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8 pages, 696 KiB

Open AccessEditor’s ChoiceArticle

Variation over Time of Length–Weight Relationships and Condition Factors for Four Exotic Fish Species from a Restored Shallow Lake in NE Iberian Peninsula

by Jorge Rubén Sánchez-González, Amadeo Arbonés and Frederic Casals

Fishes 2020, 5(1), 7; https://doi.org/10.3390/fishes5010007 - 4 Feb 2020

Cited by 6 | Viewed by 4622

Abstract

Length–weight relationships (LWRs), condition factors, and their variation over time were analyzed for four exotic freshwater fish (bleak, common carp, pikeperch, and roach) in the Estany d’Ivars i Vila-sana shallow lake in Catalonia, Northern Spain. Fish samples were collected twice a year (early [...] Read more.

Length–weight relationships (LWRs), condition factors, and their variation over time were analyzed for four exotic freshwater fish (bleak, common carp, pikeperch, and roach) in the Estany d’Ivars i Vila-sana shallow lake in Catalonia, Northern Spain. Fish samples were collected twice a year (early summer and autumn), between 2008 and 2016, by using between three and five multi-mesh nylon gillnets. This study provides novel information about four common exotic fishes outside of their natural range and within the context of a restored shallow lake, where the ichthyologic community is evolving in concordance with the ecosystem conditions and the fish community dynamics. Full article

(This article belongs to the Special Issue Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean")

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17 pages, 2127 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Distribution and Risk Assessment of Potential Invasiveness of Australoheros facetus (Jenyns, 1842) in Portugal

by Flavia Baduy, João L. Saraiva, Filipe Ribeiro, Adelino V. M. Canario and Pedro M. Guerreiro

Fishes 2020, 5(1), 3; https://doi.org/10.3390/fishes5010003 - 27 Dec 2019

Cited by 10 | Viewed by 5324

Abstract

Invasive species are recognized as a major cause of biodiversity decline. Legal regulations relating to the prevention, control, or eradication of invasive species should always be up-to-date, as the failure to recognize the problem, lack of adequate scientific information, or long legal intervals [...] Read more.

Invasive species are recognized as a major cause of biodiversity decline. Legal regulations relating to the prevention, control, or eradication of invasive species should always be up-to-date, as the failure to recognize the problem, lack of adequate scientific information, or long legal intervals required to prepare the legislation may result in irreversible, possibly catastrophic, outcomes. This implies constant monitoring of the species distribution and levels of establishment, as well as detailed knowledge about its biology to predict dissemination and viability under changing environmental conditions. Pre-screening kits for potential invasive species are valuable tools for policy makers, as they provide information about if and how management measures should be taken. The Freshwater Fish Invasiveness Scoring Kit (FISK) and the Aquatic Species Invasiveness Screening Kit (AS-ISK) have been suggested as reliable tools to assess the potential risk of a species becoming invasive. The present study highlights the spread of the non-native chameleon cichlid Australoheros facetus in several streams of the major river drainages in southern Portugal and compares the fish assemblages and ecological indices in two selected sites in the Vascão and Odelouca rivers. We reviewed the current knowledge on the distribution, physiology, and behavior of A. facetus, and applied the toolkits FISK v2 and AS-ISK to this species to evaluate whether the species should be classified as invasive in Portugal. Field data show high abundance of the species in most streams and dominance in specific hotspots. The scores reached by the kits (FISK v2: 23; AS-ISK: 37) places A. facetus as a species with high potential of invasiveness and support the recent inclusion of this species in the invasive species list in Portugal (Decree-Law 92/2019), but, most of all, highlights the importance of frequent updates in both the field monitoring and the legal regulation and watch lists of invasive organisms. Full article

(This article belongs to the Special Issue Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean")

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13 pages, 1268 KiB

Open AccessEditor’s ChoiceArticle

Seabream Larval Physiology under Ocean Warming and Acidification

by Marta S. Pimentel, Filipa Faleiro, Jorge Machado, Pedro Pousão-Ferreira and Rui Rosa

Fishes 2020, 5(1), 1; https://doi.org/10.3390/fishes5010001 - 20 Dec 2019

Cited by 15 | Viewed by 4003

Abstract

The vulnerability of early fish stages represents a critical bottleneck for fish recruitment; therefore, it is essential to understand how climate change affects their physiology for more sustainable management of fisheries. Here, we investigated the effects of warming (OW; +4 °C) and acidification [...] Read more.

