Effects of fishery closure on perch was detected as female perch was on average 5 cm longer in closed areas compared to non-closed areas. This could be a result of larger individuals surviving as an effect of reduced fishing. No effect was detected on the reproduction rate of YOY (young of the year) perch. A zooplankton survey revealed less amounts of the most important plankton groups for YOY perch in areas with failed reproduction, though the difference was statistically insignificant. The distribution of YOY perch and YOY/adult stickleback differed completely in this study with no area where the two species are both present. It is sketchy to draw any conclusions from this data but it remains a field for further investigation. The reproduction problem is concentrated to the outer parts of the archipelago which confirms previous studies of the geographic extension.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:hgo-853 |
| Date | January 2011 |
| Creators | Johansson, Karl Magnus |
| Publisher | Högskolan på Gotland, Institutionen för kultur, energi och miljö |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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