Is it true that the stronger the smell of bait for surf casting, the better?

When fishing, you can often see people setting bait with a hand that has smoked a cigarette. Even if you are alone and there are no other people around and you smoke, it is better not to set bait or prepare equipment with a hand that smells like cigarettes, as this is not good for your catch.

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Now that the cold winds are starting to blow, many anglers will be heading out to the East Sea to catch large black sea bream. Today, we will learn about the sense of smell of fish, including black sea bream. Fish use all of their senses to find food, but they are known to use both sight and smell a lot, especially smell.

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Vision is important not only for eyesight but also for color vision, which is the ability to distinguish colors. The eyesight of the black sea bream is said to be about 0.14 and it has five opsin genes, allowing it to detect light and dark, red, green, and ultraviolet light.

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Scientists say that the red sea bream has two genes that specifically distinguish green, giving it the ability to distinguish yellow, which is between green and red.

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Therefore, it seems plausible that red sea bream respond to corn and that products that use a lot of yellow as bait to catch red sea bream are sold.

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According to research on the retinal cells of black sea bream, the visual acuity of black sea bream is known to be around 0.14. For example, if a size 2 nylon leash is used, the line diameter is 0.235 mm, so the black sea bream must approach 12 cm to identify the leash. If a size 1 leash is used, the line diameter is 0.165 mm, so the black sea bream must approach 8 cm to identify the leash.

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However, since today’s topic is the sense of smell of fish, including the red sea bream, we will stop talking about sight here.

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Unlike humans, fish have two pairs of noses, and it is said that they sense smells through an organ densely packed with olfactory nerves called the olfactory plate located between the anterior and posterior nostrils.

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To explain in a little more detail, a fish’s nose has an anterior nostril through which water enters and a posterior nostril through which water leaves. It is said that fish sense the chemical components in the water entering through the anterior nostril and smell in the process of expelling the water through the posterior nostril.

The rear of the fish is made up of plates, which are densely packed with cilia that detect odors. It is known that the more plates there are, the more sensitive the fish is to odors.

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The arrangement of the plates varies from those without plates like the loach, those with only one plate in the long direction like the goby, those with one plate perpendicular to the long direction like the mackerel, and those with multiple plates in parallel like the puffer fish.

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And fish species that are relatively sensitive to smell include those with fan-shaped plates like the flounder, those with radial plates centered in a short direction like the tuna, and those with plates in right-angled or diagonal shapes centered around a thin, long central ridge like the pufferfish.

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And fish species with a relatively strong sense of smell, including red sea bream and black sea bream, have rear plates arranged in two rows at right angles along a long, raised part in the center.

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Also, as they grow from fry to adults, the number of plates increases with size, so you can see that the larger the fish, the more sensitive they are to smell.

In particular, the number of dorsum plates of the conger eel, a representative fish species for long-distance fishing on the west coast, is the largest among fish, so you can see that bait with a strong smell is effective.

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In particular, it is said that the sense of smell of the red sea bream can detect very small amounts of amino acids, and the four amino acids that the red sea bream is particularly fond of are alanine, arginine, glycine, and proline. Taking advantage of this habit of the red sea bream, the powder for red sea bream sold on the market contains various amino acid ingredients.

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And, as we’ll discuss later,  please keep in mind that fish may not be able to detect strong odors that we do, as their sense of smell differs from ours, which involves detecting water-soluble odors. So, let’s take a look at a photo of the black sea bream’s nose and dorsal plate.

As you can see in the picture, the red sea bream has about 55 to 60 plates, and the red sea bream has a similar number.

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However, it is said that conger eel has more than 100, red sea bream has 25, rock bream has 24, and flounder has about 20.

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Fish species with more than 50 dorsal plates are said to have a strong sense of smell. The shape of the dorsal plates by species is as follows.

How about this? You can see that the more sensitive the sense of smell, the more densely and numerous the plates are arranged in the fish species.

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Also, as I mentioned before, the number of plates increases as the fry grow into adults. This scientific analysis also shows that when fishing for conger eels or black sea bream, bait with a strong smell is helpful for catching them.