Squatina argentina, argentine angelshark

The Argentine Angelshark (Squatina argentina) is a small (to 138 cm total length) demersal shark species that occurs in waters in the Southwest Atlantic from Santa Catarina, Brazil, south to Buenos Aires, Argentina. This species inhabits sandy substrates at depths of 51-320 m. The species has a relatively slow life history, giving birth to 7-11 pups with a biennial or possibly triennial reproductive cycle. The Argentine Angelshark is targeted and/or caught as bycatch in demersal trawl, gillnet, and longline fisheries, and is sold and utilized for human consumption (although angel sharks are protected in Brazil). Angel sharks are notoriously difficult to identify, and catches are typically reported at the generic level and therefore include at least three species that are native to the region (the Argentine Angelshark, the Hidden Angelshark (S. occulta), and the Angular Angelshark (S. guggenheim)). Declines in CPUE during research trawls in southern Brazil indicate that the population declined substantially in the mid-late 1990s. Further research data corroborates this, indicating the equivalent of a reduction of more than 90% over three generation lengths (46.5 years). There is also heavy fishing pressure in Uruguay and Argentina, where the Argentine Angelshark is caught alongside the Hidden Angelshark and the Angular Angelshark. Landings data indicate a reduction of angel sharks in the Argentinean-Uruguayan Common Fishing Zone of over 70% over three generations, and datasets further south in Argentina indicate a reduction of over 90% over a similar timeframe (although these landings likely consist mostly of Angular Angelshark). Due to heavy fishing pressure across its range, reported declines in landings and research surveys, and the species' low productivity, it is inferred that this species has undergone, on balance, a population reduction of at least 80% over the past three generations (46.5 years). Therefore, the Argentine Angelshark is listed as Critically Endangered A2bd. Strict regulations for limits to fisheries catch are needed, as is the identification and protection of critical habitat.Fil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Awruch, Cynthia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Barreto, R.. Instituto Chico Mendes de Conservacao Da Biodiversidade; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Faria, V.. Universidade Federal Do Ceara; BrasilFil: Paesch, L.. Dirección Nacional de Recursos Acuáticos; UruguayFil: Rincon, G.. Universidade Federal Do Maranhao.; Brasi

Chondrichthyan research in South America: Endocrinology overview and research trends over 50 years (1967–2016) compared to the rest of the world

The endocrine system plays a crucial role in regulating the activity of cells and organs among vertebrates, including the class Chondrichthyes. Accordingly, Chondrichthyan endocrinology publications have been steadily increasing in the global literature. However, while interest in South American Chondrichthyan research has been growing over the last 50 years, the field of endocrinology related to Chondrichthyans has been limited. Understanding the trajectory of a scientific discipline assists researchers and stakeholders in making decisions regarding which research areas require further attention. Further, visualisation techniques based on bibliometric analysis of scientific publications assist in understanding fluctuations in the trends of specific research fields over time. In this study, Chondrichthyan research publications over time were analysed by creating visualisation maps using VOSviewer bibliometric software. Trends in South America Chondrichthyan research with an emphasis on endocrinology were explored over a 50-year period (1967–2016). These trends were compared with Chondrichthyans research worldwide for the more recent 15-year period (2002–2016). The number of South America Chondrichthyan scientific publications increased from six during the 1967–1981 period to 112 in 2016. However, only eight papers were found published in the area of Chondrichthyan endocrinology research. Fisheries, reproduction and taxonomy were the dominate research areas in South America over the 50 years. For the more recent 15 years, South American publications comprised 11% of the total literature published globally. While South America research outputs fluctuated closely with global research trends, differences appeared when comparing areas of growth. This study describes the trends in Chondrichthyan research literature globally and more specifically in South America. Although South American countries may never contribute to the same scale as the wider international scientific community, the future of Chondrichthyans would strongly benefit from the contributions of the many diverse research groups around the world.Fil: Awruch, Cynthia Andrea. University of Tasmania; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Somoza, Gustavo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Baldock, Clive. University of Tasmania; Australi

Endocrine control of embryonic diapause in the Australian sharpnose shark Rhizoprionodon taylori

The reproductive cycle of the Australian sharpnose shark, Rhizoprionodon taylori, includes a temporary suspension of development at the commencement of embryogenesis termed embryonic diapause. This study investigated levels of 17 beta-estradiol (E-2), testosterone (T) and progesterone (P-4) in plasma samples of mature wild female R. taylori captured throughout the reproductive cycle and correlated them with internal morphological changes. Levels of T were elevated through most of the embryonic diapause period, suggesting a role of this hormone in the maintenance of this condition. Increasing plasma T concentrations from late diapause to early active development were associated with a possible role of androgens in the termination of embryonic diapause. As in other elasmobranchs, a concomitant increase of E-2 with ovarian follicle size indicated a direct role of this hormone in regulating vitellogenesis, while a peak in P-4 suggested this hormone is associated with preovulation and ovulation. Additionally, significant correlations between photoperiod or water temperature and maximum follicular diameter and hepatosomatic index suggest that these abiotic factors may also play a role triggering and regulating the synchrony and timing of reproductive events

