Pollan (fish) facts for kids
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The pollan, also called the Irish pollan, is a special type of whitefish. It lives only in fresh water in five lakes in Ireland. These lakes are Lough Neagh, Lower Lough Erne, Lough Ree, Lough Derg, and Lough Allen.
The Irish pollan faces challenges from new species like pike, roach, and zebra mussel. These new species compete for food and space. Because of this, some pollan groups need help from people to survive. This help often involves adding more pollan to the lakes.
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Pollan's Conservation Status
Pollan populations are at risk due to changes in their lake homes. One big problem is eutrophication. This happens when too many nutrients enter the water, causing too much plant growth. This can harm the fish.
Other threats include more pike, roach, and zebra mussels. These species compete with the pollan for food.
Only the pollan in Lough Neagh in Northern Ireland are still doing well. There is even a small fishing business there. The pollan in Lough Erne, also in Northern Ireland, have greatly decreased. Pollan were only found in Lough Allen for the first time in 2006. Other groups of pollan need people to add more fish to the lakes to keep them alive.
What Does a Pollan Look Like?
The Irish pollan looks a lot like a herring. However, it has a small, fleshy fin on its back called an adipose fin. This fin helps tell it apart from herrings.
The pollan has a small mouth. Its teeth are tiny and fall out easily. Its scales are not too big or too small. The fin on its back is of medium length. Its tail fin is deeply forked, like a "V" shape.
It can be hard to tell different types of pollan apart. Knowing which lake a pollan came from can help scientists identify its exact species. Pollan usually grow to be about 23 to 25 centimeters (9 to 10 inches) long. They typically weigh around 170 grams (6 ounces).
Pollan's Life and Habits
The Irish pollan is a shoaling species. This means they like to swim together in large groups, or schools. This behavior helps them find food and stay safe from predators.
Pollan mostly eat small crustaceans. These are tiny creatures with hard shells, like mini shrimps. They also eat insect larvae, which are young insects.
Pollan usually breed in November and December. They lay their eggs over hard ground in deep parts of the lake. This process is called spawning.
How Pollan Are Classified
In science, the Irish pollan is often grouped with a species called Coregonus autumnalis. This is a widespread whitefish found in the Arctic regions of Siberia, Alaska, and Canada. There, it is known as the Arctic cisco.
The Arctic cisco is an anadromous fish. This means it lives in the sea but travels to rivers to lay its eggs. However, the Irish pollan does not migrate to the sea. It stays in fresh water its whole life.
Because they are so similar genetically, the Irish pollan is sometimes called a subspecies of the Arctic cisco. This means it's a special type of Coregonus autumnalis. However, groups like the IUCN and FishBase list the Irish pollan as its own distinct species, Coregonus pollan.
See also
In Spanish: Coregonus pollan para niños
