CONTINUED PROTECTION OF COD SPAWNING AREAS IN THE NORTH SEA IS RECOMMENDED

Author: Øystein Rygg Haanæs

“North Sea cod stocks are in relatively poor condition and have been characterised by several years of poor recruitment since 2020. Protection of important nursery areas can be a good measure to protect cod in the most vulnerable life stages,” says Research Director Geir Huse.

Partial protection of three growing areas

For the past five years, three presumed important cod nursery areas in the North Sea have been closed to bottom fishing from July to December. The protection zones are Egersundbanken, Lille Fiskebank and Midtbanken (see map).

The aim has been to reduce fishing pressure and give juveniles – young cod – a better chance to grow large.

Found some more young cod

In a recent report, HI has summarised the effects of five years of partial protection.

“There were somewhat more small fish than before in the areas where the protection zones were located, but we cannot point to any clear, significant trend,” says marine scientist Côme Denechaud.

He says that there were more so-called zero-year-olds – the newest cohort – on Egersundbanken and nearby areas after the protection was introduced.

“These probably drift in from spawning grounds further north and west. In the area at Lille Fiskebank and Midtbanken, there were slightly more older fry than before the protection was introduced. These probably come from spawning grounds to the east in the Skagerrak. In other words, the protection zones that were introduced in 2020 appear to be important nursery grounds for cod, and correctly selected,” says Denechaud.

Compared to reference range

The researchers used data from the international ecosystem survey IBTS (International Bottom Trawl Survey). IBTS visits the area where the protection zones are located twice a year.

Since there were few measuring stations in the protection zones, the zones were merged with nearby areas to obtain enough data. For the same reason, Lille Fiskebank and Midtbanken were merged with surrounding areas to one size in the analysis.

“The amount of fry in the areas with the protection zones is compared with a reference area that is mainly located further west and north in the North Sea. There is no protection there,” says Denechaud.

Positive signals, but unclear effect

The researchers have compared the average catch from IBTS stations in the period 2015-2019 with the catch in the period 2020-2024.

“In summary, we can say that we see positive signals, but in our models the effects of the protection were unclear. The fact that it was difficult to find clear trends is also due to the fact that there was almost a collapse in recruitment to the cod stock throughout the North Sea at the same time as the protection was introduced,” explains Denechaud.

Stronger protection can provide better effect

A study summarising results from several marine protected areas has shown that the strength, continuity and length of protection are important for significant effects of marine protected areas.

The Directorate of Fisheries has proposed that the ban on fishing in these cod nursery areas should also apply between 1 July and 31 December 2025.

“If the protection in these three zones is extended, we believe that stronger protection can have a greater effect. With support from the meta-study, we also believe that a longer protection period can be sensible,” says Denechaud.