Age, growth, and sexual maturity of two New Zealand endemic skates,<i>Dipturus nasutus</i>and<i>D. innominatus</i>

Francis, Malcolm P.; Maolagáin, Caoimhghin Ó; Stevens, Darren W.

doi:10.1080/00288330.2001.9517045

Cited by 48 publications

(53 citation statements)

References 25 publications

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“…Historically, studying the reproductive biology of elasmobranchs entailed sacrificing a relatively large number of specimens and observing the changes in gross reproductive morphology over the reproductive cycle (e.g., Hisaw and Albert 1947;Zeiner and Wolf 1993;Walmsley-Hart et al 1999;Francis et al 2001;Ebert 2005;Ruocco et al 2006). While this approach is still currently appropriate for elasmobranchs with sustainable population sizes (Heupel and Simpfendorfer 2010), it is not suitable for many because of their relatively low or unknown species abundance (IUCN 2011;Hammerschlag and Sulikowski 2011).…”

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confidence: 99%

Development of a Nonlethal and Minimally Invasive Protocol to Study Elasmobranch Reproduction

et al. 2013

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An understanding of basic reproductive biology is essential for successful species‐specific management of elasmobranch fishes (sharks, skates, and rays). Such information is often gained through gross dissection or other lethal techniques, which are not appropriate for threatened and endangered species. Previous work on other vertebrates suggested that sex steroid hormones can be extracted from muscle tissues to identify reproductive status. Collecting for muscle biopsy is quick and minimally invasive and can be done without removing an animal from the water. Thus, the objective of the current study was to determine the efficacy of using muscle steroid hormones to assess the reproductive biology of elasmobranch fishes. The results suggest that concentrations of muscle progesterone, testosterone, and estradiol can be successfully quantified to study reproduction by radioimmunoassay. Additionally, there were significant correlations between the plasma and muscle estradiol concentrations in Spiny Dogfish Squalus acanthias and the progesterone, testosterone, and estradiol concentrations in Atlantic Sharpnose Sharks Rhizoprionodon terraenovae. The present investigation thus demonstrates that skeletal muscle is a nonlethally harvestable tissue that is well suited for studying the reproductive biology of elasmobranchs. Received October 12, 2012; accepted March 12, 2013

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confidence: 99%

Development of a Nonlethal and Minimally Invasive Protocol to Study Elasmobranch Reproduction

et al. 2013

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“…Several factors have been used to estimate female maturation in elasmobranch species, including ovary weight (OW; Walmsley-Hart et al 1999;Mollet et al 2000), cloacal length (Sosebee 2005), oocyte stage or size (Fitz and Daiber 1963;Richards et al 1963;Johnson 1979;Mollet et al 2000;Francis et al 2001;Conrath and Musick 2002), histological staging, and steroid levels (Sulikowski et al 2005). Here we examine the reproductive patterns in little skate and winter skate as defined by OW and oocyte stage, using specimens collected during the spring and fall of 1999 and during all seasons of 2001-2002 in the western Atlantic from Cape Hatteras, North Carolina, to Canadian waters.…”

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Maturation of Little Skate and Winter Skate in the Western Atlantic from Cape Hatteras to Georges Bank

Frisk

Miller

2009

Mar Coast Fish

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We estimated the length and age of maturation in little skate Leucoraja erinacea and winter skate L. ocellata based on samples of 1,884 little skate and 1,153 winter skate ovaries collected from Cape Hatteras, North Carolina, to Georges Bank. Two levels of maturity were recognized: onset maturity, which marks the onset of the allocation of energy from somatic growth to reproduction; and “functional” maturity, which marks the point when mature oocytes are released. Size at maturation increased with latitude in little skate, 50% onset maturity occurring at 42.5, 43.0, and 46.5 cm (total length) and 50% functional maturity at 43, 44, and 46 cm for the mid‐Atlantic, southern New England–Georges Bank, and Gulf of Maine regions, respectively. Based on age estimates from previously published work, the age at which little skate achieve functional maturation ranged between 7.0 and 7.5 years for the U.S. northeast coast. In winter skate, no statistically significant regional differences in maturation rates were found. Size at 50% onset maturity was estimated to be 66 cm and at 50% functional maturity 76 cm for the U.S. northeast coast. In winter skate, onset maturity occurred at 9.5 years and functional maturity at 12.5 years. Thus, functional maturity in this species occurred 3 years after the onset of maturation, indicating that the species has a long adolescence before contributing offspring to the population.