Trophic ecology of an abundant predator and its relationship with fisheries

Trophic studies are key components in animal ecology and fisheries research. Although stomach samples are often obtained from fisheries, diet studies that consider the influence of fisheries on dietary results are still lacking. Here, the diet of the draughtboard shark Cephaloscyllium laticeps, an abundant mesopredator in Tasmanian waters, was investigated. Stomach samples were obtained from gillnet and craypot fisheries sourced from 4 regions: central (100% gillnet), east coast (63% gillnet, 37% craypot), northwest (100% gillnet), and southwest Tasmania (100% craypot). Overall, C. laticeps consumed the same prey types in all regions, but the importance of some prey varied significantly between regions. Generalized linear models showed that region was the main factor affecting prey abundance in the diet. Fishing method had some influence on the abundance of some prey (crabs, octopus, and other molluscs (gastropods and bivalves)), but the effect of fishing method on pot-related species such as Jasus edwardsii (lobster) and octopus was not as prevalent as expected. The common occurrence of C. laticeps as a bycatch species and its high consumption of targeted fishery species (lobsters and octopus) indicates that C. laticeps has a strong interaction with the fisheries. Therefore, the relationship between these fishery species and C. laticeps should be considered in food web studies in Tasmanian waters

Variables reproductivas e inmunológicas de peces marinos

Los datos refieren a variables inmunológicas y reproductivas obtenidas de muestras de sangre de peces marinos. Los datos fueron obtenidos en el marco del proyecto de investigación Estado de salud reproductiva e inmunológica en peces marinos expuestos a contaminación antrópica (PICT-2013-3006)Fil: Sueiro, Maria Cruz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Palacios, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Awruch, Cynthia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Somoza, Gustavo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin

Non-lethal assessment of reproductive characteristics for management and conservation of sharks

Chondrichthyans are one of the most vulnerable groups of marine species, with increasing numbers being listed as endangered or threatened. Fundamental to the conservation and management of any animal is an understanding of their reproduction and particularly, the size at which individuals enter the reproductive population. Size at maturity in sharks is typically obtained by macroscopic examination of the gonads after sacrificing the fish. Using the draughtboard shark Cephaloscyllium laticeps as a case study, we found that equivalent information can be obtained nondestructively using steroid hormone levels measured from a blood sample. This technique allowed us to release the shark after only 1 to 2 min of handling. A combination of plasma steroid hormone concentrations and an external measurement (total length for females and clasper length for males) was used to determine that over 90% of female and 95% of male sharks were either juveniles or adults. The estimates of size at maturity from the hormone analysis were within 3% of equivalent values of dissected sharks. Once validated, hormone levels can also be used to determine seasonal reproductive patterns for the adult population. Our results demonstrated how measurement of plasma levels of steroid hormones can provide a non-destructive method for obtaining reproductive data necessary for managing vulnerable and endangered shark species. The development of a non-destructive sampling tool also allows for improved ethical investigation into this vulnerable group of marine fishes

Endocrine and morphological correlates of reproduction in the draughtboard shark Cephaloscyllium laticeps (Elasmobranchii: Scyliorhinidae)

This study examined the endocrine and reproductive correlates of reproduction in 636 female and 468 male draughtboard sharks (Cephaloscyllium laticeps) captured from southeastern Australia. Females were oviparous and displayed a single external-type ovary with a maximum follicle diameter of 35mm. Vitellogenesis commenced at a follicle diameter of 10mm. Females showed a constant overlap between follicular recruitment, ovarian growth, and egg laying. The male reproductive tract consisted of paired testes with spermatocysts undergoing diametric\ud development. Plasma levels of the presumptive gonadal steroids, testosterone (T), 17b-estradiol (E2),\ud progesterone (P4), and 11-ketotestosterone (11-KT; males only) were correlated with morphological developmental stages of the gonads. In females, E2 increased as the follicle developed before declining as the follicle reached maturity. T remained low during the first stages of ovarian growth and increased as the follicle reached maturity. P4 showed a peak just before ovulation. In males, T was the only hormone that varied with maturity, increasing in adults; E2 and P4 were present at low plasma concentrations in males and did not change with stage of gonadal development. 11-KT was undetectable at all times. Endocrine changes in draughtboard sharks were consistent with\ud hormonal correlates reported for other species and suggest roles for E2 (in females) and T (in both sexes) in gametogenesis and P4 in maturational events in females

Identification of essential habitats: including chimaeras into current shark protected areas

