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Hur känslig är vild västkustlax Salmo salar för parasiten Gyrodactylus salaris? Ett fältförsök i Himleån, Varberg

Norling, Roger (2013) BIOY36 20122
Degree Projects in Biology
Abstract
Abstract

The parasite Gyrodactylus salaris has recently spread to several new wild salmon rivers at the Swedish west coast. A study was carried out in River Himleån, infected in 2005, to investigate if the salmon population was negatively influenced by the parasite. In October 2007 salmon parr were captured by electrofishing. The fish were anaesthetized and their length and weight were measured. Each fish was marked with a PIT-tag (12x2,1 mm) in the abdominal cavity and the numbers of parasites were counted on dorsal and breast fins. After recovery the fish were released back into the river. One month later, in late November, marked fish were recaptured at a second electrofishing and the procedures were repeated.
At the first... (More)
Abstract

The parasite Gyrodactylus salaris has recently spread to several new wild salmon rivers at the Swedish west coast. A study was carried out in River Himleån, infected in 2005, to investigate if the salmon population was negatively influenced by the parasite. In October 2007 salmon parr were captured by electrofishing. The fish were anaesthetized and their length and weight were measured. Each fish was marked with a PIT-tag (12x2,1 mm) in the abdominal cavity and the numbers of parasites were counted on dorsal and breast fins. After recovery the fish were released back into the river. One month later, in late November, marked fish were recaptured at a second electrofishing and the procedures were repeated.
At the first electrofishing 515 0+ and 187 1+ individuals were tagged. Of those were 127 0+ (24,7 %) and 59 (31,5 %) 1+ individuals recovered. The infection level increased from predominantly 11-100 parasites on fins of each fish at the first fishery to mainly 101-300 parasites at the recapture. For 0+ individuals recovered at the second fishery there was no significant connection between changes in weight, length and condition factor and the number of parasites at the first fishery. A significant correlation (p=0,013) was found between decreasing condition factor and high parasite numbers for 1+ parr. There was also a connection between a lower share of recovered 1+ parr, but not 0+ parr, with higher number of parasites (p=0,007). The negative correlations were probably due to that higher number of parasites influenced fish survival and growth in a negative manner. (Less)
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author
Norling, Roger
supervisor
organization
course
BIOY36 20122
year
type
H1 - Master's Degree (One Year)
subject
language
Swedish
id
3563532
date added to LUP
2013-03-12 11:28:26
date last changed
2013-03-12 11:28:26
@misc{3563532,
  abstract     = {Abstract

The parasite Gyrodactylus salaris has recently spread to several new wild salmon rivers at the Swedish west coast. A study was carried out in River Himleån, infected in 2005, to investigate if the salmon population was negatively influenced by the parasite. In October 2007 salmon parr were captured by electrofishing. The fish were anaesthetized and their length and weight were measured. Each fish was marked with a PIT-tag (12x2,1 mm) in the abdominal cavity and the numbers of parasites were counted on dorsal and breast fins. After recovery the fish were released back into the river. One month later, in late November, marked fish were recaptured at a second electrofishing and the procedures were repeated.
At the first electrofishing 515 0+ and 187 1+ individuals were tagged. Of those were 127 0+ (24,7 %) and 59 (31,5 %) 1+ individuals recovered. The infection level increased from predominantly 11-100 parasites on fins of each fish at the first fishery to mainly 101-300 parasites at the recapture. For 0+ individuals recovered at the second fishery there was no significant connection between changes in weight, length and condition factor and the number of parasites at the first fishery. A significant correlation (p=0,013) was found between decreasing condition factor and high parasite numbers for 1+ parr. There was also a connection between a lower share of recovered 1+ parr, but not 0+ parr, with higher number of parasites (p=0,007). The negative correlations were probably due to that higher number of parasites influenced fish survival and growth in a negative manner.},
  author       = {Norling, Roger},
  language     = {swe},
  note         = {Student Paper},
  title        = {Hur känslig är vild västkustlax Salmo salar för parasiten Gyrodactylus salaris? Ett fältförsök i Himleån, Varberg},
  year         = {2013},
}