Vertical distribution of the European sardine (Sardina pilchardus) larvae and its implications for their survival

This study presents results of the vertical behaviour of the European sardine (Sardina pilchardus) larvae as observed at sea off the NW Iberian coast during an oceanographic cruise conducted in May 2002. Samples were taken in a grid of 38 stations (conductivity-temperature-depth [CTD] measurements and Longhurst Hardy Plankton Recorder [LHPR] plankton hauls); a 69-h fixed station study was also performed (hourly CTD measurements and LHPR/neuston hauls every 2 h). The horizontal distribution of larvae is closely related to the circulation patterns measured by a current metre-mooring array deployed during the cruise. Larvae were mainly distributed in the upper 20-25 m of the water column, in evident association with the waters of the Western Iberia Buoyant Plume (WIBP). Large (older) larvae are found mainly in the surface layers, and larval size decreases with depth. A diel rhythm of migration to the neuston layer was observed, correlated with the inflation/deflation activity of the swim bladder. Larvae with lengths greater than 12.5 mm and inflated swim bladders were only found in this layer. Considering the near surface stratification conditions for food availability and Ekman transport in the upper few metres, even small vertical migrations of larvae can be very important for their survival and subsequent recruitment success.

[1]  A. Peliz,et al.  A study of the response of chlorophyll- a biomass to a winter upwelling event off Western Iberia using SeaWiFS and in situ data , 2005 .

[2]  P. Oliveira,et al.  Impact of a winter upwelling event on the distribution and transport of sardine (Sardina pilchardus) eggs and larvae off western Iberia: a retention mechanism , 2004 .

[3]  E. Esteves,et al.  Are sardine larvae caught off northern Portugal in winter starving? An approach examining nutritional conditions , 2003 .

[4]  N. Crato,et al.  Sardine regime shifts off Portugal: a time series analysis of catches and wind conditions , 2003 .

[5]  S. Pearre.  Eat and run? The hunger/satiation hypothesis in vertical migration: history, evidence and consequences , 2003, Biological reviews of the Cambridge Philosophical Society.

[6]  Teresa L. Rosa,et al.  Fronts, jets, and counter-flows in the Western Iberian upwelling system , 2002 .

[7]  J. Salat,et al.  Comparative study of spatial distribution patterns of the early stages of anchovy and pilchard in the NW Mediterranean Sea , 2001 .

[8]  E. K. Stenevik,et al.  Influence of buoyancy and vertical distribution of sardine Sardinops sagax eggs and larvae on their transport in the northern Benguela ecosystem , 2001 .

[9]  M. Moita.  Estrutura, variabilidade e dinâmica do Fitoplâncton na Costa de Portugal Continental , 2001 .

[10]  S. Groom,et al.  Sardine and horse mackerel recruitment and upwelling off Portugal , 2001 .

[11]  A. Fiúza,et al.  Temporal and spatial variability of CZCS-derived phytoplankton pigment concentrations off the western Iberian Peninsula , 1999 .

[12]  S. Coombs,et al.  Vertical distribution of fish eggs and larvae in the Irish Sea and southern North Sea , 1997 .

[13]  K. Thompson,et al.  Condition, buoyancy and the distribution of larval fish: implications for vertical migration and retention , 1993 .

[14]  M. Heath,et al.  Field Investigations of the Early Life Stages of Marine Fish , 1992 .

[15]  John D. Neilson,et al.  Diel vertical migrations of marine fishes: an obligate or facultative process? , 1990 .

[16]  D. Hoss,et al.  FIELD AND LABORATORYOBSERVATIONS ON DIURNAL SWIM BLADDER INFLATION-DEFLATIONIN LARVAE OF GULF MENHADEN, BREVOORTIA PATRONUS , 1984 .

[17]  R. Williams,et al.  The double LHPR system, a high speed micro- and macroplankton sampler , 1983 .

[18]  S. Coombs.  A density-gradient column for determining the specific gravity of fish eggs, with particular reference to eggs of the mackerel Scomber scombrus , 1981 .

[19]  J. Fives,et al.  Larval and post-larval stages of fishes recorded from the plankton of Galway Bay, 1972–73 , 1976, Journal of the Marine Biological Association of the United Kingdom.

[20]  J. Hunter.  Diel changes in swim bladder inflation of the larvae of the northern anchovy, Engraulis mordax. , 1976 .

[21]  I. Uotani.  Diurnal changes of gas bladder and behavior of postlarval anchovy and other related species , 1973 .

[22]  E. Worthington.  Vertical movements of fresh‐water Macroplankton , 1931 .

[23]  F. S. Russell,et al.  The Vertical Distribution of Marine Macroplankton. VIII. Further Observations on the Diurnal Behaviour of the Pelagic Young of Teleostean Fishes in the Plymouth Area , 1928, Journal of the Marine Biological Association of the United Kingdom.

[24]  F. S. Russell,et al.  The Vertical Distribution of Marine Macroplankton. III. Diurnal Observations on the Pelagic Young of Teleostean Fishes in the Plymouth Area. , 1926, Journal of the Marine Biological Association of the United Kingdom.