New information from fish diets on the importance of glassy flying squid (Hyaloteuthis pelagica) (Teuthoidea: Ommastrephidae) in the epipelagic cephalopod community of the tropical Atlantic Ocean

Squids of the family Ommastrephidae are a vital part of marine food webs and support major fisheries around the world. They are widely distributed in the open ocean, where they are among the most abundant in number and biomass of nektonic epipelagic organisms. In turn, seven of the 11 genera of this family (Dosidicus, Illex, Martialia, Nototodarus, Ommastrephes, Sthenoteuthis, and Todarodes) are heavily preyed upon by top marine predators, i.e., birds, mammals, and fish, and currently support fisheries in both neritic and oceanic waters (Roper and Sweeney, 1984; Rodhouse, 1997). Their commercial importance has made the large ommastrephids the target of many scientific investigations and their biology is consequently reasonably well-known (Nigmatullin et al., 2001; Zuyev et al., 2002; Bower and Ichii, 2005). In contrast, much less information is available on the biology and ecological role of the smaller, unexploited species of ommastrephids (e.g., Eucleoteuthis, Hyaloteuthis, Ornithoteuthis, and Todaropsis)

Observation of beam spin asymmetries in the process ep→e^{'}π^{+}π^{-}X with CLAS12

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first opportunity to extract the parton distribution function e(x), which provides information about the interaction between gluons and quarks, in a collinear framework that offers cleaner access than previous measurements. The asymmetries also constitute the first ever signal sensitive to the helicity-dependent two-pion fragmentation function G_{1}^{⊥}. A clear sign change is observed around the ρ mass that appears in model calculations and is indicative of the dependence of the produced pions on the helicity of the fragmenting quark

Communal spawning of brook and river lampreys (Lampetra planeri and L. fluviatilis) is common in the Oir River

The taxonomic status of river Lampreys (Lampetra fluviatilis) and brook lampreys (L. planeri) has been repeatedly questioned due to the high morphological similarity of these species. Here, we report a high frequency (54%) of communal spawning involving both species in the Lampetra redds of a French coastal river. These observations suggest that reproductive isolation between the two species may not be as strong as previously supposed

Echantillonnage des ammocetes

Echantillonnage des ammocete

Sea lampreys (petromyzon marinus) upstream migration and the impact of dam destruction on catchment colonisation

Sea lampreys (petromyzon marinus) upstream migration and the impact of dam destruction on catchment colonisation. DiadFish : les poissons migrateurs amphihalins d'Europ

Sea lampreys (petromyzon marinus) upstream migration and the impact of dam destruction on catchment colonisation

Sea lampreys (petromyzon marinus) upstream migration and the impact of dam destruction on catchment colonisation. DiadFish : les poissons migrateurs amphihalins d'Europ

Shad of the Northeastern Atlantic and the Western Mediterranean (Alosa alosa L. 1758 and A. fallax Lac., 1803) : Biology, Ecology and Harvesting - Fisheries and Aquaculture.

Encyclopédie en ligneShad of the Northeastern Atlantic and the Western Mediterranean (Alosa alosa L. 1758 and A. fallax Lac., 1803) : Biology, Ecology and Harvesting - Fisheries and Aquaculture

The allis shad Alosa alosa: biology, range, and status of populations

Extrait de documentFor the allis shad Alosa alosa (also known as allice shad), no subspecies have been identified. The species is morphologically distinct from the twaite shad A. fallax fallax with which it coexists, but hydridization between the two species does occur. Allis shad populations are mainly anadromous, but some landlocked populations have arisen as a result of dam construction. All anadromous populations have common biological characteristics. Recently, restoration and conservation programs have been initiated. These include the installation of fish passes and the protection of spawning areas. Currently, no stocking program exists since artificial culture has not proved reliable. To conserve and enhance the allis shad, priority areas for furher research include ecology of the juvenile stage in freshwater, the degree of homing, the marine phase, and detailed population dynamics

A new sampling technique for larval lamprey population assessment in small river catchments

Office National de l'Eau et des Milieux AquatiquesLarval lampreys were sampled in a small river using a new method modified from the Surber bottom sampler for invertebrates. This method uses a rectangular dredge to sample a constant and small surface of sediments in soft substrate areas. It was compared to a classical point abundance sampling by electrofishing. Both methods generated large numbers of small samples encompassing the spatial heterogeneity of ammocoete distributions. However, the bottom sampler provided samples with higher abundance and was more efficient for small individuals. Furthermore, the equipment is cheap and the method is cost-effective, since it can be operated by only two people. It could therefore be applied at a large scale to collect information on lamprey populations and contribute to knowledge of their distribution, abundance and, in fine, to devise better conservation measures. (C

The Allis Shad Alosa alosa: Biology, Ecology, Range and Status of Populations

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