As salmon anglers, we all hate losing fish. It is often hard enough to get a take, so losing a fish inevitably feels like a lost opportunity. Tackle companies are constantly developing different hook designs and trying to capture us with catchy phrases like “chemically sharpened” and “cutting point.” Nowadays, there are many different styles of hooks, especially if you are using tube flies. Ten years ago, most anglers would use a treble hook when fishing with a tube. However, times have changed and now more people prefer to use doubles or even in some cases single hooks. On certain rivers and beats the use of treble hooks have been banned as it can often be more challenging to remove a treble hook, especially if the fish has been deeply hooked. As catch and release is being practiced more widely, this, combined with using barbless hooks, makes perfect sense. What if, though, there are no restrictions on the type of hook you can use when fly fishing on a beat? In such circumstances, which style of hook, the single, double, or treble, provides the most secure hook hold when coupled with a tube and fly? 
Single irons were traditionally the hooks; salmon flies were tied on. You can still see some wonderful old photographs in fishing books of stunning flies like the Jock Scott and the Silver Doctor tied on these types of hooks. This was, of course, before doubles and subsequent treble hooks were devised. When it comes to tube flies, using single hooks is a relatively new concept. More and more anglers are now using single hooks in combination with a tube fly, even when there are no hook restrictions on the beat they are fishing on. I have several good friends who are ghillies on various rivers across Scotland. They now swear by using single hooks in combination with tube flies. They believe they have lost fewer fish since converting to singles from doubles or trebles. 
Considering the physical forces applied on the hook when playing a salmon, you can understand why using a single might be the best option. If a fish is hooked on a single, then all the pressure or force going through the hook is through one point. This gives you one very secure hook hold. If, however, you decide to use a double or treble hook, the same pressure is spread over two or three points, resulting in either two or three weaker hook holds. The other obvious advantage of using a single hook with a tube fly is that it usually causes much less damage to the fish, especially if the fly has been swallowed. Removing a single hook from a fish can be much easier compared to a double or treble. When you consider the physical forces imparted on the hook when playing a fish, there is a compelling argument for using a single hook with a tube fly.
Nowadays, double hooks are the most commonly used hook when fishing with a tube fly. These have replaced the traditional treble that has been preferred for decades. Indeed, double hooks are now becoming so popular that certain hook manufacturers have stopped making treble hooks. Again, this is because nowadays, we are all becoming more conservation-minded. I have found that double hooks work well with tube flies, and I have landed several fish on them. Having said that, I have also lost my fair share. I would say I have lost more fish when using a double hook than a treble, but this may be a coincidence. 
In certain circumstances, a double hook is preferred to a single. If, for example, you are fishing with a fly with a long wing like a Sunray Shadow or a Monkey, the wing has a propensity to get caught around the three points of a treble hook. This is not the case when using a single or a double. Therefore, I always use a single or a double hook when fishing with a Sunray Shadow or any other tube fly with a long wing.
The treble hook has been used with the tube fly for years. Indeed, before anglers became conservation-minded, the treble hook was always used with a tube fly. Partly this was because the Waddington fly which is similar in size and design to a tube always had a treble hook attached. In the past, I always used treble hooks when fishing with a tube fly. I have landed and lost my fair share of fish on them. One disadvantage of using the treble hook was on the rare occasion that the salmon was deeply hooked, the hook could be challenging to remove while trying not to injure the fish. 
If, however, you take into account the pressure when using a treble hook is spread over three points compared to one (when using a single hook), you would think, if anything, the treble hook would provide the weaker hook hold. Many older generations prefer to use trebles and will continue to use nothing else when fishing with a tube fly. 
When using tube flies, it is impossible to say which hook type provides the most secure hook hold. For years, we have used treble hooks and thought nothing more of it, but as we now have more options when it comes to hooks, we often wonder what hook we should be using. It is not so much about whether the hook is a single, double or treble but more about the take itself. If the fish aggressively takes the fly, then it is more likely that you will establish a secure hook hold, regardless of the hook type. Unfortunately, as anglers, we cannot control how the fish will take the fly. The most important thing is to use a hook that you have confidence in and believe is a good hooker. Nothing is worse than playing a salmon, considering you may lose it during the fight because you chose the wrong hook type. Ultimately, you can do everything in textbook fashion during the fight but still lose the fish, as so much depends on the take. I suppose the old adage is quite fitting when it comes to hooking a salmon: “If the fish is hooked, it hooked!”