A continued rather remarkable comeback for the once troubled Eastern cod stock, and another slight improvement for its Western cousins, stood out as positive highlights as the ICES Advice for the 2011 Baltic Sea TACs were made public on May 28.
Moving over to MSY
For the Eastern cod stock, one of the largest in the world as late as the early 1980s, then dramatically shrinking, the scientists at the International Council for the Exploration of the Sea (ICES), gave the EU Commission, and later the EU Council, two options:
- An 87 percent increase from this year’s agreed Total Allowable Catches (TAC), if one is to follow the principle of Maximum Sustainable Yield (MSY).
- A 15 percent increase, if one is to follow the 2007 management plan.
In its TAC-setting structure, The European Union is currently shifting from the Precautionary Approach (PA) to the Maxim Sustainable Yield (MSY) framework. The PA system is based onavoiding an undesired outcome: impaired recruitment. The MSY approach is aimed at achieving adesired outcome: a high sustainable long term yield that still does not threaten recruitment.
The EU intends to have shifted in full to the MSY framework by 2015; for the duration a step-by-step transition scheme is applied. For this year’s advice, ICES gives several options for some of the stocks: one MSY/MSY Transition Scheme option; and/or one PA option; and/or one Management Plan option, if there is such a plan for the stock.
In its recent Communication on the 2011 fishing opportunities, the Commission made clear that in those cases there is a management plan for the Baltic, that alternative will be the one proposed to the Council in the end.
The European Union Fisheries ministers will have their final word on the allowed catches at their Council meeting in October.
“Eastern Cod TAC could be almost doubled”
The eastern cod stock (areas 25-32 on the ICES Map), is more than eight times larger than the western stock, but still three times smaller than in its 1980-82 heydays. Its decline was caused partly by both overfishing and worsening environmental conditions in the Baltic Sea.
Recruitment has improved in recent years: the year classes of 2003, 2006 and 2007 were all above average for the past two decades, the latter two the strongest since 1987.
A study by Stockholm University researchers in 2008 found a synergy effect: management efforts (reduced TACs) alone could not explain the improvement, nor could environmental factors; they actually reinforced each other’s effects.
The goal of the Management Plan for the Baltic cod, adopted in 2007, is a fishing mortality of F = 0.3 (fishing mortality is a measure of the number of fish killed by fishermen). F = 0.30 is also the acceptable fishing mortality when applying the MSY approach.
F sank below that level already when last year’s assessment was made, and has continued to go down (the prediction for 2010, the basis for this year’s advice, is F = 0.17).
- Applying the MSY approach (F = 0.30), ICES recommends a 2011 TAC of 105,000 tonnes, not far from a doubling of what was agreed for this year.
- The same fishing mortality is highlighted as a goal (already reached) in the management plan. But the plan also says that a TAC change from one year to another can not be bigger than 15 percent. A 15 percent bigger outtake than what was finally agreed for 2010 would be 64.400 tonnes.
One contributing factor behind the fall in fishing mortality may be a supposed decrease in discards, and a highgrading ban that was enforced in all Baltic fisheries this year. Highgrading is the discarding of marketable fish to make room on the vessel for specimens that have a higher sales value.
ICES however warns of a higher incentive/risk now for both discarding and illegal highgrading since the fishing opportunities increase, while the fishing effort – days at sea – remains the same.
Doubts also remain concerning the data on unreported catches. The estimate used in the assessments for the advice is still, in ICES’ words, “rather uncertain”. The advice puts a finger on somewhat unclear discard figures, as well. and mentions difficulties in age-reading, essential in assessing recruitment.
Western stock still hovering, at PA
The western cod stock (areas 22-24 on the ICES Map), was twice as big in the 1970s as compared to today. The two cod stocks in the Baltic are biologically distinct, although migration between the two areas has increased slightly in recent years.
For the first time in years, ICES recommended a TAC raise last year (the 2010 TAC), based on new, revised assessment figures. The management plan stipulated a 10 percent lowered fishing mortality each year until F = 0.6 is reached, which gave that TAC increase.
- The MSY option in this year’s advice is based on the MSY transition scheme for gradually reaching Fmsy by 2015. According to that scheme, the fishing mortality next year should be F = 0.63, resulting in a 2011 TAC of 18,200 tonnes, a 2.8 percent increase.
