TY - JOUR
T1 - Between-year variability in the mixing of North Sea herring spawning components leads to pronounced variation in the composition of the catch
AU - Bierman, Stijn M.
AU - Dickey-Collas, Mark
AU - van Damme, Cindy J.G.
AU - van Overzee, Harriët M.J.
AU - Pennock-Vos, M.G.
AU - Tribuhl, Silja V.
AU - Worsøe Clausen, Lotte
PY - 2010
Y1 - 2010
N2 - North Sea herring (Clupea harengus) are managed as a single stock, but maintaining a diversity of spawning components is considered important. However, the total catch from each of these components cannot be estimated easily because the components mix during the summer feeding season. The spawning origin of herring is determined from patterns in the microstructure of the otolith core, from samples taken in the central and northern North Sea during summer of 2004–2007. The annual catch composition of Dutch vessels is determined within a statistical framework that takes account of the spatial patterns in mixing of spawning components and the classification success of the method. Mixing of components varied between years, with steep latitudinal gradients in compositions in some years, resulting in pronounced between-year differences in estimated catch compositions. Differences in lengths-at-age between spawning components, in particular of the 2000 year class, may have caused the observed between-year changes in mixing of components. Our results indicate that estimates of compositions change when assumptions of perfect spatial mixing and perfect classification are relaxed, and can be uncertain in particular as a result of misclassifications, and that it may not be appropriate to assume that ratios between components are constant through time.
AB - North Sea herring (Clupea harengus) are managed as a single stock, but maintaining a diversity of spawning components is considered important. However, the total catch from each of these components cannot be estimated easily because the components mix during the summer feeding season. The spawning origin of herring is determined from patterns in the microstructure of the otolith core, from samples taken in the central and northern North Sea during summer of 2004–2007. The annual catch composition of Dutch vessels is determined within a statistical framework that takes account of the spatial patterns in mixing of spawning components and the classification success of the method. Mixing of components varied between years, with steep latitudinal gradients in compositions in some years, resulting in pronounced between-year differences in estimated catch compositions. Differences in lengths-at-age between spawning components, in particular of the 2000 year class, may have caused the observed between-year changes in mixing of components. Our results indicate that estimates of compositions change when assumptions of perfect spatial mixing and perfect classification are relaxed, and can be uncertain in particular as a result of misclassifications, and that it may not be appropriate to assume that ratios between components are constant through time.
KW - Clupea harengus
KW - Downs herring
KW - catch composition
KW - spawning origin
KW - North Sea herring
KW - classification uncertainty
U2 - 10.1093/icesjms/fsp300
DO - 10.1093/icesjms/fsp300
M3 - Journal article
VL - 67
SP - 885
EP - 896
JO - I C E S Journal of Marine Science
JF - I C E S Journal of Marine Science
SN - 1054-3139
IS - 5
ER -