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Fishes, Volume 2, Issue 3 (September 2017)

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Open AccessCommunication Preliminary Results on the Daily and Seasonal Rhythms of Cuttlefish Sepia officinalis (Linnaeus, 1758) Locomotor Activity in Captivity
Fishes 2017, 2(3), 9; doi:10.3390/fishes2030009
Received: 7 June 2017 / Revised: 22 June 2017 / Accepted: 23 June 2017 / Published: 28 June 2017
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Abstract
This research was aimed at characterizing the daily rhythms of locomotor activity of cuttlefish Sepia officinalis (Linnaeus, 1758), a promising aquaculture species, in a captive environment. Cuttlefish were distributed within two tanks equipped with infrared photocells, allowing the monitoring of locomotor activity continuously
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This research was aimed at characterizing the daily rhythms of locomotor activity of cuttlefish Sepia officinalis (Linnaeus, 1758), a promising aquaculture species, in a captive environment. Cuttlefish were distributed within two tanks equipped with infrared photocells, allowing the monitoring of locomotor activity continuously from August to February. Results showed a preference of cuttlefish for being active during the night in summer (24.2 ± 1.3 °C) and in autumn (18.4 ± 3.4 °C), with maximum activity peaks observed, respectively, at 01:09 h and 21:47 h, in close relation with sunset time. In winter (12.7 ± 1.4 °C), this preference changed, with higher levels of activity observed during the afternoon in December (15:20 h) and in January (18:13 h), thus suggesting this species as possessing a dualistic behaviour. Levels of activity progressively decreased during autumn and winter, likely related to low temperatures. The present study offers new insights on the behaviour of Sepia officinalis, presenting a variability of patterns across seasons, regulated by environmental synchronizers; photoperiod determining the activity periods, and temperature modulating the levels of activity. Such information may be a valuable tool for the improvement of cuttlefish culture protocols in aquaculture, and consequently its welfare. Full article
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Open AccessArticle Monitoring Red Sea Bream Scale Fluorescence as a Freshness Indicator
Fishes 2017, 2(3), 10; doi:10.3390/fishes2030010
Received: 26 May 2017 / Revised: 28 June 2017 / Accepted: 3 July 2017 / Published: 10 July 2017
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Abstract
Red sea bream (Pagrus major) scale fluorescence characteristics were identified as a potential rapid and non-destructive means for assessing the fish’s freshness. To investigate this, live red sea breams were purchased, slaughtered, and prior to measurement, stored at 22 ± 2
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Red sea bream (Pagrus major) scale fluorescence characteristics were identified as a potential rapid and non-destructive means for assessing the fish’s freshness. To investigate this, live red sea breams were purchased, slaughtered, and prior to measurement, stored at 22 ± 2 °C for 27 h. During subsequent storage, the K value of the dorsal meat—as a standard freshness indicator—along with front-face fluorescence spectra of representative dorsal scales, were measured simultaneously at 3 h intervals. Two major fluorescent peaks, A and B, were identified with excitation and emission wavelength pairs of 280/310 nm and 340/420 nm, which were mainly contributed to by tyrosine and collagen, respectively. Subsequent analysis showed that the fluorescence intensity ratio of peak B to A (IB/IA) increased linearly during storage (R2 = 0.95) and is proposed as a potential non-destructive index of fish freshness. Thus, our results suggest that the fluorescence characteristics of fish scales can be used to assess fish carcass freshness during storage. Full article
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Open AccessArticle Advanced Spatial Modeling to Inform Management of Data-Poor Juvenile and Adult Female Rays
Fishes 2017, 2(3), 12; doi:10.3390/fishes2030012
Received: 20 June 2017 / Revised: 21 July 2017 / Accepted: 21 July 2017 / Published: 4 August 2017
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Abstract
Chronic overfishing has depleted numerous elasmobranch stocks in the North East Atlantic, but addressing this issue has been hampered by management complications and lacking data. Spatial management approaches have thus been advocated. This work presents a novel application and further development of an
