Sockeye salmon over Bonneville Dam on the Columbia River. Lower temperatures in 2008 North Pacific waters brought in fatter plankton, which, along with greater outflows of Columbia River water, fed the resurgent populations. Proposed legislative efforts, such as the Northern Rockies Ecosystem Protection Act, are attempting to protect the headwaters of the sockeye salmon by preventing industrial development in roadless areas. Record numbers of a once-waning population of sockeye salmon have been returning to the Northwest's Columbia Basin (as of June 2012), with thousands more crossing the river's dams in a single day than the total numbers seen in some previous years.
Environmental issues with salmon 59 years of catch and escapement data of Bristol Bay sockeye to determine age and size at maturity trends attributable to the selectivity of commercial gillnet harvests. The study found that the larger females (>550 mm) of all age classes were most susceptible to harvest. The study suggests that smaller, younger fish were more likely to successfully traverse the gillnet fishery and reproduce than the larger fish. The study also found that the average length of sockeye harvested from 1946–2005 was 8 mm larger than the sockeye who escaped the gillnet fishery to spawn, reducing the fecundity of the average