Nutritional Composition of Salmonidae and Acipenseridae Fish Eggs

Ovivorous Opportunities: Predation Events During Nest Guarding in a Freshwater Fish Species

The construction and defense of nests leading up to and following spawning is widespread across freshwater fishes. Despite the known role of nesting in sexual selection and the establishment of social hierarchy, how nesting and nest guarding behavior may shape predation risk for both offspring and nest guarding individuals remains relatively underexplored for many species. Here, we documented a novel interaction between a nest guarding fish species, the pumpkinseed sunfish (Lepomis gibbosus), and common snapping turtles (Chelydra serpentina) during the pumpkinseed nesting period. Field surveys were conducted over 3 days in an Ontario wetland to document nest densities, predator presence, and predation attempts by potential nest predators. A total of 118 pumpkinseed nests were observed, with all but five nests located in colonies. In nine instances, adult snapping turtles were recorded inspecting guarded pumpkinseed nests. On two occasions, snapping turtles were observed consuming nest contents, as indicated by a gulping motion while on the nest. Male pumpkinseed exhibited defensive behaviors, such as diversion and aggression. Following these interactions, we returned to quantify nest abandonment in three nests and observed that pumpkinseed had abandoned each nest within 48 h. While no observations of predation by snapping turtles on adult sunfish were made, other opportunistic predators made foraging attempts on guarding males. Though nest guarding can improve egg and offspring survival, our results document that predators are still capable of consuming nest contents even while guarded. Omnivorous foraging on fish eggs that are only briefly available to consumers but spatially aggregated in specific spawning habitats and nest colonies warrants future work evaluating the impact of nesting for: (1) adult and offspring survival across systems with divergent predator communities, and (2) the contribution of egg consumption to the seasonal energy budgets of egg predators.

Biochemical analysis and fertilization success of Cirrhinus mrigala ova during induced spawning

Fish egg quality is very crucial in aquaculture sector for production of healthy seed. Egg yolk is an energy reservoir for growth and development of embryo. This study evaluated the biochemical composition and quality of Cirrhinus mrigala eggs at three different hatchery sites of Pakistan, (Site 1= Fish Seed Hatchery, District Pakpattan; Site 2= Sidhuwan Hatchery, Head Balloki, District Kasur; Site 3= Chenab Fish Hatchery, Rangpur, District Muzaffargarh) during induced breeding. For this, a total of 36 (18 males and 18 females) fish brooders, 12 (06 males and 06 females) from each site were utilized. Fatty acids analysis revealed significant differences among three different sites. Saturated fatty acids i.e., palmitic acid (C16:0) and stearic acids (C18:0) were higher at site 2 compared to the others sites. Monounsaturated fatty acids i.e., Oleic acid (C18:1) and polyunsaturated fatty acids i.e., Docosahexaenoic acid (DHA) (C22:6) exhibited considerably greater values at site 2 than those of other two sites. Egg mineral contents unveiled remarkable differences, particularly at site 2 indicating significantly higher mineral contents except copper (Cu) in comparison to the other sites. Significant variation exists in fertilization and hatching rates during induced spawning, with the highest values recorded at site 2. It is concluded that biochemical composition of egg especially fatty acid profile and mineral content greatly influences the embryonic development and hatching success of farm reared Cirrhinus mrigala.

Amino Acid Content in the Muscles of the Red Deer (Cervus elaphus) from Three Types of Feeding Grounds

This study aimed to analyze the amino acid profile, with a particular focus on the nutritional value of the protein of the longissimus lumborum (LL) and the semimembranosus (SM) muscles of deer originating from three feeding grounds: forest (FFG); conventional (CFG) grounds; organic farm (OFG). This is the first time that deer from an organic farm feeding ground have been included in this study. The muscles were collected from 36 deer carcasses with equal proportions of sex and 31 months of age. This study demonstrated significantly higher essential amino acid (EAA) and non-essential amino acid (NEAA) contents in the muscles of deer from the FFG and CFG compared to the OFG. However, the EAA-to-NEAA ratio was significantly higher for the muscles of deer from the OFG. The muscles of the FFG and CFG deer were characterized by a higher concentration of lysine as well as acidic and tasty amino acids compared to the OFG deer, with the muscles of the latter exhibiting a higher percentage of branched-chain amino acids (BCAA). The results obtained can be used professionally by nutrition specialists in preventive and therapeutic diets and breeders to make decisions about farm location and deer feeding strategies.

