The Miramichi's Salmon Supremacy
How has the Miramichi, one of the world's greatest Atlantic salmon rivers, been affected by the recent decline in spawning Atlantic salmon? The answer is a relative one: while the number of salmon returning to the Miramichi to spawn in recent years has dropped significantly from historical highs, the river continues to be the largest producer of Atlantic salmon in North America. Recent runs (within the past decade) have ranged from 40,000 to 160,000 salmon, impressive numbers compared to the total of 35,000 salmon that returned to all of Iceland's salmon waters in 1995, or the 30,0000-strong run that marked the much-heralded resurgence of Newfoundland's Exploits River salmon population in the late 1990's.

In 2002, a total of almost 50,000 salmon returned to the Northwest and Southwest Miramichi river systems, a striking contrast to New Brunswick's other major river, the St. John, where salmon returns were negligible. Even in reduced numbers, Miramichi salmon runs are several times greater than those of most other rivers in the world, and for sports fishers, the Miramichi continues to reign supreme as one of the world's top Atlantic salmon fly-fishing destinations.

On the other hand, the Miramichi's comparatively high annual salmon numbers are much lower than the 600,000-strong runs of the late 1960's, or the estimated million-plus counts of the 1930's, when commercial salmon fishing was still a factor and sports angling regulations were less restrictive. And they fall far short of the 300,000 - 400,000 figure that fisheries biologists say the river can support. While there were 60% more "smolts" (young freshwater salmon making the physiological transition to salt water salmon) in the river in 2002 than in 2001 (translating to 1 -2 smolts per 100 square metres), the river system was still short of meeting its smolt production target of 3 smolts/100 square metres of area.

While researchers focus their attention on the reasons for the Miramichi's population decline - paying particular attention to smolt survival in both freshwater and marine environments - river managers continue to stress the fundamental integrity of the Miramichi as a one of the world's best Atlantic salmon producers. Among the reasons for its salmon strength:

• Comprehensive Habitat: The Miramichi River system is large, complex and highly diversified. Like a vast riparian web, it consists not only of the Northwest Miramichi, the Main Southwest Miracmichi, the Little Southwest Miramichi and the main stem of the Miramichi, but also more than 2 dozen tributaries, and hundreds of streams, brooks and fingers of water that satisfy every habitat requirement of every stage of salmon spawning and development. The Miramichi system serves as a gigantic salmon incubator, offering over 1,000 kilometres of spawning habitat covering 60,000,000 square metres of area.

• No Obstructions: Unlike the St. John River to the west, the Miramichi has not been obstructed by dams. Many of its salmon-spawning tributaries and channels in the heart of New Brunswick are virtually uninhabited.

• A Tradition of Stewardship: Much of the Miramichi's river system is owned or leased by those who have a vested interest in maintaining the integrity of the aquatic environment. In fact, almost 45% of the river's watershed is privately owned, and a further 7.2% is leased from the Province of New Brunswick. A complex system of riparian rights has evolved from traditions associated with Scotland's freshwater fishery. It includes outright ownership, government-regulated 10-year leases, Crown-operated water and Crown Reserve water (with sports angling offered through a lottery system) and Crown-closed water, and has resulted in closely-monitored sports angling and intensive management. Long stretches of the Miramichi system are owned and managed by major New Brunswick forestry companies and by private guiding and outfitting operations that depend on a healthy salmon population for their livelihoods. Even Miramichi leases come with a strict requirement to provide 24-hour-a-day wardens and to keep the riverbank clean. In addition to these management incentives, the Miramichi has a number of river stewardship groups, including the Miramichi Salmon Association (representing riparian owners) and the Miramichi Watershed Association, an umbrella group that includes riparian owners, First Nations, outfitters and guides, forestry companies, and other related river associations.

• No Commercial Fishing: The commercial salmon net fishery was cut back in the early 1970's, and eliminated in 1984. In addition, sports anglers were limited to keeping only grilse, or small salmon; large salmon - mostly females - must be released alive.

• Genetic Diversity - Each component of the Miramichi system has genetically distinct runs of salmon that enter the river almost every day from May to November; larger waterways have several separate salmon runs.

