The Job of the Crocodile!

The Spawning Ordeal and the Death of River Abundance.

The spawning run is, without question, a sacrificial rite. The prevailing understanding is that for most, it is a final act. However, the data I have accrued through decades of hands-on experience suggests a crucial part of the equation often overlooked; namely, population density. 

The number of salmon that survive the spawning ordeal and make it back to the sea is not a static figure; it is a dynamic indicator of the health and abundance of the run itself. 

A 17 Pound Cock Fish will die after spawning

When Abundance Reigned (e.g., The Spey in the Mid-80s): In times when the river was "properly stocked" and when runs exceeding 100,000 fish, the survival rate of the parent fish was crushingly low. As many as 90% of female salmon perished and for males, a staggering 99.9% died. 

In these years of plenty, the sacrificial role of the parent fish—to die, rot, and feed the next generation—was fulfilled completely. The river, teeming with life, and could absorb this enormous biological contribution. However, when Numbers Collapse (e.g., Drought Years like 2018)! In years where the run is pitifully small, perhaps less than 10,000 fish, the fish themselves appear to "know" a higher survival rate is necessary to keep the species viable, so they adapt! Female survival drastically shifts, with possibly 30% or even more, females successfully making it back to the ocean to run the gauntlet another time. In the past, with less seal and Dolphin predation, those important Multi Spawners will have made up between 4 and 7% of the following years spawning fish. Now this is 0.1 at best!   

What does the above tell us? In every part of its lifecycle, without abundance, the species struggles. The ecosystem, running on a minimal calorie budget, cannot afford to lose as many breeders as it has over the past number of years. They push for survival because the critical mass for self-sustainability has been lost. 

Abundance Feeds Abundance 

The deeply held notion, a concept mirrored in the traditions of Native or "First Nation" people—who ceremonially return the first salmon to the river—is that the parent fish must die to feed the next generation. 

Survivors are known as "kelts, however, the decomposing bodies of dead spawned-out salmon, " are the vital nutrient supply for the river. They are the protein, the fat, and the essential minerals that dramatically boost the food chain. 

 The idea that a river's capacity is fixed and can only hold a certain number of fish—the "maximum carrying capacity" mantra pushed by some modern managers—is utterly ludicrous. The output of any river is fundamentally dictated by its food supply, not some arbitrary density formula, but this made for great reading for those who were interested, but simply didn't know. A succession of Fishery Board Chairmen were perfect examples of this.   

Abundance in adults creates abundance in juveniles. The correlation is simple, observable, and confirmed by those who have spent their lives on the riverbanks. 

Myself with Sandy Smith, Sandy Milne. We spent our whole life working on and observing the river.

The Failure of Modern Management 

My memory of burying 50 to 100 dead salmon daily in the 80s speaks to an abundance that modern fishery biologists, most of whom at that time were then in primary school, simply failed to grasp. Their perception of a "healthy" river was formed after the crash, resulting in a distorted, diminished baseline. 

The catastrophic error lies in the scientific insistence that a small number of adults is "enough" to produce a viable number of juveniles. This misguided faith in "just enough," over the reality of "abundance," has been a monumental failure for the species. Density Dependence is related to food and, in this instance, food is related to adult numbers and size of floods.

Wrapped up in their own egos and relying on abstract formulas such as the Zippin, back in the 90s, these individuals produced very well written but flawed documents, dismissing the real-world, ground-level observations of the ghillies and river keepers. At this time they claimed rivers “had enough” and operating at "maximum carrying capacity" when, in fact, what was obvious to the experienced trained eye, the system was starving. 

In a scramble to correct this profound failure, modern fishery managers have used methods such as trying to artificially fertilise the River Dee's burns with deer carcasses, a desperate measure taken far too late. The damage was done, the burn in question was now down to two adults. Its sad, that it was ever left to go this far.  

The evidence presented by decades of direct, on-the-water observation is clear - Atlantic salmon is a species built on the principle of over-abundance. Any management strategy that ignores this fundamental truth—and the vital, visceral role of the dead fish in feeding the river's output, has been, and is a dereliction of duty and a direct cause of the current crisis. The simplistic "maximum carrying capacity" dogma deserves to be trashed, and those who championed it should be held accountable for confusing and failing a generation of fishery management. 

And if you think this is bad, don’t get me started on Population Dynamics in the Ocean!!!