Anatomy of a fishing hook

This is a short article about that part of our fishing tackle at the business end of our setup. Most modern hooks a made from wire that is shaped into a hook, with the thickness of the wire being referred to as the gauge of the hook. In some instances a fine wire is used to minimise the weight of the hook, e.g. for dry fly fishing. In other cases a heavier wire is used e.g. if targeting larger fish and there is a risk the wire will straighten. In some cases the hook has been forged, or flattened, to add extra strength. In most cases the hook is coated or finished to prevent rusting.

The size of the hook is expressed with a number which may fall into two ranges. For smaller hooks the number increases as it gets smaller, ranging from #1 through to a size #32 (which is tiny). For larger hooks the number increases with increasing hook size, typically ranging from 1/0 up to 20/0. The /0 scale being called the aught (pronounced ott or oh), with 10/0 being 10 aught. There is little by way of an industry standard when it comes to hook sizes, with some manufacturers claiming the size of the hook is related to the length of the hook without the eye and others the size of the gape or both.

All fishing hooks have an eye, shank, bend and point. Most hooks have a barb. Through time and for a variety of fishing needs there are a wide variety of different hooks out there with variations of each of these features.  

• The eye is used to attach the hook to the line. The spade eye, where the line is snelled around the shank, is common historically with hooks from the roman and earlier periods having eyes of this type. The ring eye is the one you have probably encountered before where the end of the hook shank is bent into a ring that ends flush with the shank. The welded eye is commonly used in salt water fishing while the needle eye is common when fishing for large fish like tuna. The eye can be inline with the shank, turned up or turned down. This apparently does not affect the success of hooking fish. Fly tying on down eyed hooks when you first start tying can be a little more challenging as you tend to crowd the eye and wraps often slip off over the eye, especially while whip finishing.
• The shank of the hook may vary in length depending on the purpose of the hook, short shanks keep the weight of the hook down and long shanks may allow a closer imitation of the prey species. Shanks may be straight or it may have a variety of bends to either keep worms or baits in pace or shape the hook for specific reasons e.g. for a klinkhammer fly which sits in the surface film. Some shanks have small barbs which are designed to keep worms or other baits in place and prevent them from sliding.

• The bend is often a defining feature of the hook and results in a number of different hook types that you will see, e.g. J-hooks, limerick, kahle, sproat or circle amongst many. The bend defines the gape of the hook, being the size of the opening between the hook point and the shank. It also defines the throat of the hook being the size of the hook between the point and the lowest portion of the bend. All of these factors affect the success of the fish hooking process and depends on the target fish species, the kind of bait you are using, the size of the target fish and their mouth shape and hardness. If the hook shape and size isn’t right you end up missing or dropping lots of fish. There is a fair amount of scientific evidence to suggest that circle hooks have a higher hookup rate and cause less damage.
• The point is designed to facilitate piercing the lip or mouth of the fish to secure it during the hooking process and consequently there are a range of different types/shapes like spear or needle. The knife point is often used for game fish with hard mouths like tuna. Many hooks are laser or chemically sharpened and there is no need to sharpen them on first use. However, they may become dulled through catching of fish or bumping against rocks, the river bed or even the boat. The point can be offset from the orientation of the shank of the hook. If offset to the right then this is said to be kirbed and if offset to the left this is reversed. I have found that offsetting, especially smaller hooks, leads to more hookups.
• The barb is designed to stop the fish from slipping off of the hook once caught. With the advent of catch and release fishing the barb is either flattened or removed or a barbless hook is used. I only fish with no barb as I release the vast majority of the fish I catch. This makes the whole process quicker, reduces stress and damage to the fish all of which increases survival rates of released fish. In most cases provided you manage the tension on the line carefully the fish will remain on the hook until it reaches the net. In 5 out of 10 landings, I don’t even have to remove the hook as it comes out once the fish is in the net.

The X-factor is another code that the industry use to designate variations in hook features. Heavier gauge hooks are often described as 2X or 3X, denoting a hook gauge that is heavier for the same hook size. In other instances the 2X is used to describe a shank that is longer or a gape that is wider.

Tight Lines

Greg