What is a baby anchovy?
Baby anchovy, or young anchovy, is the general name for anchovies that have entered the “larval” or “juvenile” stage and are only a few millimeters long. These young fish are one of the cornerstones of the marine food chain and, with their planktonic lifestyle, provide a vital food source for hundreds of different marine creatures. Despite being so small that they are difficult to see with the naked eye, their role in the ocean ecosystem is enormous.
Baby anchovies begin feeding on plankton from the moment they are born, and sea temperature, salinity, and plankton density are critical factors for their survival, especially during the first 72 hours. Individuals that fail to develop during this critical period are pushed out of the school and often become prey to other predator species. Those that survive lose their transparent structure within a few weeks, develop scales, and their fins mature, enabling them to become active swimmers within the school.
Transparent Body Defense
In their first weeks, baby anchovies have bodies that are almost entirely transparent. This serves as natural camouflage, making them invisible to predators. Transparency allows them to both transmit light from above and detect threats from below more quickly. This transparency gradually decreases over the first 2–3 weeks after hatching.
Protection Through Schooling
Even baby anchovies that are less than 1 centimeter in size move in schools. This schooling behavior provides collective defense against predators. While individual juveniles can be eliminated in seconds, they have a better chance of survival in a school of thousands. This behavior becomes more organized and coordinated with age.
Light-Following Instinct
Baby anchovies are sensitive to light. They use moonlight to track plankton that rise to the sea surface even at night. This light-tracking reflex is also utilized in fishing; in countries like Japan, Korea, and Taiwan, lighted boats are used to catch baby anchovies, and millions of juveniles are drawn to the surface by this reflex.
Foundation of the Food Chain
Seabirds, large fish, squid, and even some whale species consume baby anchovies as their primary food source. Without these young fish, many predator species in the oceans would not survive. Especially during the summer months, baby anchovy blooms trigger large-scale predator migrations. This demonstrates how these small creatures can impact larger systems despite their size.
Taste and Aroma Differences
Baby anchovies have a much more neutral and mild aroma compared to adult anchovies. For this reason, they are frequently used raw, boiled, or lightly marinated in East Asian cuisines. Dried versions are an indispensable ingredient in morning soups, particularly in Korea and China. In Japan, this form, known as “shirasu,” is considered a special variety of baby anchovy.
Salt Tolerance
Compared to adult anchovies, baby anchovies have a much lower salt tolerance. They find it particularly difficult to survive in estuaries or river mouths where there is a high concentration of freshwater. As a result, most of the young anchovies born in these areas die within a few days. This demonstrates how critical habitat selection is for the survival of baby anchovies.
From Microscopic Eggs to Millions
Baby anchovies are born from hundreds of thousands of microscopic eggs laid by adults. These eggs remain suspended at the water's surface and hatch within a few days. Most of the eggs are eaten by plankton, jellyfish larvae, or small crustaceans. Only one in a hundred thousand survives to adulthood, but those that do can reach maturity within a year and lay their own eggs.
Early Sound Sensitivity
One of the earliest senses to develop in baby anchovies is hearing. Even at just a few days old, they can detect vibrations in the water. This sensitivity allows them to detect the sounds of approaching predators and change direction with the school. This ability significantly increases their chances of survival in the underwater environment.
Life Dependent on Water Currents
Before developing the swimming strength to determine their own direction, baby anchovies are entirely dependent on water currents. This period is the most dangerous time of their lives, as natural currents can carry them either to nutrient-rich areas rich in plankton or to oxygen-depleted dead zones. In some years, nearly the entire population of a generation can be wiped out if they are caught in the wrong currents.
Fragility Brought on by Temperature
Water temperature is a decisive factor in baby anchovy development. Eggs do not hatch in waters below 13°C, while larvae develop rapidly but remain weak in waters above 24°C. This “fast but fragile” development poses serious survival challenges in rising sea temperatures caused by climate change.
Oxygen Stress
Baby anchovies are much more sensitive to dissolved oxygen than adults. Baby anchovy populations are particularly hard hit in areas of the ocean where oxygen levels are declining. Some studies have observed that when oxygen levels drop by 30%, baby anchovy mortality rates reach 80%. This situation is a harbinger of silent collapse in marine ecosystems.
Food Competition and Sibling Cannibalism
There is intense competition among baby anchovies born in the same spawning area for microscopic plankton. Those that reach food first grow larger, while the others weaken. In some cases, larger juveniles may unconsciously eat their smaller siblings within the same school. This behavior is referred to as “intraspecific cannibalism” in fish.
