Last updated on 9 March 2015
Presently, sprat in ICES DIvisions VIId and VIIe are managed as a unit. ICES provides corresponding advice based mainly on assessment of information from Lyme Bay, off the English coast of the Western Channel, where most of the catch occurs. Meanwhile the stock structure in the overall management unit is in question, and ICES advises that further work is needed to determine if a single stock is represented therein (ICES 2014a).
An acoustic survey was conducted in 2011 and 2012 in an area around Lyme Bay as part of a British Fisheries Science Partnership program (Van der Kooij et al., 2011, 2012), but a five year series is the minimum required to assess the status of the stock (ICES, 2012a). The Eastern Channel has also been surveyed as part of IBTS from 2006 (ICES, 2012b). A surplus production model was fitted beginning in 2012 by Centre for Environment, Fisheries & Aquaculture Science (CEFAS) researchers based on landings per unit effort (LPUE) series. ICES concluded that the LPUE series can be used as an indicator of stock trends although should be interpreted with caution when based on landings from a shoaling species such as sprat. The uncertainty associated with the index values is not available (ICES, 2013a).
Last updated on 17 April 2014
As for 2014, and based on a landings per unit effort (LPUE) index, ICES maintains that catches in 2015 should be limited to less than 3,832 tons(ICES, 2014).
For data-limited stocks for which a biomass index (i.e. lpue) is available, ICES bases advice on a comparison of the two most recent index values with the three preceding values, combined with recent catch or landings data (ICES 2012c). For this stock the landings per unit effort (lpue) was estimated to have increased by more than 20% between the periods 2008–2010 (average of the three years) and 2011–2012 (average of the two years). This implied an increase in catches of at most 20% in relation to the average catch of the earlier three years, corresponding to catches in 2014 of no more than 4,790 tons.However, considering the stock’s unknown exploitation status,precautionary 20% buffer was applied, resulting in catches of no more than 3,832 tons in 2014. New lpue data did not alter the perception of the stock; thus advised catches for 2015 are unchanged. Previously, ICES had advised in qualitative terms, for a reduction in catches (ICES, 2011a).
ICES has conducted exploratory analysis to develop models that would incorporate acoustic survey data along with catch data; however these models are not yet acceptable for formal stock assessment (ICES 2015).ICES acknowledges that their scientific advice for sprat could be better informed if a longer time series of the acoustic data became available, but meanwhile the lpue series remains the best available indicator of stock trends.
Last updated on 17 Apr 2014
No precautionary reference points have been defined. Recently, surplus production models incorporating landing per unit effort (LPUE) and acoustic survey data have been used to estimate Maximum sustainable yield (MSY). In 2013, MSY was estimated to be 3,094 tonnes(ICES 2013C), and an updated analysis in 2014 did not result in changes to this estimate (2014b).
Last updated on 12 March 2015
Due to the lack of fishery-independent data, there is insufficient information with which thoroughly assess the status of the stock.However, the average LPUE of mid-water trawl is considered to be a stock size indicator (kg hour−1). In recent years (2011–2012) it was 137% higher than the average of the three previous years (2008–2010) (ICES, 2013a).
The second of two sprat population assessments from acoustic survey data was published in 2012, and reported an estimated biomass of 27,971 tons for that year, and a revised estimate of 33,861 tons for 2011 (Van der Kooij et al., 2012). The 2013 annual landings of 3,793t would constitute only a relatively small fraction of the 2012 biomass estimate (ICES 2014a), an amount well below the 30% which is determined to be supportable by other low-trophic level species such as sardine and anchovy (ICES, 2012b). However, while the acoustic survey data has yielded estimates that are comparable to the mid-water trawl LPUE, several more years of data are needed before stock status can be reliably evaluated based on this information(ICES 2013a).
Last updated on 12 Mar 2015
Landings have averaged 3,017 tons over the recent 20-year time series (ICES 2014a). Occasional large catches have been reported, the largest at 7,215 tons in 1992, and over 5,000 tons in 1988, 1994, 1998 and 1999 (sum of official landings by country, (ICES 2013a)). The lowest catches were 840 tons reported in 2004. Since then, an increasing trend has occurred, reaching 4,435 tons in 2012.