Mustelus Schmitti Research Articles

The potential influence of photoperiod and temperature on the male reproductive physiology of the narrownose smooth hound shark, Mustelus schmitti

The potential influence of photoperiod and temperature on the male reproductive physiology of the narrownose smooth hound shark, Mustelus schmitti

Unraveling the environmental influence on inter-annual fishery yield in a small-scale gillnet fishery under Rio de la Plata influence, South America

The study focuses on understanding the influence of the environment on the relative yields of a gill net fishery operating in San Antonio Cape, Argentina. The research was conducted during five austral warm periods covering spring to summer from 2008 to 2013, aiming to assess the potential impacts of climate change on small-scale fisheries. The hierarchical species composition of 563 fishery landings encompasses 41 registered species. Among these species, Cynoscion guatucupa, Micropogonias furnieri, Mustelus schmitti, and Parona signata were found to be dominant. The species composition showed a similarity ranging from 36.22% to 57.59%, with significant differences observed among most of the warm seasons. The Multivariate Regression Tree analysis showed that the temperature was the variable with the greatest influence on the composition of the landings. During warmer conditions (>20.4 °C), the location of the draft became a significant factor, while variation in turbidity played a role in the northern zone. In colder warm conditions (<20.4 °C), the composition differed based on the volumes of Río de la Plata discharge. Specifically, the freshwater outflow was further differentiated by depth (∼9 m) at lower volumes (<20 649 m3/s) and by turbidity at intermediate values (20 649–22 908 m3/s). The vulnerability of the fishery was explained by a combination of specific ranges of various stressors. These stressors led to significant variations in the composition of fishery landings, ultimately affecting the economic income of the fishermen. By understanding the relationship between environmental factors and fishery yields, this study provides valuable insights into anticipating the potential impacts of climate change on small-scale, vulnerable fisheries.

Narrownose smoothhound (Mustelus schmitti) shark liver: From a residue to a high added value biocompounds

The exploration of fishery wastes for the extraction of value-added biocompounds has become a topic of current interest. The aim of this work was to promote a circular economy model by obtaining oil by enzymatic hydrolysis from Mustelus schmitti livers and incorporating it into bread. The oil extraction reaction was carried out using Alcalase® 2.4 L at pH 8.0, 55 °C of temperature for 60 min. Fatty acid analysis showed that the oil was rich in ω-3 long chain fatty acids (LCω3PUFAs), with the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) being the main constituents (13 and 70 % of total PUFAs, respectively). Then, an external gelation method was developed to produce alginate capsulates loaded with the extracted oil. The encapsulation efficiency (EE) was 93.41 %. Finally, capsulated and unencapsulated fish oil were used to develop breads and more than 95 % of EPA and DHA were recovered after baking. Thus, 20 g of baked product can provide about 45 % of the recommended minimum daily intake of EPA plus DHA. The results suggest that it is possible to use the liver from the narrownose smoothhound (Mustelus schmitti) shark fishery to produce value-added products based on a circular economy.

Bioenergetic Model of the Highly Exploited Shark Mustelus schmitti under a Global Warming Context

Bioenergetic models are tools that allow the evaluation of the effect of environmental variables on fish growth. Successful implementation of this approach has been achieved in a few elasmobranch species. Our objective was to develop a bioenergetic model for Mustelus schmitti. The model developed showed a good fit to the field data available and accurately described the growth of this species. The practical example developed in this study provides novel population estimates of prey consumption and daily ration for the species. Results also indicate that this species would be susceptible to the effects of climate change. In the simulated climate change scenarios, the energy budget of M. schmitti was significantly altered, with increased food consumption and impaired growth. While there exists a number of limitations for the model developed in this article, namely its limitation to immature individuals, and its restricted temperature model, it provides an important tool for the management of this and other shark populations under heavy exploitation.

Occurrence, behavior and the associated health risk of organochlorine pesticides in sediments and fish from Bahía Blanca Estuary, Argentina.