The vulnerability of early fish stages represents a critical bottleneck for fish recruitment; therefore, it is essential to understand how climate change affects their physiology for more sustainable management of fisheries. Here, we investigated the effects of warming (OW; +4 °C) and acidification (OA; ΔpH = 0.5) on the heart and oxygen consumption rates, metabolic enzymatic machinery—namely citrate synthase (CS), lactate dehydrogenase (LDH), and ß-hydroxyacyl CoA dehydrogenase (HOAD), of seabream (Sparus aurata) larvae (fifteen days after hatch). Oxygen consumption and heart rates showed a significant increase with rising temperature, but decreased with pCO₂. Results revealed a significant increase of LDH activity with OW and a significant decrease of the aerobic potential (CS and HOAD activity) of larvae with OA. In contrast, under OA, the activity levels of the enzyme LDH and the LDH:CS ratio indicated an enhancement of anaerobic pathways. Although such a short-term metabolic strategy may eventually sustain the basic costs of maintenance, it might not be adequate under the future chronic ocean conditions. Given that the potential for adaptation to new forthcoming conditions is yet experimentally unaccounted for this species, future research is essential to accurately predict the physiological performance of this commercially important species under future ocean conditions. Full article

(This article belongs to the Special Issue Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean")

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11 pages, 3630 KiB

Open AccessArticle

Diet of European Catfish in a Newly Invaded Region

by Marco Ferreira, João Gago and Filipe Ribeiro

Fishes 2019, 4(4), 58; https://doi.org/10.3390/fishes4040058 - 8 Dec 2019

Cited by 19 | Viewed by 4817

Abstract

Biological invasions are considered to be one of the leading causes of biodiversity loss worldwide. Freshwater ecosystems are amongst the most biodiverse, containing about 50% of the world’s known fish species but, ironically, are the most invaded ecosystems. In Portuguese freshwaters, there are [...] Read more.

Biological invasions are considered to be one of the leading causes of biodiversity loss worldwide. Freshwater ecosystems are amongst the most biodiverse, containing about 50% of the world’s known fish species but, ironically, are the most invaded ecosystems. In Portuguese freshwaters, there are currently 20 identified non-native fishes, arriving at an unprecedented rate of a new species every two years. A recent non-native is the European catfish Silurus glanis, a top predator native to Central and Eastern Europe, that arrived at the Lower Tagus (Portugal) circa 2006. This study compares the dietary habits of this top predator in two different habitats of the Lower Tagus in order to evaluate its potential impact. The stomach contents of 96 individuals were analyzed, 61 from the lotic environment and 35 from the lentic systems. A total of 66 stomachs contained prey items, 38 from the lotic and 28 from the lentic. Diet varied considerably between habitats, with shrimp and crayfish being the most abundant prey items in the lentic systems and shrimp and fish the most abundant prey items in the lotic section. Tendency to piscivory was observed in large-sized individuals. Overall, the findings in this study provide the first evidence of the potential impacts of European catfish through predation on the fish communities. Full article

(This article belongs to the Special Issue Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean")

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17 pages, 2883 KiB

Open AccessArticle

Modulation of Pituitary Response by Dietary Lipids and Throughout a Temperature Fluctuation Challenge in Gilthead Sea Bream

by Sergio Sánchez-Nuño, Sandra C. Silva, Pedro M. Guerreiro, Borja Ordóñez-Grande, Ignasi Sanahuja, Laura Fernández-Alacid and Antoni Ibarz

Fishes 2019, 4(4), 55; https://doi.org/10.3390/fishes4040055 - 22 Nov 2019

Cited by 1 | Viewed by 2901

Abstract

Low temperatures provoke drastic reductions in gilthead sea bream (Sparus aurata) activity and nourishment, leading to growth arrest and a halt in production. However, scarce data exist concerning the implications of central core control during the cold season. The aim of [...] Read more.

