TY - JOUR
T1 - Estimating total mortality and asymptotic length of Crangon crangon between 1955 and 2006
AU - Hufnagl, Marc
AU - Temming, Axel
AU - Siegel, Volker
AU - Tulp, Ingrid
AU - Bolle, Loes
PY - 2010
Y1 - 2010
N2 - Hufnagl, M., Temming, A., Siegel, V., Tulp, I., and Bolle, L. 2010. Estimating total mortality and asymptotic length of Crangon crangon between 1955 and 2006. – ICES Journal of Marine Science, 67: 875–884.Total mortality (Z, year−1) of southern North Sea brown shrimp (Crangon crangon) was determined as Z = θK, based on the von Bertalanffy length–growth constant (K, year−1) and θ derived from length-based methods. Mortality estimates were based on length frequency distributions obtained from four long-term dataseries (1955–2006): German Demersal Young Fish Survey, Dutch Demersal Fish Survey, and two German Bycatch series (Büsum and East Frisia). Four methods to estimate θ and L∞ were evaluated. Highest total mortality (Z = 8 year−1) was estimated for the early 1990s, and the lowest (Z = 4 year−1) for the 1960s. Accounting for these differences, a median Z rather than mean values was calculated for the whole series, and the value ranged from 5.74 (Ssentongo and Larkin method), through 5.65 (Beverton and Holt method) and 5.64 (Jones and Zalinge method), to 5.35 (length-converted catch curves). Over the whole period, an increase in θ and a decrease in the proportion of shrimps >60 mm in the catch was observed, whereas asymptotic length L∞ remained constant (at 79.3 mm total length).
AB - Hufnagl, M., Temming, A., Siegel, V., Tulp, I., and Bolle, L. 2010. Estimating total mortality and asymptotic length of Crangon crangon between 1955 and 2006. – ICES Journal of Marine Science, 67: 875–884.Total mortality (Z, year−1) of southern North Sea brown shrimp (Crangon crangon) was determined as Z = θK, based on the von Bertalanffy length–growth constant (K, year−1) and θ derived from length-based methods. Mortality estimates were based on length frequency distributions obtained from four long-term dataseries (1955–2006): German Demersal Young Fish Survey, Dutch Demersal Fish Survey, and two German Bycatch series (Büsum and East Frisia). Four methods to estimate θ and L∞ were evaluated. Highest total mortality (Z = 8 year−1) was estimated for the early 1990s, and the lowest (Z = 4 year−1) for the 1960s. Accounting for these differences, a median Z rather than mean values was calculated for the whole series, and the value ranged from 5.74 (Ssentongo and Larkin method), through 5.65 (Beverton and Holt method) and 5.64 (Jones and Zalinge method), to 5.35 (length-converted catch curves). Over the whole period, an increase in θ and a decrease in the proportion of shrimps >60 mm in the catch was observed, whereas asymptotic length L∞ remained constant (at 79.3 mm total length).
U2 - 10.1093/icesjms/fsq003
DO - 10.1093/icesjms/fsq003
M3 - Journal article
VL - 67
SP - 875
EP - 884
JO - I C E S Journal of Marine Science
JF - I C E S Journal of Marine Science
SN - 1054-3139
IS - 5
ER -