Modeling environmental,temporal and spatial effects on twaite shad (Alosa fallax) by‐catches in the central Mediterranean Sea

Modeling the relationships between environmental factors and the distribution at sea of species of conservation interest can be useful in predicting their occurrence from a local to a regional scale. This information is essential for planning management and conservation initiatives. In this study, generalized additive models (GAMs) were applied to investigate the influence of environmental, temporal and spatial variables on the catch rates of the twaite shad Alosa fallax (Lacepède) by the pelagic trawl fishery in the north‐central Adriatic Sea. Presence/absence and abundance [catch per unit effort (CPUE)] data between 2006 and 2012 were separately modeled, and the two models were then validated using a test data set. The most important factor influencing the presence and abundance of adult twaite shads was the spatial predictor (latitude × longitude). Two areas of major shads aggregations were observed, the most important of which being located near the estuaries of three main river systems of northern Italy. The twaite shad presence was also significantly affected by season, the largest and lowest occurrences being observed in autumn and spring, respectively. Among the environmental variables tested, only sea surface temperature was included in both models. Alosa fallax showed a wide thermal tolerance (6–27°C) with preference for temperature around 23°C. The model developed from the abundance data showed a moderate predictive power, whereas the accuracy of the presence/absence model was rather low. Some conclusions on the ecological requirements of A. fallax at sea arising from this study are useful to orient future monitoring and research programs and to develop effective conservation actions.     

The 70-kDa Heat-shock Protein as a Potential Biomarker of Quality of the Parapenaeus longirostris Shrimp Flesh

The deep-water rose shrimp, Parapenaeus longirostris, is a target species of the Mediterranean fisheries mostly caught by trawlers offshore, processed, and frozen on board. The effects of thawing on shrimp muscle exudate collected at 0, 1, 2, 3 days after thawing were investigated. In total, 70-kDa heat-shock protein (Hsp70), alpha (α)-enolase, and manganese superoxide dismutase (Mn-SOD) were selected as metabolic and stress-related proteins and analyzed by immunoblotting on exudates. Data were compared for the amount of exudates collected and the pH values. Among the investigated proteins, only the Hsp70 levels showed a decrease related to the post-thawing period and correlated with both the significant increase of the exudate amount and the pH values. These data strongly suggest the potential use of Hsp70 as an early predictive biomarker for quality of the P. longirostris shrimp after thawing.     

Environmental DNA reveals the temporal and spatial extent of spawning migrations of European shad in a highly fragmented river basin

1. Artificial barriers on lowland rivers impede the spawning migrations of anadromous fishes, preventing access to historical spawning areas. In the cryptic European shads Alosa alosa and Alosa fallax (‘shad’ hereafter), this has resulted in population declines across their range. Conservation programmes aim to facilitate the passage of migrators over these barriers and so require baseline information on the spatial and temporal extent of current migrations.
2. Here, a shad-specific environmental DNA (eDNA) assay was used to quantify the spatial extent of shad spawning migrations in the River Severn basin, western England. This basin is characterized by the presence of multiple barriers in the lower catchment. In 2017, the eDNA assay was piloted in the River Teme, an important shad spawning tributary, and then applied in 2018 and 2019 across the lower Severn basin.
3. In all years, shad DNA was detected between mid-May and mid-June, with the maximum spatial extent of shad distribution being in early June when shad eDNA was detected upstream of weirs that were generally considered as impassable. In 2018, this included the detection of shad above the most upstream weir on the main River Severn that required individual fish to have passed six weirs.
4. Although barriers inhibit the spawning migrations of shad, this eDNA assay showed that some highly vagile individuals might be able to ascend these barriers and migrate considerable distances upstream. This suggests that efforts to increase the permeability of these barriers could result in relatively high numbers of migrating shad reaching upstream spawning areas. These results demonstrate that this eDNA assay could also be used across their range, to further quantify the spatial extent of their spawning, including in highly fragmented rivers and those where shad are believed to spawn only occasionally and are rarely observed.

     

Population structure of short‐finned pilot whales in the oceanic archipelago of Madeira based on photo‐identification and genetic analyses: implications for conservation

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Dietary lysine requirements of Colossoma macropomum (Cuvier, 1818) based on growth performance,hepatic and intestinal morphohistology and hematology

Veterinary Research Communications - This study aimed to determine the dietary lysine requirements of juvenile Colossoma macropomum tambaqui based growth performance, hepatic and intestinal...     

