Spatio‐temporal trends of sailfish,Istiophorus platypterus catch rates in relation to spawning ground and environmental factors in the equatorial and southwestern Atlantic Ocean

Spatial and temporal trends of sailfish catch rates in the southwestern and equatorial Atlantic Ocean in relation to environmental variables were investigated using generalized additive models and fishery‐dependent data. Two generalized additive models were fit: (i) ‘spatio‐temporal’, including only latitude, longitude, month, and year; and (ii) ‘oceanographic’, including sea surface temperature (SST), chlorophyll‐a concentration, wind velocity, bottom depth, and depth of mixed layer and year. The spatio‐temporal model explained more (average ~40%) of the variability in catch rates than the oceanographic model (average ~30%). Modeled catch rate predictions showed that sailfish tend to aggregate off the southeast coast of Brazil during the peak of the spawning season (November to February). Sailfish also seem to aggregate for feeding in two different areas, one located in the mid‐west Atlantic to the south of ~15°S and another area off the north coast of Brazil. The oceanographic model revealed that wind velocity and chlorophyll‐a concentration were the most important variables describing catch rate variability. The results presented herein may help to understand sailfish movements in the Atlantic Ocean and the relationship of these movements with environmental effects.     

Recruitment of catarina scallop (Argopecten ventricosus) larvae on artificial collectors off the NE coast of the Gulf of California

We evaluated recruitment of larvae of catarina scallop, Argopecten ventricosus, in the area of Puerto Peñasco, NE Gulf of California. We moored artificial collectors in six sites from June 2007 to August 2008 and replaced them every 2 months. We used monthly (July 2002–September 2011) sea surface temperature (SST, °C) and surface chlorophyll‐a concentration (SSChl, mg m^?3) Aqua/MODIS satellite data to describe seasonal environmental behaviour study area. Also, we recorded bottom temperature at each site every 4 h, and every 2 months measured sea surface salinity, temperature and dissolved oxygen. We used a repeated measures anova to evaluate differences in the number of recruited spat between main factors, and analysed the presence of multimodal spat shell size frequency distributions. Overall, spat recruitment was negatively correlated with seawater temperature and showed higher spat recruitment abundances throughout winter, which is the season with the highest surface chlorophyll a concentration. We estimated multimodal shell size frequency distributions characterized by more than one modal size. The natural collection of A. ventricosus spat on artificial collectors in the area can be successfully performed over a protracted period (November–December to May–June). Our results extend the area where collection of A. ventricosus spat can be successful.     

Changes in selected stress and immune‐related genes in Atlantic cod,Gadus morhua,following overcrowding

Using Atlantic cod, Gadus morhua, as a model for the stress response in gadoid fish, the changes in the expression of some stress and immune genes as well as the profiles of plasma cortisol were examined. Adult fish were kept at a density of ca. 100 kg m^?3 by lowering the water level in the rearing tank for 1 h and this short‐term crowding stress was repeated thrice over a 12‐h interval period. Blood samples were collected before exposure and at 2, 24 and 72 h post crowding. Plasma cortisol level significantly increased at 2 h post crowding but returned to pre‐crowding levels 24 h after exposure. The relative expression of the stress response genes, glucose transporter‐3 and a putative heat shock protein 70 significantly increased at 2 and 24 h post crowding respectively. Significant up‐regulation of the pro‐inflammatory cytokines, interleukin (IL)‐1β and IL‐8, as well as anti‐bacterial genes, g‐type lysozyme and bactericidal permeability‐increasing protein/lipopolysaccharide‐binding protein (BPI/LBP) was also observed at 2 h and the levels were maintained until 72 h post exposure, except for BPI/LBP which had maximum up‐regulation at 24 h. The present observations have implications with respect to fish welfare and assessment of the health status of the farmed fish.     

