Ecological Status Report: results from the CPR Survey 2004/2005.

Using a number of ecological indices, this report summarises unusual species found, large phytoplankton blooms, changes in community structure and trends in hydrobiological indicators from regions in the North Atlantic (with an emphasis on the North Sea). In the majority of cases the term unuasual or large in referring to phytoplankton blooms refers to population increases greater than four standard deviations above the species recorded baseline mean (baseline mean: 1980-2003). Notable blooms that are geographically lareg refer to patch sizes greater then 100 km in diameter. The primary regional assessment area used to monitor changes in community structure, biomass and phenological changes is the central North Sea. Most data analysis has been performed to highlight the year 2004 in relation to the long-term dataset. 2005 sample data is presented but has not yet undergone quality checks. Annual abundance estimates were calculated for each CPR box when eight or more months were sampled, no annual estimate of abundance was calculated. Sea surface temperature was used as an indicator of ocean climate and climate change.

Spatial patterns and trends in abundance of larval sandeels in the North Sea: 1950-2005

Early recruitment indices based on larval fish data from the Continuous Plankton Recorder (CPR) have the potential to inform stock assessments of Ammodytes marinus in the North Sea. We evaluate whether the CPR data are reliable for sandeel larvae. Spatially, CPR larval data were comparable with catches by dedicated larval samplers (Gulf and bongo nets) during ICES coordinated surveys in 2004 and 2009. ICES data are also used to explore environmental influences on sandeel distributions. Temporally, CPR data correlate with larval data from plankton surveys off Stonehaven (1999–2005), with sandeel 0-group trawl data at the east Fair Isle ground (since 1984), and with recruitment data (since 1983) for the Dogger Banks stock assessment area. Therefore, CPR data may provide an early recruit index of relative abundance for the Dogger Banks assessment area, where the majority of the commercial catch of A. marinus is taken, and the Wee Bankie area that is particularly important for seabird foraging. While warm conditions may stimulate the production of sandeel larvae, their natural mortality is typically greater, in the Dogger Banks and Wadden Sea areas, when the larvae are hatched in warm years and/or with abundant 1-year-old sandeel that are likely to be cannibalistic.