Microsatellite based population structure of <Emphasis Type="Italic">Plasmopara viticola</Emphasis> at single vine scale

The genetic structure of a Plasmopara viticola population was characterized on five single vines, one for each cultivar Regent, Merlot, Isabella, Müller-Thurgau and Solaris, using four neutral specific polymorphic microsatellite markers. Five-hundred and seventy samples were collected at four dates in the period between the 10th of July and the 23rd of August 2006. On average over all five cultivars, 67% of the genotypes present on the single selected vines derived from primary infections and caused 37% of the lesions genotyped. Fifty-three percent of these genotypes occurred only once on the vine throughout the survey period, while 14% were able to asexually reproduce on the selected single vine throughout the survey period, causing 23% of the lesions. Thirty-three percent of the genotypes on the single vine derived from other vines, 28% from vines of other cultivars in the other rows, and 5% from vines of the same cultivar in the same row. New primary infections appear all along the sampling dates. The overwhelmingly quantitative role of primary infections at vineyard scale was known, however here we observed the phenomenon also at the single vine scale and the reduced contribution of secondary lesions to the populations present on more resistant cultivars compared to the susceptible cultivars. As the sampling extended almost to defoliation, the results are judged to be representative of a typical P. viticola epidemic.     

Evidence for BTV-4 circulation in free-ranging red deer (Cervus elaphus) in Cabañeros National Park, Spain

Bluetongue (BT) is an infectious disease of wild and domestic ruminants caused by bluetongue virus (BTV). BTV-4 spread through southern Spain from 2004 to 2006, whereas a BTV-1 outbreak that started in southern Spain in 2007 is still ongoing. Vaccination and movement restriction regulations are applied to domestic ruminants to control BT, but the potential reservoir role of wild European ungulates has not been clarified so far. The aim of this study was to describe the epidemiology of BTV in the wild free-ranging red deer (Cervus elaphus) population of Caba?eros National Park (CNP) in central Spain during the BTV-4 and BTV-1 epizootics, assessing the potential role of this deer population as a BTV reservoir. Blood samples from 2885 (2542 adults, 208 calves and 135 undetermined) wild red deer were collected from 2005 to 2010 in CNP and surrounding hunting estates. All sera were tested for antibodies against the BTV VP7 protein by ELISA. Ninety-four of the ELISA-positive samples were analysed by serum neutralization to detect BTV-4 and BTV-1 specific antibodies, and 142 blood samples were analysed by RT-PCR for BTV RNA. A total of 371 (12.9%) out of the 2,885 deer (35/208 calves, 307/2,542 adults, and 29/135 undetermined) were positive for antibodies against BTV. Prevalence increased in adult deer from 2005-2006 to 2008-2009, declining thereafter. No positive samples for BTV-1 were found by serum neutralization, whereas 43 deer (38 adults, four calves and one undetermined) were positive for BTV-4 specific antibodies. No BTV RNA positive deer were found by RT-PCR. Antibody detection throughout the study period suggests a maintained circulation of BTV in red deer. However, the lack of BTV RNA detection suggests a minor transmission risk to livestock.     

Astaxanthin profiles and corresponding colour properties in Australian farmed black tiger prawn (Penaeus monodon) during frozen storage

The colour of commercial cooked black tiger prawns (Penaeus monodon) is a key quality requirement to ensure product is not rejected in wholesale markets. The colour, due to the carotenoid astaxanthin, can be impacted by frozen storage, but changes in colour or astaxanthin profile, during frozen storage, have not been studied in detail. Subsequently in this study, the aims were to define the astaxanthin (as cis, trans, mono‐ester and di‐ester forms) content, together with the colour properties, in both pleopods (legs) and abdominal segments. Changes in astaxanthin content and colour properties were further determined during frozen storage (?20°C). Total astaxanthin content was seen to decrease in all samples over time, with the rate of degradation being significantly greater (P < 0.05) in pleopods than abdomen. In both pleopods and abdomen, rate of degradation of esterified forms was significantly greater (P < 0.05) than non‐esterified forms. Hue angle (increase), a* value (decrease) and L value (increase) were all seen to significantly change (P < 0.05) during storage, with changes being more prevalent in the pleopods. The pleopods are the key indicator of astaxanthin and colour loss in cooked black tiger prawns and preservation strategies are required to preserve astaxanthin and colour during frozen storage.