Relationship of salmonine production to lake trophic status and temperature

Data on trout, charr and salmon from lakes in several geographic areas indicate that salmonine production (P, kilograms per hectare per year) increases with total phosphorus concentration (TP, micrograms per litre) as log₁₀P = 0.47 + 0.95 log₁₀TP. A positive relationship was also found between P and phytoplankton productivity and this relationship suggests that energy transfer efficiencies from phytoplankton to salmonines are reduced in eutrophic lakes. Lake area and mean depth had no signficant statistical effect on P but salmonine production was significantly lower in warmer climates. Data suggest that projected global increases in air temperatures could lead to about 50% reductions in salmonine production and yield in the north temperate zone. -Authors