Use of parasites as biological tags for separating stocks of the starspotted dogfish Mustelus manazo in Japan and Taiwan

ABSTRACT:   The parasite fauna of Mustelus manazo from seven localitiesin Japan and Taiwan was assessed for the feasibility of using parasitesas biological tags for the identification of different host stocks.Examination of 1038 host specimens resulted in 13 parasite speciesrecorded: one nematode, two myxosporeans, two copepods and eightcestodes. Although relatively low overall prevalence of the firstfive species at different localities showed some significant differences,the samples collected in Tokyo Bay bore the lowest similarity (19.2%).These results support previous studies, which suggested the existenceof a unique host stock in Tokyo Bay. Accordingly, combinations ofprevalence data may provide useful information on stock identification.Cestodes probably have the greatest potential for use as biologicaltags. Detailed examination of 25 specimens of M .  manazo fromAomori and Tokyo Bay disclosed eight species of intestinal cestodes.A canonical discriminant analysis based on these species separatedthe two localities clearly.     

Extraction and Characterization of Collagen from Elasmobranch Byproducts for Potential Biomaterial Use

With the worldwide increase of fisheries, fish wastes have had a similar increase, alternatively they can be seen as a source of novel substances for the improvement of society’s wellbeing. Elasmobranchs are a subclass fished in high amounts, with some species being mainly bycatch. They possess an endoskeleton composed mainly by cartilage, from which chondroitin sulfate is currently obtained. Their use as a viable source for extraction of type II collagen has been hypothesized with the envisaging of a biomedical application, namely in biomaterials production. In the present work, raw cartilage from shark (Prionace glauca) and ray (Zeachara chilensis and Bathyraja brachyurops) was obtained from a fish processing company and submitted to acidic and enzymatic extractions, to produce acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC). From all the extractions, P. glauca PSC had the highest yield (3.5%), followed by ray ASC (0.92%), ray PSC (0.50%), and P. glauca ASC (0.15%). All the extracts showed similar properties, with the SDS-PAGE profiles being compatible with the presence of both type I and type II collagens. Moreover, the collagen extracts exhibited the competence to maintain their conformation at human basal temperature, presenting a denaturation temperature higher than 37 °C. Hydrogels were produced using P. glauca PSC combined with shark chondroitin sulfate, with the objective of mimicking the human cartilage extracellular matrix. These hydrogels were cohesive and structurally-stable at 37 °C, with rheological measurements exhibiting a conformation of an elastic solid when submitted to shear strain with a frequency up to 4 Hz. This work revealed a sustainable strategy for the valorization of fisheries’ by-products, within the concept of a circular economy, consisting of the use of P. glauca, Z. chilensis, and B. brachyurops cartilage for the extraction of collagen, which would be further employed in the development of hydrogels as a proof of concept of its biotechnological potential, ultimately envisaging its use in marine biomaterials to regenerate damaged cartilaginous tissues.     

Elasmobranch pericardial function. 1. Pericardial pressures are not always negative

Acute studies have led to the generalization that negative pericardial pressure is necessary for optimal cardiac function in elasmobranchs. We chronically instrumented horn sharks with pericardial catheters to test the hypothesis that ejection of pericardial fluid through the pericardioperitoneal canal (PPC) during routine handling could have accounted in part for previous measurements of exclusively negative pressures (–0.3 to –9.1 cm H₂O) in elasmobranchs. Maximum and minimum pericardial pressures measured immediately following routine handling (acute pressures) were more negative than those measured in resting horn sharks at intervals from 1 to 27 days following handling (chronic pressures). Chronic pericardial pulse pressure was less than acute. Entirely positive pericardial pressures were observed on occasion. Handling of chronically catheterized horn sharks resulted in ejection of 21 per cent (range=10–26, n=5) of the initial pericardial fluid volume through the PPC and reduced pericardial pressure. Operating pericardial fluid volume of horn sharks averaged 2.0 ml.kg^–1 (range=1.6–2.6, n=9). The PPC opened after 4.3±0.2 ml.kg^–1 (x±S.E.) of elasmobranch saline had been slowly infused into the pericardium, corresponding to an average pressure of 1.3±0.2 cm H₂O (n=10). The presence of the PPC plus a comparatively large pericardial fluid volume allows horn sharks to regulate pericardial pressure. Our analysis of pericardial pulse pressure, which can be an index of cardiac activity, suggests in contrast to previous studies that the elasmobranch heart can have relatively high stroke volumes at pericardial pressures near ambient. Thus, for venous return in resting or even moderately active elasmobranchs, it is more important that pericardial pressure be pulsatile than at a mean level which is negative.     

Branchial carbonic anhydrase is present in the dogfish, Squalus acanthias

The distribution of branchial carbonic anhydrase (CA) in the shark, Squalus acanthias, was studied using in situ measurements of pH disequilibrium states in post-branchial saline, and immunological techniques, immunofluorescence microscopy and Western analysis, employing rabbit polyclonal antibodies against rat pulmonary membrane associated CA IV and chick retinal cytosolic CA II. In the in situ saline perfused gill preparation, the CA inhibitor acetazolamide produced a pH disequilibium (0.063 ± 0.022 pH units) while control and bovine carbonic anhydrase perfusions did not (0.012 ± 0.017 and 0.023 ± 0.018 pH units, respectively). These results indicate that the HCO₃ ^- dehydration reaction is accelerate by endogenous extracellular CA. Western analysis of saline perfused gill membrane preparations revealed an immunoreactive 48 kDa band with the CA IV probe. In crude gill homogenates, a 33 kDa and 31 kDa pair of bands is identified by the CA II probe. The pattern of immunolabeling for CA II in the gill epithelium was either diffuse or punctate within both lamellar and filament epithelial cells while eyrthrocytes and pillar cells displayed a diffuse staining pattern.     

