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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/50215

Title: Life history traits and exploitation affect the spatial mean‐variance relationship in fish abundance
Authors: Ting-Chun Kuo
Atsushi Yamauchi
Sandip Mandal
Chih-hao Hsieh
Contributors: 國立臺灣海洋大學:海洋事務與資源管理研究所
Date: 2016-05
Issue Date: 2018-09-25T07:18:49Z
Publisher: Ecology
Abstract: Abstract: Fishing is expected to alter the spatial heterogeneity of fishes. As an effective index to quantify spatial heterogeneity, the exponent b in Taylor's power law (V = aMb) measures how spatial variance (V) varies with changes in mean abundance (M) of a population, with larger b indicating higher spatial aggregation potential (i.e., more heterogeneity). Theory predicts b is related with life history traits, but empirical evidence is lacking. Using 50‐yr spatiotemporal data from the California Current Ecosystem, we examined fishing and life history effects on Taylor's exponent by comparing spatial distributions of exploited and unexploited fishes living in the same environment. We found that unexploited species with smaller size and generation time exhibit larger b, supporting theoretical prediction. In contrast, this relationship in exploited species is much weaker, as the exponents of large exploited species were higher than unexploited species with similar traits. Our results suggest that fishing may increase spatial aggregation potential of a species, likely through degrading their size/age structure. Results of moving‐window cross‐correlation analyses on b vs. age structure indices (mean age and age evenness) for some exploited species corroborate our findings. Furthermore, through linking our findings to other fundamental ecological patterns (occupancy‐abundance and size‐abundance relationships), we provide theoretical arguments for the usefulness of monitoring the exponent b for management purposes. We propose that age/size‐truncated species might have lower recovery rate in spatial occupancy, and the spatial variance‐mass relationship of a species might be non‐linear. Our findings provide theoretical basis explaining why fishery management strategy should be concerned with changes to the age and spatial structure of exploited fishes.
Relation: 97(5) pp.1251-1259
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/50215
Appears in Collections:[海洋事務與資源管理研究所] 期刊論文

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