Evaluation of the instantaneous growth of juvenile smooth dogfish sharks (Mustelus canis) in their natural habitat, based on the RNA/DNA ratio

Tavares, Rafael; Lemus, Mairín; Chung, Kwansoo

doi:10.7773/cm.v32i21.1060

Cited by 3 publications

(8 citation statements)

References 12 publications

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“…Taking into consideration that mammals lactate, which could imply different RNA for females, and that calves of both species have been commonly recorded in Madeiran waters 27,68 , higher variability in the RNA/DNA ratios could be expected in females, in at least one of the seasons. However, our findings showed similar ratios between sexes, which is in agreement with a study on smooth dogfish sharks (Mustelus canis) 69 . This suggests that, contrarily to invertebrates and small fishes, the RNA directly involved in protein synthesis does not vary significantly between females and males in large top predators; yet this lacks support from further studies.…”

Section: Discussionsupporting

confidence: 93%

Ecophysiological traits of highly mobile large marine predators inferred from nucleic acid derived indices

Alves

Dromby

Baptista

et al. 2020

Sci Rep

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Nucleic acid-derived indices such as RNA/DNA ratios have been successfully applied as ecophysiological indicators to assess growth, nutritional condition and health status in marine organisms given that they provide a measure of tissue protein reserves, which is known to vary depending on changes in the environment. Yet, the use of these biochemical indices on highly mobile large predators is scarce. In this study, we tested the applicability of using nucleic acids to provide insights on the ecophysiological traits of two marine mammal species (common bottlenose dolphins and short-finned pilot whales) and explored potential related factors (species, sex, season, and residency pattern), using skin tissue (obtained from biopsy darts) of apparently healthy and adult free-ranging animals. Significantly higher RNA/DNA ratios were obtained for bottlenose dolphins (p < 0.001), and for visitor pilot whales when compared with resident pilot whales (p = 0.001). No significant changes were found between the sexes. Based on the percentile approach, the samples contain individuals in a general good condition (as the 10th percentile is not closer to the mean than the 75th percentile), suggesting that the studied region of Macaronesia may be considered an adequate habitat. The combination of this effective tool with genetic sexing and photographic-identification provided an overall picture of ecosystem health, and although with some limitations and still being a first approach, it has the applicability to be used in other top predators and ecosystems.

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Section: Discussionsupporting

confidence: 93%

Ecophysiological traits of highly mobile large marine predators inferred from nucleic acid derived indices

Alves

Dromby

Baptista

et al. 2020

Sci Rep

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“…, Baum et al 2003. Consecuentemente, es fundamental para su conservación y manejo, como para el de cualquier especie, contar con datos reproductivos que permitan asegurar que las poblaciones contribuyan a generaciones futuras (Walker 2005, Tavares et al 2006.…”

Section: Biological Measurementsunclassified

“…En los últimos 20 años se ha observado una marcada reducción de las poblaciones de varias especies objetivo o no objetivo de tiburones, rayas y mantas (Pauly et al 1998, Stevens et al 2000, Graham Baum et al 2003. Consequently, and fundamental to the conservation and management of any species, reproductive data are needed to ensure that populations contribute to future generations (Walker 2005, Tavares et al 2006.…”

Section: Introductionunclassified

Reproductive biology of the angular angel shark Squatina guggenheim (Chondrichthyes: Squatinidae) off Patagonia (Argentina, southwestern Atlantic)

et al. 2008

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The reproductive biology of the angel shark Squatina guggenheim was described based on 584 animals sampled in the San Matías Gulf, Argentina, between January and December 1996. Both sexes of S. guggenheim reached similar total length and matured at similar sizes (between 73 and 76 cm total length). In males, testes were paired and showed diametric development. Adult males were predominant in the austral autumn and winter, and were capable of mating all year round. In females, only the left ovary was functional. The maximum follicular diameter recorded (6 cm) was observed during the austral autumn and winter, with ovulation occurring during spring and summer. The size distribution of the follicles indicated that adult females presented different maturational stages in all the seasons. No post-ovulatory follicles were distinguished in any of the females examined. The seasonal analysis showed significant differences in sex abundance. Adult males were predominant in autumn and winter, juvenile males in spring, and adult females in summer. Only a few pregnant animals were caught in January, May and September. The results suggest that S. guggenheim females show a biannual reproductive cycle with gestation taking at least one year, and that the San Matías Gulf is not one of their main breeding areas.

