Unveiling the Secrets of Salmon Migration and Why are Females Easier to Catch!?

I’m writing this on the 27th March for a reason. This is the week where “traditionally”, the first runs of salmon enter most of our rivers in the Northeast of Scotland. I’m not talking about before the 1980s, but since then, this is week the first "real” run of fish come into the river. But what type and size of fish arrive during this week?   

Most 90% of the salmon arriving here on the Spey will be female fish of between 8 and 9lbs in weight, they will have spent 2 winters at sea [SW], and this will be their first time back. There will be some male fish come in at this time, they tend to be 3 SW and weigh anything between 15 and low 20lbs, however, most of them are about elusive as the Loch Ness monster, especially when trying to tempt them with a fly. Using a bait is slightly different.  

Two months later, in late May, more fish will enter the river, again a high percentage will be 2SW females, but the average weight will now be a few pounds heavier. The Male fish are the same, mainly 3SW fish but now weighing 20 – 35lbs.  

When it comes to fishing for salmon any time before mid-June, when the Grilse begin to arrive, 2SW Females are the bread and butter of all our fisheries. They show in the pools, stopping off first in the area they remember when last leaving the river as a smolt. Depending on the number of Juveniles and from which part of the river they originate, this shoaling behavior takes place in a similar part of the river each season, so it's at this time the small fish become “imprinted” with the memory of its natal river.  This is what makes certain beats/parts in every river continually outperform others. Delfur, Rothes and Arndilly on the Spey. Forglen and Netherdale on the Deveron. Park and Crathes on the Dee [Although this has been ruined by flooding and subsequent gravel movement and its influence on this process]. Taymount on the Tay. Sprouston, Henderside and Junction on the Tweed. All those beats do particularly well due to the congregating of smolts during their migration, its why they are so consistent. The remainder of beats on all those rivers fare better only if the run of fish is bigger.  

A 36lb Salmon Caught on Delfur River Spey in May 2010

But what happens to the fish after this initial pausing? What happens after this? Also, what about those big male fish, where do they disappear to and why are they more elusive?  

Tony Black with a huge fish caught on the Tay in what looks like late April or early May

For females, after the initial pause, and this is not because they are tired, the pause takes place for the reason above and if you happen to be there or find yourself fishing in the right area of the pool when they stop, then “Bob’s your uncle”! What’s the right area of the pool? To those of us who know, this is easy and why you fish the pool fast for those early pausing fish. I’ll give you a clue. Not in deep water! Thats all I’m saying! 

What about the bigger male fish. Why is it we never seem to catch so many of those. We catch them as old Crocs at the end of the year in decent numbers, so why not in the Spring? Their colour and condition confirms they have been in fresh water for a similar time to the females, but we catch very few as “fresh” fish.  Why is this the case? Well, the answer to this is both simple and interesting.  

Across the animal kingdom the behavior of males and females are very different, and fish, particularly migratory fish, are no different. Should we be surprised that each would act differently? Of course, we shouldn't, and even more so when they are in breeding part of their lifecycle! No one needs to over think this at all. Female “Atlantic” Salmon tend to keep together in groups and, apart from the feisty ones, the group generally works. Whilst male Atlantic Salmon, particularly the older ones, for the greater good, will tolerate one another, but are much more individuals. When entering the river, they will go into energy save mode and under the cover of darkness, will move slowly upstream before finding their “Summer Hole”! By that I don’t mean anything but a deep part of the river! Older Males know they need to save energy for what happens later in the evening! Interestingly, from time to time, particularly in low warm water conditions, and in the evening, they will have a little cruise out of the Deep pool in the search for some oxygen rich water and at this time they will take a fly. Even when we know it's not right, sometimes we just can't help ourselves! 

What about the small male fish, or Grilse? Do they act any differently? Well, yes is also the short answer. Like most groups of young males, they are happy in one anthers company, until, that is, they find some females and the testosterone kicks in, then all hell breaks out and they’ll fight with their shadow, and in the case of the Atlantic Salmon, he’s vulnerable. Nothing is different in the world of the Atlantic Salmon. Over the past 30 years various groups have conditioned us to think about salmon as being the most complex creature on the planet. In fact, when you begin to think about them simplistically then not only will you catch more, but you will also find you will enjoy Salmon Fishing at a totally different and much higher level.   

Although I could write much more in depth about this subject, I really need to stop. However, one more thing is going through my head. I can totally get why grilse are easy and big salmon predictable in that they are almost impossible, but what is it that makes the feisty female break away from the group and so become easy to catch? I have my own theory!  Fortunately, we now have many more female anglers out there now. I wonder if they could share their thoughts?