1. Can a Straight Piece of Metal Catch a Fish, and Why Is It Not Used?
The writer of one outdoor magazine article explains how a straight hook is thought to work. A fish sucks the bait in, and the whole straight hook goes into its mouth. When one end pricks the flesh, the other end swings around and wedges across the mouth [1]. The same article says the writer has not tried it, and warns that such a hook is probably very hard to remove and probably hurts the fish a lot. It is not suited to fishing where the fish is released.
The idea is old. Wikipedia describes a prehistoric tool called a gorge, a double-pointed stick tied to a line at the middle, which turns sideways in a fish's throat in the same way [2]. (That passage is not backed by a cited source on the page, so treat it as a general background statement.)
A bent hook with a barb can be read as a way of building this "catch and hold" job into the hook itself, so it does not depend on how the fish happens to swallow. That is my own way of putting it, not a claim from a single source. What is stated plainly in the sources is what the barb does: it is a small spike pointing backward that grips the surrounding flesh and stops the hook from sliding out [2].
2. What Are the Parts of a Hook Called?
Hooks in English-speaking countries are usually described with these parts: the eye (the loop where the line is tied), the shank (the straight section), the bend (where it curves back), the point (the sharp tip), and the barb [2]. The opening between the point and the shank is called the gap. A Japanese fishing magazine uses a matching set of Japanese words for bait hooks, and says the "gap" corresponds to what Japanese anglers call futokoro, literally the "chest pocket" or "bosom" of the hook, which is the space below an imaginary line from the point to the shank [3].
Many Japanese bait hooks also have no eye at all. Instead the end of the shank is hammered flat, and that flat part is called the tataki, from a word meaning "to pound" [3]. Section 5 returns to it. First, the part that has been tested most: the barb.
3. Does a Barb Really Help Catch More Fish, and What Does It Cost?
A study in the Gulf of Mexico near St. Petersburg, Florida, compared barbed and barbless hooks directly. Anglers fished with natural bait, using a barbed hook for half of the day and a barbless hook for the other half. The researchers recorded catches, lost bait, where each hook landed, how badly fish were hurt, and how long it took to take the hook out [4].
The results were mixed. Anglers landed 22% more fish with barbed hooks, which means about 122 fish for every 100 caught on barbless hooks. More hooked fish were lost with barbless hooks. On the other side, taking out a barbless hook was faster, and barbless hooks reduced injuries during unhooking. Bleeding was about the same either way, because it depended mostly on where in the mouth the hook went. Overall the authors concluded that in this fishery barbless hooks "probably did not reduce hooking mortality" and gave only slight benefits at the cost of smaller catches [4].
One study at one place does not settle the matter. The authors themselves note that the effect appeared to differ among species, and I could read only the published abstract, not the full paper. So the safest reading is not "barbs are good" or "barbs are bad," but "a barb trades easier removal for a better grip." The study does not say which choice is right for every angler. It only shows that each choice has a price.
4. Does a Wider Gap Hold a Fish Better?
The gap is another thing hook makers adjust. In a guide to hooks for ayu (a river fish popular in Japan), the writer says that the angle of the point and the width of the gap both matter, and that a wider gap is said to make the fish less likely to come off [1]. The same guide says a point that curves slightly inward is harder to set than a straight point, but once it is in, it is harder for the fish to shake off.
These are the opinions of an experienced angler, not measurements, and I did not find a controlled test of gap width. It is better read as a rule of thumb that people argue about than as a law. Even so, it fits the pattern you have seen so far: a shape that sets easily and one that holds firmly are often not the same shape.
5. Why Do Many Japanese Hooks End in a Flat Plate Instead of a Loop?
In Europe and North America, the eye (a ring) is the common way to tie on the line. In Japan, bait hooks very often use the flattened tataki instead. A magazine from a Japanese angling publisher, based on a book prepared with the hook maker Gamakatsu, lists the trade-offs [5]:
- A flattened end is lighter and more compact, so it gives the fish less of a strange feeling when it takes the bait. But the line is harder to tie on well, and a loose knot can slip off.
- An eye makes it easier to tie, even with thick line, and the line is less likely to slip off. But it takes more wire, so the same hook gets heavier and larger.
The flat part is made by hammering the end of the wire. The wider it is, the better it holds the line, but the thinner it becomes, so the weaker it gets. The usual width is about twice the thickness of the shank. The flat end is also bent slightly outward from the shank, because if it were perfectly straight, the line could rub against it and break when a fish pulls [5]. Again the pattern repeats: holding the line better and staying strong pull in opposite directions.
The same magazine says flattened-end hooks are not only Japanese. They are also used in China and Europe, and one explanation it gives is that Japanese hooks became popular abroad after being exported [5]. That is only one explanation offered by the magazine, and I could not check it independently.
6. How Old Is the Idea of a Bent Hook?
Very old. In a limestone cave called Sakitari Cave on Okinawa Island in Japan, researchers found fishhooks carved from sea snail shells. They are estimated to be nearly 23,000 years old, and a report appeared in the journal Proceedings of the National Academy of Sciences in 2016 [6]. The team's lead author, Dr. Masaki Fujita, said people there also made beads and scrapers, and caught freshwater crabs in autumn. Reports list the hooks as older than ones from Timor (at least 16,000 years old) and Papua New Guinea (at least 18,000 years old) [6].
Hook materials later changed to wood, bone, horn, stone, and metal. According to Wikipedia, quality steel hooks began to appear in Europe in the 17th century and hook making became a job for specialists [2]. This is a single, loosely sourced statement, so read it as "around the 1600s," not as an exact date.
So the bend, barb, gap, and flat end are not the end of a story. They are the current stage in a design that people have kept reshaping for tens of thousands of years, always trading one thing for another.
7. How Can You Compare Hook Parts Safely Yourself?
You can do this without touching a hook. Look at photos of hooks on a maker's website, or at the packages in a tackle shop, and try to find the point, barb, gap, shank, and eye or flat end. Then place a small hook and a big one side by side and compare the gap. Does it look as if the shape changes with the size of the fish the hook is meant for? Hooks are sharp, so please look only, and ask an adult before handling any real hook.