Organochlorine pesticides (OCPs) were assessed for their occurrence, behavior and the associated human health and ecological risks in four fish species (Micropogonias furnieri, Cynoscion guatucupa, Mustelus schmitti, and Ramnogaster arcuata) and sediments from the Bahía Blanca estuary, Argentina, an important coastal environment of South America. Total OCPs values ranged from 0.86 to 6.23ng/g dry weight in sediments and from <LOD (method detection limits) to 0.74ng/g wet weight in fish. While lindane and α-endosulfan were the dominant congeners in sediments, β-endosulfan and p,p'-DDE were dominant in fish. OCP levels and residues patterns varied within the fish species and life stage. Finally, after cancer and non-cancer risk analysis, results concluded that the consumption of fish from the estuary would pose no health threats associated with these pollutants.

Representatividad de la composición de tallas del gatuzo Mustelus schmitti (Chondrichthyes, Triakidae) capturado por la flota artesanal y de arrastre comercial en la costa atlántica uruguaya

The determination of the optimal sample size is important to obtain an adequate estimation of the size frequency distribution, as well as consistent estimators of the population parameters corresponding to the size composition, such as the mean value. In this work, the optimal sample size was determined to obtain a consistent estimate of the mean and a representative length frequencies distribution for Mustelus schmitti caught by artisanal and industrial fisheries off the Uruguayan coast. With representative samples, the mean estimators, its confidence interval, and the median with the 25 and 75% quartiles could be used to analyze temporal trends related to changes in the size structure.

The diet of Mustelus schmitti in areas with and without commercial bottom trawling (Central Patagonia, Southwestern Atlantic): Is it evidence of trophic interaction with the Patagonian shrimp fishery?

The study compares the diet composition between juveniles and adults of the narrownose smooth-hound Mustelus schmitti in areas with and without commercial bottom trawling using stomach contents. Individuals (n = 291) were caught as by-catch by the bottom-trawl shrimp fishery and by coastal sport anglers in Central Patagonia (Southwestern Atlantic between 43° and 45° S). Results showed that M. schmitti is a mesocarnivorous with a mean trophic level of 3.58. The diet was based mostly on crustaceans (decapods, stomatopods, isopods and amphipods), polychaetes, fishes and cephalopods, in a decreasing order of importance. The diet varied between juveniles and adults, and between individuals captured by the trawling fishery and sport anglers. Crabs were the main prey item observed in the stomach of individuals caught by anglers while the shrimp Pleoticus muelleri was the most consumed prey by individuals caught as by-catch. Juveniles consumed more polychaetes than adults, while the latter consumed mostly shrimp. The presence of shrimp in stomach contents of M. schmitti caught by the commercial fishery is evidence of a trophic interaction between M. schmitti and the fishery. The interaction may be due to the shark and the fleet targeting the same resource, or due to the shark using the discarded shrimp as a food source.

Seasonal distribution pattern and bioaccumulation of Polycyclic aromatic hydrocarbons (PAHs) in four bioindicator coastal fishes of Argentina

Polycyclic aromatic hydrocarbons (PAHs) are pollutants of global concern in coastal environments. They have a wide range of biological toxicity and due to their inherent properties, can easily bioaccumulate in organisms and concentrate in the environment. This work evaluated, in an integrated way, the seasonal PAH distribution patterns in sediments and four bioindicators fish species in a highly impacted estuary of Argentina; besides, their bioaccumulation patterns were assessed for the first time as indicator of ecological risk. The highest PAH levels in fish were found for Ramnogaster arcuata with an average of 64 ng g−1 w.w., followed by Micropogonias furnieri (45 ng g−1 w.w.), Cynoscion guatucupa (28 ng g−1 w.w.), and Mustelus schmitti (16 ng g−1 w.w.). Fish presented the highest PAH levels in fall with a predominance of petrogenic PAHs in colder seasons and pyrolytic PAHs in warmer seasons. Sediments presented an average of 233 ng g−1 d.w. with the same seasonal composition pattern of the fish tissues. Additionally, the data suggested that the main source of PAHs are wastewater discharges. The bioaccumulation factor (BAF) of PAHs in the tested fishes were found to range from 0.3 to 8. The highest values were observed during fall and winter, while bioaccumulation did not occur in moist spring and summer samples, which would suggest a high biotransformation process during these seasons. Results suggested that class III of juvenile C. guatucupa and M. furnieri, and adults R. arcuata are more sensitive bioindicators of chronic PAH contamination and that their bioaccumulation is independent of the compound hydrophobicity; this could have a positively influence on the criteria used for biological monitoring programs along the Atlantic coast. In addition, the presented BAF data on the target species will serve as a useful pollution indicator for South Atlantic coastal fish.

