Author: Ibon Cancio, UPV/EHU Associated Professor in Cell Biology; researcher in the ‘Cell Biology & Environmental Toxicology’ (CBET) research group of the Plentzia Marine Station (PiE-UPV/EHU); Spanish scientific representative in the EMBRC Committee of Nodes

Johan Hjort, Norwegian fisheries scientist and marine zoologist, travelled extensively but he died in the same city (Oslo, 1948) where he was born (Christiania, the former name of Oslo, 1869). Hjort, who from childhood was obsessed with the life history of animals, was the first child of a professor of ophthalmology. So imagine the scene: 

  • Young Hjort: 'Dad (I suppose that it must have been more formal… Father), I want to study zoology!' 
  • Hjort's father: 'What is the use of a zoologist? You better study medicine!'
Picture of Johan Hjorrt
Picture of Johan Hjort (public domain)

So young Hjort took initial courses in medicine at the University of Oslo. There he met a different kind of advisor, a spiritual or inspirational one, so to say, Fridtjof Nansen (1861-1930), who would later become a hero of Norway (sportsman, explorer, oceanographer, zoologist expert in the nervous system, promotor of the first marine stations in Norway, politician, ambassador, Nobel Peace Prize winner, rector of the University of St Andrews, etc). Following Nansen’s advice, he left for his zoology studies in Germany. At the University of Munich, his mentor was the eminent forerunner of developmental biology and expert in echinoderms and cnidarians, Richard Hertwig, who had himself been a student of Ernst Haeckel, who in turn had been student of Johannes Müller (what a pedigree!). Once there, he had the opportunity to go to the Stazione Zoologica in Naples to work on the development of the ascidian Botryllus, a study that was the core of his PhD work presented in Munich in 1892. He returned to Norway to become curator of the University Zoological Museum, and in 1894 he succeeded Georg O. Sars as Research Fellow in Fisheries. He did not stay long as he wanted to learn chemical oceanography. So he moved for one year to the University of Jena (Germany) until he was appointed to direct the Biological Station of the University of Oslo in Drøbak in 1897.

Botryllus schlosseri colonial ascidian
Botryllus schlosseri colonial ascidian. Photo by Ibon Cancio.

Hjort then began a close collaboration with Swedish and Danish scientists. The Danish marine biologist C. G. Johannes Petersen (one of the fathers of fisheries research) was investigating the shallow Danish waters with the otter-board trawling system that he had devised. Hjort adapted the system to use it on the soft bottoms of the deep Norwegian fjords discovering rich stocks of the deep-water prawn Pandalus borealis in 1898. He immediately saw great possibilities to exploit this resource and expanded his explorations to other fjords in Southern Norway. A scientist was practically showing fishermen a new profitable fishery that they would soon begin to harvest and sell internationally.

Pandalus borealis and its fisheries
Pandalus borealis and its fisheries (Wikimedia commons). The scheme shows the otter trawling system devised by C.G.J. Petersen and modified by Hjort fir shrimp fishing as published in The Depths of the Ocean.

Governments love scientists who show results that can be transferred and create socioeconomic growth. Hjort therefore did not have too many problems to convince the Norwegian government to build a dedicated deep-sea fisheries research ship. This vessel received the name Michael Sars (Father of Georg O. Sars and marine zoologist himself) that was launched in 1900. This also meant a new move for Hjort, becoming director of the Norwegian Institute of Marine Research in Bergen, a position he held from 1900 to 1916, a period of great fisheries expansion.

Georg O. Sars had shown that the eggs of most economically relevant fish in the North Atlantic are pelagic, and this had been taken as a proof that sea bottom trawling meant no danger for commercially important fish populations. Hjort thought practically on this discovery. He developed an ichthyoplankton survey along the Northern Norwegian Atlantic and commanded an extensive expedition on the Michael Sars to analyse the relative abundance of cod eggs, with yet again very impactful commercial outcomes. He was able to associate presence of high concentrations of eggs with the existence of abundant cod stocks. Hjort’s application of ecological scientific approaches opened up some of the most profitable new fishing grounds, never fished before, to the cod fishermen of Norway in 1902. Hjort’s two practical achievements showed the value of investing in fisheries research and scientific surveys for best harvesting the richness of marine bioresources.

Picture of Atlantic cod
Atlantic cod in the aquarium of Tromso, Norwat. Photo by Ibon Cancio.

Later in 1909, the father of oceanographic research, Sir John Murray asked the Norwegian government permission to use the Michael Sars vessel for a four-month research cruise. He offered to pay for all the expenses (after all, he had won a lot of money out of phosphate mines in the Indian Ocean) putting the expedition under Hjort's scientific command. The North Atlantic expedition of 1910 resulted in the publication of The Depths of the Ocean (1912) by Murray and Hjort, which has become a classic for marine biologists and oceanographers.

Depths of the Ocean publication cover

Hjort had become very interested in statistical approaches to study nature and the causes of the fluctuations in fish populations. Consequently, he was the first to apply statistical methods to fisheries, adding fish scale and otolith (structures formed by calcium carbonate concentric layers in the inner ear of vertebrates) analyses to estimate the age of sampled fish. All this led to his 1914 paper, Fluctuations in the Great Fisheries of Northern Europe, still massively cited and the cornerstone upon which modern fisheries science was built, marking Hjort as its putative father. He became further interested in population dynamics and began to show concern in the effects of over-fishing, working on methods for determining optimum catches for a sustainable exploitation of populations.

A scale of herring
 as published by Hjort and Murray in The Depths of the Ocean and an otolith (Photo by Ibon Cancio) of a thicklip grey mullet. Counting the number of rings allows inferring fish age.

During World War I, Hjort was involved in foreign relations, negotiating fish-purchase agreements between Norway and England in the belief that this would be made public. Norway's foreign minister, afraid of German reprisals, decided to keep it secret so Hjort resigned from all his positions and left Norway to work for some years in Denmark and the UK to return to a professorship in Oslo in 1921. Hjort's entire research career was in fact highly international, characterised by studies and collaborations abroad. The best example is his decisive participation in the creation of the International Council for the Exploration of the Seas, ICES (the oldest intergovernmental science organisation in the world) in which he was one of the founding fathers in 1902. He was the Norwegian delegate at ICES from 1902 to 1938, when he was elected President, a position he held to his death in 1948.

Recognition of course came nationally but also internationally with medals and honorary degrees from the universities of Cambridge, London and Harvard. In 1936, he travelled to Harvard to receive his honorary degree. Navigating along the New England coast, he recognised ecological conditions similar to those that were making deep-shrimp fisheries such a profitable activity in Norwegian fjords. He was immediately offered the command of a research ship finding huge amounts of shrimp. This led to the formation of a shrimp fishery on the US side of the Atlantic. Bubba never mentioned that to Forrest Gump! But you know? ‘Shrimpin’ ain’t easy!’

Image of several boats
In the Norwegian tradition research vessel named after famous Norwegian marine biologists since the S.S. Michael Sars (photo courtesy of the University of Bergen Library) to the research vessels now on duty for the Institute of Marine Research of Norway, the Johan Hjort (1990), the G.S. Sars (2003) and the Fridthof Nansen (2017) The new Michael Sars (1979) is a training vessel with Finish flag (Wikimedia commons).


Sabrina Gaber
Communication Officer

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