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Ultrasound….What do you use that for?
Midwest Region, June 17, 2014
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Fish biologist Justin Chiotti and contaminants specialist Jeremy Moore collecting ultrasound images from a lake sturgeon captured in Southern Lake Huron, 2014.
Fish biologist Justin Chiotti and contaminants specialist Jeremy Moore collecting ultrasound images from a lake sturgeon captured in Southern Lake Huron, 2014. - Photo Credit: USFWS
An ultrasound image collected from a male lake sturgeon during the spawning season in the Detroit River, 2014.
An ultrasound image collected from a male lake sturgeon during the spawning season in the Detroit River, 2014. - Photo Credit: USFWS
An ultrasound image collected from a female lake sturgeon during the spawning season in the Detroit River, 2014.
An ultrasound image collected from a female lake sturgeon during the spawning season in the Detroit River, 2014. - Photo Credit: USFWS

Typically when we pull out the ultrasound unit on our boat, the question we get is, “What do you use that for?” An ultrasound unit is not something that you commonly see on a boat, but a lake sturgeon telemetry project in the St. Clair-Detroit River System (SCDRS) has provided fish biologists from the Alpena Fish and Wildlife Conservation Office with a unique opportunity to evaluate the use of a portable ultrasound to determine the sex of lake sturgeon.

Sex determination of fish species in the field is difficult to assess when sexual dimorphism and gametes are not apparent. For threatened and endangered fish species such as lake sturgeon, unobtrusive techniques are needed to minimize stress and the potential for mortality. Some of the more common techniques used to determine sex of lake sturgeon include: gonadal biopsy, endoscopy, blood plasma, and ultrasound. All of these techniques have their pros and cons, however collecting images using ultrasound may be done in the field and results can be obtained immediately.

 

Lake sturgeon are captured on setlines during the spring spawning season and biological information such as total length, girth, and weight, is recorded from each fish. Adult lake sturgeon, those typically greater than 1300 mm, are implanted with an acoustic transmitter. The small incision used to insert the transmitter allows us to visually determine the sex of the lake sturgeon. Ultrasound images are then collected at six different locations along the body of the fish. Back in the office, the sex and maturity status of each lake sturgeon is assigned based on the ultrasound images and compared to the information we obtained in the field by visually determining the sex through the incision. If our data suggests we can determine the sex and maturity with little error, ultrasound images will be collected from all lake sturgeon in the future to assign sex and maturity status even when gametes are not apparent.

This project is conducted in cooperation with the U.S. Geological Survey, Michigan Department of Natural Resources, and Ontario Ministry of Natural Resources. For more information about lake sturgeon work in the SCDRS please visit the following websites: http://www.fws.gov/midwest/alpena/; http://www.huron-erie.org/


Contact Info: Justin Chiotti, (248) 891-0087, Justin_Chiotti@fws.gov



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