This is a panorama shot of the St. Mary river consisting of about 8 images merged into one.
The St. Mary’s River in Nova Scotia was a delight I discovered about 10 to 15 years ago. I was surprised by the beauty. So today I was not surprised. I was confirmed in my high expectations. This is an area of simple, yet great, beauty. After all, it’s a river in a forest. What can be special about that?
The St. Mary’s River runs for about 250 km. (160 mi.) and drains an area of approximately 1,350 sq. km. it has 4 branches with 130 lakes. The river was named Rivère Isle Verte by one Canada’s premier explorers, Samuel de Champlain. A fort in the area was also called Fort Sainte Marie when the French built it in the 17th century, but it was later taken over the English who changed the name of the fort and the river to English versions of the old French names. Sort of like Donald Trump who wants to change the name of the Gulf of Mexico to Gulf of America. Little minds do things like that.
The river is one of the many east coast rivers that contain the extremely interesting northern Atlantic Salmon (Salmo salar) species. This is the 3rd largest of the members of Salmonidae family behind the Pacific Chinook and Siberian taimen salmons. Sadly, it is now an endangered species. Most populations of salmon of are anadromous, meaning that they return up river to spawn where the offspring hatch in natal streams and rivers but move out to the oceans when they grow older and mature. The adults then move seasonally upstream again to spawn.
But interestingly some populations only migrate to lakes and become “landlocked” and spend all of their lives in freshwater. So iot is not true that they must return to salt water. Some of them just choose to do so. When the mature fish return to rivers and streams they change colour and appearance.
Unlike the Pacific salmon species, the Atlantic salmon can survive spawning and return to the sea to repeat the process again in another year. About 5-10% of them do exactly that, returning to the sea to spawn again. Such individuals grow to extremely large size.
The life stages of Atlantic salmon are the following: alevin, fry, parr and smolt. The first stage is the alevin stage when the fish stay in their breeding grounds and use the nutrients from their yolk sac. During this stage their gills develop and they become hunters. The next stage is called fry, where the grow and then leave their breeding ground looking for foodk so they move where more food is available. During this stage in freshwater they develop into parr where they start preparing for their trek to salt water.
Young salmon spend from 1 to 4 years in their natal rivers and when they are large enough they smoltify, which means their skins change colours from colours adapted to streams to colours adapted to the oceans. They also are subjected to endocrinological changes to adapt to the differences in fresh water to ocean water. When smoltification is finished, the young fish (parr) learn to swim with the current instead of against it. That behavioral change allows the fish to follow ocean currents and find prey such as plankton or fry from other species of fish such as herring. Apparently during their time at sea they can sense changes in the Earth’s magnetic fields. Nature never ceases to astound
After a year of strong growth, they will move to those sea surface currents that lead the fish back to their natal rivers. It is believed by some scientists that they use their sense of smell to detect the “right” rivers as well. They don’t move thousands of kilometres as many have suggested, instead scientists have learned that they “surf” through sea currents. Only 5% of the salmon go up the “wrong” river. As a result, it is more likely that they stay close to the rivers where they were born when they are out to sea and swim in circular paths to do that.
Atlantic salmon have been severely affected by humans as a result of heavy recreational and commercial fishing as well as habitat destruction, all of which have affected their numbers. As a result serious efforts have been made to conserve including aquacultural methods, though those have also been criticized by environmentalists. 50% of farmed Atlantic salmon now come from Norway where the aquaculture has been most effective.
The natural breeding grounds of the Atlantic salmon are rivers in Europe and northeastern coast of North America in both the United States and Canada. In Europe they can be found as far south as Spain and as far north as Russia. Sport-fishing in Europe has been so popular that some of the species in Europe southern populations have been growing smaller. The distribution of Atlantic salmon is strongly influenced by changes in freshwater habitat and climate, particularly changes in water temperatures, which of course are affected by climate change.
When the salmon leave their natal streams they experience very fast growth during the 1 to 4 years that they live in the ocean. In the ocean they must face an ocean of predators including seals, Greenland sharks, skate, cod, halibut, and of course humans. Dolphins have been seen “playing” with salmon but it is not clear that they eat them.
Once the salmon are large enough to undergo the tough track back upstream to their natal streams, the stop eating entirely prior to spawning. It is believed by some scientists that odour allows them to sense when they are again in their natal streams.
You will not be surprised to learn that Atlantic salmon populations were significantly reduced in the United States and Canada after European settlement. Rivers were degraded by the activities of humans in the fur trade, timber harvesting, logging mills and the spread of modern agriculture. As a result, the carrying capacity of most North American rivers and streams was also degraded as the fish habitat declined. The historian D.W. Dunfield claimed in 1985 already that “over half of the historical Atlantic salmon runs had been lost in North America by 1850.” In Canada a bill was presented to the Canadian Parliament that called for the protection of salmon in Lake Ontario. In the Gulf region of Nova Scotia where we have been travelling 31 of 35 salmon streams and rivers were blocked off by lumber dams and as a result many watersheds lost all of their salmon.
Where humans come damage often follows. Then when damage occurs humans learn to regret the error of their ways and sometimes make heroic efforts at great cost to change things back to the way they were. Could there be a better way?
Despite all of that such rivers are flanked by the incredible variety of trees of the eastern forest as shown by the incredible variety of the autumn colours.
