THIS IS AN APPEAL TO PADDLERS TO AVOID PADDLING OVER OR WALKING THROUGH GRAVEL BEDS ON RIVERS FOR THE NEXT COOUPLE OF MONTHS.
Salmon are endangered and becoming more and more scarce; please don’t assist in their demise.
May we grow together by better understanding
Thank you.
The following is abstracted from an American article on salmon spawning but never the less is described adequately what is taking place on many gravel beds on many of our rivers at this time and for teh next couple of months.
“Spawning Biology
Spawning, or redd (spawning nest) building, is a lengthy process taking 15 to 20 days to complete and includes the following three stages:
1. Pre-spawning – Over a period of five days, the female selects a spawning site and begins a set of tentative redd excavations. She may retreat to areas of cover adjacent to her test excavations and be difficult to observe. Disturbance from boat traffic at this time could result in prevention of redd establishment, displacement of fish to less suitable habitats, or creation of poorly- constructed redds (i.e., too shallow to protect eggs adequately).
2. Spawning – The female cleans out all loose gravel and fine sediment in a “pit” in preparation for depositing her eggs within a larger area called a “redd.” She alternately digs at the redd and settles back into the depression to release eggs. The male accompanies her continuously and releases sperm or “milt” over the newly laid eggs, which settle into spaces between the gravel. The result is a series of egg filled pits within the cleaned redd perimeter that takes approximately 5 days and is a period which the fish expend a tremendous amount of energy. Disturbance of fish during this period by boaters could result in improperly constructed egg pockets, open scattering of eggs, or prevent spawning all together.
3. Post-Spawning – The males are no longer attentive while the females remain at the redd for approximately 10 days until the great majority die. The females protect the redds by preventing other fish from digging up their redds and damaging the eggs. Disturbance of fish during this period from boating would result in inadequate post spawning gravel covering and early mortality of females.
Egg to Fry Development
The average female lays around 4000 eggs. The eggs take around 90 to 150 days to develop before emerging from the gravels as fry, usually in late January or February. Egg development time depends primarily on the water temperature. Cooler water slows egg development while warmer water speeds development. While the eggs are in the gravel they are very vulnerable to damage and mortality from the effects of trampling or boat grounding on redds. Many of the redds are located next to the river’s edge and near gravel bars where boaters may enter and exit the river.
You may well say that this paper only relates to America and it has no relevance to Atlantic salmon and sea trout but I doubt this is the case as Atlantic salmon go through the same spawning process without the mortality stage of some females.
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