These results then indicate that in order to enhance the stream at all age-classes in the most cost effective manner, debris catchers that create scour plunge pools in both high and low velocity waters should be installed in conjunction with alcoves to enhance overwinter survival. In this experiment, habitat enhancements included the construction of small dams with rocks and logs which formed pools up to 1m deep, the placement of large rocks in the pools for visual isolation, and the addition of cover in the form of logs, stumps and rafts of alders. It was determined that the test section had a lightly higher level of invertebrate production over the control section and that the trout density and biomass also increased in the improvement section. Such an increase in the trout biomass could be a result of the increased invertebrate density. One of the best ways to increase the food supply to salmonids would be through inorganic fertilization of streams or lakes.
Aquatic insects feed on benthic algae which is enhanced by nutrient additions.
When looking at the Lake Enrichment Program through the SEP, and in particular the historical recovery of the Barkley Sound sockeye stocks, one can see that the stocks which had been depressed to less than 100,000 adults in the early 1900's was rebuilt to levels of 300,000 to 1,600,000 returning adults since fertilization of the Sound began. Examination of all British Columbia enriched lakes shows the current annual landed value of the sockeye to be 10-15 million dollars such that the total landed value for the past 20 years would exceed 300 million dollars. Such analysis has yet to be conducted on rivers which have been fertilized. Through the examination of these studies on the effects of in-stream structures and river or lake fertilization, it is evident that there are some promising techniques for enhancing failing fisheries. Generally, it would seem that the best way to recover a salmonid population in a river setting would be to place structures that scour plunge pools in areas of high and low velocity in order to increase the carrying capacity for adult and fry salmonids.