar grew to an average length of 9.5 inches.
  • 102 fish were shipped to Pvt. John Allen NFH (averaging 9.46 inches, 0.14 lbs.) to be coded wire-tagged and distributed to the Hatchie River in Tennessee in July 2006.
  • Our staff began collaboration with Alabama program in 2007, by providing technical expertise and guidance to their biologists.

 

2007 – Research

  • Collected additional sperm samples for a cryopreservation study. Modified sperm collection technique to provide sufficient quantities of sperm for research. Frozen sperm samples were placed in a repository for future studies.
  • Small lots of eggs from alligator gar females were collected and fertilized with sperm that was frozen in 2005 and 2006. The cryopreserved sperm fertilized eggs at a relatively good percentage, validating the techniques used in the past two years.

 

2008

  • Provided assistance to Pvt. John Allen NFH staff with broodfish collection from St. Catherine’s Creek NWR, spawning, culture, and research efforts. Alabama Department of Conservation also transported several fish to the Pvt. John Allen NFH for assistance in spawning alligator gar for the Alabama restoration program.
  • Spawned only one Mississippi female at Pvt. John Allen NFH. The strip spawning of alligator gar produced viable eggs but within 24 hours the eggs were dead. The cause of mortality is unknown.
  • Several lots from crosses of Alabama fish were used in an egg de-adhesion study conducted by Fish Technology Center personnel. At the end of this study, 1,300 fry were transported back to Warm Springs and transferred to us for grow-out. Even though we had minimal success (12%) with raising Alabama fry, we were still able to ship out 159 fish that were stockable size (greater than 12”). These fish were stocked into the Mobile River by Alabama DNCR staff on July 31st. The fish were measured, tagged and hauled by DNR personnel and stocked into the Mobile River. This event was the first stocking ever of alligator gar in Alabama.
  • The hatchery also received about 2,400 fry to culture from gar spawned at Golden Ranch, Nicholls State University, Louisiana. The fish were raised for refugia and research purposes. We had relatively good success (41%) in culturing the batch of Louisiana fry. Our hatchery transferred 50 of these fish to Auburn University for a fish host mussel study (average 50.8mm and 0.85g), 450 fish to the University of Southern Mississippi for salinity studies (average 38.1mm and 0.5g), and 500 fish were sent back to Nicholls State University for continued culture and grow-out (average 210.04mm and 41.7g).
  • Intensive culture protocols at Warm Springs NFH were refined. Adjustments in the feeding protocol and improving water quality were attempted to yield a higher survival rate. Fry were reared in a series of tanks (25-gallon round, black tanks; 50-gallon oval tanks; 130-gallon round tanks; concrete raceways; and a 20’ raceway).
  • Fish were graded as time permitted to help minimize predation. In our observations in the past couple of years, we saw that the fish are surface feeders. However, any disturbance or if they see something it will send the fry to the bottom of the tank and they will not eat. We were also able to take more time to observe feeding behavior at all stages of development this year so that feeding amounts and schedules could be changed accordingly. The fish were fed SilverCup pellets from Starter all the way up to 3.2mm, after being weaned off brine shrimp at 10-20 days of culture.

 

2008 – Research

  • Collected a small quantity of fresh sperm from three males for cryopreservation for the repository. The fertilization trials as part of the cryopreservation study were not attempted due to shortage of eggs.
  • Collected additional samples for developing short-term storage techniques for use during the spawning season. The results of study were not successful.

 

2009

  • Provided assistance to Pvt. John Allen NFH staff with broodfish collection from St. Catherine’s Creek NWR, spawning, culture, and research efforts.
  • Provided assistance to Alabama Department of Conservation staff with broodfish spawning at Marion Fish Hatchery.
  • Spawned only one Mississippi female at Pvt. John Allen NFH. The strip spawning of alligator gar produced viable eggs but within 24 hours the eggs were dead. The cause of mortality is unknown.
  • Continued with intensive culture of alligator gar for both the Tennessee and Alabama restoration programs.
  • The hatchery received 3,600 fry (Mississippi strain) from Pvt. John Allen NFH in May. Fish were reared for two months and 1,952 tagged fish were stocked into Hatchie River in June.
  • The hatchery also received 1,600 fry (Alabama strain) from Marion in May. These fish were also raised intensively but were kept separate from the Mississippi fish. Exactly 143 fish were tagged and stocked into Claiborne Lake in August.

 

2009 – Research

  • Cryopreservation Study was not attempted this year due to lack of samples. The fertilization trials as part of the cryopreservation study were not attempted due to shortage of eggs.
  • Collected additional samples for developing short-term storage techniques for use during the spawning season. The results of study were not successful due to shortage of samples.
  • Attempted a new study to develop a vitellogenin ELISA. This research will hopefully produce a way to determine gender of fish. Several attempts were made to draw blood samples, but the collection was difficult.

 

Future Work:

  • Provide assistance to biologists from Pvt. John Allen NFH and Alabama DCNR with broodfish collection, spawning, and research.
  • Refine feeding protocols to include various forms of artificial feed.
  • Produce an Alligator Gar Culture Manual that can be disseminated to other stations.
  • Run fertilization trials using cryopreserved sperm to finalize protocols for short-term and cryopreservation storage of alligator gar sperm.

 

For more information about the alligator gar program, please contact Carlos Echevarria at 706-655-3382 ext. 1224 or carlos_echevarria@fws.gov.

 

Alligator Gar Species and Background Information

 

 

 

To Learn More About:
Alligator Gar Species, Background, & Life History Information

 

 

Alligator Gar feeding on fathead minnows. Credit: USFWS Image.

Alligator Gar feeding on fathead minnows. Credit: USFWS Image.

 

 

 

 

Six-week old alligator gar. Credit: USFWS Image.

Six-week old alligator gar. Credit: USFWS Image.

 

 

 

 

FWS biologist holding an adult alligator gar. Credit: USFWS Image.

FWS biologist holding an adult alligator gar. Credit: USFWS Image.

 

 

 

 

The natural olive-green coloring can sometimes make the alligator gar appear unusual. Credit: USFWS Image.

The natural olive-green coloring can sometimes make the alligator gar appear unusual. Credit: USFWS Image.

 

 

 

 

Biologists insert a PIT tag near the dorsal fin. Credit: USFWS Image.

Biologists insert a PIT tag near the dorsal fin. Credit: USFWS Image.

 

 

 

 

Five-day old alligator gar fry.  Credit: USFWS Image.

Five-day old alligator gar fry. Credit: USFWS Image.

 

 

 

Last updated: July 11, 2011

 

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