Effect of dietary supplementation of inulin and W. cibaria on haemato‐immunological parameters of hybrid surubim (Pseudoplatystoma sp)

The dietary supplementation of prebiotics, probiotics and symbiotic in hybrid surubins (a Pseudoplatystoma corruscans and P. fasciatum cross) was evaluated for the effects on their autochthonous intestinal microbiota and on haematological and immunological parameters. A total of 160 fish were divided into four treatment groups with four replicates each. The treatment groups were fed with the following diets for 15 days: control diet without supplementation; 0.5% inulin (prebiotic) supplementation; Weissella cibaria (CPQBA 001‐10 DRM 02) (7.87 ± 0.2 log CFU g^?1) supplementation; or 0.5% inulin and W. cibaria supplementation (symbiotic group). The midgut intestines of the fish with the symbiotic diet supplementation had higher concentrations of lactic acid bacteria (7.07 ± 1.11 log CFU g^?1) and low levels of Vibrio spp (1.90 ± 0.60 log CFU g^?1) and Pseudomonas spp (2.23 ± 1.48 log CFU g^?1). In addition, increased erythrocytes and reduced circulating neutrophils were observed in this group. No differences in blood glucose, serum protein or lysozyme levels were detected between treatment groups. However, a higher concentration of total immunoglobulin was observed in fish fed with the probiotic and symbiotic diets. The addition of 0.5% inulin (prebiotic) thus W. cibaria (probiotic) to the diet of Pseudoplatystoma hybrid surubins reduce the number of pathogenic bacteria and stimulate the beneficial intestinal microbiota and may possibly alter their immune defence system.     

Biochemical,Physical, Chemical,and Microbiological Assessment of Blue Shrimp (Litopenaeus stylirostris) Stored in Ice

Postmortem changes in blue shrimp (Litopenaeus stylirostris) muscle were studied on the basis of biochemical, chemical, physical, and microbiological changes during an 18 day storage period at 0°C. Adenosine 5′-triphosphate (ATP) content, breakdown products, K-value, pH, trimethylamine nitrogen (TMA-N), total volatile basic nitrogen (TVB-N), water holding capacity (WHC), color, and texture (shear force) changes were examined. Also, total mesophilic and psychrophilic bacterial counts were measured. K-value increased linearly (r² = 0.98) from an initial value of 1.37 ± 0.59 to 59.42 ± 6.05% at Day 18. Spoilage indicators TVB-N and TMA-N increased from 29.56 ± 1.33 and 0.69 ± 0.25 to 39.04 and 2.04 ± 0.59 mg of N/100 g at Day 18, respectively; meanwhile, the total viable counts of mesophilic and psychrophilic bacteria increased from 3.48 ± 0.44 and 2.61 ± 0.29 log CFU/g to 6.27 ± 0.21 and 7.14 ± 0.39 log CFU/g, respectively, which indicated spoilage at the end of the storage period. The pH, texture, WHC, and color were affected (p < 0.05) during the storage period. Overall, results indicate that blue shrimp muscle quality was maintained for 12 days of storage in ice.     

The influence of antibiotics on the immune system: immuno-pharmokinetic investigations on the primary anti-SRBC response in carp, Cyprinus carpio L., after oxytetracycline injection

Abstract. The present study was performed to obtain further details on the immuno-modulating effects of oxytetracycline (OTC) in carp, Cyprinus carpio L. The immuno-logical study was extended by investigating the pharmacokinetic behaviour of OTC. Oxytetracycline, at a dosage of 60 mg/kg, was administered five times intra-peritoneally at 3-day intervals; the first injection was given 1 day before immunization. The kinetics of the primary anti-sheep red blood cell (SRBC) response, during a short-term OTC treatment revealed that the kinetics of the plaque-forming cell (PFC) response was not significantly affected by OTC nor its solvent. In contrast, the number of plaque-forming cells was significantly decreased. The anti-SRBC antibody production was delayed by 2–4 days in both experimental groups (OTC and solvent). However, within 12–14 days post-immunization, the same antibody levels were detected as in the control group. High OTC plasma levels (>50 μg/ml) were detected about 10 h after a single i. p. injection. A mean plasma elimination half-life (T¹/₂) of 34·5 h was calculated.     