Unusual record of a multiple predation of the Patagonian seahorse Hippocampus patagonicus by the Narrownose smooth-hound Mustelus schmitti in Argentine coastal waters

Seahorses (Genus Hippocampus) are rarely reported as prey items. Their low population numbers, their ability to blend with the environment and their low palatability are the features making them an unsuitable option for predators. Five individuals of the Patagonian seahorse Hippocampus patagonicus were found in the stomach of a single narrownose smooth-hound shark Mustelus schmitti from a sample of 959 stomachs analyzed. This rare record in a single stomach out of hundreds analyzed suggests that these individuals might have clustered in a group which was detected by the opportunistic M. schmitti.

Water, sediments and fishes: First multi compartment assessment of metal pollution in a coastal environment from the SW Atlantic

This is an integrated assessment of the distribution of Cd, Cr, Hg and Pb in dissolved water, sediments and muscle fish tissues (Cynoscion guatucupa, Micropogonias furnieri, Mustelus schmitti and Ramnogaster arcuata) from the Bahía Blanca estuary, Argentina.Within the water fraction (μg L−1), Hg and Pb concentrations ranged from below the limit of detection (<LOD) to 0.53 and 54, respectively. For Cd and Cr, values varied from 0.060 to 0.56 and from 1.6 to 18, respectively. In the sediment fraction (μg g−1) values ranged from <LOD to 0.21 and 0.47 for Cd and Hg, respectively, from 11 to 18 for Cr and from 5.1 to 10 for Pb. Metals in fish muscle tissues (μg g−1) ranged from <LOD to 2.8, 0.53 and 0.52 for Cr, Hg and Pb, respectively. All Cd values were <LOD.This marine environment is potentially vulnerable to anthropogenic pollution since dissolved Cr, Hg and Pb values exceeded established environmental quality guidelines. Moreover, the sediment pollution indices indicated a deterioration of the estuarine environment, with Cr and Pb associated to anthropogenic impacts, whereas Hg could be occasionally associated with adverse biological effects.The biota to water accumulation factor (BWAF) reflected that fish species showed potential to accumulate Cr (BWAF: 73–510) and, especially, Hg (BWAF: 1000–8000). The high biota to sediment accumulation factor found for Hg (up to 9.8) indicated that fish species behaved as macro or micro concentrators.These results highlights the importance of a multi compartment approach in pollution assessment, with implicances for future works.

Uso de BRUVS para describir el ensamble de peces y su estacionalidad en dos caletas marinas poco profundas dentro de áreas protegidas de la Patagonia, Argentina

Baited Remote Underwater Video Stations (BRUVS) complemented with fishing methods were used to describe the fish assemblage and its seasonal pattern in two marine inlets from Patagonia. The combined results for BRUVS and fishing sessions identified 13 fish species. Our results agree with the biogeographic schemes proposed for the southern Southwest Atlantic. The fish species belonging to the Argentine Biogeographic Province presented a seasonal pattern with a peak of maximum abundance (Notorynchus cepedianus and Galeorhinus galeus) or were recorded during warm months only (Mustelus schmitti, Myliobatis goodei, and M. ridens), coinciding with the general latitudinal pattern expected for fish species richness. The use of BRUVS in this study allowed for the assessment of different fish species and wide range of sizes, from large sharks (N. cepedianus) to small cryptic species (Patagonotothem sp.). However, three of 13 species were only recorded by fishing methods, like it was the case for M. ridens. The record of M. ridens is the first in Patagonian waters, extending its distribution for c. 180 km south of the previously known southern limit. This study contributes to filling large data gaps along the Southwest Atlantic regarding the description and understanding of the temporal dynamics of fish assemblages in particular environments within protected areas.

