The determinants of sexual segregation in the scalloped hammerhead shark,Sphyrna lewini

Klimley, A. P.

doi:10.1007/bf00002325

Cited by 245 publications

(230 citation statements)

References 14 publications

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“…The zebra sharks comprising this aggregation appear to be all reproductively mature adults as TL ranged from 1875 to 2460 mm and zebra sharks reach sexual maturity at TLs between 1470 and 1830 mm for males and 1690 and 1717 mm for females (Compagno 2002). Klimley's (1987) sexual dimorphism hypothesis predicts that oviparous species, such as the zebra shark, do not have sexual dimorphism in body size and our TL data for male and female zebra sharks supports this. We found an overall female bias in the aggregation, though the sex bias changed temporally with more males at the beginning of the aggregation season, reversing to a female bias for the duration.…”

Section: Population Descriptionsupporting

confidence: 70%

“…Furthermore, sex and size segregation in aggregations are common, and have been found to be correlated with reproductive strategy (Klimley 1987, Economakis & Lobel 1998, Sims et al 2001, Hight & Lowe 2007. Klimley (1987) found that sexual dimorphism and gender bias were more prevalent in viviparous than oviparous species, which may be due to females seeking either warmer waters to aid in gestation, or richer food sources to aid in growth for reproductive output. Sev-eral species show size segregation particularly in the use of juvenile nursery areas.…”

Section: Introductionmentioning

confidence: 99%

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Abundance and demography of a seasonal aggregation of zebra sharks Stegostoma fasciatum

Dudgeon¹,

Noad²,

Lanyon³

2008

Mar. Ecol. Prog. Ser.

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Seasonal aggregations commonly occur in the marine environment where typically wide-ranging organisms come together to exploit temporary resources or find conspecifics for mating events. The zebra shark Stegostoma fasciatum is a demersal carpet shark that aggregates over the austral summer months in the coastal waters of southeast Queensland, Australia. This study employed photo-identification and mark-recapture methods over a 3 yr period (2003 to 2006) to investigate the population size and structure of this aggregation. In total 327 individual zebra sharks were identified from 570 photographs. Numbered dart-tags on 15 zebra sharks were used to confirm that pigmentation patterns were unique and persistent in wild zebra sharks for up to 810 d. Pollock's robust design resulted in an annual population estimate of 458 individuals (95% CI = 298-618). The mean number of zebra sharks observed on a single day was 8 (± 8 SE) and the maximum number of zebra sharks seen on a single day was 34. In total, 27% of the sharks were sighted in more than one summer aggregation period and males had greater re-capture probabilities than females. The aggregation consisted exclusively of large (>1800 mm total length) adults with an overall female sex bias of 3.8:1 though sex-ratios varied temporally. Predictable visitation of large, presumably mature individuals to the site raises conservation concerns if aggregations of similar size and structure occur in regions where zebra sharks are fished.KEY WORDS: Mark-recapture · Seasonal aggregation · Zebra shark · Stegostoma fasciatum · Photo-identification · AbundanceResale or republication not permitted without written consent of the publisher

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Section: Population Descriptionsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Abundance and demography of a seasonal aggregation of zebra sharks Stegostoma fasciatum

Dudgeon¹,

Noad²,

Lanyon³

2008

Mar. Ecol. Prog. Ser.

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“…Furthermore, R. oligolinx from this study attained a greater maximum size (93.0 cm TL) than previously reported from elsewhere (80 cm TL by Abdul Nizar et al, 1988; 70 cm TL by Compagno et al, 2005; 85 cm TL by Moore et al, 2012). The difference detected between size-frequency distributions of females and males is probably a consequence of sexual segregation, a general characteristic of shark populations that is normally associated with reproduction, migration or competition (Springer, 1967;Klimley, 1987;Stevens and Mcloughlin, 1991;Motta et al, 2005).…”

Section: Length-weight Relationshipssupporting

confidence: 45%

Reproductive biology and diet of the grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhinidae) from the north-eastern Arabian Sea

et al. 2017

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Information on reproductive biology is presented for the grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhiniformes), collected off the north-west coast of India in the Arabian Sea. A total of 711 individuals, of 27.0 to 93.0 cm total length (TL), 180 to 2600 g total weight (TW) were used for the study. The lengthweight relationships were significantly different between the sexes. The size-at-maturity (Lm 50 ) for females and males was estimated to be 62.3 and 59.5 cm TL respectively. Number of embryos ranged from 1 to 7 and the size at birth was estimated between 25 to 30 cm TL. Overall sex ratio favoured the females slightly at the rate of 1.27:1. There was significant positive correlation between maternal TL and number of embryos (p<0.001). Dietary analysis of stomach contents (%IRI) revealed that R. oligolinx feeds primarily on teleosts (95.5%), cephalopods (3.2%) and crustaceans (1.2%). This study presents the first detailed biological observation on size, sex composition, size-at-maturity (Lm 50 ) and length-weight relationship of R. oligolinx from the northern Arabian Sea.

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“…Differences in home range use between males and females have also been found in some species (Bradbury et al, 1995). For several shark species, males and females have been found to segregate into single sex aggregations and this behaviour is an important factor in the structuring of populations in time and space (Klimley, 1987;Sims et al, 2001). For terrestrial animals, McLoughlin and Ferguson (2000) suggested that a hierarchical pattern of ecological and physiological factors including body size, seasonal food availability, predation and even climate change might determine home range size.…”

Section: Home Range Movementsmentioning

confidence: 99%

Movements of Marine Fish and Decapod Crustaceans: Process, Theory and Application

Pittman

McAlpine

2003

Advances in Marine Biology

217

177

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The determinants of sexual segregation in the scalloped hammerhead shark,Sphyrna lewini

Cited by 245 publications

References 14 publications

Abundance and demography of a seasonal aggregation of zebra sharks Stegostoma fasciatum

Abundance and demography of a seasonal aggregation of zebra sharks Stegostoma fasciatum

Reproductive biology and diet of the grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhinidae) from the north-eastern Arabian Sea

Movements of Marine Fish and Decapod Crustaceans: Process, Theory and Application

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