Mystery continues to surround the state of health of a fish stock which is vital for the North Sea fleet.
For incredibly little is known about the whiting stock which, with cod and haddock, forms the traditional mixed fishery for many skippers.
The strange saga of North Sea whiting is spelled out in Marine Scotland’s new fish and shellfish stocks survey which admits that that the state of the stock is simply unknown.
But long-term information on the historical yield and catch composition, and the survey-based assessment covering the more recent period, all indicate that the present stock size is at a “historical low.”
Total mortality has been higher in the last decade than in the previous one and recruitment in the most recent years is estimated to be very low, the Scottish Government report goes on.
North Sea whiting is already giving cause for concern this year due to the speed its reduced catch quota is being netted. This year’s UK share is only 7,391 tonnes compared with 8,426 tonnes last year and around 37% of this year’s quota has already been caught.
North Sea saithe and whiting quotas are both tipped for exhaustion well before the end of this year. But whiting has been in a downward spiral for long enough and according to the report has seen North Sea catches drop from 224,000 tonnes in 1980 to 27,000 in 2008.
Localised distribution of North Sea whiting, a well-known predator of other fish species, is also known to result in substantial differences in quota uptake, resulting in the likelihood of localised discarding problems.
Meanwhile, while most stocks of nephrops in the North Sea appear to be stable according to the report, it is a different picture in the West of Scotland where the North Minch stock is being exploited “unsustainably.” Underwater TV surveys have indicated that this stock population has declined in size by around 40% over the past two years from a previous time series high in 2006.
In the South Minch the TV survey indicates that the population has declined from a record high in 2004 to a record low in 2007 but has increased in 2008. In the Clyde, the stock is being exploited unsustainably.
Meanwhile, still in the West Coast grounds, recent management of the West Coast herring fishery has been made difficult by uncertainties over the size of the total catch. Improvements in the accuracy of catch reporting would help, but poor information on landings over the last few years will continue to cause problems “for some time to come,” the study goes on.
The key North Sea haddock fishery has been assessed as being at full reproductive capacity although the spawning stock biomass has been declining since 2002. Discards of haddock from the North Sea fishery during 2006-7 were fairly substantial due to the moderately sized 2005 year class but were considerably lower in 2008, possibly due to the growth of the 2005 year class past minimum landing size. Further improvement in gear selectivity techniques would reduce the level of discards.
Due to the 2006-2008 year classes being weak the spawning stock biomass is likely to continue to decline from this year onwards although there are early indications, according to the report that the 2009 year class would be “rather better”, nevertheless it was too early to say if this would contribute to the fishable stock.
The Scottish Government’s Fish and Shellfish Stock 2010 report can be found at http://www.marlab.ac.uk/
Story from www.fishnewseu.com