Intuition Coded in the Genetic Code
Baby anchovies rely not only on instinct but also on genetic coding to find their way. Research has shown that these juveniles have the ability to recognize the magnetic field of the area where they were born, enabling them to return to their birthplace to spawn when they mature. This magnetic mapping is processed at the molecular level in their brains.
Low Fat Content and Energy Reserve
Baby anchovies have a much lower fat content than adults. Their bodies are largely composed of protein. This structure allows them to produce energy quickly but also causes them to weaken rapidly when they go without food. As a result, if they cannot find enough plankton for a few hours, their risk of death increases dramatically.
Threat of Industrial Depletion
In some countries, baby anchovy fishing is so intensive that the natural population cycle has begun to suffer. Early fishing, especially for the Asian market, causes juveniles to be caught before they reach maturity, preventing the formation of subsequent generations. Scientists warn that anchovy species could disappear entirely from some regions if sustainable fishing policies are not established.
Cultural Significance and Rituals
Baby anchovies are not only ecologically important but also hold cultural significance. In South Korea, it is a tradition to serve “myeolchi,” or baby anchovy soup, as part of postpartum nutrition. It is believed that this soup increases the mother's milk supply after childbirth. In Japan, baby anchovies symbolize the first fishing season of the year and are celebrated with festivals in some coastal towns.
Microscopic Migrations
At night, plankton rise to the water's surface, and baby anchovies follow them. These micro-migrations occur every night and are one of the most biologically diverse vertical movements in the world. This movement has significant impacts on both ecosystems and climate, as large amounts of carbon are transported to the surface, contributing to photosynthesis.
Transparent Eyes, Dark Dangers
Baby anchovies have eyes that are almost completely transparent, but this does not hinder their ability to perceive their surroundings. On the contrary, these eyes are extremely sensitive to light. They can even detect sudden shadows created by predators. However, they may experience temporary blindness under extremely bright light, which forces them to dive deeper during daytime hours.
Sensitivity to Harmful Algal Blooms
Algal blooms, such as “red tides,” which occasionally occur in the oceans, are deadly for baby anchovies. During these blooms, toxins spread throughout the water, clogging the gills of the young and causing death within minutes. While adult fish can swim away from the area, baby anchovies often cannot escape this deadly trap.
Adaptability and Evolutionary Success
Anchovies have evolved very little over millions of years because they have a structure that allows them to adapt quickly to environmental changes. Baby anchovies can adjust their growth rate within a few weeks according to the salinity, temperature, and plankton density of the water they are in. This rapid biological adaptation makes them one of the most successful fish species in the world.
Bone Formation at the Nano Scale
The skeletal structure of baby anchovies consists of flexible cartilage tissue immediately after birth. However, this structure begins to ossify within days through nano-scale mineral accumulation. The ossification process accelerates in waters with high salinity and calcium content. This rapid hardening makes them resistant to both predators and currents.
Traces in Human History
Historical records indicate that baby anchovies were consumed as far back as Ancient Rome. They were the primary ingredient in “garum,” a famous ancient fish sauce. This sauce was considered one of the most valuable table products of the time. Traces of this sauce have been found in broken amphorae uncovered during archaeological excavations.
Genetic Twin Explosion
In some regions, a significant portion of baby anchovy eggs are genetically identical. This means that eggs from the same female are not only siblings but also clone-like twins. While this enables rapid reproduction in certain environments, it also reduces genetic diversity, leading to increased vulnerability to diseases in the long term.
Laboratory Experiments on Visual Perception
Research has shown that baby anchovies are more sensitive to certain color tones. In laboratory experiments, they were observed to respond more strongly to yellow and orange lights. This suggests that they use color filters to distinguish plankton density or predator species in the ocean.
The Plastic Risk for Baby Anchovies
Microplastics have become one of the greatest threats to baby anchovies in the oceans. Plastic particles the size of plankton are mistaken for food and ingested by the young. These materials are indigestible and accumulate in the intestines. Studies have found that up to 15% of baby anchovies have microplastics in their stomachs.
Surprising Migration Start
While most marine organisms begin migrating after reaching a certain size, baby anchovies initiate their migratory reflex when they are only a few centimeters long. These journeys typically head from coastal areas toward the open sea, and thousands often perish during the first migration. However, this process enables the species to disperse over vast areas and helps maintain the balance of the food chain.
The End of Childhood
The baby anchovy stage is very short. Within an average of 30 days, they transition from the juvenile form to the young anchovy stage. During this transition, those that survive transform from prey to predators within a few months. This brief yet intense phase is one of the most dramatic and fragile processes in marine life.