Migratory Fish: the why and wherefore

A fine brown trout struggling against the odds: (2009)

This excellent photo provided by Hilary captures a good size trout jumping in vain at a barrier on the Brit river system:

Hilary's trout:

Even non-migratory brown trout need to negotiate obstacles to reach their spawning grounds. This one is estimated to be 1.5 to 2 lbs.

Here's a real sea-trout! (2008)

Regular visitors to this site may have been excused for wondering what all the fuss is about (especially non-fishermen).

Wonder no more! This is what it is all about! Keen fishers Clifford & Winnie have provided the evidence. Firstly, a mammoth 13-14lb sea-trout lifted from the Brit between West Bay and Palmers by Clifford (and put back again):

Update 8th Oct 2012:

It is with regret that we have to report that Clifford Tattershall sadly passed away on 19th August 2012. He will be sorely missed.

Clifford's prize sea-trout:

This outstanding cock fish rivals the best caught in prime locations like the River Towie in Wales, where the largest caught this year was 17lbs. Winnie estimates that it may have been in the river for 2-4 weeks judging from the reduced silvery colouring. Could this be evidence of difficulty moving upstream? Maybe not because it was caught in August, slightly earlier than the main migration period in September/October.

The following beautiful sea-trout, caught by Winnie, is smaller at 5.5lbs, but has the striking silvery skin which indicates it is fresh in from the sea:

Winnie's runner-up:

This fish, too, was put back. So here is ample proof that there are healthy sea-trout lining up to migrate up the Brit river systems, but probably frustrated in their attempts by all the man-made obstacles before them. Many thanks to Winnie and Clifford for providing the photos.

Migratory fish continued:

The best known migratory fish are the salmon family which include salmon, sea trout and native brown trout. They all seek gravel, well oxygenated and in clean water. These gravels called redds are usually found towards the higher reaches of a river. Any gravels in the lower reaches tend to silt up.

Although some migrate in autumn, most Atlantic salmon begin their spawning migration in the spring. Spawning takes place in October or November with the females seeking out a gravel stream bottom to build her redd (nest). Eggs fertilized by the male's milt develop over the winter and hatch in the early spring. After spawning, the kelts (adults) either swim back to the ocean or stay in the river until spring. Newly hatched alevins remain in the gravel redd until May or June.

As they feed and grow, they develop from fry to fingerlings (three to four inches long) to parr (four to five inches long). The parr, known for their vertical striped bars, spend one to two years feeding and growing in fresh water while their bodies change to prepare them for life at sea. When the parr lose their vertical bars and turn silver, they are called smolts and are ready to head downstream to the ocean. Once there, they swim to feeding grounds off the coasts of Canada and Greenland. After one to two years in the ocean, they return to the rivers of their birth to spawn. Unlike sea lampreys, Atlantic salmon do not die when spawning is completed.

In passing down stream the smolts release a pheromone(scent) which the mature fish sense and this leads them back to the breeding grounds. The fish always seek the fastest running water as this gives the best chance of getting to the upper reaches.

Salmon do not feed when they reach fresh water, their fat is sufficient to sustain them to the breeding ground. This has evolved because by this means they overcome the need to feed in the rivers, where the food they would need to keep going, is inadequate.

See Links page to connect to the US Fish & Wildlife Service for many more Fish Facts