The greater amberjack, (Risso, 1810), is a promising candidate for the diversification of European aquaculture production, but inconsistent reproduction in captivity prevents commercial production. Recent studies showed that greater amberjack confined in sea cages exhibited scarce gonad development and early interruption of gametogenic activity during the reproductive season. The aim of the present study was to improve our understanding of the observed impairment of spermatogenesis. Adult wild and captive-reared males were sampled during 3 different phases of the reproductive cycle: early gametogenesis (EARLY; late April to early May), advanced gametogenesis (ADVANCED; late May to early June), and spawning (SPAWNING; late June to July). Spermatogonial stem cells and proliferating germ cells were identified through the immunohistochemical localization of and proliferating cell nuclear antigen, respectively. Apoptotic germ cells were identified throughout the terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling method. Sperm quality of captive-reared fish was evaluated using computer-assisted sperm analysis. Captive-reared males exhibited seminiferous lobules of a smaller diameter, a precocious and progressive decrease of spermatogonial mitosis, and a high level of apoptosis at the beginning of the reproductive season, concomitant with a many-fold higher 17β-estradiol plasma concentration. The motile spermatozoa percentage of captive greater amberjack was lower than in other teleosts, and a drastic decrease of spermatozoa motility duration, velocity, and ATP content occurred along the reproductive season. An abnormal increase of sperm concentration as well as an increase of dead spermatozoa occurred during the SPAWNING phase, probably because of lack of sperm hydration and ejaculation and consequent sperm ageing. The present study demonstrates the extreme susceptibility of greater amberjack to rearing stress and underscores the need for improvement of the rearing and handling procedures to ameliorate gametogenesis dysfunctions in commercial aquaculture production.

Engraulis encrasicolus and Sardina pilchardus stocks are highly variable in terms of recruitment, biomass and spatial distribution. Changes in habitat conditions may influence both the survival of the early life stages and the adult stages. Detailed studies on the spatial distribution and habitat selection of such species have been performed in different areas of the world, highlighting the importance of environmental processes. The present study analyzes the spatial distribution of anchovy and sardine in the Tyrrhenian Sea in relation to environmental heterogeneity. Four acoustic surveys were carried out in this area in the period 2009–2014. Analysis of the environmental dataset permitted identification, in two specific areas, of a pattern of variables driving enrichment processes and impacting on the habitat suitability of the two species. In the northern and central parts of the study area, both anchovy and sardine showed a marked preference for shallower areas characterized by lower salinity. In these areas, PCA results on an environmental dataset highlighted a strong link between primary production, particulate organic carbon, distance from the mouth of the river, salinity and depth. A less clear picture was obtained for the southern part of the Tyrrhenian sea, characterized by a narrow continental shelf, moderately complex coastline morphology and the presence of very small rivers. Most of the anchovy biomass was found to be located in enclosed areas (gulfs) under the influence of relatively small rivers. This finding, taking into account that the surveys were carried out during the anchovy spawning period, highlights for such species a positive effect of the interaction between coastal morphology and riverine input, probably favoring food supply and retention of spawning products.

Copyright © 2017To cite this article: BASILONE, G., MANGANO, S., PULIZZI, M., FONTANA, I., GIACALONE, G., FERRERI, R., GARGANO, A., http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 12/05/2018 11:19:51 | ARONICA, S., BARRA, M., GENOVESE, S., RUMOLO, P., MAZZOLA, S., & BONANNO, A. (2018). European anchovy (Engraulis encrasicolus) age structure and growth rate in two contrasted areas of the Mediterranean Sea: the paradox of faster growth in oligotrophic seas. Mediterranean Marine Science, 18(3) IntroductionThe European anchovy (Engraulis encrasicolus, Linnaeus, 1758) is an important commercial resource and constitutes almost 30% of the total Mediterranean fish production (Lleonart & Maynou, 2003). Landing statistics including both Mediterranean and Black Sea waters, noting that among small pelagic fishes, anchovy is the most important species contributing approximately 50% of total landings (FAO, 2011). Clupeoid fish populations, especially anchovies and sardines, exhibit large fluctuations in abundance in several areas around the world (Crawford, 1987;Schwartzlose et al., 1999;Palomera et al., 2007). In the Strait of Sicily (Geographical Sub Area -GSA 16, as defined by the General Fisheries Commission for the Mediterranean; GFCM, 2009), the average annual catches have been estimated at around 5000 tons, while approximately 100 vessels of different types employing different fishing gears are actively exploiting anchovy in this area (Data Collection Framework, years 2007; http://stecf.jrc.ec.europa.eu/reports/dcf-dcr). In the same area, acoustic and ichthyoplankton-based biomass evaluation methods showed that the high interannual variability in biomass is largely controlled by environmental variability Bonanno et al., 2014a).In the Tyrrhenian and Ligurian seas (GSAs 10 and 9), anchovy and sardine landings in the period [2009][2010][2011][2012] were in the ranges 8000 -12000 tons and 2000 -9000 tons, respectively (IREPA, 2012). Although some acoustic surveys in the Tyrrhenian Sea during the last years highlighted the consistent presence of these resources, the management of small pelagic fishes in this area is impeded by the considerable lack of information independent of the fishery . The present study provides the first set of observations on the biology and ecology of anchovy in the Tyrrhenian Sea and compares them with data acquired in other areas. Comparative studies at the species-level are very important as they reveal the effect of habitat conditions on growth and recruitment of fishes (Brander, 1995;Planque & Frédou, 1999). Indeed, pooling data from a number of populations broadens the range of conditions and helps to detect general patterns (Brander, 1995;Brunel & Boucher, 2006), allowing a modelling of the species' responses to climate change (Clark et al., 2003;Drinkwater, 2005).Knowledge on the fish's growth is historically fundamental for fishery sciences. Growth information provides an integrated assessment of habitat suitability because it reflects the prevailing environmental conditions...

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An alternative method to the traditional hydrated oocyte (HO) method has been evaluated for the Sicilian anchovy, Engraulis encrasicolus. The method is based on the processing of ovarian whole mount images and the identification of the spawning batch in oocyte size frequency distributions and shows the advantage that it can be applied to various oocyte stages rather than strictly to the HO stage. Despite the peculiar elliptical shape of anchovy oocytes, this image analysis technique was fully successful since the yolked stage appeared to perform equally to the HO stage for anchovy batch fecundity measurements.

The monitoring of water bio-physical parameters and the management of aquatic ecosystems are crucial to cope with the current state of inland water degradation. Not only does water quality monitoring support management decision making, it also provides vital insights to better understand changing structural and functional lake processes. Remote sensing has been widely recognized as an essential integrating technique for water quality monitoring, thanks to its capabilities to utilize both historical archive data for thousands of lakes as well as near-real time observations at multiple scales. To date, most of the applications developed for inland water have been based on multispectral and mid to coarse spatial resolution satellites, while a new generation of spaceborne imaging spectroscopy is now available, and future missions are under development. This review aims to present the exploitation of data gathered from two currently orbiting hyperspectral sensors (i.e., PRISMA and DESIS) to retrieve water quality parameters across different aquatic ecosystems, encompassing deep clear lakes and river dammed reservoirs.