EGGS FARMED FROM COD IN NORWAY FOUND IN THE WILD

Eggs from farmed cod in Norway found in the wild

During an egg hunt on the Nordland coast in Norway in the first week of March, a total of 38 cod eggs were found, of which 29 eggs were from farmed cod, seven from wild fish and two eggs were of uncertain origin.

The stations that were investigated were randomly selected in an area where it is suspected that eggs from farmed cod may occur.

“It is not possible to find out whether the spawning has taken place inside the breeding cages or whether farmed cod have escaped and spawned. Several of the discoveries have been made on known spawning grounds for wild cod,” says researcher Terje van der Meeren, who was recently on fieldwork in the area, and who is now starting round two of egg collection.

In the past, the Norwegian Institute of Marine Research has detected escaped farmed cod in this area, which is located in Meløy municipality. The results are summarized in a previous report to the Directorate of Fisheries (pdf).

The genes provide answers

In connection with earlier investigations into whether farmed cod had escaped in the area, genetic samples were taken of farmed cod from the cages and what the fishermen believed to be farmed cod. The researchers also obtained new samples of wild cod from fishermen during the spawning season.

“This genetic material was now used when the eggs were analysed,” says van der Meeren.

The researchers thus have DNA profiles that show how the genes look in both farmed cod and wild cod.

“These profiles clearly show whether it is wild fish or not, already at the egg stage, because the genetic difference between these two types of cod is large enough.”

50 stations – 1900 fish eggs and 38 cod eggs

In total, van der Meeren has collected eggs from 50 stations, some in close proximity to the cod farming facilities in the area and some located in areas where we know wild cod spawn.

“In total, we found 1,900 fish eggs. Of these, we analyzed 200 eggs from 30 of the stations. 38 of these eggs were from cod, where 29 were from farmed cod, seven from wild fish and two were uncertain,” he says.

At first glance, it may sound like these are few cod eggs, but according to van der Meeren, the quantity is completely normal:

“When we did the surveys, it was early in the cod’s spawning season, so there are fewer eggs than later when spawning is at its peak. At the same time, the fish spawn in the bodies of water and the eggs are spread out by currents and wind.

“The eggs are collected by dragging a net with a diameter of 56 cm vertically up from a depth of 50 m to the surface.

“So it’s almost a bit like looking for a needle in a haystack,” he explains.

Two “wild fish” were farmed cod

In addition to the samples from eggs and farmed cod, the researchers have been given access to fish collected by local fishermen. These were initially supposed to be wild cod that the fishermen picked out based on their appearance. To be absolutely sure that all were wild cod, they were checked against the gene profile of the farmed cod.

“This fish was caught a good distance north of the farm to ensure that it would not be an escaped farmed fish. In total, we got 80 pieces that visually looked like wild cod, of which our genetic analyses identified two as farmed cod and one as uncertain,” says van der Meeren.

“We also checked the ear stones of these three cod, and this confirmed the results from the genetic analyses.

The researchers are thus currently left with 77 wild cod from Meløy. These now form the main stock in the genetic profile of wild cod from this area.

“We will get hold of 80 new cod now, we will also take gene samples from these.”

In addition to examining cod eggs, the marine researcher experienced an unprecedented egg catch record in this area.

“In the heart of Bjærangfjorden, we got a whopping 1,056 eggs in one haul, which is the most I have ever caught in one haul. There was an increasing amount of eggs in this fjord, in total we found 1666 eggs at the four innermost stations here. We currently do not know what species they are, only that the eggs are at least designed to be cod, which the genetic analyses have also confirmed,” says the experienced fish egg collector.

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