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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Record number 444729
Title So what should a natural mortality curve look like for oysters?
Author(s) Mann, R.M.; Walles, B.; Troost, K.
Source In: 104th Anual Meeting, National Shellfisheries Association, Seattle, Washington, March 24–29, 2012. - Washington : National Shellfisheries Association - p. 317 - 317.
Event Washington : National Shellfisheries Association 104th Annual Meeting, National Shellfisheries Association, Seattle, Washington, 2012-03-24/2012-03-29
Department(s) Wageningen Marine Research
Aquaculture and Fisheries
Publication type Contribution in proceedings
Publication year 2012
Abstract Natural mortality rate (M) of a population describes the interaction of recruitment, growth and loss to environmental factors (both physical and biological). It reflects species life history traits, a product of selection over evolutionary time scales. Fishing mortality (F) describes loss to exploitation. Estimates of natural mortality in extant oyster populations arguably diverge fromthese evolved norms because of cumulative impacts of environmental degradation, age truncation by disease, and fishing. Pre-1900 literature describes very large oysters that, extrapolating from truncated modern growth curves, are suggested to have terminal ages in the 15–20 year ranges. The lengths of these oysters can be used with Hoenig plots to estimate natural mortality in preexploitation, pre-disease situations. A Hoenig plot inherently suggests a constant mortality rate with increasing age, but is this correct for oysters? We describe a length frequency distribution for an unexploited population of Crassostrea gigas, currently invading the Oosterschelde in the Netherlands, that includes representation of all size classes up to 200mm in length – an analog of a preexploitation, pre-disease population. From this demographic we suggest a probabilistic age structure and estimate age specific mortality for a long-lived, undisturbed oyster population.
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