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Fishing with light is an old and common practice yielding a substantial catch volume globally. Despite the popularity of the method and the efforts to improve it, there is a lack of field studies on the effects of light on the feeding preferences of the attracted fishes. A previous report suggested that purse seine fishing lights can differentiate the feeding preferences of the approaching fishes, such as Atherina boyeri Risso, 1810 in Lake Trichonis (Greece). The presently reported study aims to verify these findings by investigating the diet of the endemic Scardinius acarnanicus Economidis, 1991. The feeding behavior of S. acarnanicus was studied from 2016 to 2019 through gut content analysis, in specimens from Lake Trichonis that came from purse seining with light and specimens caught without light. The same investigation was carried out comparatively in specimens taken by gillnets from two nearby lakes (lakes Ozeros and Amvrakia), where S. acarnanicus is present, but no fishing with light is exercised. The stomach content analysis conducted on 699 S. acarnanicus specimens revealed the intense effect of light on its diet resulting in the alteration of its feeding habits towards fish predation and especially Atherina boyeri. On the contrary, the specimens taken with the use of gillnets, from the three lakes, showed a typical omnivorous feeding behavior. The findings of the presently reported study support the assumption that the elevated concentration of fish close to fishing lights alters the feeding behavior of certain species making them predators. Considering that fishing with light is practiced worldwide, this could be of great ecological significance to the ichthyofauna not only of inland waters but also of marine areas, affecting perhaps several commercial species. [ABSTRACT FROM AUTHOR]

In this study was investigated some biometric properties of the sand smelt with ANN's, Atherina boyeri Risso, 1810, population in Íznik Lake. Twenty-three morphometric characters of samples were measured. The fork length of individuals which were caught (TL) were between 6.20 and 10.40 cm, and their weight (W) were ranged between 1.70 and 7.20 g. The effect of Artificial Neural Networks was investigated in predicting the statistical of fishery industry. The present study provides the first information on the biometric properties of Atherina boyeri in Íznik Lake by Artificial Neural Networks. [ABSTRACT FROM AUTHOR]

It is aimed to predict of length-weight relationship (LWR) parameters by using Artificial Neural Networks (ANNs). The present study investigates the properties of the Big-scale Sand Smelt. Atherina boyeri Risso, 1810 in Yamula Dam Lake (Kayseri, Turkey). Minimum and maximum fork length size and weight were found 3.5 and 8.3 cm; 0.38 and 4.82 g for all individuals. The weight-length relationships were W = 0.01285708 L2.8167 (R2 = 0.934) for females, W = 0.00972323 L2.8690 (R2 = 0.950) for males and W=0.1014131 L2.8476(R2 = 0.940) for all individuals. The condition factor was calculated as 0.812, 0.797 and 0.804 for females, males and all individuals respectively. The results obtained by ANNs and LWR equation are compared to those obtained by the growth rate. LWR and ANNs models was found for females, males and all individuals. [ABSTRACT FROM AUTHOR]

This study was conducted in Karacaoren I Dam Lake between December 2009 and April 2010, which also covers the spawning period of sand smelt. In the study, the sex ratio, length and weight distributions, condition factor and length-weight relation of sand smelt were examined. A total of 513 sand smelt were caught with an electroshocker. The sex ratio of the samples was found to be 1:1.24 in favour of male individuals. The total length of sand smelt ranged from 4.5 to 8.5 cm. It was determined that individuals with a length of 5.0-5.9 cm constituted the majority of the population. Individuals with an average weight of 0.80-1.6 g constituted the majority of the population. The value of average condition factor was found to be 0.673 for all individuals. The length-weight relation parameters were calculated as a= 0.0096, b= 2.7912, r²= 0.8722 for all individuals and it was determined that the individuals exhibited negative allometry. A. boyeri's growth states under Karacaoren I Dam Lake conditions and their interactions with other fish species should be monitored periodically. In this way, invasive fish species can be kept under control, and necessary precautions can be taken to prevent their spread in our inland waters. [ABSTRACT FROM AUTHOR]

Ecological factors affect many animals, especially the aquatic animals that are highly dependent on the living environment. Atherina boyeri are accidentally introduced to rivers, lakes, and reservoirs in Turkey and the invasive fish species pose to threats lentic, lotic ecosystems, habitats or species. Their unique features make it easy to adapt to different habitats and ecological conditions. Invasive species may lead to changes in biological attributes and biodiversity; therefore, identification of the non-indigenous fish populations is quite important in the fisheries management. In the current study, morphometric otolith characters such as length, weight, perimeter, width, area, aspect ratio, roundness, circularity, rectangularity, ellipticity and form factor were investigated in order to discriminate invasive A. boyeri populations from Hirfanh Dam Lake, Lake Iznik, and Lake Egirdir (Turkey). The overall classification score was determined as 92.0% by of the Canonical Discriminant Analysis for A. boyeri populations. The lowest and highest classification scores were detected for Iznik (87.7%) and Egirdir (94.6%) populations, respectively. The otolith morphometrics can provide easy and reliable discrimination tool for the invasive fish populations. [ABSTRACT FROM AUTHOR]

Background. Purse seining with the use of light is among the most common fishing practices around the world, but there is lack of studies on the effect of light on the feeding of the target species in this kind of fishery and the possible consequences for other prey species. The presently reported investigation intended to provide indications on this issue by studying the diet of Atherina boyeri Risso, 1810, which is the target species of professional purse seine fishery, conducted using light in Lake Trichonis (Greece), and by comparing the acquired results with those of previous studies where the samples were taken without using light. Materials and methods. A seven-month (June through December 2014) purse seining fishing was conducted at night around two lamp rafts: 1) a traditional lamp raft producing white LED light and 2) an autonomous photovoltaic-battery-LED lamp raft producing green LED light. Stomach content analysis was conducted on 100 randomly selected specimens from each sample and the relative prey abundance and frequency of occurrence for each prey category was estimated. Calculations of predation pressure of A. boyeri upon the fish larvae of a goby, Economidichthys trichonis Economidis et Miller, 1990, were performed. Results. The study revealed the intense effect of light on the attraction and capture of prey species rarely found in previous studies, such as the larvae of the native and endangered fish E. trichonis, amphipods, and copepod nauplii. No significant differences were observed between the two light colours. A preference shift to larger prey with the increase of ontogenetic stage of A. boyeri was observed. Several thousands of pre-recruited E. trichonis larvae may be preyed upon each night around a single lamp especially during summer. Conclusion. Fishing with light may alter the dietary preference of the target fish species and even of the entire fish community. This may have serious consequences on the younger ontogenetic stages of other fish populations, especially when it coincides with their reproductive period. Considering the lack of similar field studies, the present results may stimulate analogous investigations on the effects of fishing lights in other marine and freshwater ecosystems worldwide. [ABSTRACT FROM AUTHOR]