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Chronic overfishing has depleted numerous elasmobranch stocks in the North East Atlantic, but addressing this issue has been hampered by management complications and lacking data. Spatial management approaches have thus been advocated. This work presents a novel application and further development of an advanced spatial modeling technique to identify candidate nursery grounds and spawning areas for conservation, by subsetting already limited data. Boosted Regression Tree models are used to predict abundance of juvenile and mature female cuckoo (Leucoraja naevus), thornback (Raja clavata), blonde (Raja brachyura), and spotted (Raja montagui) rays in the Irish Sea using fish survey data and data describing fishing pressure, predation and environmental variables. Model-predicted spatial abundance maps of these subsets reveal distinct nuances in species distributions with greater predictive power than maps of the whole stock. These resulting maps are then integrated into a single easily understood map using a novel approach, standardizing and facilitating the spatial management of data-limited fish stocks. Full article
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Open AccessArticle Ethmalosa fimbriata (Bowdich 1825), a Clupeid Fish That Exhibits Elevated Batch Fecundity in Hypersaline Waters
Fishes 2017, 2(3), 13; doi:10.3390/fishes2030013
Received: 11 July 2017 / Revised: 11 August 2017 / Accepted: 14 August 2017 / Published: 18 August 2017
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Abstract
Little is known about the concerted influence of temperature and salinity on the fecundity of clupeid fishes. Due to a globally changing climate, both physical parameters might act as stressors, severely affecting the reproductive potential of clupeid fish populations inhabiting tropical estuaries. Differences
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Little is known about the concerted influence of temperature and salinity on the fecundity of clupeid fishes. Due to a globally changing climate, both physical parameters might act as stressors, severely affecting the reproductive potential of clupeid fish populations inhabiting tropical estuaries. Differences in relative batch fecundities, the gonado-somatic index, and the condition index of bonga shad (Ethmalosa fimbriata) were analysed in individual females sampled at the Senegalese coast and inside the inverse Sine Saloum estuary, where salinity increases upstream in all seasons. Multiple linear regression models on fecundity and gonadal energy storage show that clupeids can adapt towards increasing their reproductive investment at temperatures (26–30 °C) and salinities (42–51), which by far exceed marine conditions, in an effort to maximize recruitment success. This reproductive strategy, however, is accompanied by a trade-off between reproductive effort and somatic growth, which ultimately limits the species’ reproductive potential inside the estuary. The observed high variability in batch fecundities might be a viable mechanism to adjust to fluctuating and rather extreme environmental conditions. Understanding the spawning biology of exploited clupeid fishes in drastically changing environments is crucial for evaluating the reproductive potential of stocks at the outer reach of their physiological performance curve. Full article
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Open AccessCommunication Discovery of an Earliest-Stage “Mystery Circle” and Development of the Structure Constructed by Pufferfish, Torquigener albomaculosus (Pisces: Tetraodontidae)
Fishes 2017, 2(3), 14; doi:10.3390/fishes2030014
Received: 25 July 2017 / Revised: 17 August 2017 / Accepted: 18 August 2017 / Published: 23 August 2017
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Abstract
Male pufferfish (Torquigener albomaculosus) construct “mystery circles”, geometric circular structures with radially aligned peaks and valleys, on sandy seabeds for reproduction. We discovered an earliest-stage mystery circle composed of dozens of irregular depressions. The structure changed to a primitive circular form
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Male pufferfish (Torquigener albomaculosus) construct “mystery circles”, geometric circular structures with radially aligned peaks and valleys, on sandy seabeds for reproduction. We discovered an earliest-stage mystery circle composed of dozens of irregular depressions. The structure changed to a primitive circular form with radially aligned valleys and a circular depression in the central area on day 2. The number of valleys increased, and the radius of the structure was much smaller than that of the final structure. These features were observed from days 2 to 4, considered the early stage of construction. The mystery circle had radially aligned peaks and valleys with a central flat area, while the radius and the differences in elevation between the peaks and valleys were increasing. These features, which were observed from days 5 to 8, were considered the middle stage of construction. On day 9, the mystery circle was completed. An irregular pattern was formed in the central area, and the radially aligned peaks were decorated with shell and coral fragments. These are the first recorded observations of construction of a mystery circle from the earliest stage. Full article
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Open AccessArticle Recognition and Distribution of Two North Atlantic Gadiculus Species, G. argenteus and G. thori (Gadidae), Based on Otolith Morphology, Larval Pigmentation, Molecular Evidence, Morphometrics and Meristics
Fishes 2017, 2(3), 15; doi:10.3390/fishes2030015
