Determining the age and growth of fish from temperate waters from hard structures is a classical ... more Determining the age and growth of fish from temperate waters from hard structures is a classical procedure in fisheries science, with scales usually used when a nondestructive process is required. The ability to accurately determine ages from scales is therefore crucial, especially as the data generated are the foundation for determining population growth rates, mortality rates, ages at maturity, recruitment patterns, and production (Ricker 1975, Bagenal and Tesch 1978, Campana 2001)-information integral to the formulation of many fisheries management strategies. Ageing fish from scales is prone to errors arising from the subjective interpretation of their features (Mann and Steinmetz 1985). Interpretation is made difficult when, for example, annuli overlay each other at the scale margin-a common feature of scales taken from older fish-and when false checks are produced during a growth year. These factors may ultimately result in an age misclassification (Beamish 1979, Campana 2001). This paper reports on a case study regarding the effects of the subjectivity of scale ageing on subsequent growth and recruitment outputs. Research investigating the factors affecting the recruitment of roach, Rutilus rutilus (L.), in the River Stour, Essex, England, between 1969 and 1996 had revealed annually variable recruitment patterns and the infrequent recruitment of strong year classes
Determining the age and growth of fish from temperate waters from hard structures is a classical ... more Determining the age and growth of fish from temperate waters from hard structures is a classical procedure in fisheries science, with scales usually used when a nondestructive process is required. The ability to accurately determine ages from scales is therefore crucial, especially as the data generated are the foundation for determining population growth rates, mortality rates, ages at maturity, recruitment patterns, and production (Ricker 1975, Bagenal and Tesch 1978, Campana 2001)-information integral to the formulation of many fisheries management strategies. Ageing fish from scales is prone to errors arising from the subjective interpretation of their features (Mann and Steinmetz 1985). Interpretation is made difficult when, for example, annuli overlay each other at the scale margin-a common feature of scales taken from older fish-and when false checks are produced during a growth year. These factors may ultimately result in an age misclassification (Beamish 1979, Campana 2001). This paper reports on a case study regarding the effects of the subjectivity of scale ageing on subsequent growth and recruitment outputs. Research investigating the factors affecting the recruitment of roach, Rutilus rutilus (L.), in the River Stour, Essex, England, between 1969 and 1996 had revealed annually variable recruitment patterns and the infrequent recruitment of strong year classes
Determining the age and growth of fish from temperate waters from hard structures is a classical ... more Determining the age and growth of fish from temperate waters from hard structures is a classical procedure in fisheries science, with scales usually used when a nondestructive process is required. The ability to accurately determine ages from scales is therefore crucial, especially as the data generated are the foundation for determining population growth rates, mortality rates, ages at maturity, recruitment patterns, and production (Ricker 1975, Bagenal and Tesch 1978, Campana 2001)-information integral to the formulation of many fisheries management strategies. Ageing fish from scales is prone to errors arising from the subjective interpretation of their features (Mann and Steinmetz 1985). Interpretation is made difficult when, for example, annuli overlay each other at the scale margin-a common feature of scales taken from older fish-and when false checks are produced during a growth year. These factors may ultimately result in an age misclassification (Beamish 1979, Campana 2001). This paper reports on a case study regarding the effects of the subjectivity of scale ageing on subsequent growth and recruitment outputs. Research investigating the factors affecting the recruitment of roach, Rutilus rutilus (L.), in the River Stour, Essex, England, between 1969 and 1996 had revealed annually variable recruitment patterns and the infrequent recruitment of strong year classes
Determining the age and growth of fish from temperate waters from hard structures is a classical ... more Determining the age and growth of fish from temperate waters from hard structures is a classical procedure in fisheries science, with scales usually used when a nondestructive process is required. The ability to accurately determine ages from scales is therefore crucial, especially as the data generated are the foundation for determining population growth rates, mortality rates, ages at maturity, recruitment patterns, and production (Ricker 1975, Bagenal and Tesch 1978, Campana 2001)-information integral to the formulation of many fisheries management strategies. Ageing fish from scales is prone to errors arising from the subjective interpretation of their features (Mann and Steinmetz 1985). Interpretation is made difficult when, for example, annuli overlay each other at the scale margin-a common feature of scales taken from older fish-and when false checks are produced during a growth year. These factors may ultimately result in an age misclassification (Beamish 1979, Campana 2001). This paper reports on a case study regarding the effects of the subjectivity of scale ageing on subsequent growth and recruitment outputs. Research investigating the factors affecting the recruitment of roach, Rutilus rutilus (L.), in the River Stour, Essex, England, between 1969 and 1996 had revealed annually variable recruitment patterns and the infrequent recruitment of strong year classes
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Papers by Stephen Axford