The Fraser River is being overrun by sockeye salmon.

Sockeye Salmon (freshwater coloration)

Officials from the fishery are now estimating that the number of sockeye returning has climbed to roughly 30 million, which is a 5 million increase from their previous count of 25 million earlier this week.

This is the highest number of returning salmon recorded since 1913, when around 39 million sockeye made their way back to the Fraser River, just before a rock slide into the river gave birth to Hells Gate and caused a huge disruption in the stocks of salmon for decades.

The run this year is looking to be almost three times higher than the 11 million originally estimated before the season started.

The late run this year is projected to be large as well, due to the fact that it will include the peak cycle Adam River run.

However, this run has really turned a lot of heads, as the Pacific Salmon Commission this past Friday has raised its estimate of late run sockeye to an astounding 21.4 million, which is a far cry from their 8.5 million prediction prior to the start of the season.

Up till now, more than 6.4 million salmon have swum their way upriver, avoiding the gilnetters on the lower Fraiser, as compared to the 5.7 million which were estimated as having being caught.

And there doesn’t seem to be any sign of a shortage.

It’s good to see mother nature replenishing her stocks, after such a long “dry spell”. Hopefully this is just a taste, and the salmon runs will continue to be as plentiful in the years to come.

Telling a wild salmon from a farmed one can be tricky, especially if you don’t want to kill or injure the fish in question. To solve this problem, Dr Elizabeth Adey of the Scottish Association for Marine Science (SAMS) have developed a way of using fish scale analysis to determine the origin of a salmon.

Fish scales grow like tree rings and preserves a chemical record of the water in which the fish lived as each new section of the scale was formed. The new method, which was developed in collaboration with the National Oceanography Centre in Southampton, checks the amount of manganese present in the fish scale. During her work, Dr Adey discovered that the scales of farmed salmon have a very high manganese content compared to the levels found in scales coming from their wild counterparts.

“This is probably caused by manganese supplements in fish food, and also because conditions underneath the fish cages promote recycling of manganese in the water column,” Dr Adey explains. Using the new method, Dr Adey and her team was able to distinguish between farmed and wild salmon with 98% accuracy.”Because of its non-destructive nature, this technique could be used to assess the proportion of farmescape salmon present in any river, and therefore identify where additional conservation and wildlife protection measures are needed,” says Dr Trueman, a geochemist with the University of Southampton’s School of Ocean and Earth Science, based at that National Oceanography Centre. “Salmon farming is a big, intensive business. In 2006, around 130,000 tonnes of salmon were farmed in Scotland for the table. Wild populations of Atlantic salmon are in serious decline across their whole range and the total wild population returning to Scottish rivers in the same year is estimated at less than 5000 tonnes. Wild fish are rare and expensiveso there is a strong incentive for fraudulent labeling. Farmed fish also escape into rivers, harming the wild population. Unfortunately, it can be difficult to distinguish between farmed and wild fish.“

In the future, the new technique may also be able to point out which individual fish farms that need to implement more efficient methods for keeping their salmons in. In some Norwegian rivers, more than 50 percent of the salmon are now escapees. Escaped fish can carry disease to wild populations, and there is also a risk of genetic pollution since farmed fish haven’t gone through the same natural selection process as wild fish.

The Salmon runs in British Columbia are known to fluctuate, with good years being followed by poorer ones. Since the mid-1990s, most years have however been bad and many explanations for this situation have been offered, from El Nino and too warm streams, to over-fishing and habitat destruction. It is of course tempting for the fishing industry to place the blame solely on natural phenomena like El Nino, but it is hard to turn a blind eye on the immense amounts of salmon caught from the rivers of British Columbia each year.

Take for instance Fraser River, the longest river in British Columbia with a total length of 1,375 km (870 mi) and a drainage area of roughly 220,000 km² (85,000 sq mi). This is a heavily exploited river and the lower reaches are especially affected by habitat destruction brought on by agricultural, industrial and urban developments. The last great salmon run in this river took place as far back as 1913, when an estimated 38 million sockeye salmons returned to spawn. Out of those 38 millions, no less than 32 millions were caught and utilized as food fish. Four years later, the run had been diminished to a mere 8 million sockeyes, but this didn’t stop the government from allowing 7.3 millions of them to be caught. In 2008, an estimated 1.6 million sockeye salmon returned to Fraser River, but despite the extremely low figure the federal Department of Fisheries and Oceans allowed commercial, sport and native fishermen to continue their fishing activities. Since the early 1900s, about 40 to 70 per cent of any given run has normally been allowed to be taken in nets.