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Nautilus pompilius life history and demographics at the Osprey Reef Seamount, Coral Sea, Australia.

Dunstan AJ, Ward PD, Marshall NJ - PLoS ONE (2011)

Bottom Line: We found sexual dimorphism in size at maturity (males: 131.9±SD = 2.6 mm; females: 118.9±7.5 mm shell diameter) in a population dominated by mature individuals (58%).Mean growth rates of 15 immature recaptured animals were 0.061±0.023 mm day(-1) resulting in an estimate of around 15.5 years to maturation.Our results provide strong evidence of a K-selected life history for Nautilus from a detailed study of a 'closed' wild population.

View Article: PubMed Central - PubMed

Affiliation: School of Biomedical Science, University of Queensland, Brisbane, Queensland, Australia. andy.dunstan@gmail.com

ABSTRACT
Nautiloids are the subject of speculation as to their threatened status arising from the impacts of targeted fishing for the ornamental shell market. Life history knowledge is essential to understand the susceptibility of this group to overfishing and to the instigation of management frameworks. This study provides a comprehensive insight into the life of Nautilus in the wild. At Osprey Reef from 1998-2008, trapping for Nautilus was conducted on 354 occasions, with 2460 individuals of one species, Nautilus pompilius, captured and 247 individuals recaptured. Baited remote underwater video systems (BRUVS) were deployed on 15 occasions and six remotely operated vehicle (ROV) dives from 100-800 m were conducted to record Nautilus presence and behavior. Maturity, sex and size data were recorded, while measurements of recaptured individuals allowed estimation of growth rates to maturity, and longevity beyond maturity. We found sexual dimorphism in size at maturity (males: 131.9±SD = 2.6 mm; females: 118.9±7.5 mm shell diameter) in a population dominated by mature individuals (58%). Mean growth rates of 15 immature recaptured animals were 0.061±0.023 mm day(-1) resulting in an estimate of around 15.5 years to maturation. Recaptures of mature animals after five years provide evidence of a lifespan exceeding 20 years. Juvenile Nautilus pompilius feeding behavior was recorded for the first time within the same depth range (200-610 m) as adults. Our results provide strong evidence of a K-selected life history for Nautilus from a detailed study of a 'closed' wild population. In conjunction with population size and density estimates established for the Osprey Reef Nautilus, this work allows calculations for sustainable catch and provides mechanisms to extrapolate these findings to other extant nautiloid populations (Nautilus and Allonautilus spp.) throughout the Indo-Pacific.

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Size frequency distribution for Nautilus pompilius at Osprey Reef.Size frequency records for 2067 individuals range from 76 to 145 mm with a mean of 128.6±28.01 mm. Mature male and female mean shell lengths are shown.
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pone-0016312-g002: Size frequency distribution for Nautilus pompilius at Osprey Reef.Size frequency records for 2067 individuals range from 76 to 145 mm with a mean of 128.6±28.01 mm. Mature male and female mean shell lengths are shown.

Mentions: 2067 captured individuals were measured for maximum shell diameter. The results show a distribution dominated by mature or near-mature animals (Fig. 2). This is a left-skewed distribution due to size based sexual dimorphism, minimized by the low percentage of females in the sample population (Fig. 3). Note that juveniles of less than 80 mm shell diameter (<50 mm shell width) were able to escape the trap mesh and are under-estimated by this sampling method.


Nautilus pompilius life history and demographics at the Osprey Reef Seamount, Coral Sea, Australia.

Dunstan AJ, Ward PD, Marshall NJ - PLoS ONE (2011)

Size frequency distribution for Nautilus pompilius at Osprey Reef.Size frequency records for 2067 individuals range from 76 to 145 mm with a mean of 128.6±28.01 mm. Mature male and female mean shell lengths are shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3037366&req=5

pone-0016312-g002: Size frequency distribution for Nautilus pompilius at Osprey Reef.Size frequency records for 2067 individuals range from 76 to 145 mm with a mean of 128.6±28.01 mm. Mature male and female mean shell lengths are shown.
Mentions: 2067 captured individuals were measured for maximum shell diameter. The results show a distribution dominated by mature or near-mature animals (Fig. 2). This is a left-skewed distribution due to size based sexual dimorphism, minimized by the low percentage of females in the sample population (Fig. 3). Note that juveniles of less than 80 mm shell diameter (<50 mm shell width) were able to escape the trap mesh and are under-estimated by this sampling method.

Bottom Line: We found sexual dimorphism in size at maturity (males: 131.9±SD = 2.6 mm; females: 118.9±7.5 mm shell diameter) in a population dominated by mature individuals (58%).Mean growth rates of 15 immature recaptured animals were 0.061±0.023 mm day(-1) resulting in an estimate of around 15.5 years to maturation.Our results provide strong evidence of a K-selected life history for Nautilus from a detailed study of a 'closed' wild population.

View Article: PubMed Central - PubMed

Affiliation: School of Biomedical Science, University of Queensland, Brisbane, Queensland, Australia. andy.dunstan@gmail.com

ABSTRACT
Nautiloids are the subject of speculation as to their threatened status arising from the impacts of targeted fishing for the ornamental shell market. Life history knowledge is essential to understand the susceptibility of this group to overfishing and to the instigation of management frameworks. This study provides a comprehensive insight into the life of Nautilus in the wild. At Osprey Reef from 1998-2008, trapping for Nautilus was conducted on 354 occasions, with 2460 individuals of one species, Nautilus pompilius, captured and 247 individuals recaptured. Baited remote underwater video systems (BRUVS) were deployed on 15 occasions and six remotely operated vehicle (ROV) dives from 100-800 m were conducted to record Nautilus presence and behavior. Maturity, sex and size data were recorded, while measurements of recaptured individuals allowed estimation of growth rates to maturity, and longevity beyond maturity. We found sexual dimorphism in size at maturity (males: 131.9±SD = 2.6 mm; females: 118.9±7.5 mm shell diameter) in a population dominated by mature individuals (58%). Mean growth rates of 15 immature recaptured animals were 0.061±0.023 mm day(-1) resulting in an estimate of around 15.5 years to maturation. Recaptures of mature animals after five years provide evidence of a lifespan exceeding 20 years. Juvenile Nautilus pompilius feeding behavior was recorded for the first time within the same depth range (200-610 m) as adults. Our results provide strong evidence of a K-selected life history for Nautilus from a detailed study of a 'closed' wild population. In conjunction with population size and density estimates established for the Osprey Reef Nautilus, this work allows calculations for sustainable catch and provides mechanisms to extrapolate these findings to other extant nautiloid populations (Nautilus and Allonautilus spp.) throughout the Indo-Pacific.

Show MeSH
Related in: MedlinePlus