The Mystery of the Salmon Smolts
Why are so many smolts not returning to their rivers as mature adults? Atlantic Canada researchers are conducting long-term studies to find out; the results of their investigation are likely to be of interest to all those concerned about declining Atlantic salmon runs. (In North America, the number of large salmon returning to their native rivers has dropped by 90% in the past 25 years; in 2002, 50% of the rivers monitored by Fisheries and Oceans Canada failed to meet their minimum spawning targets. Many Canadian rivers that experienced an 8% - 10% smolt survival rate a decade ago are now experiencing survival rates of 1% - 2%.)

In the past, a healthy population of juvenile salmon, or "smolts" in a salmon-producing river was a reliable predictor of a similarly healthy population of "grilse" (single-sea-winter) or "salmon" (multi-sea-winter) returning to spawn in following years. But in recent years, while smolt populations in many rivers - including the Miramichi - have remained high, numbers of returning salmon have declined.

Researchers are studying several possible reasons for smolt mortality, including:
--Inadequate food supply in both the freshwater and marine environments.
--Over-predation by animals such as seals and cormorants.
--Negative impacts of aquaculture.
--Loss of fish in the by-catch (accidental catch) of other fisheries.
--Temperature changes, water level fluctuations, and other variable water conditions.
--Effects of pollution, including estrogen-mimicking nonylphenols that may disrupt the hormonal-based changes that allow the smolts to adapt to salt water. Nonylphenols are surfactants used in a wide range of products, including insecticides used on New Brunswick forests, dishwashing detergents, cosmetics, plastics and spermicides. Researchers have observed that smolts exposed to excessive levels of nonylphenols fail to thrive when they enter salt water; early indications are that the pollutant affects their pituitary glands, causing salt to accumulate in their bloodstreams.

Smolt Tracking on the Miramichi
In an effort to find out how many smolts there are in the Miramichi, how many are migrating to the ocean, and where smolt mortality is occurring (in the river or the ocean), researchers are using a variety of counting and tracking techniques to mark, release and recapture the juvenile fish. They include:

Smolt Wheels - With the appearance of a cement-mixer drum, the smolt wheel, or rotary screw fish trap, is designed to capture fish and release them back to the river. The device floats between the pontoons of a catamaran, which is tethered to a cable strung high above the water. The drum's wide end faces upstream into the current, at a depth of about 1 metre (the depth at which most smolts travel downstream). As water strikes the drum, the wheel rotates, forcing fish into a series of water pockets within the drum. The salmon are lifted into a live well to be counted and tagged before being placed back in the river.

Sonic Tagging - Juvenile salmon in Miramichi tributaries are captured, equipped with surgically-implanted sonic tags and released. Their movements are tracked by means of a recording device.

Counting Fences and Electro-fishing - Fences are installed to catch fish returning to the river to spawn. A low voltage shock immobilizes the fish long enough for researchers to scoop them out and count them.

Pesticides, Preservatives and Pulp and Paper Pollutants

While much of the Miramichi River system of the sparsely-populated New Brunswick interior has remained free of industrial and urban development, it has been subject to decades of aerial pesticide spraying. From 1952 - 1967, New Brunswick's forests and waterways were sprayed with DDT in an early effort to control spruce budworm infestations. In 1968, the DDT aerial program was replaced with an organophosphate-based spray, and between 1975 - 1985, carbamate pesticides were added to the applications. Recent research has focused on the long-term effects of New Brunswick's aggressive aerial spraying programs on Miramichi salmon populations, with particular attention to the endocrine-disrupting effects of solvents used in the pesticides.

The effects of pulp and paper chlorine bleaching processes, a creosote-based wood preservative plant, an effluent-producing groundwood mill, and a wafer board and plywood manufacturing operation in the lower reaches and estuary of the Miramichi (in the Miramichi City communities of Newcastle, Chatham and Nelson) are also being studied. A 1992 report of the Miramichi River Environmental Assessment Committee identified an extensive list of pollutants - including DDT, PCB's, dioxins and furans - in the river's water, sediment and aquatic organisms.