NMFS Releases Report on The Effects of Salmon Fisheries on Southern Resident Killer Whales
In June 2011, NOAA Fisheries and Canada's Department of Fisheries and Oceans commissioned an independent scientific panel that was asked to determine to what extent salmon harvests affect the survival and recovery of Southern Resident killer whales by reducing the abundance of their prey. The panel has submitted its final report, The Effects of Salmon Fisheries on Southern Resident Killer Whales, to both agencies. The Report includes the following conclusions:
"The SRKW population has been observed to increase at an average rate of 0.71% per year, and would be expected to increase at about 1% per year in the long term if sex ratio at birth were 50:50."
"The panel believes that the existing delisting criterion of 2.3% growth rate is unlikely to be achieved given current circumstances or by reducing Chinook salmon fisheries. But if the total abundance continues to increase, a point will be reached where a reappraisal of their status would be likely."
"The evidence for strong reliance on Chinook salmon in the summer is convincing, but it is also clear that SRKW will switch to alternative, more abundant chum salmon when Chinook of suitable size and quality are not readily available in the fall."
"Photographic evidence supports the assertion that poor condition, which is linked to mortality, and by implication to fecundity, may reflect nutritional stress. However, unless a large fraction of the population experienced poor condition in a particular year, and there was ancillary information suggesting a shortage of prey in that same year, malnutrition remains only one of several possible causes of poor condition."
"The maximum long-term increases in abundance of Chinook salmon that might theoretically be available to SRKW would be achieved by eliminating all ocean fishing (typically at least 20% increase in ocean abundance of age-4 and age-5 hatchery and wild fish due to elimination of ocean fishery interception of immature fish) and by maximizing recruitment through manipulation of freshwater exploitation rates to maximize recruitment (6-9% increase in recruitments of wild fish; no impact on hatchery fish). The best potential for increased Chinook salmon abundance is restoration of freshwater habitat, reducing downstream migration mortality and a change in ocean conditions."
"The panel sees many potential reasons why not all foregone Chinook salmon catch would be available to SRKW, and is therefore skeptical that reduced Chinook salmon harvesting would have a large impact on the abundance of Chinook salmon available to SRKW."
"The statistical analysis by NOAA and DFO scientists are excellent, but the Panel believes considerable caution is warranted in interpreting the correlative results as confirming a linear causal relationship between Chinook salmon abundance and SRKW vital rates."
"The Panel is not confident that understanding of the interaction between Chinook salmon fisheries, other predators and SRKW vital rates, is sufficient to expect the model predictions of increased SRKWs to be accurate. The Panel expects the model predictions to overestimate the impact of reductions in Chinook salmon catch on SRKW."
Click here to read Report