Size,growth, temperature and the natural mortality of marine fish |
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Authors: | Henrik Gislason Niels Daan Jake C Rice John G Pope |
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Institution: | 1. National Institute of Aquatic Resources, Technical University of Denmark, Charlottenlund Slot, DK‐2920 Charlottenlund, Denmark;2. Institute for Marine Resources and Ecosystem Studies, PO Box 68, 1970 AB IJmuiden, The Netherlands;3. DFO Science Advisory Secretariat, Department of Fisheries and Oceans, 200 Kent Street, Ottawa, ON, Canada K1A 0E6;4. Norwegian College of Fishery Science, University of Troms?, N‐9000 Troms?, Norway |
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Abstract: | The natural mortality of exploited fish populations is often assumed to be a species‐specific constant independent of body size. This assumption has important implications for size‐based fish population models and for predicting the outcome of size‐dependent fisheries management measures such as mesh‐size regulations. To test the assumption, we critically review the empirical estimates of the natural mortality, M (year?1), of marine and brackish water fish stocks and model them as a function of von Bertalanffy growth parameters, L (cm) and K (year?1), temperature (Kelvin) and length, L (cm). Using the Arrhenius equation to describe the relationship between M and temperature, we find M to be significantly related to length, L and K, but not to temperature (R2 = 0.62, P < 0.0001, n = 168). Temperature and K are significantly correlated and when K is removed from the model the temperature term becomes significant, but the resulting model explains less of the total variance (R2 = 0.42, P < 0.0001, n = 168). The relationships between M, L, L, K and temperature are shown to be in general accordance with previous theoretical and empirical investigations. We conclude that natural mortality is significantly related to length and growth characteristics and recommend to use the empirical formula: ln(M) = 0.55 ? 1.61ln(L) + 1.44ln(L) + ln(K), for estimating the natural mortality of marine and brackish water fish. |
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Keywords: | Asymptotic length fish growth length natural mortality temperature |
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