Nocturnal feeding reduces sea bass (Dicentrarchus labrax, L.) pellet-catching ability

European sea bass exhibits a feeding rhythm with seasonal phase inversions: nocturnal feeding is predominant in winter, and diurnal feeding during the rest of the year. This explains the increased growth of sea bass fed at night during the winter months, but to fully assess such feeding practices, it is important to monitor food-catching efficiency in the dark. To evaluate the influence of nocturnal feeding on pellet-capture efficiency under laboratory conditions, we developed an infrared pellet detector linked to on-line recording with a microcomputer. Feed waste was recorded for eight groups of four sea bass (54.6±15.8 g body weight) fed either diurnal or nocturnal meals with long (>60 s) or short (<20 s) feed availability times. With short feed availability times, food-catching efficiency in complete darkness (0 lx) was reduced to 78.6%, compared to 93.5% in diurnally fed fish. This was confirmed in a second experiment, performed during winter, involving 4000 sea bass in four sea cages (1000 per cage) provided with self-feeders and pellets detectors. Feed waste amounted to less than 13% of the food distributed, but nocturnal demands (29% of total feed demands) were accompanied by higher levels of uneaten pellets (68% of the total feed waste) than diurnal demand. This suggests that if the aim is to reduce feed waste, nocturnal feeding should be restricted in sea cages.     

The effects of using crab zoeae (Maja brachydactyla) on growth and biochemical composition of Octopus vulgaris (Cuvier 1797) paralarvae

Octopus vulgaris farming at large scale can only be attained using live prey during the paralarvae stage. Presently, only Artemia complies with this requirement. Nevertheless, its sole use delivers poor paralarvae growth and survival. Some species of marine zooplankton are better prey for marine fish larvae compared to Artemia, since its composition is richer in several important nutritional components. Among these are phospholipids and specific fatty acids, namely docosahexaenoic acid, eicosapentaenoic acid and arachidonic acid. During the present experiment, octopus paralarvae were fed a co-feeding scheme of spider crab (Maja brachydactyla) zoeae and Artemia (1:2, Artemia/Crab zoeae). The use of spider crab zoeae was justified by their availability in commercial facilities, where adult spider crabs are maintained to be sold to the public. There, fecund and spawning females are present in large numbers, and zoeae availability is often high and implies no production or zoeae collection costs. O. vulgaris paralarvae fed on Artemia and crab zoeae grew larger (3.00 ± 0.56 mg dw^?1) after 30 days, compared to previous published papers. Also, the paralarvae lipid content was substantially enhanced in highly unsaturated fatty acids and phospholipids. However, survival after 30 days was still very low (1.75 % after 30 days) and needs to be greatly improved.     

Analysis of flowering,stigmas yield and qualitative traits of saffron (Crocus sativus L.) as affected by environmental conditions

Saffron is well known for its use as a condiment spice, as a dye and traditional medicine. Saffron is experiencing an increasing interest mainly due to its peculiar and manifold properties of the metabolic pool of its stigmas, mainly crocetin esters and picrocrocin. This species is cultivated in environments with very different climatic conditions and with very different corm rates from place to place, passed down over the centuries. The aim of this study was therefore the evaluation of the influence of rainfall, temperature and corm density on flower phenology, stigmas yield and main compositional characteristics of two saffron corms provenience. Flowering beginning in saffron seems to be influenced by the combination of temperature and soil moisture, whilst its flowering calendar proves independent of corm provenance, environment and plant density. On the contrary, the studied factors exert a strong effect on both total stigmas yield and qualitative characteristics: colder environment resulted in a higher flower production, but lower quality of stigmas. Flower number was positively correlated with the stigmas yield, but negatively with its unitary weight. The content of crocetin esters and picrocrocin has been evaluated according to the spectrophotometric ISO normative, which ranked the samples into three qualitative decreasing categories (I–III). The spectrophotometric data showed positive correlation with the unitary stigmas weight and negative with stigmas production.