Environmental influence on the inter-annual demographic variation of the narrownose smooth-hound shark (Mustelus schmitti, Springer 1939) in the Northern Argentine Coastal System (El Rincón, 38–42°S)

ABSTRACT Understanding the environmental influence on the demographic structure of a shark population within a specific ecosystem has direct implications for developing effective management and conservation measures. We studied the physical environment influence on the inter-annual demographic variation of the narrownose smooth-hound shark (Mustelus schmitti) in a key coastal ecosystem. The analyses were based on the size assemblage concept of co-occurring length classes that share common traits. We used bottom-trawl datasets (n = 334) collected over 8 spring periods (1994-2012). The analyses indicated that the population was structured in eight size assemblages that represented its main ontogenetic levels. Those corresponding to sub-adult females, young adult males, and juveniles contributed to most of the population similarity. The population structure presented high (>57.7%) inter-annual dissimilarities and showed three main similarity levels with significant differences associated with a higher abundance and similarity contribution of the main assemblages. All size assemblages were more abundant in shallow (<34.5 m), warmer (>14.9 °C), and fresher (<33.24) waters. Although the temperature variations better explained the spatial distribution of abundance, the inter-annual variation in the population similarity matched the spatial coverage of low salinities (<33.5). Overall, the environmental variation explained the variability in the abundance of size assemblages in consecutive years.

Marcación y recaptura del gatuzo (Mustelus schmitti) en el Ecosistema Costero Bonaerense (Argentina)

El presente trabajo está referido a los primeros resultados obtenidos sobre marcado y recaptura en el gatuzo, Mustelus schmitti, como medio para reconocer sus desplazamientos y migraciones en el Ecosistema Costero Bonaerense (ECB). Este tiburón es relevante no sólo por su gran abundancia a lo largo del ECB sino también por su importancia comercial para la flota pesquera de arrastre argentina. Entre noviembre de 2010 y mayo 2011 se marcaron 2.483 ejemplares cerca de Monte Hermoso, dentro del sector marino conocido como “El Rincón”, utilizando como plataforma una embarcación de la flota artesanal. Se logró recuperar 43 individuos entre 2010 y 2013. A partir del análisis de los individuos recapturados se señalaron los patrones de movimientos, migración, distribución espacial y temporal en el ECB, y además se discutieron y relacionaron dichos patrones con el ciclo de vida. Los resultados pusieron en evidencia la utilización por parte del gatuzo de áreas extensas, mayoritariamente costeras, sin alta afinidad con áreas particulares. Este es el modelo tradicional propuesto para tiburones pequeños como el gatuzo. Sin embargo, la modalidad reproductiva indicaría un ajuste al modelo señalado para grandes tiburones. Por lo tanto, el gatuzo en su comportamiento parece contener aspectos correspondientes a ambas modalidades con fidelidad por los sitios de reproducción pero sin evidencias de filopatría.

Spatio-temporal dynamics of the fish community associated with artisanal fisheries activities within a key marine protected area of the Southwest Atlantic (Uruguay)

