Tope Shark Galeorhinus Galeus Research Articles

First report on a pupping area of the tope shark Galeorhinus galeus (Carcharhiniformes, Triakidae) in the south-west Atlantic.

Neonates of the tope shark Galeorhinus galeus are captured in sport and recreational coastal fisheries from January to April each year in Engaño Bay (42° 58'-43° 41' S), Chubut, Argentina. The presence of these neonates is the first evidence of a pupping area for this shark in the south-west Atlantic Ocean. Knowledge of the pupping areas of chondrichthyans is important for establishing conservation measures and appropriate fishing regulations.

Microsatellite loci confirm a lack of population connectivity among globally distributed populations of the tope shark Galeorhinus galeus (Triakidae).

This study used 11 polymorphic nuclear microsatellite loci to determine the population connectivity of five geographically isolated populations of tope shark Galeorhinus galeus (Africa, Australia, North America, South America and western Europe). Genetic analyses revealed significant structure among all populations indicating a lack of population connectivity. These findings indicate that globally distributed populations of G. galeus are isolated and should be managed as distinct, independent stocks.

Patterns of extirpation. II. The role of connectivity in the decline and recovery of elasmobranch populations in the German Bight as inferred from survey data

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 25:209-223 (2014) - DOI: https://doi.org/10.3354/esr00583 Patterns of extirpation. II. The role of connectivity in the decline and recovery of elasmobranch populations in the German Bight as inferred from survey data Heino O. Fock*, Wolfgang Nikolaus Probst, Matthias Schaber Thünen-Institute of Sea Fisheries, Palmaille 9, 22767 Hamburg, Germany *Corresponding author: heino.fock@ti.bund.de ABSTRACT: Abundance trends and distribution patterns from 1902 to 1932 for 7 elasmobranch species in the German Bight (eastern central North Sea) were analyzed and compared to survey trends for 1991 to 2009. Abundances of thornback ray Raja clavata, common skate Dipturus batis, smoothhound Mustelus spp., tope shark Galeorhinus galeus, and spiny dogfish Squalus acanthias declined and common skate was extirpated, while abundances of starry ray Amblyraja radiata and lesser spotted dogfish Scyliorhinus canicula increased. A meta-population approach was developed to analyze connectivity in terms of the surrogate parameter Ĉ representing donor population Nj, separation distance Di,j, and migration range parameter α. As populations declined, connectivity between sub-populations was lost before resident populations finally collapsed. The loss of connectivity was caused by both a loss of sub-populations and a subsequent increase in the distance separating the remaining sub-populations. For lesser spotted dogfish, an increase in the donor population fostered the establishment of a local sub-population after 2000. For starry rays, an apparent increase in Nj due to a concentration of the donor population near the study area increased connectivity with the local sub-population. The interpretation of local abundances in terms of meta-population dynamics demonstrates the importance of seasonally resolved survey information for conservation planning. KEY WORDS: Meta-population models · North Sea · Fish diversity · Historic time series Full text in pdf format Supplementary material PreviousNextCite this article as: Fock HO, Probst WN, Schaber M (2014) Patterns of extirpation. II. The role of connectivity in the decline and recovery of elasmobranch populations in the German Bight as inferred from survey data. Endang Species Res 25:209-223. https://doi.org/10.3354/esr00583 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 25, No. 3. Online publication date: October 17, 2014 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2014 Inter-Research.

Diving behaviour of the critically endangered tope shark Galeorhinus galeus in the Natural Reserve of Bahia San Blas, northern Patagonia

BackgroundTope sharks (Galeorhinus galeus) aggregate in large numbers during spring and summer in closed gulfs and bays in northern Patagonia; these locations are considered the main nursery areas for the species. However, little is known about the spatial ecology or diel behaviour of this critically endangered species. The aim was to evaluate the short-term diving behaviour and habitat preferences of tope sharks using electronic tagging.FindingsFive female tope sharks, four adult and one sub-adult, were tagged with pop-up satellite archival tags in the Natural Reserve of Bahía San Blas, northern Patagonia, during spring 2011 and 2012. High-resolution archived data were collected for 40 days, including 29 days for two recovered tags. Sharks travelled up to 51.2 km after release. Archived data indicated that female tope sharks preferred to remain within 24.5 m of the surface and that there were no diel changes in preference. Individuals spent most of the time within 10 m of the surface during the day (80%) and at night (83%), and were primarily in water between 17°C and 19°C (day, 75%; night, 70%). Moreover, tope sharks exhibited vertical oscillatory movement (‘yo-yo diving’). Maximum vertical speeds and dive depths were recorded at night. Ascents from depth had a greater speed than descents, overall.ConclusionsFemale tope sharks were found in shallow coastal areas during November at Bahía San Blas, near the surface at relatively restricted depths and temperatures. Longer tracking periods will be important for describing the species’ migratory movements across the south-west Atlantic.

Antecedentes preliminares sobre la alimentación del cazón Galeorhinus galeus (Linnaeus, 1758) (Carcharhiniformes: Triakidae) en la zona centro-sur de Chile

Information on the feeding habits of the tope shark Galeorhinus galeus (Linnaeus, 1758) in Chilean waters is given. The diet of the studied specimens is based on fish and cephalopods. The most recurrent prey item was the benthopelagic fish Merluccius gayi (Guichenot, 1848), the South Pacific common hake, followed in abundance by the jumbo squid Dosidicus gigas (Orbigny, 1835).

Feeding ecology of five commercial shark species of the Celtic Sea through stable isotope and trace metal analysis

In order to trace their feeding habits, stable carbon and nitrogen isotope ratios (delta15N and delta13C), as well as trace metal concentrations (Zn, Cd, Fe, Cu, Se and Hg) were analysed in the tissues of five commercial shark species from the Celtic Sea: the tope shark Galeorhinus galeus, the black-mouthed catshark Galeus melastomus, the starry smooth hound Mustelus asterias, the spiny dogfish Squalus acanthias and the lesser-spotted dogfish Scyliorhinus canicula. Our results were compared to previously described stomach contents and isotopic composition of potential preys. Isotopic ratio delta15N suggested that tope sharks fed at a higher trophic level (16.7 per thousand in the muscle) than the other species, reflecting its piscivorous diet. The lower values of spiny dogfish (11.6 per thousand in the muscle) might be explained, amongst other things, by either its migratory behaviour or its preference for preys from lower trophic levels. Cd and Hg were correlated with isotopic ratios delta13C and delta15N, and were shown to be diet-related whereas Zn, Fe and Cu seemed much more linked to species-specific metabolism. Although this multidisciplinary approach is revealed as a useful tool for the study of shark ecology, the lack of known trophic fractionation suggests that isotopic data be compared to traditional diet analyses.