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Inter-annual plasticity of squid life-history and population structure: ecological and management implications


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Pecl, GT, Moltschaniwskyj, NA, Tracey, SR ORCID: 0000-0002-6735-5899 and Jordan, AR 2004 , 'Inter-annual plasticity of squid life-history and population structure: ecological and management implications' , Oecologica, vol. 139, no. 4 , pp. 515-524 , doi: 10.1007/s00442-004-1537-z.

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Population size and structure, as well as individual growth rates, condition, and reproductive output, respond to environmental factors, particularly in short-lived and fast-growing squid species. We need to understand the mechanisms through which populations respond to environmental conditions, to predict when or if established relationships, used as management tools to forecast recruitment strength, might break down completely.
Identifying characteristics of successful recruits who have grown under different environmental scenarios may
improve our understanding of the mechanistic connections between environmental conditions and the temporal variation in life history characteristics that ultimately affect recruitment. This 5-year study sought to determine the association between key life history characteristics of southern calamary Sepioteuthis australis (growth rate, body size, and patterns of repro-somatic energy allocation) and the environmental conditions experienced by individuals on the east coast of Tasmania, Australia. Among years, all population and individual parameters examined were highly variable, despite the environmental regime during the study not encompassing the extremes that may occur in this dynamic region. Temperature was not clearly
associated with any of the individual or population differences observed. Populations of apparently similar
abundance were composed of individuals with strikingly different biological characteristics, therefore seeking
relationships between abundance and environmental parameters at gross levels did not shed light on the
mechanisms responsible for population size. Importantly, inter-annual differences in squid size, condition, reproductive investment, and possibly growth rate, were sexspecific, indicating that males and females responded differently to similar factors. Among years differences in body size were extreme, both among the male component of the population and between genders. The relative importance of many size-based processes that contribute to population size and structure (e.g. predation, starvation, competition, and reproductive success) will therefore vary inter-annually.

Item Type: Article
Authors/Creators:Pecl, GT and Moltschaniwskyj, NA and Tracey, SR and Jordan, AR
Keywords: Temporal variability . Growth . Environmentrecruitment . Reproduction . Condition
Journal or Publication Title: Oecologica
ISSN: 0029-8549
DOI / ID Number: 10.1007/s00442-004-1537-z
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