Is 2016 and the stock of salmon is reduced , more than before .Salmon is now a delicacy for the rich and a never end meal for the poor .Salmon is become more trendy for the become- wanna be chefs and star -tv-s.In 2001 commercial fishing of the Alaskan Portion of the Yukon River was closed, due to poor runs recorded in the previous years. The 2006 Joint Technical Committee of the Yukon River US/Canada Panel documented the size and sex composition of Yukon River chinook salmon and found “limited, but suggestive” evidence that the fish morphology has changed. Specific findings included a decrease in the mean weight of commercial harvests, a reduction in the prevalence of the largest fish, and the apparent near disappearance of age-8 fish.
The committee also reported that mean length-at-age, another important metric, had not substantially changed. In addition to changes in physical characteristics of Chinook salmon, a protozoan pathogen (Ichthyophonus sp.), not previously present in the Yukon River began appearing in increasing numbers of fish.
First reported in 1988 the parasite prevalence increased continually until it peaked at a 40% in 2003-2004. During this time it was reported that up to 60% of infected fish died before they could successfully spawn. Beginning in 2004 the infection prevalence has decreased in parallel with a decrease in the Chinook population. Causes of these changes, whether environmental or fishery-induced, were not clear and the committee found expanded monitoring was needed.
Natural spawning takes place in autumn. The use of temperature and light manipulation has enabled to modify spawning time and have year-round egg availability for Icelandic salmon hatcheries or for export. In Iceland, high quality well-water and geothermal water is available for use by the hatcheries. Geothermal water is used to control the water temperature for eggs, fry and juveniles in hatchery. The final stage of the production cycle is when the salmon reach the final stages of smoltification and should be prepared for transfer into sea water for on-growing or export. In sea-cages salmon will reach market size (ca. 4-5 kg) about three years after hatching and two years at land-based farms. Wild salmon are collected from rivers in late summer and autumn for the production of parr and smolt for stocking. In early summer next year the fry have reached 5-7 g and the producer is able to sell a limited quantity of parr for stocking in rivers, but a suitable number is kept for next year’s smolt production.
Smolt is released in rivers in spring and after a few weeks of local adaptation they will migrate towards their natural feeding grounds in the ocean. The fish return to release sites as sexually mature grilse or salmon after one or two years in the sea.
During the fishing season, the fisherman will often curse at the ADF&G for not giving them more fishing time, to open up this river or that river for fishing, or to lower unrealistic escapement figures. But pervasive is a deeper understanding that the management of the fishery is necessary. The ADF&G and the fishermen of Bristol Bay don’t have to puzzle themselves with thought experiments of little girls falling down wells to understand the importance of preserving the environment. If the Bay is polluted, overfished, or if the delicate balance that keeps the salmon coming back is disturbed, the fishermen will loose their way of life. And so the fishermen are forced to come together in solidarity to protect their own. It is this selfishness on the part of Alaska and the fishermen that has kept the largest salmon run in the world sustainable in the face of ever-higher environmental threat.
The Alaskan Board of Fisheries identified six “stocks of concern” in late 2000, categorizing them as having yield concern. This is defined as “a chronic inability (over four to five years, despite use of specific management measures) to maintain yields or harvestable surplus above escapement needs.”