Seafish Insight Blog: Why it's OK to eat North Sea and West of Scotland haddockSubscribe
Posted by Bill Lart, Sustainability and Data Advisor on 17 March 2017
Since around 2007, spawning stock biomass (SSB) has been above the reference point for maximum sustainable yield (MSY) with fishing mortality being lower than the MSY reference point (the basis for a well-managed sustainable fishery).
During the 2016 stock assessment an error in the assessment model was discovered. In addressing this matter, fisheries scientists at the International Council for the Exploration of the Seas (ICES) corrected the statistical model, reviewed the reference points for fishing mortality and reassessed the advice.
The reassessment showed that the spawning stock biomass had been above the reference point for maximum sustainable yield (MSYB trigger) for the period 2002 until 2015, but the target fishing mortality (or fishing pressure), which is the rate at which the fish are harvested, was set too high at approximately twice the rate it should be for Maximum Sustainable Yield (FMSY). The reassessment took into account the consistently lower levels of recruitment of young fish since 2000. When implemented, such a rate would enable better survival of haddock to maturity and hence potentially better reproduction and improved sustainability.
In the 2016 reassessment, this stock was assessed by ICES to be in the 'at risk' category; this means there was a risk of the spawning stock biomass being below the level required to sustain a fishery while the fishing pressure was also too high. The ICES advice for total catch in 2017 was 39,461 tonnes which is consistent with maximum sustainable yield (F at FMSY of 0.19 in 2017) and includes 6071 tonnes which was expected to have been discarded.
However, all vessels in the North Sea in 2017 using gear of 100 mm or more (whitefish) and 80-99 mm gear (Nephrops) will need to land all haddock, and vessels targeting cod, haddock, whiting and saithe in West of Scotland waters will also need to land all their catches of haddock. These fisheries account for most of the haddock catch so that provided The Landing Obligation is adhered to we can expect the total catches to be close to the agreed Total Allowable Catch (TAC).
The EU-Norway agreed TAC is 39,409 tonnes. If this number is the total catch then the projected spawning stock biomass in 2018 is expected to be 205,595 tonnes which is above the reference point for maximum sustainable yield (MSYBtrigger) of 132,000 tonnes and not in the at risk category.
We would need to catch 119,463 tonnes in 2017 to drive the stock to MSYBtrigger in 2018. The above results suggest that there is some margin for error; the main imperative is to aim for a lower rate of fishing mortality, which should enhance future sustainability.