The objectives of this study were to assess the density and biomass of a local population of Cancer polyodon in La Herradura Bay, Chile, and to describe its population dynamics: growth (absolute and relative), mortality (natural and fishing) and spawning. Female crabs grew at a higher von Bertalanffy growth rate (k = 0.57) but reached a smaller asymptotic size (CW(infinity) = 160.5 mm) than males (k = 0.54, CW(infinity) = 198). A parallel growth study in the laboratory yielded higher k and and lower CW(infinity) values than for wild specimens and lower values for the growth performance index-phi'. For both sexes, relative growth (post-moult/pre-moult relationship) was better described by a 2-line model instead of a single 'Hiatt-line'. The intersection of the 2 lines is suspected to mark the onset of gonad formation. Age at massive maturity is ca 2 yr in females and males (at 98 and 124 mm CW respectively). Males seem to moult 16 times and females 14 times after the megalopa stage. Spawning occurred over most of the year with pulses in winter and early summer. Average total mortality (Z) was higher in males (2.58) than in females (1.85). A tendency of Z to increase with age indicates that larger specimens are more vulnerable to the traps or have a higher rate of natural mortality (M). M for both sexes was estimated to be between 0.75 and 1.1. Mean annual biomass estimated from Jones' length cohort analysis was 2.4 times and spawning biomass 4 times higher in females than in males. Using the turnover ratio (Z = P/B) an average annual production of 221 g m-2 (fresh weight) was estimated from the density data.
Wolff M. and Soto M. (1992) Population dynamics of Cancer polyodon in La Herradura Bay, northern Chile. Marine Ecology Progress Series 85: 69-81. 10.3354/meps085069
@article{Wolff1992,
Title = {Population dynamics of Cancer polyodon in La Herradura Bay, northern Chile},
Author = {Wolff, Matthias and Soto, M},
Editor = {},
Journal = {Marine Ecology Progress Series},
Year = {1992},
Pages = {69-81},
Volume = {85},
Doi = {10.3354/meps085069},
Abstract = {The objectives of this study were to assess the density and biomass of a local population of Cancer polyodon in La Herradura Bay, Chile, and to describe its population dynamics: growth (absolute and relative), mortality (natural and fishing) and spawning. Female crabs grew at a higher von Bertalanffy growth rate (k = 0.57) but reached a smaller asymptotic size (CW(infinity) = 160.5 mm) than males (k = 0.54, CW(infinity) = 198). A parallel growth study in the laboratory yielded higher k and and lower CW(infinity) values than for wild specimens and lower values for the growth performance index-phi'. For both sexes, relative growth (post-moult/pre-moult relationship) was better described by a 2-line model instead of a single 'Hiatt-line'. The intersection of the 2 lines is suspected to mark the onset of gonad formation. Age at massive maturity is ca 2 yr in females and males (at 98 and 124 mm CW respectively). Males seem to moult 16 times and females 14 times after the megalopa stage. Spawning occurred over most of the year with pulses in winter and early summer. Average total mortality (Z) was higher in males (2.58) than in females (1.85). A tendency of Z to increase with age indicates that larger specimens are more vulnerable to the traps or have a higher rate of natural mortality (M). M for both sexes was estimated to be between 0.75 and 1.1. Mean annual biomass estimated from Jones' length cohort analysis was 2.4 times and spawning biomass 4 times higher in females than in males. Using the turnover ratio (Z = P/B) an average annual production of 221 g m-2 (fresh weight) was estimated from the density data.},
}
TY - JOUR
AU - Wolff, Matthias
AU - Soto, M
TI - Population dynamics of Cancer polyodon in La Herradura Bay, northern Chile
T2 - Marine Ecology Progress Series
PY - 1992
SP - 69-81
VL - 85
DO - 10.3354/meps085069
AB - The objectives of this study were to assess the density and biomass of a local population of Cancer polyodon in La Herradura Bay, Chile, and to describe its population dynamics: growth (absolute and relative), mortality (natural and fishing) and spawning. Female crabs grew at a higher von Bertalanffy growth rate (k = 0.57) but reached a smaller asymptotic size (CW(infinity) = 160.5 mm) than males (k = 0.54, CW(infinity) = 198). A parallel growth study in the laboratory yielded higher k and and lower CW(infinity) values than for wild specimens and lower values for the growth performance index-phi'. For both sexes, relative growth (post-moult/pre-moult relationship) was better described by a 2-line model instead of a single 'Hiatt-line'. The intersection of the 2 lines is suspected to mark the onset of gonad formation. Age at massive maturity is ca 2 yr in females and males (at 98 and 124 mm CW respectively). Males seem to moult 16 times and females 14 times after the megalopa stage. Spawning occurred over most of the year with pulses in winter and early summer. Average total mortality (Z) was higher in males (2.58) than in females (1.85). A tendency of Z to increase with age indicates that larger specimens are more vulnerable to the traps or have a higher rate of natural mortality (M). M for both sexes was estimated to be between 0.75 and 1.1. Mean annual biomass estimated from Jones' length cohort analysis was 2.4 times and spawning biomass 4 times higher in females than in males. Using the turnover ratio (Z = P/B) an average annual production of 221 g m-2 (fresh weight) was estimated from the density data.
ER -