Exploitation of fish species within marine protected areas (MPA) requires knowledge about fish and fleets dynamics in order to provide reasonable management actions. Our study analyzes a multi-specific artisanal fishery (<10 TGR) operating from La Paloma port (Uruguay, South America) within the MPA of the Rocha Lagoon Protected Landscape (MPA-RLPL) through the temporal assessment (September 2005 to January 2010) of daily catch composition, fishing gear, and fish community dynamics. Seventeen vessels operated inside and outside the MPA-RLPL and they reached 202,773 kg of total catch within that MPA. This amount represents 9.1% of landings registered in La Paloma port during the study period (5 years). Following the seasonal dynamics of catch composition and fishing gears it was revealed a differential use of this coastal protected area by the artisanal fisheries and the fish community. Higher catches of Squatina guggenheim, Mustelus schmitti, Galeorhinus galeus, Urophycis brasiliensis, Paralichtys orbignyanus, and Cynoscion guatucupa occurred from spring-summer, whereas in fall-winter, the higher catches were composed of Micropogonias furnieri (adults and juveniles), Umbrina canosai, Pomatomus saltatrix, and Parona signata. A multiclass classification tree (CART) method confirmed the strong relationship between the catch composition, fishing gear, and time of fishing (month, season); this method successfully classified the dominant catches in 72% of the sets (error = 18%, n = 294). Squatina guggenheim (a threatened coastal shark), and Micropogonias furnieri (a overexploited bony fish) were the dominant catch in most fishing sets. At the present there are no specific measures to regulate fishery activities inside the MPA of the RLPL. Thus, our study results were used to propose an adaptive strategy to management small-scale fisheries within MPAs in balance with natural resources conservation. The key role of the MPA-RLPL in conservation ecology was revealed through a comparative analysis with larger areas distributed in the jurisdictional waters of Uruguay or under binational management with Argentina.

Effects of temperature on the reproductive physiology of female elasmobranchs: The case of the narrownose smooth-hound shark (Mustelus schmitti)

The knowledge of how temperature influences elasmobranchs reproductive physiology allows a better understanding of their reproductive patterns. This study describes the relationship between temperature fluctuations and the plasmatic changes of the sex steroids related to reproduction: testosterone (T), estradiol (E2) and progesterone (P4), throughout the female reproductive cycle of the shark Mustelus schmitti. A total of 123 adult females were bi-monthly sampled in Buenos Aires, Argentina, coastal waters. Bottom temperatures were recorded at each sampling point and blood samples were taken from each female for plasma sex steroids measurement. Sex steroid plasma levels were analyzed in relation with maximum follicular diameter (MFD), uterosomatic index (USI, as indicator of pregnancy) and temperature using Generalized Additive Models. Plasmatic E2 and T increased during follicular growth until MFD reached 1.34 and 1.46 cm, respectively. Peak of T occurred at the follicular stage associated with parturition (MFD, 1.4–1.6 cm), just prior to final maturation and ovulation (MFD, 1.6–2.0 cm). Progesterone significantly increased at this last ovarian phase, while T and E2 decreased. The increase of USI with pregnancy was associated to a decrease in T and mainly E2 levels, while P4 remained unaffected. Prior to ovulation, T plasma levels decreased with temperature below to 13 °C and then increased progressively with a pronounced elevation above 17 °C, while E2 presented an opposite pattern. Progesterone plasma levels changed with temperature showing a similar pattern to that observed for T. Using M. schmitti shark as model species, this study shows a clear picture of how seawater temperature variations can affect the reproductive physiology in elasmobranch females. A hypothetical mechanism (based on T elevation driven by temperature increase and its connection by feedback with a P4 rise and parturition/ovulation induction) is proposed as evidence to support that the increase in temperature can trigger reproductive events in elasmobranchs. In addition to its ecological scope, this work contributes to reinforce the relatively scarce general knowledge of elasmobranchs reproductive physiology.

Conservation of Body Sections and Organs of the Narrownose Smooth-hound, Mustelus schmitti (Pisces, Chondrichthyes), by Silicone Injection at Room Temperature to be Used in Comparative Anatomy learning

Fil: Popp, Albertina Ines. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Bahia Blanca. Instituto de Ciencias Biologicas y Biomedicas del Sur. Universidad Nacional del Sur. Departamento de Biologia, Bioquimica y Farmacia. Instituto de Ciencias Biologicas y Biomedicas del Sur; Argentina

Metals in coastal zones impacted with urban and industrial wastes: Insights on the metal accumulation pattern in fish species

