Between 1747 and 1809 herring were prolific in the Bohuslän province, which made such a drastic difference to daily life that it is hard to imagine today. Suddenly it was easy to haul in enormous catches, and salting and train oil factories appeared like mushrooms from the earth, and there were shortages of labour. Fish and train oil were exported to Europe, and the volume became so large that for several years fish products represented about 17% of Sweden’s total exports (second only to iron). Incomes rose, people from inland moved out to the coast and the populations of fishing villages and coastal towns increased dramatically. For example the population of Uddevalla doubled between 1750 and 1800, and Marstrand grew even more, with a tripling between 1750 and 1795


Herring move around

It is not clear why the herring period started. On the other hand it is known that during such a period the herring approach land every autumn to play, and that they were fished for the 2 or 3 months that this took place. The first catches were near to Strömstad, but soon herring were numerous along the whole coast of Bohuslän. From 1750 and for about 15 years thereafter the supply was greatest in the Gothenburg area, but then the herring began to move north and from about 1775 to the end of the period there was most activity outside Orust and Tjörn. The best years were in the 1790s, then it started to decline and after 1809 was definitely over. Although this was the general picture, the supply varied a great deal between different regions and years. There was also a tendency for the herring to arrive later each year; instead of beginning in August, which was usual for the first decades, towards the end it could be as late as December before the season began. These variations created local economic problems, but also led to worry and speculation about the reason, which in the end resulted in major consequences.


Catching and preparation methods

Since the herring were close to land, the catching methods were relatively simple. Often land-based nets were used, rowed out to be set and then pulled in from the rocks.

The vast quantities of fish meant that conservation methods had to be used, to prevent the fish from rotting. The difficulty was not in catching the fish, but rather of taking care of the catch quickly enough. Fish had for a long time been salted, and salting remained in use on a large scale for the whole period. Already before the herring period in the 18th century train oil had been manufactured for household needs, but since the technique was not suitable for large scale manufacture, innovations were needed. Commercial train oil manufacture therefore began in 1760 after new methods had been developed.

The number of salting works and train oil boilers increased rapidly and by 1787 there were 336 salting works and 409 train oil boilers in Bohuslän. There would often be a salting works and train oil boiler next to each other, since this allowed the waste from the salting works to be used in train oil manufacture. There were at that time about a dozen train oil boilers in the Mollösund area, including two at Lervik/Carlsholmen (where the small boat harbour is now) and one at what is now the Torneviks bathing area.


Boiling train oil

A train oil boiler had on its ground floor one or more large kilns with associated chimneys. There were up to 4 kettles on each kiln. These were large iron or copper vessels in which the boiling took place. The size of the boilers varied a great deal, sometimes there was just one chimney, while the largest boiler had nine, serving 36 kettles. The Mollösund boilers, for example the one at Åkervik, had two chimneys and 8 kettles. For boiling the herring were winched up to the upper floor where the kettles were. 1/3 herring was added to 2/3 water and the mixture was then heated to boiling point while being stirred vigorously. The fat floated to the top and could eventually be poured into a “clearing keg” where the waste and water sank to the bottom before the train oil was tapped off. A boiling session took 6 hours and it was usual to have three sessions per day. A barrel of herring (80 pots = about 210 litres) gave about 8 pots of train oil. Boiling required one man to fire two ovens and two men at each kettle to stir.


Environmental considerations at that time

There was some sort of environmental movement even in those days. The waste from train oil boiling gave rise to a kind of environmental movement as far back as the 18th century, perhaps the first such in Sweden. The background to this was that during the first decades of the herring period the waste from train oil boiling was thrown straight into the water below the boilers. The waste sediment consisted of scales, fins and bones. There was a lot of it and the sea bed was soon covered with a thick gray layer of sediment. This led to concerns about the pollution frightening the herring away, and the variations in herring supply seemed to lend credence to this theory. However the concerns were probably unfounded – the herring moved around long before there were train oil boilers - but that’s another story. Anyway, the result was that the fishing laws were amended to demand that the waste should be buried. Since many of the boilers were situated on rocky islands this requirement was not followed, so the authorities took a harder line.


Rebuttal document and train oil waste

In 1783 it was decided that in cases where the train oil waste could not be buried, the affected boiler would have to be shut down. Suddenly no less than 120 train oil boilers were threatened with closure, which caused a lot of anger, and the owners counterattacked. In 1784 they wrote a rebuttal document, the so-called “train oil dossier” which claimed that the waste was not at all harmful. This succeeded in preventing the closures. Instead it was decided that the waste should be released into special “waste ponds” that acted as closed-off areas in inlets. The effect of the waste on the environment due to this made the situation even worse. Instead of being reasonably quickly washed away after the end of the season, the rotting waste remained in the ponds. The smell was terrible and the waste had in any case to be released into the sea or carried away. These failed ponds are today all that remains here and there as a reminder of this industrial age. In Åkervik for example all that is left of the waste ponds is a low stone wall straight across the inlet, otherwise everything else is gone. However the waste did have one positive side, it formed excellent fertiliser that, according to a travel description from 1797 provided “tremendous advantages to the farmers” above all for new crops. On the other hand it was worse for already cultivated land “since it upset the fertility immediately”.


Clear-felling in Bohuslän

The herring period meant a huge economic advance for Bohuslän, but also created problems, including the adverse effect on the environment. In addition to the waste created by train oil production, it also contributed to continued clear-felling along the coast. Large quantities of wood went into building the salting works and train oil boilers, and the train oil kettle kilns burned wood. To be sure, wood-burning was forbidden in 1778, but most of the damage had already been done.  There was a kind of gold rush fever along the coast, where the ingredients were overambitious hopes of wealth, hard work, alcohol and wild living.


Success and downfall

The herring period ended about the same way as it had begun, in principle unexpectedly, but the end was preceded by large variations in the amount of fish. When the herring finally stopped coming it was like pulling the cork out of a barrel. As if by magic the archipelago lost its population. The salt works and train oil boilers fell into disuse and the new-found wealth turned into long and difficult poverty.  The following description from 1832 says most about the situation. “The way the Bohuslän Archipelago was 25 years ago compared to now almost reduces one to tears.  It offered a splendid sight. Out of the sea itself rose expensive walls and pilings, on which rested many Salt works and Train oil boilers: further in from the beach one saw rich Warehouses and busy Factories: on top buildings of stout character, along with thousands of fishing cottages and workers dwellings. One saw the beaches covered in people and the sea a mass of sails -----

Of all this wondrous sight there is no more but empty ruins: only here and there one finds a leaning shed, as in an abandoned graveyard, awakening a sad emotion in the stranger who sees it”