Fatty Acid Transport in Cartilaginous Fish: Absence of Albumin and Possible Utilization of Lipoproteins

There are conflicting reports over whether albumin is present in the Chondrichthyes. In addition, it is unknown whether given their low levels of extrahepatic β-oxidation, there is actually a need for a plasma FFA transport system. We examined the plasma of several Chondrichthyan species, including representatives of both the Holocephali and the Neoselachii using a combination of agarose gel electrophoresis, [¹⁴C]palmitic acid binding, SDS-PAGE, and Oil Red O staining following cellulose acetate electrophoresis. None of the eight species examined had a major acidic palmitate-binding protein with the characteristics of albumin and they all lacked proteins with the mass of albumin, 66 kDa. Palmitate was bound to specific plasma proteins in all elasmobranch species examined and these palmitate-binding proteins resembled lipoproteins based on their diffuse and variable mobilities and Oil Red O staining. These lipoproteins are potentially LDL and VLDL based on their migration positions. Albumin appears to be absent from Chondrichthyan plasma and lipoproteins bind LCFA in its absence.     

Standardized catch and survival rates,and effect of a ban on shark retention,Palau pelagic longline fishery

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Benefits of marine protected areas for tropical coastal sharks

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Estimating trends and magnitudes of bycatch in the tuna fisheries of the Western and Central Pacific Ocean

Minimising the unintended capture of fish, marine mammals, reptiles, seabirds and other marine organisms is an important component of responsible fisheries management and for stabilising declines and rebuilding populations of threatened species. The analyses presented were designed to establish the first quantitative baseline of historical catches, catch rates and species composition for the dominant tuna fisheries operating in the western and central Pacific, the world's largest in terms of tuna catch. Using records from 612,148 fishing events collected by independent ‘at sea’ observers, estimates for finfish, billfish, elasmobranchs, marine mammals and sea turtles show that the composition and magnitude of catches varied considerably by fishery type and practice for the period 2003–2019. Simulations indicated that precision in longline estimates would be improved by monitoring a proportion of fishing sets from all fishing trips rather than full coverage from a proportion of all fishing trips. While attributing reasons for temporal trends in estimated bycatch was difficult due to the confounding impacts of changing abundances and fishing practices, the trends identified the nature of potential relationships for species that are not accurately quantified, or not covered, by fishing vessel logbooks. The trends in catch estimates, and the catch rate models, have utility in identifying species which may require targeted additional analyses and management interventions, including species of conservation interest (either due to their threatened status or vulnerability to fishing) such as elasmobranchs and sea turtles. Moreover, the estimates should support future evaluations of the impact of these industrial-scale fisheries on bycatch species.     

Review. Levels of Recirculating Reproductively-related Steroid Hormones in Female Elasmobranchs. Implications for Reproduction in a Captive Environment

Chondrichthyans are a diverse group in terms of reproductive mode, which range from extended oviparity to placental viviparity. Although the reproductive biology of several species has been investigated, the reproductive physiology of only a few species has been reported. Only recently have the physiological factors of reproduction in cartilaginous fishes received attention. The information gained on reproductive cycles (both gonadal and uterine) has shown some similarities as well as differences between species. The serum levels of androgens, oestrogens, and progestins have been examined in several elasmobranch species and it has been shown that they are important in regulating key events in reproduction. The endocrine control of reproduction in elasmobranchs is more similar in many ways to higher vertebrates such as mammals than to teleosts. In general, the role of progesterone becomes more important than that of oestrogen in the transition from oviparity to viviparity. In addition, the roles of peptide hormones such as relaxin and the neurohypophysial hormones become increasingly important in viviparous species as in higher vertebrates. It is vital to understand the environmental and hormonal control of reproduction in elasmobranchs if more success is to be achieved in their reproduction in captivity. Knowledge gained from studies of the endocrine regulation of the reproductive cycle can be used to enhance the reproductive success of captive sharks, skates, and rays. This revised version was published online in August 2006 with corrections to the Cover Date.     

Interactions between the renin-angiotensin system and catecholamines on the cardiovascular system of elasmobranchs

The interaction between homologous dogfish angiotensin II ([Asn¹, Pro³, Ile⁵]-AngII) and catecholamines was examined using blood pressure bioassay. Both noradrenaline and [Asn¹, Pro³, Ile⁵]-Ang II elicited a pressor response. Pre-treatment with phentolamine (1 mg kg^-1) completely abolished the noradrenaline pressor response but did not alter the magnitude of the [Asn¹, Pro³, Ile⁵]-Ang II pressor response although there was an initial delay in the response to [Asn¹, Pro³, Ile⁵]-Ang II. These results indicate that the Ang II-induced pressor response is a direct Ang II-mediated vascular response in elasmobranchs.