See also:

Temperatures at Old Crow
 
Peel River fish
 
Waterfowl on the Old Crow Flats

Arctic Borderlands Ecological Knowledge Co-op

What is happening?

• This graph shows the number of chum salmon which arrive to spawn at the Fishing Branch River (tributary to the Porcupine River) each year.
• There was an unexpectedly high run in 2005 and this has been followed by five years with modest runs; just over 15,000 chum were estimated in 2010.
• The size of the chum run over the last five years has been at the lower limit of the spawning goal set by managers for the period between 2008 and 2010.

Why is it happening?

• The majority of chum salmon return from the ocean to spawn four years after they hatch. High numbers of returning spawners will often be followed by another high return four years later. This four-year cycle is apparent in the data for the 1970s (note the peaks in 1971, 75 and 79).
• Salmon stocks of the Porcupine River are fished in both Canada and the United States. Significant harvests of chum in Alaska have decreased the number of chum which are able to make it to the upper Porcupine River watershed each year. Canadian catches, though far smaller than Alaskan catches, were increasing until 2002 when the harvest was reduced within the Porcupine watershed.
• Fisheries biologists believe that ocean conditions (poor marine survival) are responsible for the low returns of chum to the Fishing Branch River between 1997 and 2003.

Why is it important?

• The Vuntut Gwitchin people carry out a traditional chum fishery near Old Crow. Between 2002 and 2004 they adopted a voluntary fishing closure because of conservation concerns with low numbers of returning chum.
• The number of returning salmon (escapement numbers) are affected by many factors, such as fishing pressure from humans, predation by freshwater, marine and terrestrial wildlife, water level fluctuations and diseases.
• Fish numbers may be sensitive to changes in river and ocean environments that result from global climate change, such as changes in predator-prey relationships, water levels, water temperatures, and sediment loads in streams.

Technical Notes

• "Escapement" refers to the number of salmon that reach a specific location. When escapement is used alone, it generally refers to the number of salmon that reach their spawning grounds.
• The data for 1971, 1976-84 and 1990 are estimates based on aerial surveys while the remaining data in this graph are estimates based on the actual fish weir counts.