ISSN:
1573-5117
Schlagwort(e):
Salmo salar
;
radio telemetry
;
intragastric tagging
;
regurgitation
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Regurgitation rates of tagged salmon in the wild are difficult to estimate as few fish are recovered and thus the fate of the majority of tags is difficult to assess unambiguously. During a study on the River Tweed between 1994 and 1996, 281 returning adult salmon were caught by net and coble, and radio tagged. Salmon recaptured by rod and line were used as a sample of the radio-tagged population from which the frequency of tag regurgitation was determined. A total of 27 tagged fish were recaptured by anglers over the 3 year study period, of which 4 (14.8% ± 1.2% standard error) did not have radio tags in their stomach. Regurgitation rates were consistent between years; 16.7% in 1994 (2 out of 12), 12.5% in 1995 (1 out of 8) and 14.3% in 1996 (1 out of 7). Regurgitation was not associated with the immediate aftermath of tagging. However, too few salmon were recaptured in the present study to identify other factors which may be important in determining transmitter regurgitation rates in radio tracking studies. No statistically significant relationship could be demonstrated between the lengths of the fish regurgitating their tags and those of the fish which retained them (Mann Whitney test: N = 27, U = 33.5, P = 0.392). Fish which regurgitated tags were tagged over a wide range of months (between April and September) and the subsequent positions of regurgitated tags were widely scattered within the river system.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1017095409731
Permalink
