Growth, mortality and yield per recruit of the king soldier bream Argyrops spinifer (Sparidae) from the Oman coast of the Arabian Sea

The King soldier bream Argyrops spinifer at Arabian Sea (Omani waters) was assessed using Beverton and Holt yield per recruit model. A total of 5520 specimens were collected during five trawl surveys between September 2007 and August 2008. The maximum life span was 11 years for length range of 11.0 – 62.1 cm TL. The von Bertalanffy growth parameters were K = 0.22 year^-1, L∞ = 65.51 cm, to = -0.75 year and W∞ = 5430g. The rates of total mortality Z, natural mortality M and fishing mortality F were 0.85, 0.26 and 0.59 year^-1 respectively. The exploitation ratio E was 0.69 indicating the high level of exploitation. The estimated total length at 50% maturity was 31.8 cm. Yield per recruit analysis revealed over-fished stock conditions particularly because small fish are effectively unprotected by current minimum size regulations. Therefore measures such as closed seasons or changes in fishing patterns would be desirable to safeguard the spawning stock and recruits. Also, the commercial fishery of Arabian Sea, Oman should be subjected to a total allowable catch and a maximum size limit be implemented

First record of the Pacific bluefin tuna Thunnus orientalis (Temminck Schlegel, 1844) from the coast off Sur, Sultanate of Oman

A single specimen of the Pacific bluefin tuna Thunnus orientalis was caught on 11 May 2017 in a long-line operated about 40 nautical miles off the coast of Sur atconfluent of Sea of Oman and Arabian Sea coast of Oman. This first record of its occurrence indicates the extension of distributional range of the species to the Arabian Sea coast of Oman

First record of Gymnocranius griseus (Temminck & Schlegel, 1843) (family Lethrinidae) from southern Oman, Western Indian Ocean

Primer registre de Gymnocranius griseus (Temminck & Schlegel, 1843) (família Lethrinidae) del sud d’Oman, oest de l’oceà Índic Es va recol·lectar un únic espècimen (285 mm longitud estàndard) de Gymnocranius griseus (Temminck & Schlegel, 1843) a la ciutat de Salalah (Oman), a la costa del mar d’Aràbia. És el primer registre d’aquesta espècie a les aigües d’Oman. Presenta característiques específiques: cos alt (2,17 vegades la longitud estàndard); els perfils dorsal i ventral del cap són uniformement convexos; el perfil de la part ventral del cos és recte; la vora inferior de l’ull se situa lleugerament per sota de la línia que uneix la part anterior de la boca amb el centre de l’aleta caudal lobulada; l’ull és relativament ample, de diàmetre pràcticament igual o lleugerament superior a les distàncies preorbitària i interorbitària; la boca és relativament petita i la part posterior dels maxil·lars arriba pràcticament al nivell dels orificis nasals anteriors; presenta tres parells de fines canines a la part anterior del maxil·lar superior i un parell a la part anterior de l’inferior, com també altres dents vil·liformes que adquireixen forma cònica a les parts laterals. L’espècimen va ser identificat com un G. griseus atès que les seves característiques corresponen a la descripció diagnòstica de Carpenter & Allen (1989). Palabras clave: Gymnocranius griseus, Salalah, Mar de Arabia, Primer registro.A single specimen (285 mm SL) of Gymnocranius griseus (Temminck & Schlegel, 1843) was collected from Salalah, Arabian Sea coast of Oman. It is the first record of this species from the Omani waters. It shows specific characters: deep body (2.17 times SL); evenly convex dorsal and ventral profile of head; ventral part of body profile straight; lower edge of eye slightly above a line from tip of snout to middle of caudal fin fork; eye relatively large, its diameter about equal to or slightly larger than preorbital and interorbital widths; mouth relatively small, posterior part of jaws reaching to about level of anterior nostrils; three pair and one pair of slender canines at front of upper and lower jaw, respectively, other teeth villiform, becoming conical on lateral sections. The specimen was identified as G. griseus as these characters fit the diagnostic description of Carpenter & Allen (1989). Key words: Gymnocranius griseus, Salalah, Arabian Sea, First record.Primer registre de Gymnocranius griseus (Temminck & Schlegel, 1843) (família Lethrinidae) del sud d’Oman, oest de l’oceà Índic Es va recol·lectar un únic espècimen (285 mm longitud estàndard) de Gymnocranius griseus (Temminck & Schlegel, 1843) a la ciutat de Salalah (Oman), a la costa del mar d’Aràbia. És el primer registre d’aquesta espècie a les aigües d’Oman. Presenta característiques específiques: cos alt (2,17 vegades la longitud estàndard); els perfils dorsal i ventral del cap són uniformement convexos; el perfil de la part ventral del cos és recte; la vora inferior de l’ull se situa lleugerament per sota de la línia que uneix la part anterior de la boca amb el centre de l’aleta caudal lobulada; l’ull és relativament ample, de diàmetre pràcticament igual o lleugerament superior a les distàncies preorbitària i interorbitària; la boca és relativament petita i la part posterior dels maxil·lars arriba pràcticament al nivell dels orificis nasals anteriors; presenta tres parells de fines canines a la part anterior del maxil·lar superior i un parell a la part anterior de l’inferior, com també altres dents vil·liformes que adquireixen forma cònica a les parts laterals. L’espècimen va ser identificat com un G. griseus atès que les seves característiques corresponen a la descripció diagnòstica de Carpenter & Allen (1989). Palabras clave: Gymnocranius griseus, Salalah, Mar de Arabia, Primer registro

Measurement of the Spectral Shape of the beta-decay of 137Xe to the Ground State of 137Cs in EXO-200 and Comparison with Theory

We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden non-unique $\beta$-decay transition ^{137}\textrm{Xe}(7/2^-)\to\,^{137}\textrm{Cs}(7/2^+). The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultra-low background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal-to-background ratio of more than 99-to-1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden non-unique $\beta$-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.Comment: Version as accepted by PR

Generative Adversarial Networks for Scintillation Signal Simulation in EXO-200

Generative Adversarial Networks trained on samples of simulated or actual events have been proposed as a way of generating large simulated datasets at a reduced computational cost. In this work, a novel approach to perform the simulation of photodetector signals from the time projection chamber of the EXO-200 experiment is demonstrated. The method is based on a Wasserstein Generative Adversarial Network - a deep learning technique allowing for implicit non-parametric estimation of the population distribution for a given set of objects. Our network is trained on real calibration data using raw scintillation waveforms as input. We find that it is able to produce high-quality simulated waveforms an order of magnitude faster than the traditional simulation approach and, importantly, generalize from the training sample and discern salient high-level features of the data. In particular, the network correctly deduces position dependency of scintillation light response in the detector and correctly recognizes dead photodetector channels. The network output is then integrated into the EXO-200 analysis framework to show that the standard EXO-200 reconstruction routine processes the simulated waveforms to produce energy distributions comparable to that of real waveforms. Finally, the remaining discrepancies and potential ways to improve the approach further are highlighted.Comment: 20 pages, 10 figure