distribution and abundance of sardine (sardina pilchardus) eggs in the english channel from continuous plankton recorder sampling, 1958–1980

Abstract

continuous plankton recorder (cpr) samples from the english channel and adjacent celtic shelf, taken over the period 1958–1980, were analysed for sardine (sardina pilchardus) eggs. results showed the progression of sardine spawning along the english channel from west to east from march to august and a return from east to west from september to november. this corresponds with the two seasonal peaks of sardine egg abundance in the western channel: the main summer peak being in may/june, with a smaller autumn peak in october/november. long-term changes in sardine egg abundance in cpr samples showed a decline in summer spawning from the late 1960s, but no clear trend in autumn-spawned egg abundance. similar patterns were observed in the numbers of sardine eggs sampled by conventional plankton net tows at the time-series station l5 off plymouth. this supports the use of the longer time-series of sardine egg data at l5 as being representative of a wider area and emphasizes the importance in continuation of the l5 time-series.

Spawning season and temperature relationships for sardine (Sardina pilchardus) in the eastern North Atlantic

“…The predictions of spawning seasons based on average annual temperature cycles are generally consistent with ¢eld observations, although with some di¡erences: for example, in the English Channel, ¢eld sampling shows a marked reduction in egg abundance in August and September (Coombs et al, 2005), which is less evident in the temperature-based predictions; in Biscay, a de¢nite autumn season from October to December is predicted from the temperature data, while only rather low and sporadic autumn spawning has been reported for this area (e.g. Sola¤ et al, 1990); ¢nally, for the north-west African regions, the predicted spawning seasons imply a rather more coherent pattern than occurs in reality, due to spatial and temporal variability in upwelling and topographic in£uences of coastal capes and bays on the current system (Binet, 1988;Ettahiri et al, 2003).…”

Long-term variability of the siphonophores Muggiaea atlantica and M. kochi in the Western English Channel

“…Standardising counts to unit volume of water sampled mitigates these factors, but some bias undoubtedly still exists (Coombs and Halliday, 2009). Nevertheless, seasonal patterns of variability remain representative (Southward, 1970;Coombs et al, 2005).…”

Changing states of North Atlantic large marine ecosystems

“…Up to the late 1980s, the northern boundary of anchovies and sardines was in the English Channel (sardines) and in Dutch waters in the southwestern corner of the North Sea (anchovies). Sardines have always been spawning in the Channel (Coombs et al 2005(Coombs et al , 2010 and the same is probably true for anchovies in the Schelde estuary and, until 1932 when it was closed by a dam, in the Zuider Sea (Boddeke and Vingerhood 1996). Stray specimen of both species have been observed occasionally at other areas of the North Sea or the western Baltic, but large quantities were not reported since the 1960s.…”