Lake Sturgeon Radio Telemetry Study

Ontario Ministry of Natural Resources
Lake Superior Management Unit

Map showing location of radio telemetry study of adult and juvenile lake sturgeon in the Kaministiquia River (figure 1)Natural resource agencies in Canada and the United States have developed a Lake Sturgeon Rehabilitation Plan for Lake Superior.  The goal of the plan is to maintain, enhance and rehabilitate self-sustaining populations where the species historically occurred basin wide. 

One of the strategies to achieve this goal is to protect and rehabilitate habitats for all lake sturgeon life stages.  With support from the Ontario Federation of Anglers and Hunters, the Great Lakes Sustainability Fund and the Lake Superior Binational Program, the Lake Superior Management Unit has initiated a radio telemetry study of adult and juvenile lake sturgeon in the Kaministiquia River (figure 1).  This study will allow us to determine the seasonal distribution and movements patterns of these fish and identify important habitat areas (i.e. spawning and feeding).

 

MATERIALS AND METHODS

From Sept 6 to October 2/ 2000, lake sturgeon were captured using 114 (4.5), 216 (8.5), 241 (9.5), 254 (10), 305 (12) and 381 mm (15) stretched mesh, multifilament gill nets.  Net lengths were 50, 85 and 100 yards.  All sturgeon were sampled for fork length, total length, legal length, weight and were tagged with a five digit, orange floy tag applied along the left hand side of the dorsal fin.  Some sturgeon were also tagged with a six digit, clear disc tag applied anterior to the dorsal fin.  Sex determination was attempted by internal examination using an autoscope.

Figure 2.  Radio telemetry equipment showing antennae and transmitter.Twenty Advanced Telemetry Systems radio transmitters, with trailing external whip antenna, were surgically implanted into the body cavities of adult and juvenile lake sturgeon.  Sturgeon were selected for transmitter placement so that the weight of the transmitter did not exceed 2% of the fish weight.  Seventeen 75g tags (figure 2) with a life of 1095 days, two 26g tags with a life of 400 days and one 20g tag with a life of 280 days were used.  Each transmitter is coded with a unique frequency between 150.000 151.990 MHz.

Prior to surgery the magnet taped to the transmitter was removed to activate the tag.  The receiver was then turned on, locked on the frequency of the tag and the volume turned up until the pulse of the tag was heard.  This verified the tag was functioning properly before implantation.  The surgical procedure was as follows.

  A solution of 1.2 ml clove oil to 10.8 ml ethanol was used as an anesthetic.

  36 ml of the clove oil/ethanol solution was mixed into 60 litres of water.

  Fish were immersed in a tub containing the anesthetic for approximately 5 minutes depending on fish condition and size.

 Once immobilized, the fish was placed belly up in a foam lined, v-shaped tagging trough.

  A squirt bottle containing the anesthetic solution was used to irrigate the gills.  This ensured the fish would not recussitate during the surgery (figure 3).

  A scalpel, (# 60 blade) was used to make a 2 inch incision just off the midline of the body, half way between the pectoral and pelvic fins (figure 3).

  A 4 (10cm) # 11 Jamshidi Bone Marrow Biopsy/Aspiration Needle was used to make a small hole approximately 2 cm behind the main implant incision (figure 4).

  The end of the needle was pushed forward until the end was visible in the main incision.

 The antenna was then threaded into the end of the needle and pushed far enough until it exited the body.

  The tag was then inserted into the body cavity (figure 5).

  At this point the gills were then irrigated with water to wash off the anesthetic and allow the fish to start recovering.

  The main incision was then sutured using Ethicon absorbable nylon prethreaded cutting sutures (figure 6).

 For 10-15 minutes the fish was allowed to recover in a tub that was situated in the river.

  Once able to swim off the fish was released.  


Image of a lake sturgeon showing insertion of a radio telemetry tag

 

RESULTS

Fifteen overnight gill net sets and 16 short term sets were carried out between September 6 and October 2, 2000.  Twenty sturgeon implanted with radio transmitters ranged in weight from 1.7 kg to 24.7 kg.  Forty additional sturgeon were captured during the netting. 

Recaptured individuals included three from 2000, ten from 1998 and one from an unidentified source (orange floy tag # 12090).  One radio-tagged fish was recaptured 14 days after the surgery and the incision was healing well. 

None of the fish could be sexed based on internal examination.     

All fish have been located and are moving throughout the Kaministiquia River.

 


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