Exploring the Multifaceted Potential of Endangered Sturgeon: Caviar, Meat and By-Product Benefits

Sturgeons are facing critical endangerment due to overfishing, habitat destruction, pollution and climate change. Their roe, highly prized as caviar, has driven the overexploitation, severely depleting wild populations. In recent years sturgeon aquaculture has experienced significant growth, primarily aimed at providing high-quality caviar and secondarily meat. This sector generates significant quantities of by-products, which are mainly treated as waste, being mostly discarded, impacting the environment, even though they are a source of bioactive molecules and potential applications in various sectors. This article presents a review of the proximate composition and nutritional value of sturgeon caviar and meat, also exploring the potential of the by-products, with an emphasis on the processing of these components, the chemical composition and the functional and bioactive properties. Although sturgeon caviar, meat, and by-products are highly valuable both nutritionally and economically, adopting sustainable practices and innovative approaches is crucial to ensuring the industry's future growth and maintaining ecological balance. Despite some limitations, like the deficient standardization of the methods for extracting and processing, sturgeon by-products have a tremendous potential to increase the overall value of sturgeon aquaculture and to promote a zero-waste approach, contributing to achieving the Sustainable Development Goals adopted by all United Nations Member States in 2015.

Determination of thyroid hormones in lake sturgeon (Acipenser fulvescens) tissues at different developmental stages using a sensitive liquid chromatography-mass spectrometry method

Thyroid hormones (TH) are known to play an important role in the growth and development of vertebrates. In fish species, TH regulates the larval-juvenile metamorphosis, and is crucial for development during early life stages. Monitoring the variations in TH levels at different life stages can provide insights into the regulation of metamorphosis and fish development. In this study, we developed an extremely sensitive method for the quantification of thyroxine (T4), triiodothyronine (T3), and reverse-triiodothyronine (rT3), in lake sturgeon (Acipenser fulvescens) tissues from eggs, free embryos, larvae, and juveniles. The target compounds were extracted by an enzymatic digestion method, followed by protein precipitation. Further cleanup was performed by liquid-liquid extraction (LLE) and solid phase extraction (SPE) using SampliQ OPT cartridges. The liquid-chromatography tandem mass spectrometry (LC-MS/MS) method used to quantify TH compounds showed remarkably high sensitivity with the limit of detection (LOD) and the limit of quantification (LOQ) ranging from < 1 pg/mL to 10 pg/mL and linearity in the range of 10-50,000 pg/mL. This method was validated for tissue samples across several early developmental stages and was checked for intra- and inter-day accuracy (78.3-111.2 %) and precision (0.1-4.9 %), matrix effect (75.4-134.1 %), and recovery (41.2-69.0 %). The method was successfully applied for the quantification and comparison of T4, T3 and rT3 in hatchery raised lake sturgeon samples collected at unique time points (i.e., days post fertilization dpf) including fertilized eggs (11 dpf), free embryos (14 dpf), larvae (22 dpf), juveniles (40 dpf) and older juveniles (74 dpf). With modifications, this method could be applied to other species important for agriculture or conservation.

Survival of Embryos and Fry of Sea Trout (Salmo trutta m. trutta) Growing from Eggs Exposed to Different Concentrations of Selenium during Egg Swelling

Adequate selenium (Se) availability enhances the health and growth of organisms, but overdose of it can be harmful and pathogenic. The study's objective was to analyse the impact of short-term exposure of sea trout fertilised eggs to inorganic selenium (SeO₂) at concentrations from 0 to 32 mg Se L^-1 to find the optimal and toxic dose of Se on early fish development. Se accumulated in the body, embryos' survival rate, and growth in the first four months of life was examined. Swelling of fertilised eggs in water supplemented with Se at a concentration from 0.5 to 8 mg Se L^-1 was associated with a slightly positive impact on the hatching rate. At higher Se concentration, a harmful effect on the survival of the embryo was observed. The survival of fry was similar in all groups, while the fry length and weight correlated positively with Se concentration in its body. Immersion of fertilised eggs in water enriched with Se during egg swelling can constitute a method to supplement the element to non-feeding stages of fish. In selenium-poor areas, this innovative method can be implemented in aquaculture to improve breeding outcomes. Se concentration should be adjusted to the chemical compound, fish species, and Se's content in the yolk.