The pollution of aquatic environments is a worldwide problem of difficult solution since these areas are used for the disposal and dilution of anthropogenic wastes. This study evaluated the concentrations of Cd, Cu, Ni and Zn in the gills, liver and muscle tissues of six economically important fish species from the Bahía Blanca estuary in Argentina, a coastal environment that is under anthropogenic pressure. Metal contents in 147 fish samples were determined by digestion and a subsequent analysis with an ICP OES. The concentrations (μg/g, wet weight) of each metal in the fish tissues ranged from below the limit of detection for the four metals to 5.2 in the case of Cd, 340 for Cu, 20 for Ni, and 101 for Zn. The results suggested that metal burden in fishes varied with the species and metal elements, with Cd, Cu and Zn mean maximum accumulation towards the liver tissue. Ni showed a high number of samples with concentrations below the limit of detection. Among species, Cynoscion guatucupa was found to have the highest concentrations of Cu and Zn in the liver tissues, whereas the gills and liver tissues of Mustelus schmitti showed the lowest levels of Ni and Zn. As regards the human health risks, two samples of muscle tissue belonging to C. guatucupa reached to Cd levels that exceeded the permissible levels for human consumption. Moreover, the estimated daily intakes calculated suggest that people would not experience significant health risks from the intake of individual metals through fish consumption.

Distribution and human health risk assessment of PAHs in four fish species from a SW Atlantic estuary.

The aim of this study is to assess-for the first time-the concentration of the 16 polycyclic aromatic hydrocarbons (PAHs) in the muscle tissues of four fish species (Micropogonias furnieri, Cynoscion guatucupa, Ramnogaster arcuata, and Mustelus schmitti) from Bahía Blanca estuary, Argentina and to evaluate their sources, distribution, and the human health risks implicated. Considering the four species under study, mean total PAH concentrations showed the following decreasing accumulation trend: M. schmitti, R. arcuata, C. guatucupa, and M. furnieri. Low molecular weight PAHs, such as naphthalene and phenanthrene, were generally predominant, displaying properties of PAH mixtures generated from petrogenic pollution. Of the four fish species analyzed, M. furnieri was the only one that did not raise any human consumption warning. In the case of the other species, exceeding values were found above the safety human consumption guidelines. Nevertheless, the screening criteria for carcinogenic PAHs proposed by the USEPA indicated a good quality status for these fish species.

Age and growth of the highly exploited narrownose smooth-hound (Mustelus schmitti) (Pisces: Elasmobranchii)

Fil: Molina, Juan Manuel. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Tracing Cr, Pb, Fe and Mn occurrence in the Bahía Blanca estuary through commercial fish species

Over the last decades the anthropogenic contamination impact has substantially increased in the Bahía Blanca estuarine area, and scarce information exists regarding metals in the biotic compartment of this estuary. Thus, fish tissues were used to evaluate metal accumulation within this aquatic environment. The study focused on the determination of Cr, Pb, Fe and Mn in the gills, liver and muscle tissues of six commercial fish species (Brevoortia aurea, Odontesthes argentinensis, Micropogonias furnieri, Cynoscion guatucupa, Mustelus schmitti and Paralichthys orbignyanus).From the results it can be summarized that C. guatucupa tends to accumulate higher metal levels in the liver tissues, mostly Cr and Fe, than the other studied species. O. argentinensis and P. orbignyanus, both permanent inhabitants of the BBE, achieved the highest metal values in the gill tissues, mostly in comparison to M. schmitti. The gill tissues were found to be the main organ of Mn and Ni accumulation for most species, whereas in general, minimum concentrations were found for all the analyzed metals in the muscle tissues. Nevertheless, and according to the guidelines, all fish species showed at least one sample with concentrations of Mn and/or Cr above the permissible levels for human consumption.Finally, it was highlighted the usefulness of selecting these fish species as bioindicators of metal pollution, since they are either permanent inhabitants of the estuary or, according to the sizes under analyses, spend much of their time in this coastal waters.