The hatchery for salmon fry at Ullern

Although the first hatchery in Hokksund was built in 1855, I will stick to the years from around 1950 when, as a little boy, I started accompanying my father Hilmar Olsen up to the exciting facility. Over time, I actively participated in this work.

The hatchery building was located on the Ullern site. When you walk down the road to the Ullern site and have passed the Lien garages, you can look to the right down the field. Down in the first "dæla" was the hatchery. Down to the hatchery we walked a path across the field. After heavy snowfalls I remember that we walked up to our knees.

The hatchery had 18 hatching boxes and each had space for about 5 liters of roe, which at that time corresponded to about 25,000 roe grains. The water supply was a pipe from a collecting basin about 100 meters above. Several drainage ditches were laid into this basin and this provided a satisfactory water supply.

The building was not insulated and during periods of extreme cold there was a thick layer of frost inside. The hatchery building was renovated in 1928 and had hatching boxes that were carved from wood. In the 1960s these were replaced by aluminum boxes. In order for the roe to lie still in the water flow through the boxes, the bottom was covered with a layer of fine stones that were slightly larger than peas. On this layer of stones, the salmon roe was scattered in a thin layer, and then they were to lie still until you began to see the eyes of the fry through the roe shell. At that time they could withstand quite rough treatment, and at the same time it was high time to wash both the roe and the stones. The washing was done by removing a bottom plug at the bottom of the water flow and letting the water and roe drain into a tall bucket. Most of the roe then followed the water, but you also had to help by waving a chicken feather in the water. When all the roe had been taken out, all the stones in the box were scraped clean and neatly laid out again. Then the roe, which was now clean, was laid out on top of the stones. In this process, the roe that had not been fertilized had turned white and had to be picked out. This was done with a wooden pick and was painstaking work. We probably never measured this, but I would estimate that about 5% of the roe was unfertilized.

When the eggs hatched in April/May, the fry had brought a packed lunch in a large bag under their belly and were called bladder fry. They lay quite still in the boxes at first, but as they grew they became more active and eventually followed the water current and ended up in a collection box. They had then used up almost the entire "nista" and it was very important to release it into the river and tributary streams so that it immediately had access to natural nutrition. If you waited too long to release it when the "nista" was exhausted, the fry lost their "grass" and the ability to eat. In the old hatchery there were no feeding options so we had to release everything by mid-June. The releases were very labor-intensive, and the fry should certainly have been spread out significantly more if you had had access to more resources.

The hatchery had no electricity during the first few years I was there. When checking in the evening we therefore had to rely on candles. Eventually we were able to install electric lighting.