No abstract

Swimming performance was compared among groups of juvenile rainbow trout Oncorhynchus mykiss (5-10 g) with and without intraperitoneally implanted radio transmitters. The generally accepted rule of 2% body weight : transmitter weight was extended to a 6-12% ratio, and swimming performance was not altered by the presence of the transmitter or effects of the operation. Also, no relationship was found between the weight of the fish and its swimming performance among the groups examined. Although we found swimming performance was not affected by implantation of transmitters weighing up to 12% of the body weight, changes in behavior were not evaluated. We suggest further research be done so that the ''2% rule'' can be replaced by an index with a more scientific basis. Instead of using a scale based on percentage of transmitter to body weight in air, preferred indices could be weight in water, volume of the tag, or both.

No abstract

clinicaltrials.gov Identifier: NCT01421342.

Development of rehabilitation strategies and accurate assessment of anthropogenic impacts relies on a thorough understanding of a species’ life history. In the case of the lake sturgeon Acipenser fulvescens, a better understanding of the juvenile life history stages is needed to improve conservation efforts for this imperiled species. Home range size and seasonal movement of juvenile lake sturgeon in the Winnipeg River, Manitoba, were examined using mark–recapture and acoustic telemetry. Over a 30‐month period (May 2006–October 2008), 5,671 juvenile lake sturgeon (213–879 mm fork length [FL]) were marked with Floy tags and the movements of 23 juvenile lake sturgeon (364–505 mm FL) were monitored by means of acoustic transmitters. Despite the potential for movement over 49 km of naturally connected riverine habitat, the results indicated that juvenile lake sturgeon exhibited strong site fidelity. As determined from the mark–recapture data set, 90.8% of recaptured fish were recaptured less than 2.0 river kilometers (rkm) from their original capture location. Similarly, acoustic telemetry data indicated that 50% of the tagged fish moved 1.5 rkm or less from their initial release locations. Finally, the results of both methodologies indicated that juvenile lake sturgeon rarely move through rapids characterized by high water velocities (>1.5 m/s), complex turbulent flows, boulder and bedrock substrates, and various cross‐sectional water depths ranging from 1.0 m to approximately 15.0 m in either an upstream or downstream direction. These results suggest that the year‐round habitat requirements for juvenile lake sturgeon can be met in relatively short sections of a large river. Furthermore, owing to strong site fidelity and a lack of movement through rapids, macroscale habitat use in juvenile lake sturgeon occupying large rivers may be dependent on dispersal at either the larval or young of the year life history stages.