Baltic Sea Centre critical of recent TAC advice for Baltic fisheries

The International Council for the Exploration of the Sea (ICES) recommends continued high catch quotas for the herring fishery in the Gulf of Bothnia, and increased catches for both Central Baltic herring and the hard-pressed western Baltic cod next year. Risky, and not in line with the actual status of the stocks, says Baltic Sea Centre’s fishery researcher Henrik Svedäng.

Silll. Foto: Oceana.

Overall, things look bleak for most Baltic Sea fish stocks. Although some stocks vary up and down, most commercial stock's long-term trend points downward.

Following the collapse of the eastern cod stock in 2019, recent years have been marked by a heated debate about the large-scale pelagic trawl fishery and the lack of herring along the Swedish east coast. There have been many calls for drastic measures to help stocks recover. However, no such measures are included in ICES' annual advice on next year’s TACs (Total Allowable Catch), which was released on Tuesday, May 31.

Herring in Gulf of Bothnia

For the Gulf of Bothnia herring, ICES recommends a TAC of just over 102,000 tonnes, according to the target of maximum sustainable fishing mortality (Fmsy). It represents a reduction of just over seven per cent compared to the sharp increase introduced in the middle of last year.

Fishing mortality (F) and spawning stock biomass (SSB) for the Gulf of Bothnia herring. Source: ICES

In the small print parts of the advice, ICES notes that the spawning stock biomass (SSB) has declined sharply since 2010 and is now very close to the MSY Btrigger safety level. It also concludes that if spawning stock biomass is to be maintained above this level next year, the fishing mortality rate (F) should not exceed some 80,000 tonnes, corresponding to the limit value Fmsy lower.

Henrik Svedäng, fishery researcher at Stockholm University Baltic Sea Centre, is very critical of ICES choosing to continue recommending too high TACs for a stock that obviously has major problems. 

"They rely entirely on results from a new and untested assessment model and seem to ignore all other important information", he says.

The Commission requested “better” advice

The new model he is referring to has to do with the fact that ICES had problems with insufficient data regarding the Gulf of Bothnia herring. From being a so-called Category 1 stock (with sufficient stock estimation data), the stock was downgraded to Category 3 in 2019 and then to Category 5 (data-poor stock) in 2020. This forced ICES to recommend lower TACs for both 2020 and 2021 (65 000 to 88 000 tonnes/year) in accordance with the precautionary principle.

ICES then received a special request from the European Commission to ”do its utmost to provide again category 1 MSY advice for the fishing year 2022, and if possible, to modify its advice for the fishing year 2021 in view of a possible adjustment of the TAC-level”. (ICES WGBFAS, 2021, page 344)

Subsequently, a new calculation model, the Stock Synthesis Assessment Reference Model (SS3), was introduced, which yielded new results. The spawning biomass turned out to be much larger than previously thought. The stock was upgraded to Category 1 again – and the current TAC advice was significantly increased. Already during the current fishing year (2021), the TAC advice was increased by just over 80 percent. For 2022, the increase was just over 70 percent compared to the original TAC for 2021.

"The problem is that the spawning stock biomass continued to decline in 2018-2020, even though the TAC was lowered. It was a clear signal that something was not correct", says Henrik Svedäng.

According to him, there are several indications that fishing mortality has been underestimated while spawning stock biomass has been overestimated.

"Another important signal is that commercial fishing landings decreased slightly in 2021 compared to the previous year, despite the fact that the TAC was increased by 80 percent", he says. 

ICES believes that the decline in spawning stock biomass since 2010 is probably due to the fact that the larger herrings are growing poorly. There has been a slight weight loss in the very oldest age groups in recent times. However, in terms of the entire stock, the average weight of herring of different ages (weight-at-age) has not changed significantly since 2010. In contrast, the number of large (and older) herrings in the stock has decreased.

Risk of sub-stocks being fished out

In recent years, coastal fishermen and herring producers in the Gulf of Bothnia have sounded the alarm about an acute shortage of herring on the coast. Henrik Svedäng recalls new genetic studies from Uppsala University, showing that the Baltic herring in the Gulf of Bothnia consists of several different sub-stocks. 

"There are strong indications suggesting that the lack of large herring is due to the fact that one or more sub-stocks are being fished out. To continue recommending high TACs in that situation is risky", he says.

