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Fishery Bulletin 98(4) 



to water temperatures of 10°C. At 6 months of age, ca. 1000 

 juveniles were transfen-ed to Maryland and reared at 17°C 

 at Maryland Department of Natural Resources (Maryland- 

 DNR) and Potomac Electric Power Company hatchery facili- 

 ties (Charles County, MD). Owing to differences in rearing 

 temperature between juveniles held in Pennsylvania and 

 Maryland hatcheries, two size classes resulted. At time of 

 stocking, size class I ranged between 6 and 15 cm TL. Size 

 class II ranged between 22 and 36 cm TL. 



All stocked sturgeon were injected with an internal 

 coded wire tag (CWT) to identify size class and stocking 

 site. In tank-rearing studies conducted at the MD-DNR 

 hatchery, CWT retention was >95''7f. Size class II juve- 

 niles were also tagged with external Floy T-tags inserted 

 through their dorsal musculature below the fourth dorsal 

 scute. Totals of 2306 and 969 juveniles from size classes 

 I and II, respectively, were released into the Nanticoke 

 River (MD) at river kilometers 36 and 50 on 7 July 1996 

 (Table 1, Fig. 2). River conditions at stocking sites were 

 and 3.0 ppt salinity, 26° and 27°C, and 4.2 and 7.7 mg/L 

 dissolved oxygen (D.O. ) at rkm 36 and 50, respectively 

 Site conditions varied less than anticipated in the study 

 design, which stipulated release into divergent salinity 

 levels because of high freshwater discharge rates to the 

 Nanticoke River during spring and summer 1996. 



Telemetry 



To investigate short-term dispersal in the Nanticoke River, 

 32 juveniles were released at 5 sites over 7 occasions 

 (Table 2) and tracked with Sonotronics® ultrasonic trans- 

 mitters. Two size transmitters were used: 28 mm long by 

 8 mm diameter (2.5 g) and 64 mm long by 16 mm diam- 

 eter (8 g) for Atlantic sturgeon <45 cm TL (released 7 

 July-12 August) and >45 cm TL (released 21 October), 

 respectively. Both transmitters had a detection radius of 1 

 km; life spans were 60 days and 14 months for the small 

 and large transmitters, respectively. Transmitters were 

 attached by using a leather punch to drive 4.5-kg test 



monofilament through the third and fifth dorsal scutes. 

 Line was affixed to the transistor by using a cyanocrylate 

 glue, looped through the scutes and glued to the other end 

 of the transmitter. A 50-day laboratory experiment on 10 

 dummy-tagged sturgeon showed lOO'^f retention of trans- 

 mitters with this method. 



Thirteen biotelemetry surveys were conducted through- 

 out the Nanticoke River from July 1997 to February 1998. 

 Tagged fish were located by using a hydrophone and identi- 

 fied by their coded signals. Position, temperature, salinity, 

 and dissolved oxygen were recorded at each location site. 

 On seven surveys, an otter trawl or 5-cm square gill net, or 

 both, were deployed to capture juveniles that might be in 

 the vicinity of the individual located through telemetry. 



Relocation data were used to characterize overall dis- 

 placement and to evaluate potential correlations with 

 salinity, temperature, and dissolved oxygen conditions. 

 Fish released at river kilometers 36 and 38 were com- 