Received: 28 July 2017 / Revised: 3 August 2017 / Accepted: 3 August 2017 / Published: 29 August 2017
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Abstract
The silvery pout genus Gadiculus consists of small aberrant codfishes with several extinct and currently only one recognized extant species. The oldest representatives of a Gadiculus lineage known from otoliths are Early Miocene in age. Fossil evidence has showed Gadiculus to originate from
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The silvery pout genus Gadiculus consists of small aberrant codfishes with several extinct and currently only one recognized extant species. The oldest representatives of a Gadiculus lineage known from otoliths are Early Miocene in age. Fossil evidence has showed Gadiculus to originate from older genera diverging early from other true cods of the family Gadidae. As adult specimens of different species have been found to be highly similar and difficult to distinguish based on meristic and morphometric data, the number of species in this gadid genus has been controversial since different larval morphotypes were first discovered some 100 years ago. For almost 70 years, Gadiculus thori and Gadiculus argenteus have been considered subspecies only, with a distribution in the Northeast Atlantic Ocean including the Mediterranean. In this study, we resolve the long-standing issue of extant Gadiculus not being monotypic. New results in the form of distinct adult otoliths and molecular data unambiguously show two species of Gadiculus present—in agreement with larval morphotypes. Morphometric, meristic and molecular characters, as well as larval pigmentation are discussed in addition to present and past geographic distributions of the two taxa from distributions of fossil otoliths. At present, the cold-water species Gadiculus thori (northern silvery pout) is distributed in cold-temperate and subarctic latitudes in the Northeast Atlantic, including a new range extension off Southeast Greenland. Gadiculus argenteus (southern silvery pout) occurs in warmer waters and is distributed in the warm-temperate East Atlantic and Mediterranean. Fossil otoliths show that both species often co-existed in the Mediterranean from the Late Pliocene to the Middle Pleistocene. Full article
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Open AccessArticle Water Oxygen Content Affects Distribution of T and B Lymphocytes in Lymphoid Tissues of Farmed Sea Bass (Dicentrarchus Labrax)
Fishes 2017, 2(3), 16; doi:10.3390/fishes2030016
Received: 9 August 2017 / Revised: 3 September 2017 / Accepted: 11 September 2017 / Published: 14 September 2017
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Abstract
Intensive aquaculture systems have stimulated proper management in order to limit stressful stocking conditions and environmental impact. This should improve fish wellness and counteract adverse water characteristics such as high concentrations of carbon. The oxygen can be considered a key factor since critical
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Intensive aquaculture systems have stimulated proper management in order to limit stressful stocking conditions and environmental impact. This should improve fish wellness and counteract adverse water characteristics such as high concentrations of carbon. The oxygen can be considered a key factor since critical conditions leading to chronic rise of blood catecholamines can depress the number and Oxygen-carrying capacity of erythrocytes. In this research, we evaluated the effects of variation in water oxygen (from 6 ± 1 to 13 ± 1 mg/L) on lymphocytes density in sea bass by using flow cytometry and immunohistochemistry. Gut, gill, and thymus T-cells were significantly enhanced in percentage in hyperoxygenated fish compared with normo-oxygenated group, while Peripheral Blood Leukocytes (PBL), head kidney, and spleen T-cells were not significantly different. Contrarily, in PBL, head kidney and spleen hyper-oxygenation treatment provoked an enhancement of B lymphocyte percentages. The distribution of positive T-cells in hyper-oxygenated fish varied in the organs and followed the relative increments/decrements observed in flow cytometry. This study remarks the sensitivity of sea bass adaptive immunocytes to oxygen concentration, evidenced by the modification of parameters. Sea bass culture under high-flow water recycling and at around 12–13 mg/L oxygen concentrations is therefore suggested to enhance the immune response capacity. Full article
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Open AccessCorrection Pieter A. M. Gaemers. Taxonomy, Distribution and Evolution of Trisopterine Gadidae by Means of Otoliths and Other Characteristics. Fishes 2016, 1, 18–51.
Fishes 2017, 2(3), 11; doi:10.3390/fishes2030011
Received: 22 June 2017 / Accepted: 26 June 2017 / Published: 17 July 2017
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Abstract
The author has made the following corrections to his paper [1], which has been republished in order to comply with the rules of the International Code of Zoological Nomenclature (I.C.Z.N.). [...]
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