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Strong year classes for flatfish, cod in trouble

Gepubliceerd op
30 juni 2020

Many of the most important fish stocks for Dutch fisheries in the North Sea are in good shape, but there are concerns about cod, sea bass and sole, among other things, according to the International Council for Exploration of the Sea (ICES). The European Council of Fisheries Ministers will set the new catch quotas for 2021 at the end of 2020. ICES catch advice plays an important role in this.

At the request of the European Commission, ICES provides advice on the maximum quantities of catch that can be achieved within the agreed objectives in the European Fisheries Policy. ICES also provided advice in 2020, albeit in a concise form due to the COVID-19 pandemic. The consequences of the pandemic on the advice will mainly become clear next year.

Healthy herring stock, but catch advice reduction

The size of the herring stock fluctuates due to natural causes. It is estimated that 1.3 million tons of adult herring swim in the North Sea, Kattegat, Skagerrak and the eastern part of the English Channel. Due to lower growth, the stock has declined in recent years, and is now around the target level required to achieve the long-term sustainable harvest ('maximum sustainable yield', MSY). Fishing pressure is low and has been below the MSY target level since 1996. In order to keep the stock around the target level, ICES recommends a lower herring catch of 365 792 tons for these areas for 2021, of which 359 367 tons for human consumption and 6 425 tons for industrial fisheries.

Revised perception for North Sea sole

The perception of the sole stock was adjusted downwards in 2020 due to an improvement in the calculation method, in which an extra survey study was added. Due to this adjustment, ICES now estimates that the stock is just above the spawning stock limit level. Since 1997, the fishing pressure on this stock has decreased sharply towards the MSY target level. For sole, a European multi-annual management plan for mixed fisheries in the North Sea (Multi-Annual Plan, hereinafter: North Sea MAP) applies. With this plan, the target species in the mixed North Sea fisheries must be jointly managed in such a way that the maximum sustainable yield (MSY) is (ultimately) achieved and retained for each individual stock. The very strong new year class from 2018 ensures a higher ICES catch advice, which means that the total catch of sole in the North Sea must remain within the range of 13 237 tons and 32 920 tons.

Plaice stock health undiminshed

The North Sea and Skagerrak plaice stock is still at a record size, well above the MSY target level. The fisheries researchers estimate that there are now more than 1.2 million tons of adult plaice (1,253,492 tons). Since the start of the stock estimate in 1957, never before has so much plaice been measured. The strong increase in the stock is mainly linked to the sharp decrease in fishing pressure. Plaice has been fished at or below the MSY target level for fishing pressure for 11 years. This fish stock is a shared stock with Norway. Based on the MSY approach, ICES recommends a total catch of up to 162 607 tons of plaice for the North Sea and the Skagerrak.

By-catch species show a varied picture

ICES also issued catch advice for a number of species that are not among the main target species of Dutch fisheries, but that are of value, as they constitute commercial by-catch in the flatfish fishery (turbot, brill, cod, whiting, sea bass).

Turbot stock healthy, but reduced catch advice

The stock of turbot has been above the MSY target level since 2013, and is estimated at almost 8 400 tonnes. Fishing pressure has been below the MSY target level since 2012 and at this level in most recent years. Turbot is part of the North Sea MAP. For 2021, an MSY advice will be issued by ICES for the first time, where previously advice was based on the precautionary principle. The fishing pressure appropriate to MSY is lower than that under the precautionary principle. The catch advice for 2021 comes to a maximum of 3 948 tons of turbot in the North Sea. According to ICES, the estimate of the turbot stock could be further improved by a targeted annual survey study in the North Sea. The Dutch fishing sector, together with Wageningen Marine Research, therefore started a sector survey in 2018 focusing on turbot and brill.

