Biotechnology applied to fish reproduction: tools for conservation

This review discusses the new biotechnological tools that are arising and promising for conservation and enhancement of fish production, mainly regarding the endangered and the most economically important species. Two main techniques, in particular, are available to avoid extinction of endangered fish species and to improve the production of commercial species. Germ cell transplantation technology includes a number of approaches that have been studied, such as the transplantation of embryo-to-embryo blastomere, embryo-to-embryo differentiated PGC, larvae to larvae and embryo differentiated PGC, transplantation of spermatogonia from adult to larvae or between adults, and oogonia transplantation. However, the success of germ cell transplantation relies on the prior sterilization of fish, which can be performed at different stages of fish species development by means of several protocols that have been tested in order to achieve the best approach to produce a sterile fish. Among them, fish hybridization and triploidization, germline gene knockdown, hyperthermia, and chemical treatment deserve attention based on important results achieved thus far. This review currently used technologies and knowledge about surrogate technology and fish sterilization, discussing the stronger and the weaker points of each approach.     

Manufacture of Biquara (Haemulon Plumierii - Lacepède, 1801) Fishburger with Addition of Wheat Bran

Biquara is one of the main fish species caught in the northeast coast of Brazil but presents low commercial value. Therefore, the elaboration of biquara-based products with the addition of plant bran as a source of dietary fiber should be studied as a way to add value to biquara. The objective of the present study was to evaluate the physicochemical, microbiological, and sensory aspects of fishburgers made with biquara fillet with the addition of wheat bran (WB) (0, 1, 2, and 3%). The increase in WB decreased moisture and increased protein levels, ash, fiber, carbohydrates, and energy value. In addition, the inclusion of WB increased the cooking shrinkage and decreased hardness and cohesiveness of the samples. The fishburgers with the greatest WB levels presented a reddish-yellow hue. The microbial counts of the products were below the maximum limit allowed by the Brazilian legislation. The overall acceptance of the fishburgers improved with the addition of 0 to 2% WB. Therefore, the biquara fillets have a potential for the elaboration of fishburgers with the addition of 2% WB, once the products presented suitable physicochemical composition, sensory acceptance, and hygienic sanitary control according to the current national legislation.     

A procedure for estimating the number of green mature apples in night-time orchard images using light distribution and its application to yield estimation

A procedure for estimating the number of mature apples in orchard images captured at night-time with artificial illumination was developed and its potential for estimating yield was investigated. The procedure was tested using four datasets totaling more than 800 images taken with cameras positioned at three heights. The procedure for detecting apples was based on the observation that the light distribution on apples follows a simple pattern in which the perceived light intensity decreases with the distance from a local maximum due to specular reflection. Accordingly, apple detection was achieved by detecting concentric circles (or parts of circles) in binary images obtained via threshold operations. For each dataset, after calibration of the procedure using 12 images, the estimates of the number of apples were within a few percent of the number of apples counted by visual inspection. Yield estimations were obtained via multi-linear models that used between two and six images per tree. The results obtained using all three cameras were only slightly better than those obtained using only two cameras. Using images from only one side of the tree did not worsen the results significantly. Overall, the yield estimated by the best models was within \(\pm\)10 % of the actual yield. However, the standard deviation of the yield estimation errors corresponded to ~26–37 % of the average tree yield, indicating that improvements are still needed in order to achieve accurate yield estimation at the single-tree level.     

不同豆科植物对土壤酸化的影响

以9种豆科牧草为试材,在缺磷砂土上研究施用Ca(H₂PO₄)₂后对其产酸量的影响.结果表明:Lupinus albus,Lupinus lutens和Biserrula pelecinus施磷需求量比Cicer aritimum,Vicia faba,Medicago polgmorpha,Ornithopus sativus和Trifolium subterraneum低,而Lupinus angustifolius需求量最高.当增施磷肥,使其达到中度缺磷水平时,比酸度有所增加,但进一步增施磷肥则使植株产酸量减少,在几种植物中,C.arietinum产酸量最高,B.pelecinus最低.比酸度与过量阳离子、灰碱、钙和镁等浓度有关.在不考虑施磷和植物品种的情况下,植物产酸总量与植株地上部分过量阳离子总量恰好一致;在施磷量不同的情况下,豆科植物产酸量主要由其吸收阳离子和阴离子的差异决定.     

Practical diets with essential oils of plants activate the complement system and alter the intestinal morphology of Nile tilapia

The effect of the essential oils (EOs) of peppermint, Mentha piperita L., and tea tree, Melaleuca alternifolia (Maiden & Betche) Cheel, on the haematological, biochemical, and immunological parameters and intestinal morphology of Nile tilapia, Oreochromis niloticus L., was evaluated. Fish (58.09 ± 5.87 g) were fed 100 mg/kg and 250 mg/kg of each EO and sampled on days 7, 14, 30 and 60 after starting supplementation. The haematological and biochemical parameters were not altered by the supplementation of EOs compared to the control (p > .05). With regard to the immunological parameters, the activation of the complement system of fish fed 250 mg/kg peppermint and 100 mg/kg and 250 mg/kg tea tree EOs were significantly higher compared to the control after 60 days of feeding (p < .05). The complement system plays an essential role in innate immunity and contributes significantly to the acquired immune response; thus, its activation through supplementation with EOs is promising for the formulation of nutritional additives in aquaculture. Regarding intestinal morphology, fish fed 250 mg/kg tea tree EO presented higher villus size compared to all other groups (p < .05), which represents a healthier gut. These fish present a larger intestinal surface, which can result in better absorption and utilization of the nutrients. Based on the responses found in this study, both EOs were considered promising for the formulation of feed additives for Nile tilapia.     

Population dynamics of roundjaw bonefish Albula glossodonta at a remote coralline Atoll inform community‐based management in an artisanal fishery

Fisheries management requires knowledge on the population dynamics of exploited stocks. To that end, the present study used a mark–recapture approach to characterise the population demographics of roundjaw bonefish Albula glossodonta (Forsskål) and their interaction with a data‐limited fishery on Anaa Atoll in the Tuamotu Archipelago of French Polynesia. Over the course of the study, 2,509 bonefish were tagged and 12.3% were recaptured. The L_∞ of bonefish was estimated at 71 cm fork length (FL) with a K of 0.17, based on changes in FL between capture events. Artisanal fish traps located in the migratory corridors of the atoll accounted for 94% of recaptures and these movements occurred during the waning moon. Fishing mortality increased as bonefish reach sexual maturity, recruiting to the trap fishery at age 4 with the onset of spawning behaviour. Bonefish abundance between ages 3 and 5 was estimated to be 29,079 individuals. This case study demonstrated the utility of mark–recapture in filling knowledge gaps that impede the management of data‐limited fisheries. Ultimately, these results supported the creation of an Educational Managed Marine Area and the resurgence of rahui (seasonal closure) to manage this fishery.     

Effluent from Citrus Industry: Toxic Parameters of Orange Vinasse

Water, Air, & Soil Pollution - Laboratory snow melting experiments were conducted with actual late-winter snow samples, collected just before the final snowmelt, in two similar northern Swedish...