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“…Even though RD values seemed to increase with shark’ size for the species D. profundorum , E. pusillus and S. ringens and decrease for the species D. calcea and G. melastomus , none of those relationships were significant (Supporting Information Figure S2). Previous studies attempted to apply nucleic acid‐derived indices to evaluate the nutritional condition of other elasmobranchs where an inverse relationship was found between RD values and size (Tavares et al ., 2006) and age (Cruz‐Ramírez et al ., 2017). However, we cannot establish direct comparisons with the above studies because their RD values were not standardized as in this study.…”

Section: Discussionmentioning

confidence: 99%

“…Among the most used condition indices at the organism level in marine ecology are the nucleic acid‐derived indices, such as RNA/DNA values (RD). This ratio has been successfully applied as an indicator of growth ( e.g ., Bulow, 1987; Caldarone et al ., 2003; Tavares et al ., 2006), nutritional condition ( e.g ., Alves et al ., 2020; Chícharo et al ., 2003; Chícharo & Chícharo, 1995), productivity ( e.g ., Cruz et al ., 2017), health status ( e.g ., Tavares et al ., 2006) and as an indicator of natural or anthropogenic impacts in marine populations and communities (Chícharo & Chícharo, 2008; Müller et al ., 2020). The RD values provide a short‐term measure of nutritional condition (1–3 days Buckley et al ., 1999), based on the fact that DNA concentrations within individual cells remain relatively constant (Wallace, 1992) while RNA concentrations increase as protein synthesis increases (Buckley et al ., 1999).…”

Section: Introductionmentioning

confidence: 99%

A glimpse into the trophic ecology of deep‐water sharks in an important crustacean fishing ground

Aranha

Teodósio

Baptista

et al. 2023

Journal of Fish Biology

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Deep-water sharks are among the most vulnerable deep-water taxa because of their extremely conservative life-history strategies (i.e., late maturation, slow growth, and reproductive rates), yet little is known about their biology and ecology. Thus, this study aimed at investigating the trophic ecology of five deep-water shark species, the birdbeak dogfish (Deania calcea), the arrowhead (D. profundorum), the smooth lanternshark (Etmopterus pusillus), the blackmouth catshark (Galeus melastomus) and the knifetooth dogfish (Scymnodon ringens) sampled onboard a crustacean bottomtrawler off the south-west coast of Portugal. We combined carbon and nitrogen stable isotopes with RNA and DNA (RD) ratios to investigate the main groups of prey assimilated by these species and their nutritional condition, respectively. Stable isotopes revealed overall small interspecific variability in the contribution of different taxonomic groups to sharks' tissues, as well as in the origin of their prey. S. ringens presented higher δ 15 N and δ 13 C values than the other species, suggesting reliance on bathyal cephalopods, crustaceans and teleosts; the remaining species likely assimilated bathy-mesopelagic prey. The RD ratios indicated that most of the individuals had an overall adequate nutritional condition and had recently eaten. This information, combined with the fact that stable isotopes indicate that sharks assimilated prey from the local or nearby food webs (including commercially important shrimps), suggests a potential overlap between this fishing area and their foraging grounds, which requires further attention.

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Evaluation of the instantaneous growth of juvenile smooth dogfish sharks (Mustelus canis) in their natural habitat, based on the RNA/DNA ratio

Cited by 3 publications

References 12 publications

Ecophysiological traits of highly mobile large marine predators inferred from nucleic acid derived indices

Ecophysiological traits of highly mobile large marine predators inferred from nucleic acid derived indices

Reproductive biology of the angular angel shark Squatina guggenheim (Chondrichthyes: Squatinidae) off Patagonia (Argentina, southwestern Atlantic)

A glimpse into the trophic ecology of deep‐water sharks in an important crustacean fishing ground

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