Healthy situation for brill

There is insufficient data for the brill stock to perform an extensive stock estimate. Brill is therefore a data-limited stock. The index, which is calculated on the basis of the fishing success of Dutch cutters, indicates that the stock has been declining since 2015, but increased again in 2019. Over the past five years, this amounts to a decrease of 22%. However, the stock is still above the MSY level. The fishing pressure is less than the MSY target level and therefore at a healthy level. For data-limited stocks, ICES always advises according to the precautionary approach. ICES advises for brill in the North Sea, Kattegat, Skagerrak and the Channel a maximum catch of 2,047 tonnes in 2021.

Cod stock below the limit level

After a historic low in 2004, the cod stocks in the North Sea, Skagerrak and in the eastern part of the Channel were out of danger in 2015. The cautiously initiated growth did not continue and the stock is now well below the limit level again. This means that the stock has a reduced capacity to reproduce. It is estimated that approximately 56,000 tonnes of adult cod are swimming in the North Sea. The fishing pressure has increased and is now above the limit level. Because, just like plaice, this is a shared stock with Norway, ICES recommends using the MSY approach. In addition, ICES advises for these areas that the fishery may catch a maximum of 14 755 tonnes of cod in 2021.

Whiting stock is growing steadily

The whiting stock in the North Sea and the eastern part of the Channel is at the MSY target level. The stock of adult whiting is estimated at nearly 170,000 tonnes. The fishing pressure is slightly higher than the MSY target level. This is also a stock shared with Norway. The advice is that with fishing pressure at MSY level, a maximum total of 26 304 tons of whiting may be caught, of which 19 759 tons from the North Sea for human consumption.

Sea bass stocks on an incline

Sea bass stocks in the southern and central North Sea, Irish Sea, English Channel, Bristol Channel and Celtic Sea are just above the limit level and are estimated at 11,000 tonnes. Fishing pressure has declined sharply from 2013 and is below MSY level, resulting in a slight growth of the stock. ICES recommends, based on the Western Waters MAP, that the total catch for these areas in 2021 should remain within the range of 1 684 tonnes and 2 000 tonnes. For recreational fisheries this means a catch of between 442 and 526 tons.

Advice by ICES

Researchers from Wageningen Marine Research presented the ICES fisheries advice for the most important species for the Dutch sector to the Ministry of Agriculture, Nature and Food Quality, the fisheries sector and social organizations on 30 June. ICES estimates stocks and levels of fishing pressure each year, and then advises the European Commission on how much should be caught in order to achieve the goals of the Common Fisheries Policy. European policy aims to regulate fishing pressure in such a way that the maximum sustainable yield (MSY, "Maximum Sustainable Yield") is achieved. This is the fishing pressure that leads to the highest possible long-term harvest of a fish stock. ICES has provided advice for more than 20 fish stocks in the North Sea. In December, the European Commission will make fishing arrangements with Norway for a number of jointly managed stocks. At the end of the year, the Council of Fisheries Ministers sets the allowable catches for 2021.

Table: Developments spawning and fishing pressure, total allowable catches in 2020 and ICES advice for 2021 (in tonnes) of fish species that are important for Dutch fisheries.
Table: Developments spawning and fishing pressure, total allowable catches in 2020 and ICES advice for 2021 (in tonnes) of fish species that are important for Dutch fisheries.

1 TAC = total catch = fish meeting the minimum size (sizes) + undersized fish. For herring and whiting (North Sea part) shown in this table for fisheries for human consumption.

2 Due to the introduction of the European landing obligation, ICES provides advice for the total catch (sizes + undersized). For herring and whiting (North Sea part) shown in this table for fisheries for human consumption.

3 Percentage difference between the advised TAC 2021 (including undersized catch) and the established TAC for 2020 (including undersized catch). Herring and whiting are fisheries for human consumption. The undersized catch for herring is negligible.

4 MSY-level

5 MSY-bandwidth

6 The joint total TAC applies to turbot and brill. It is not possible to calculate the difference between the advice per species and the determined joint TAC.

7 TAC North Sea

8 The European Council of Fisheries Ministers has not set a TAC for 2020. Limited catch is permitted under certain conditions.