1. Essential habitats are areas required to support specific functions, such as providing foraging grounds, shelter or used for reproductive purposes. For mobile aquatic species that move throughout numerous components of the seascape, identifying essential habitats within a species' broader distribution range is crucial to understanding their ecology and provide vital information needed to underpin effective conservation and management (e.g. the implementation of protected areas). 2. In Tasmania (Australia), a number of coastal habitats have been declared shark refuge areas (SRAs), where fishing for elasmobranchs (sharks, rays and skates) is prohibited. 3. Chimaeras are relatives of elasmobranchs (class Chondrichthyes) and share traits that predispose many elasmobranch species to be vulnerable to overfishing (e.g. slow growth rates and low reproductive output). However, fishing for elephantfish Callorhinchus milii (the chimaera species found in coastal Tasmania) is still permitted in SRAs. 4. Here, a combination of acoustic tracking, catch data and reproductive information was used to determine the significance of the SRA coastal habitats for C. milii. 5. Results suggest that these areas are essential habitats for reproduction and likely important for other purposes, such as foraging. 6. Given that a key strategy in managing fish stocks is protecting areas important for reproduction, and the importance of these coastal areas of Tasmania for C. milii reproductive purposes, we recommend including C. milii in current SRAs, and decreeing these areas as chondrichthyan refuge areas

Immunity and health of two wild marine fishes naturally exposed to anthropogenic pollution

There are increasing global concerns of the alarming pollution impacts on marine life, thus it is becoming essential to generate reliable tools to monitor and understand the effects of these impacts on aquatic organisms. We performed a field study assessing how exposure to anthropogenic pollution impacts immunological and health-state parameters and parasite infection of a wild marine fish, the Brazilian sandperch Pinguipes brasilianus. Then we compared this information to previously published data of a sympatric species, the Patagonian rockfish Sebastes oculatus inhabiting the same polluted and pristine areas. The field study revealed that exposed P. brasilianus showed chronic stress, poor immune condition and higher prevalence and abundance of acanthocephalan parasites. By comparing these former results with already published in S. oculatus, we concluded that, although both species exhibited physiological alterations associate to inhabiting sites exposed to pollution, their specific immunological and health-state responses differed. Our results demonstrate that Patagonian reef-fish assemblages inhabiting sites exposed to pollutant are being affected in their immune and heath condition, which could potentially result in higher susceptibility to disease and in turn population decline. These findings highlight the necessity of more studies incorporating interspecific comparisons to assess variation in fish susceptibility in an ecoimmunotoxicological context and get a more profound understanding of anthropogenic impacts on wildlife.Fil: Sueiro, Maria Cruz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Awruch, Cynthia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. University of Tasmania; AustraliaFil: Gilardoni, Carmen Mariangel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Demetrio, Muriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Palacios, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentin

Seasonality of Immunological and Health-State Parameters of Wild Broadnose Sevengill Shark, Notorynchus cepedianus

Seasonal fluctuation in environmental parameters can influence immune responses of vertebrates and consequently influence their health and disease resistance. Although seasonality of immune function is well documented in a broad range of vertebrate taxa, this information remains virtually unexplored in cartilaginous fish. Here we examine seasonal variation in immune and general-health parameters of free-living adult broadnose sevengill sharks, Notorynchus cepedianus, along an annual cycle. We sampled sharks during autumn/winter (i.e., coolest temperatures and nonreproductive period) and spring/summer (i.e., warmest temperatures and active reproductive period) and assessed aspects of immunity, general condition, and reproductive hormone levels. A seasonal influence was observed in some, but not all, parameters evaluated. Lower lymphocyte counts and higher heterophil counts and granulocyte to lymphocyte (G∶L) ratios were observed in sharks sampled during autumn/winter than in those sampled during spring/summer. On the other hand, total leukocyte counts, eosinophil counts, bacterial agglutination mediated by natural antibodies, and hematocrit did not vary seasonally. The observed seasonal patterns could be explained as (1) greater levels of stress based on the G∶L ratio, (2) a sign of immunosuppression or depressed immune investment based on the low lymphocyte counts, and/or (3) a sign of ongoing infection based on the higher heterophil counts in the colder seasons with respect to the warmer ones. In addition, the pattern is in line with the notion that while acquired components are usually depressed by lower temperatures, some innate components might increase to offset that reduction. Immune and health-state parameters were mostly independent of reproductive hormone levels, providing little support for a trade-off with reproduction. Overall, the observed seasonal pattern in immunity of broadnose sevengill sharks could be related to changes in abiotic environmental condition, such as water temperature and photoperiod, although other factors such as availability of high-quality food may play a part.Fil: Sueiro, Maria Cruz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Awruch, Cynthia Andrea. University of Tasmania; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Irigoyen, Alejo Joaquin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Argemi, Federico. Aquarium Fundación Temaikèn; ArgentinaFil: Palacios, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentin