Water / Eau



Où vont les saumoneaux du saumon sauvage de l'Atlantique ?

Le cycle de vie complexe du saumon de l'Atlantique et sa sensibilité aux changements environnementaux le rendent d'autant plus vulnérable aux tribulations de la vie moderne.

De nos jours, malheureusement, le saumon de l'Atlantique doit encore surmonter plusieurs des mêmes obstacles qui menaçaient ses ancêtres 3 siècles auparavant, y compris les rivières endiguées, la surpêche, les effluents industriels, ainsi que des multitudes de nouveaux problèmes reliés aux habitats en eau douce et en eau salée. 

En collaboration avec le Conseil provincial du Nouveau-Brunswick de la Fédération du saumon de l'Atlantique et la Miramichi Salmon Association, des chercheurs sont en train d'identifier les facteurs qui mènent à la disparition des saumoneaux du saumon de l'Atlantique (que rencontre-t-il où et quand). Cette recherche conjointe de haute technicité effectuée dans la Miramichi est l'une des plus importantes recherches sur le saumon à travers le monde.

Déterminer les causes de la mortalité croissante en haute mer est donc d'une importance capitale si l'on veut développer des plans de conservation efficaces pour ramener les populations du saumon sauvage de l'Atlantique à des niveaux appropriés.

 

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Dr. Fred Whorisky, ASF’s Vice President - Research and Environment, prepares to dive beneath the water to position a receiver unit in Falls Brook on the SW Miramichi River
(photo: ASF)

 

Where Do Wild Atlantic
Salmon Smolts Go?


Muriel Ferguson
Atlantic Salmon Federation
October 21, 2002

he wild Atlantic salmon has fascinated and inspired humans since the earliest of times. Their images were the subject of art drawn more than 25 000 years ago on the walls of caves in France. Common and prolific, the Atlantic salmon provided food, income, and pleasure for many North Atlantic countries, including colonial New England and Eastern Canada. Beginning in the 1700s, however, the pressures of dammed rivers, over-fishing, and industrial waste began to take their toll and this noble creature began disappearing from across much of its historic range. Unfortunately, today’s Atlantic salmon still struggle to overcome many of the same threats their ancestors faced 300 years ago, as well as a multitude of new problems in both their fresh and saltwater habitats.


(photo: ASF)

Researchers work on a smolt wheel in Rocky Brook
where it enters the SW Miramichi River to live
capture salmon presmolt and parr for research


The Atlantic salmon’s complex life cycle and its sensitivity to environmental change make it all the more vulnerable to the tribulations of modern life. It begins life in the gravel of a river or stream as a tiny orange egg in the fall to emerge as a 2 cm long alevin the following spring. Its fragile system must then contend with the stresses of the river, including fluctuating temperatures, an array of predators, pollution, disease, parasites, and an uncertain food supply. Most do not survive this early stage. Those that do remain in the river for another two to six years, depending on water temperatures and availability of food. 

When juvenile salmon reach between 10 and 24 cm in length, they experience a remarkable transformation, usually in the spring, known as smoltification. Their bodies change, inside and out, in preparation for their entry into salt water, where they may spend years before embarking on a treacherous 4000 km ocean voyage to return to their home rivers to spawn. Researchers believe that the early part of ocean life is especially hazardous for salmon smolts. In recent years, despite the elimination of commercial salmon fishing in North America’s coastal waters, thousands of salmon smolt leave New Brunswick’s rivers each year and just disappear. The Atlantic Salmon Federation (ASF) is very concerned about what happens to these smolts during their first and, in many cases, only migration and has been conducting research to track them as they leave the river and enter the ocean.  


(photo: ASF)

Dr. Whoriskey and Blake Munn of Bowater drill holes through ice, ranging from 30 cm to 125 cm deep, on the Miramichi River. The ladder is used as a safety precaution. When standing on it, their weight is distributed over a larger area of ice surface, lessening the stress on the ice directly beneath them. After drilling, the holes are enlarged to a size that will allow a diver to descend into the water to retrieve receiver units containing data.


Using state-of-the-art ocean-tracking equipment, ASF has tracked salmon smolt into the Bay of Fundy and, more recently, began tracking them in the Miramichi River in cooperation with the New Brunswick Council – Atlantic Salmon Federation, Inc. and the Miramichi Salmon Association.  These researchers are attempting to identify where, when, and what the wild disappearing Atlantic salmon smolts encounter.

This highly sophisticated, joint research on the Miramichi is among the most valuable salmon research being conducted anywhere in the world today.  Determining the causes of their increased mortality at sea is crucial to developing effective conservation plans to return wild Atlantic salmon populations to healthy numbers.

As part of this intensive research, we are monitoring smolt movements from the Miramichi’s tributaries to the main river in the fall and from the main river to the ocean in the spring to determine why some salmon parr begin the transition to smolthood in the fall instead of the spring of the year they migrate to sea.  Researchers need to establish how important the presmolt’s autumn movement may be to the species’ overall survival. Two current theories are (1) this is an adaptive movement to position smolts closer to the ocean, improving their odds of reaching the ocean during the narrow window of optimal conditions in spring and (2) the fish have simply outgrown their habitat and must find other suitable habitat to spend the winter.  Smolt inventories and assessments, focusing on smolt production and distribution, from which researchers will be able to develop migration statistics, are also being conducted.


(photo: ASF)

Gino Doucet, 
ASF researcher,
downloads data
from a receiver unit
that was placed in
the Miramichi River
to track the
movements of wild
Atlantic salmon
presmolt and
precocious parr
over the winter
months


Results from this research could have important implications for many other salmon rivers. By following autumn presmolts in the Miramichi, a river which has been unaffected by dams, researchers can develop a profile of their normal movements in an open river. This information will help with the development of corrective strategies for other rivers, such as the St. John, which has a significant autumn run of presmolts. These fish frequently stop in the head ponds of dams and it is unclear if this is a deviation from normal behaviour, caused by the altered habitat, or if it is a normal resting strategy.

The long-term agreement to eliminate Greenland's commercial salmon fishery reached this summer, our in-river conservation and restoration work and public education programs, combined with this expensive but essential exploration of salmon mortality at sea, will, hopefully, soon have a positive impact on our rivers and our prized wild Atlantic salmon populations.


(photo: ASF)

Biologists measure and count salmon
presmolt and parr collected in a smolt
wheel on Rocky Brook.  Researchers surgically
implanted many of these juvenile salmon
with acoustic tracking devices before
returning them to the water.
Their movements were then recorded
on receiver units, strategically placed
throughout the river


Although threatened, endangered, and, in many river systems, already extinct, the wild Atlantic salmon continues to capture our hearts and imaginations as it struggles valiantly against great odds to survive in the precarious conditions of its river and ocean environments.  For that reason, we must do whatever we can to preserve and restore this majestic fish, not only for its sake, but also for ours.

ASF greatly acknowledges the contributions to this research being made by International Paper, Bowater, J.D. Irving Limited, Fisheries and Oceans Canada, and the Norcross, Molson, Donner, and Turner Foundations.

 

ASF - Take a Giant Leap for NB Rivers! Click here!For more information on the wild Atlantic salmon, ASF’s ongoing efforts to conserve and restore this valuable creature, or how you can help, please visit our web site www.asf.ca or call us at 1.800.565.5666.