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“…A variety of mineralised structures may be used for age and growth estimation in chondrichthyans, i.e., vertebrae (Francis et al, 2001;Gedamke et al, 2005;Ainsley et al, 2014;Natanson et al, 2014), dermal denticles (Moura et al, 2004;Campana et al, 2006;Serra-Pereira et al, 2008), and caudal thorns (Henderson et al, 2004;Francis & Ó Maolagáin, 2005;Arkhipkin et al, 2008;Francis & Gallagher, 2009). A popular ageing technique in elasmobranch is the sagittal-sectioning of vertebral centra from the thoracic region (Cailliet et al, 2006).…”

Section: Age Growth and Longevitymentioning

confidence: 99%

“…Intense local fisheries with unmanaged landings are often accompanied by a lack of biological information required to maintain a healthy fishing stock (Ferretti et al, 2008(Ferretti et al, , 2010, and it has been suggested that longnose skates are generally vulnerable to stock collapse even when subjected to low levels of fishing pressure (Agnew et al, 2000). (Casey & Myer, 1998;Francis et al, 2001;Dulvy et al, 2008;Dulvy & Forrest, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Skate-ing on thin ice: molecular ecology of longnose skates in the Southeast Pacific Ocean

Vargas-Caro¹

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Longnose skates may be one of the most vulnerable taxa of elasmobranch fishes, with documented local extinctions and population declines worldwide. Longnose skates are the main component of the commercial elasmobranch fisheries in the south-east Pacific Ocean, especially in Chilean waters where target and bycatch fisheries have led two species to the brink of collapse. The yellownose skate Zearaja chilensis and the roughskin skate Dipturus trachyderma are endemic of southern South America yet little is known about population ecology and stock structure.Additionally, the external morphology of longnose skates is remarkably similar, especially in early life stages, and a lack of accurate species identification has compromised official landings records which in turn has impacted fishery management. Overall abundance of longnose skates has declined substantially over the last decade due to intensive fishing pressure and the fishery is considered to be `fully exploited'.Based on all available information in peer-reviewed and grey literature, a comparative synthesis of the biology and ecology was conducted on Z. chilensis and D. trachyderma. A positive increase in relation to scientific knowledge over the past decade was noticeable, although several basic aspects of their biology and ecology are still missing. There is an urgent need to fill knowledge gaps on, for example, movement patterns, feeding ecology and habitat use, population size and structure, and levels of connectivity. In this study, taxonomic clarity was provided, and relevant information with regard to the biology, ecology and fisheries that interact with longnose skates was collated.Confusion of identity between longnose skates occurs to the present day. In order to address this issue, morphometric and genetic tools are provided to aid in species identification of early-life stage specimens. Thirty-seven morphometric measurements and three meristic characters were used to identify specimens. These results suggest that the number of midline, nuchal and inter-dorsal thorns could be used to discriminate between specimens of Z. chilensis and D. trachyderma. Previously, the presence of a single nuchal thorn was considered to be a feature that could be used to separate species, however, this morphological feature has proven to be variable in Z. chilensis. Additionally, partial sequences of the 16S, cox1, nadh2 and the control regions of the mitochondrial DNA were amplified and analysed for intraspecific and interspecific divergence. Amplified fragments of cox1 gene and the control region contained information to separate the target species; however, specimens of D. trachyderma and Z. chilensis were grouped indistinctly within a single clade using 16S and nadh2 fragments.-iiiThe evolutionary history of Zearaja was also explored, in a broad taxonomic context by using whole mitochondrial genomes (mitogenomes) to understand higher-level phylogenetic relationships among batoids. A data set of 56 mitogenomes of 47 batoids and four outgroups was analysed. O...

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Age, growth, and sexual maturity of two New Zealand endemic skates,Dipturus nasutusandD. innominatus

Cited by 48 publications

References 25 publications

Development of a Nonlethal and Minimally Invasive Protocol to Study Elasmobranch Reproduction

Development of a Nonlethal and Minimally Invasive Protocol to Study Elasmobranch Reproduction

Maturation of Little Skate and Winter Skate in the Western Atlantic from Cape Hatteras to Georges Bank

Skate-ing on thin ice: molecular ecology of longnose skates in the Southeast Pacific Ocean

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