The Central Baltic herring

When ICES revised its assessments of the Central Baltic herring stock last year, it turned out that the assessments had been inadeqaute for many years. The spawning stock biomass, that in 2017 was estimated to be just over 1.3 million tonnes, was in fact less than almost 600,000 tonnes that year. And the fishing mortality, which in the same year was stated to rest safely below Fmsy (0.2), was in fact around 0.5 and above the precautionary level Fpa.

Fishing mortality (F) and spawning stock biomass (SSB) for Central Baltic herring. Source: ICES

Although the stock situation has not changed significantly over the past year, with continued fishing mortality over Fmsy and low biomass, ICES recommend a 30 percent increase in TAC for 2023. The main reason seems to be the slightly larger year-class of he herring born in 2019. These herrings have now grown enough to be fished commercially during next year.

“At the same time, the trend for stock recruitment is declining. And ICES does not discuss the poor situation along the Swedish east coast, the division into different sub-stocks, or the risks and negative consequences that can arise if you base your fishing on a single strong year-class”, says Henrik Svedäng.

However, ICES do incorporate some warnings in the advice text, for instance that the  estimate of the year-class 2019 is uncertain, and that there seems to be incorrect reporting of herring and sprat catches, which complicates the scientific assessments.

The Western Baltic cod stock

The western cod stock is in deep crisis, and targeted fishing is not allowed. Nevertheless, ICES proposes to increase the TAC (bycatch and recreational fishing) by 35 percent compared to last year, to a maximum of 943 tonnes. This is because the latest year-class is estimated to be slightly stronger than in the previous year. At the same time, ICES emphasizes that there is a high risk that the spawning stock biomass has been overestimated.

Fishing mortality (F) and spawning stock biomass (SSB) for the Western cod stock. Source: ICES 

The stock remains at a historical low and shows clear signs of being overfished: spawning stock biomass is well below all sustainability levels, while the fishing mortality exceeds the sustainability limits Fmsy and Fpa. Last year, recreational fishing accounted for 46 percent of the total catch, according to ICES. Most of the by-catches of commercial fishing took place in flatfish fisheries.

The Eastern Baltic cod stock

Perhaps the most expected feature of ICES advice for next year's Baltic Sea fishery was that the fishing ban for eastern cod will continue in 2023 – for the fifth year in a row.

Fishing mortality (F) and spawning stock biomass (SSB) for Eastern Baltic cod. Source: ICES

ICES notes that continued cod fishing, including bycatch, would further deplete the stock. Recreational fishing has been closed since 2020. At the same time, a lot of cod is still caught as a by-catch in trawling for flatfish. According to ICES, these bycatches must be reduced in order to strengthen the stock's chances of recovery. There are trawl gears for flatfish that effectively reduce bycatch of cod, but these are not currently used.

“The eastern cod stock seems to have stabilized in terms of size at sexual maturity and condition. It is nevertheless still in very bad shape and should not be exposed to any fishing”, says Henrik Svedäng.

Text: Henrik Hamrén

Read ICES recommendations for all fish stocks in the Baltic Sea

Fisheries abbreviations 

MSY = Maximal Sustainable Yield: The maximum amount of fish that can be fished from a stock while leaving enough fish for the stock to develop sustainably.

SSB = Spawning Stock Biomass: The amount of sexually mature fish in a stock.

B = Biomass: The total weight of a fish stock.

MSY Btrigger = If the biomass reaches this level, a requirement is triggered for ICES to recommend a lower TAC in relation to Fmsy.

Bmsy = The biomass that provides maximum sustainable yield.

Bpa = A precautionary level to avoid Blim. As long as the stock biomass is above Bpa, the risk of reduced recruitment is considered low.

Blim = If the stock's biomass falls below this level, there is a great risk of reduced recruitment. With continued unchanged F, the stock eventually collapses.

F = Fishing mortality: The proportion of the stock that is killed by fishing.

Fmsy = A fishing pressure at or below this level is considered sustainable and is unlikely to lead to a decrease in biomass from year to year.

Fpa = A precautionary level to avoid ending up on Flim. If the fishing pressure reaches Fpa, management measures must be taken in order to protect the stock.

Flim = If a stock is fished above this level, the stock's biomass will be greatly reduced and fall below Blim.