Low temperatures provoke drastic reductions in gilthead sea bream (Sparus aurata) activity and nourishment, leading to growth arrest and a halt in production. However, scarce data exist concerning the implications of central core control during the cold season. The aim of this work was to study the effects of low temperature and recovery from such exposure on the pituitary activity of sea bream juveniles fed 18% or 14% dietary lipid. A controlled indoor trial was performed to simulate natural temperature fluctuation (22 °C to 14 °C to 22 °C). Meanwhile, we determined the regulatory role of the pituitary by analyzing the gene expression of some pituitary hormones and hormone receptors via qPCR, as well as plasma levels of thyroidal hormones. In response to higher dietary lipids, hormone pituitary expressions were up-regulated. Induced low temperatures and lower ingesta modulated pituitary function up-regulating GH and TSH and thyroid and glucocorticoid receptors. All these findings demonstrate the capacity of the pituitary to recognize both external conditions and to modulate its response accordingly. However, growth, peripheral tissues and metabolism were not linked or connected to pituitary function at low temperatures, which opens an interesting field of study to interpret the hypothalamus–pituitary–target axis during temperature fluctuations in fish. Full article

(This article belongs to the Special Issue Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean")

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19 pages, 1454 KiB

Open AccessArticle

From Transient to Sedentary? Changes in the Home Range Size and Environmental Patterns of Movements of European Eels (Anguilla anguilla) in a Mediterranean River

by Mercedes Herrera, Raquel Moreno-Valcárcel, Ramón De Miguel Rubio and Carlos Fernández-Delgado

Fishes 2019, 4(3), 43; https://doi.org/10.3390/fishes4030043 - 13 Aug 2019

Cited by 5 | Viewed by 2993

Abstract

The habitat use of eels during the development of sedentary behavior, which depends on the animals’ body size, is unknown. Our objective was to analyze, for two years, the changes in the home range of a population of European eel (Anguilla anguilla [...] Read more.

The habitat use of eels during the development of sedentary behavior, which depends on the animals’ body size, is unknown. Our objective was to analyze, for two years, the changes in the home range of a population of European eel (Anguilla anguilla, Linnaeus, 1758) in Southern Europe in relation to the animals’ body length (TL), and the influence of environmental factors (water temperature and flow) on the local movements of this population through observation of their sedentary behavior. We used a previously-validated mark–recapture methodology, obtaining a low deviation in the estimation of the extension of the eels’ movements. Our results revealed relatively short movements in relation to other populations, and we hypothesize that this could be related to the high habitat diversity and low eel population density in the study area. The home range size showed a high variability and dispersion among the smallest eels, however, as TL increased, the variability of home range size decreased, and home ranges were larger. These changes could be associated with the acquisition of a sedentary lifestyle. Once eels had become sedentary, an environmental pattern was observed between their movements and the water temperature and flow, with larger movements observed as the flow increased and water temperature decreased. This suggests that the temporal and spatial scales of observation are of crucial importance for monitoring eel populations and for the study of population size structure, population dynamics, and biology, which can be used to improve conservation strategies. Full article

(This article belongs to the Special Issue Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean")

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19 pages, 2709 KiB

Open AccessArticle

Seasonal Variation of Captive Meagre Acoustic Signalling: A Manual and Automatic Recognition Approach

by Manuel Vieira, Beatriz P. Pereira, Pedro Pousão-Ferreira, Paulo J. Fonseca and M. Clara P. Amorim

Fishes 2019, 4(2), 28; https://doi.org/10.3390/fishes4020028 - 18 Apr 2019

Cited by 24 | Viewed by 5371

Abstract

Many species rely on acoustic communication to fulfil several functions such as advertisement and mediation of social interactions (e.g., agonistic, mating). Therefore, fish calls can be an important source of information, e.g., to recognize reproductive periods or to assess fish welfare, and should [...] Read more.