- If the management plan is to be followed, F should be lowered by 10 percent from this year’s 0.74. Translated into TAC, that would be 18,800 tonnes, a 6.2 percent raise.
On a more doubtful note, it should be noted that the Spawning Stock Biomass (SSB) for this stock – SSB is the number of reproductively mature fish – has been hovering around what is acceptable in recent years, according to the precautionary approach. The recruitment has at the best been average since 2004. Both the SSB and the total biomass is predicted to be a bit lower in 2010 than last year.
As in the advice for the eastern cod stock, ICES makes several reservations while judging the state of the western cod:
- Recruitment data do not take into considerations migration between the two Baltic stocks, which has increased.
- As for the eastern stock, discard/highgrading data may be unreliable, and age-reading is difficult.
- When ICES found that the management plan lived up to the precautionary approach, it was under the assumption that the fishing effort would be reduced and the fishing mortality lowered in line with that. ICES now finds that F has not decreased as much as anticipated, indicating that the effort reductions have not been effective.
- Signs are that significant amounts of cod are removed from the area in recreational fisheries. Those are not included in the assessments.
Baltic Herring: Mixed blessings
Herring in the Baltic Sea is managed in four separate areas, the biggest of whose stocks is the one in the Bothnian Sea (joint management with Bothnian Bay). The remaining three areas are Western Baltic and Kattegat (joint management), the central Baltic, and the Gulf of Riga.
Advice for the Western Baltic/Kattegat herring will be released later.
Central herring (areas 25-29 + 32): After more than five years of steady growth, the assessments for both 2008 and 2009 indicated a set-back, and the size of this stock in 2009 was not much more than half of the long-term average. F has been above PA since 2005, and 2002 produced the last strong year-class.
- The TAC should be decreased by 25 percent, ICES says, the MSY approach and the PA giving the same result.
Since herring is caught together with sprat in these waters, and most of the herring TACs have been taken, ICES points out that there may have been an incentive to misreport herring as sprat, the extent of which, if so, is unknown. In that case the actual fishing mortality for the herring stock may have been even higher.
In the Gulf of Riga (area 28-1), fishing mortality for the herring stock has exceeded PA again in 2009, after a rare dip below in 2008. A major factor in the sea-saw trend is the unique dependency on environmental conditions – primarily the ice cover in mild/cold winters – for the strength of the year classes. Mild winters give strong years classes (2005, 2007, 2008). The consequences of this extreme winter have yet to be assessed.
- The TAC should be decreased by 9.3 percent, ICES says, the MSY transition scheme and the PA giving the same result.
Herring from the Bothnian Sea (area 30) is for most Swedes associated with the local tradition of preparing the foul-smelling fermented herring (“surströmming”) for the fall season, starting on the third Thursday in August. That industry has lately been suffering from a size problem: a presumed ecosystem change and following nurturing problems have made the herring in the stock smaller, often not living – or growing – up to the canners’ needs.
- With fishing mortality below PA for almost 40 years and stable recruitment, however, ICES recommends an 11 percent TAC increase for 2011.
One remaining problem for this stock – and the salmon in the area – is the high dioxin content, a consequence of the many pulp mills spread along these shores.
The concentration has for many years exceeded the EU limit, but Sweden and Finland has an exemption that expires after 2011. There have been no signs that the dioxin level is going down, however: low exploitation favours a growing portion of old fish in the stock, and older fish has accumulated more dioxin.
A recent report has contended that many local fisheries would have to close down if the exception is taken away, and the Swedish Minister of Fisheries has said he will ask the Commission to prolong it.
Fishermen and cod compete for sprat
The sprat stock, the largest fish stock overall in the Baltic, is highly steered by the abundance of cod, since sprat is a main food source for the latter. With the cod stock recovering, needing sprat for food, it may be a problem that the fishing mortality for sprat in 2009 was the highest ever recorded.
- For 2011, ICES recommends a TAC decrease by 36 percent.
The current recovery of the eastern cod stock may require that future exploitation of the sprat stock will have to be reduced even more. The increase in the cod stock 2007-2008, for example, gave a 20 percent increase in predation mortality (a measure of the amount of fish eaten by other fish) for sprat.