Johan Hjort facts for kids

Quick facts for kids Johan Hjort
Born	(1869-02-18)February 18, 1869 Christiania, Norway
Died	October 7, 1948(1948-10-07) (aged 79) Oslo, Norway
Nationality	Norwegian
Alma mater	Ludwig Maximilian University of Munich
Spouse(s)	Wanda Maria von der Marwitz
Children	4
Scientific career
Fields	Marine biology, Oceanography, Fisheries science
Thesis	Ûber den Entwicklungscyclus der zusammengesetzten Ascidien (1893)

Johan Hjort (born February 18, 1869, in Christiania, Norway – died October 7, 1948, in Oslo) was a very important Norwegian scientist. He was a fisheries scientist, a marine zoologist, and an oceanographer. This means he studied fish, sea animals, and the ocean itself. He was one of the most famous and influential marine zoologists of his time.

Early Life and Education

Johan Hjort was the first child of Johan S. A. Hjort, who was a professor. His mother was Elisabeth Falsen. Johan always wanted to study animals, especially sea creatures, ever since he was a young boy.

To make his father happy, he first started studying medicine. But he soon followed his dream and went to the University of Munich to study zoology. He then worked at a famous research station in Naples, Italy. There, he studied how sea animals develop from eggs. He earned his doctorate degree in Munich when he was just 23 years old, in 1892.

After his studies, he returned to Norway. He became the curator at the University Zoological Museum. He helped create more modern courses for students. In 1894, he took over from another famous scientist, G. O. Sars, as a Research Fellow in Fisheries. By 1897, he was made the director of the University Biological Station in Drøbak.

Leading Ocean Research

Johan Hjort became the director of the Norwegian Institute of Marine Research in Bergen. He held this important position from 1900 to 1916. Because of his early experiences studying abroad, he stayed involved in international research. He was one of the main people who helped start the International Council for the Exploration of the Sea (ICES) in 1902. This group helps countries work together to study the ocean. He was Norway's representative at ICES for many years, from 1902 to 1938. He was then chosen as the President of ICES and stayed in that role until he passed away in 1948.

The Michael Sars Expedition

In 1909, a famous oceanographer named Sir John Murray asked the Norwegian government for help. He wanted to borrow their research ship, the Michael Sars, for a four-month trip. Murray offered to pay for everything if Hjort was in charge of the science.

After a lot of planning, this became the biggest ocean research trip ever at that time. In 1912, Murray and Hjort wrote a book called The Depths of the Ocean. This book quickly became a classic for anyone studying the ocean and its creatures.

Understanding Fish Populations

For many years, Hjort was very interested in why fish populations change so much. Sometimes there are lots of fish, and sometimes there are very few. He was the first scientist to use special math methods, like those used to study human lifespans, to understand these changes in fish. He also used new ways to figure out the age of fish they caught.

Hjort's studies led to a very important article in 1914. It was called Fluctuations in the Great Fisheries of Northern Europe. This work was a huge step forward in the field of fisheries science.

Sustainable Fishing and Shrimp Discovery

These studies made him interested in how populations of all living things grow and change. He looked at everything from tiny yeast cultures to whales, fish, and even humans. He believed that understanding these things was important for human society too.

Hjort was one of the first to worry about overfishing. He saw that whale populations in the Antarctic were getting smaller, which was an early warning sign. He worked on ways to figure out the optimum catch. This is the perfect amount of fish or whales to catch so that there are still enough left for the population to stay healthy and strong for the future.

Johan Hjort was a very clever person who could use his scientific knowledge in practical ways. In 1924, he invented new machines to get whale oil from whale blubber. He is also known for being the "practical inventor of shrimp fishery". This means he helped start the big shrimp fishing industry we know today.

Before Hjort, deep-water shrimp like the Pandalus borealis were known, but people thought they were rare and not worth catching. Around 1898, Hjort changed some fishing nets to work better on the soft bottoms of deep Norwegian fjords. He soon found huge amounts of Pandalus borealis shrimp!

At first, fishermen weren't impressed. But Hjort didn't waste time arguing. He went shrimp fishing himself and came back to the harbor with a huge catch. He simply dumped it on the dock. That was enough! With this clear example, he started a very profitable fishing business and a thriving export trade for shrimp.

Many years later, in 1936, he traveled to Harvard University in the USA. He predicted that deep-sea shrimp would be found off the New England coast. He thought this because the ocean conditions there were similar to the Norwegian fjords. He took time to test his idea. He was given command of a research ship called Atlantis. He found vast amounts of shrimp exactly where he thought they would be! This led to the start of a shrimp fishing industry on the US side of the Atlantic.

Later Career and Recognition

After some time away from Norway, Hjort was given a professorship in Oslo in 1921. He often shared his ideas in public discussions. He wrote books, essays, and newspaper articles about many topics. These ranged from making science easier to understand to talking about politics and philosophy.

For all his important work in science and practical ocean research, Hjort received many awards. He was given special honorary degrees from famous universities like Cambridge, Harvard, and London. He was also chosen as a member of many scientific groups, including the Royal Society. He received the very first Alexander Agassiz Medal, which is a high honor in oceanography. He also received special awards from Norway, Sweden, and Denmark.

Sir Alister Hardy, another famous scientist, said about Hjort: "He was one of the great leaders in oceanography whose names will live in the history of that science." He also said that Hjort was the most outstanding person in ICES since it began.

Johan Hjort had four children with Wanda Maria von der Marwitz. His oldest son, Johan Bernhard Hjort, became a lawyer.

Selected Publications

• 1912 (with Sir John Murray): The Depths of the Ocean.
• 1914: Fluctuations in the Great Fisheries of Northern Europe.
• 1921: The Unity of Science.
• 1931: The Emperor's New Clothes. Confessions of a Biologist.
• 1938: The Human Value of Biology.

The abbreviation "J.Hjort" is used to show that Johan Hjort is the author when citing a botanical name.

Named After Hjort

Several things have been named in honor of Johan Hjort:

• The research vessel Johan Hjort. Three different ships have had this name.
• Idioteuthis hjorti, a type of whip-lash squid.
• Balaenanemertes hjorti, a ribbon worm.
• Echinoclathria hjorti, a sponge.
• Prionoglossa hjortii, a sea mollusc.
• Saccopharynx hjorti, a gulper eel.
• Hjort Massif, a mountain range in Antarctica.
• Hjort Trench, a deep part of the ocean.
• Hjort maturity scale, a way to measure how mature fish are.
• Johan Hjorts vei ("Johan Hjort Street") in Bergen, Norway.

See also

• Age class structure
• International Whaling Commission