Table 1
Summary of whitefish population regulation in Pyhäjärvi, SW Finland. Successive life stages, factors affecting each, and possible effects observed (FAI = Food availability index).
| Variables | Explanatory factors |
|---|---|
| Population fecundity in autumn | |
| Population biomass of mature females | Year-class size, fishery, FAI explains 91% of population fecundity |
| Adult mass at age | FAI (variable) |
| Egg size | FAI? (No changes) |
| Relative fecundity (eggs g−1) | FAI (decreased) |
| Water content of eggs | FAI (increased) |
| Density of larvae in spring | |
| Population fecundity previous autumn | Major factor |
| Roe quality ? | |
| Fertilization success ? | no data |
| Winter mortality due to O2 deficit | Lack of O2 not in Pyhäjärvi |
| Egg mortality, due to predators | Signal crayfish ?, ruffe ?, other fish ? |
| One-summer-old juveniles | |
| Density of larvae previous spring | Major factor |
| Spring mortality by starvation ? | Possible mismatch with zooplankton food production due to climate change |
| Spring and summer predation mortality | Predation by perch, smelt, other fishes |
| Spring temperature | Strengthens predation effects when low |
| 1st winter fishing mortality | Bycatch in winter seining for vendace |
| 1st winter predation mortality ? | Predation by perch, smelt |
| Adult whitefish | |
| 2nd summer predatory mortality ? | Predation by perch, pike |
| 2nd summer high temperature mortality ? | High temperature periods |
| Fishing mortality of adults | Fyke net fishery |
| Gillnet fishery | |
| Winter seine fishery | |
| Predatory mortality of adults | Predation by big pike |
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.