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Marine Ecology Progress Series

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MEPS 264:57-71 (2003)  -  doi:10.3354/meps264057

Variation in age, growth and maturity in the Australian arrow squid Nototodarus gouldi over time and space‹what is the pattern?

George D. Jackson1,*, Belinda McGrath Steer1, Simon Wotherspoon2, Alistair J. Hobday3

1Institute of Antarctic and Southern Ocean Studies, University of Tasmania, Private Bag 77, Hobart, Tasmania 7001, Australia
2Department of Maths & Physics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia
3CSIRO Marine Research, GPO Box 1538, Hobart, Tasmania 7001, Australia

ABSTRACT: Age, growth and maturity parameters were examined for the southern Australian ommastrephid squid Nototodarus gouldi. Squid were obtained from the fishing ports of: Ulladulla, New South Wales; Port Lincoln, South Australia; Lakes Entrance, Victoria; and Hobart, Tasmania. Squid were collected during 2 seasonal periods: summer/autumn-caught (warm-season squid) and spring-caught (cool-season squid) over 2 consecutive years (2000, 2001). N. gouldi is a sexually dimorphic species, with females generally reaching larger sizes than males. Initial genetic analysis has found only a single species in Australian waters. Statolith ageing revealed that squid completed their life cycle in <1 yr, and appear to hatch throughout the year. Trends in size, growth and maturity varied considerably between sites, seasons and years. Squids hatched in summer/autumn grew consistently faster than squid that hatched in winter/spring, presumably due to the influence of temperature on growth. Squid in 1999/2000 also grew faster than squid in 2000/2001. Growth of female squid in winter correlated with sea surface colour (SSC) during peak hatch periods, but the SSC relationship did not exist for males. Ulladulla squid were generally smaller, younger, had smaller gonads than most other squid and were possibly a smaller morph of the species. Tasmania and Lakes Entrance tended to have larger older individuals with larger gonads, while Port Lincoln was variable and intermediate. However, during spring 2001 both Tasmania and Port Lincoln had individuals that were much smaller than those of the other seasons for these sites, and were more like those from Ulladulla. Trends in age of mature individuals showed considerable variability (over 100 d from youngest to oldest) and there appeared to be a cline across all sites and seasons. Arrow squid appear to reveal marked plasticity in age, growth and maturity parameters, but currently the extent to which the environment or genetics control plasticity is unclear.

KEY WORDS: Ommastrephid squid · Cephalopod · Population dynamics · Statoliths · Age · Growth

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