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

Abstract

Lynam, C. P., Halliday, N. C., Höffle, H., Wright, P. J., van Damme, C. J. G., Edwards, M., and Pitois, S. 2013. Spatial patterns and trends in abundance of larval sandeels in the North Sea: 1950–2005 – ICES Journal of Marine Science, 70: 540–553. 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.

A Resolution to the Blue Whiting (Micromesistius poutassou) Population Paradox?

“…This work provides another example of the utility of the CPR for investigating the characteristics of fish populations [33], [50], [51]. The study of the spawning distribution of this species in this region using fisheries surveys is made extremely difficult by the large areas over which blue whiting spawn: more than 1500 km north-south and 500 km east-west.…”

Productivity and recovery of forage fish under climate change and fishing: North Sea sandeel as a case study

“…In the early 2000s, the stock biomass declined rapidly, and so did the landings and profitability of the fishery (Dickey‐Collas et al., ; Engelhard et al., ; Figure a,b). In order to promote stock recovery, the fishery has been under quota regulations for almost a decade, yet stock biomass has remained low and not returned to the productive levels of the 1980s (Engelhard et al., ; ICES, ; Lynam et al., ; Van Deurs, van Hal, Tomczak, Jónasdóttir, & Dolmer, ). Lesser sandeel in the central North Sea spend most of the year buried within the bottom sediment (Van Deurs, Hartvig, & Steffensen, ; Wright, Jensen, & Tuck, ).…”

Prey or predator—expanding the food web role of sandeel Ammodytes marinus

“…Sandeel cannibalism has been suggested as a possible explanation for the weak relationship between spawning stock biomass and recruitment in sandeel (Lynam et al 2013). The same causality has been hypothesized by Arnott & Ruxton (2002) based on their documentation of a highly negative effect of age 1 sandeels on recruitment of age 0 sandeels.…”

“…Cannibalism is widespread among teleosts (Smith & Reay 1991), and theory predicts that cannibalism in general can have profound effects on population structure and dynamics (Kohlmeier & Ebenhöh 1995, Magnússon 1999; cannibalism could thus potentially be a hitherto overlooked co-driver of forage fish population dynamics. In support, sandeel cannibalism has been suggested by Lynam et al (2013) as an explanation for the weak relationship between spawning stock biomass and recruitment in the North Sea sand eel stocks. However, reports of forage fish cannibalism are almost absent from the literature.…”