Many species rely on acoustic communication to fulfil several functions such as advertisement and mediation of social interactions (e.g., agonistic, mating). Therefore, fish calls can be an important source of information, e.g., to recognize reproductive periods or to assess fish welfare, and should be considered a potential non-intrusive tool in aquaculture management. Assessing fish acoustic activity, however, often requires long sound recordings. To analyse these long recordings automatic methods are invaluable tools to detect and extract the relevant biological information. Here we present a study to characterize meagre (Argyrosomus regius) acoustic activity during social contexts in captivity using an automatic pattern-recognition methodology based on the Hidden Markov Model. Calls produced by meagre during the breading season showed a richer repertoire than previously reported. Besides the dense choruses composed by grunts already known for this species, meagre emitted successive series of isolated pulses, audible as ‘knocks’. Grunts with a variable number of pulses were also registered. The overall acoustic activity was concurrent with the number of spawning events. A diel call rhythms exhibit peak of calling activity from 15:00 to midnight. In addition, grunt acoustic parameters varied significantly along the reproduction season. These results open the possibility to use the meagre vocal activity to predict breeding and approaching spawning periods in aquaculture management. Full article

(This article belongs to the Special Issue Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean")

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11 pages, 1981 KiB

Open AccessConference Report

Performance of a Pool and Weir Fishway for Iberian Cyprinids Migration: A Case Study

by Anna Pedescoll, Rafael Aguado, Carlos Marcos and Gustavo González

Fishes 2019, 4(3), 45; https://doi.org/10.3390/fishes4030045 - 16 Aug 2019

Cited by 10 | Viewed by 3381

Abstract

One of the movement barriers that fish populations must overcome for migration success in the upper basin of Tormes river (Salamanca, Spain) is a 20 m high dam. The design of its pool and weir fishway for potamodromous fishes (mostly Iberian barbel—Luciobarbus [...] Read more.

One of the movement barriers that fish populations must overcome for migration success in the upper basin of Tormes river (Salamanca, Spain) is a 20 m high dam. The design of its pool and weir fishway for potamodromous fishes (mostly Iberian barbel—Luciobarbus bocagei—and Northern straight-mouth nase—Pseudochondrostoma duriense) to overcome the obstacle was improved in 2013. The aim of this study was to assess the efficiency of the fishway using FDX passive integrated transponder (PIT)-Tags inserted into the fish and PIT-Tag detection antennas at the fishway. During several sampling events, 7113 barbel and nase individuals were tagged and released at the point of capture along the basin (2538 and 4575 of which were tagged downstream and upstream, respectively). PIT-Tag Detection Antennas close to the top and bottom of the fishway monitored tagged fish continuously for 10 months (from March to December 2017), to analyze the performance of the fishway. Upstream passage efficiency was greater for barbel (60% and 25% for barbel and nase, respectively). Differences in passage efficiency between species may be due to differences in their size. Mean length for barbels attempting to pass was 336 mm (±47 mm) while for nases was 143 mm (±26 mm). Moreover, both the number of attempts to pass and ascend time for nases were higher than for barbels. Entrance efficiency was low (3.5% and 10.8% for barbel and nase, respectively), although 2017 was a very dry year, thus these results are most likely influenced by flow rates. Therefore, the fishway has proved to be functional but is actually poor for efficiency purposes, especially for small fish. Full article

(This article belongs to the Special Issue Selected Papers from the "VII Iberian Congress of Ichthyology - SIBIC2018 Where rivers meet the ocean")

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