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1.
Evaluation of codends with sorting grids, exit windows, and diamond meshes: Size selection and fish behaviour 总被引：1，自引：0，他引：1
This paper presents the results of an experiment aimed at improving the size selection of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) in the Nordic bottom trawl fishery. Three systems simulating commercial conditions were tested: a 135 mm diamond-mesh codend fitted with a 55 mm sorting grid (Sort-V); a 135 mm diamond-mesh codend fitted with two lateral exit windows; and a codend built entirely of 155 mm diamond mesh. The selectivity curves showed similar selection ranges (SR) for the three systems. For cod, the mean SRs were around 8 cm, while for haddock, they were around 6 cm. All the estimated l50 values were far above the minimum landing sizes (MLS). For cod, the mean l50s were 56.1, 53.9, and 60.7 cm for the sorting grid, exit windows, and diamond-mesh configurations, respectively, while for haddock, they were 50.2, 50.6, and 49.9 cm, respectively. Underwater observations revealed that most of the fish escaped from the grid and exit-window codends as soon as they reached the vicinity of the sorting device. In contrast, fish remained inside the diamond-mesh codend for a longer time, and consequently were more exposed to physical damage before escape. In addition, many fish escaped from this codend during haul back and these fish were not likely to survive due to the rapid changes in pressure. Thus, the selectivity results obtained with this type of codend should be interpreted carefully. 相似文献
2.
捕虾桁拖网网囊网目的选择性研究 总被引：33，自引：2，他引：33
当网囊网目分别为４０ｍｍ,４５ｍｍ和５０ｍｍ时,哈氏仿对虾的５０％选择体长分别为８５．８８,９０．２６,９５．３２ｍｍ;中华管鞭虾的３０％选择体长为８７．５８,８８．０９,９２．５６ｍｍ;鹰爪虾的５０％选择丛长为８５．０４,８５．９６％,８８．３２ｍｍ。三种虾类的５０％选择体长和网囊网目内径的线性回归方程为,哈氏仿对虾Ｌ０．５－４８．０３＋０．９４Ｍｅ中华管鞭虾;Ｌ０．５＝６７．０＋０．４９８Ｍｅ 相似文献
3.
《Journal Of Aquatic Food Product Technology》2013,22(3):39-61
Abstract Seasonal variations in physicochemical and textural properties of minced cod muscle from Icelandic coastal areas were evaluated. Measurements were performed on mince from the white muscle. Compared to the winter and summer values, hardness and cohesiveness, as measured by Instron, showed a drop in March to May and another drop was observed for cohesiveness during the autumn months. Expressible moisture changed slightly from March to August whereas results from the winter months indicate greater fluctuations. A minimum was observed for protein solubility in March and July. The surface hydrophobicity of proteins, increased gradually from November to May followed by a sudden drop, then a gradual increase again. 相似文献
4.
Håkon Otterå Oddvard Garatun-Tjeldstø Kåre Julshamn Erland Austreng 《Aquaculture International》2003,11(1-2):217-224
There are indications that low ingestion ratesof formulated feed may limit the growth ofearly juvenile fish, including cod. This hasparticularly been observed during the weaningperiod, when the fish must change from apresumably palatable live prey to usually a drydiet. The study of the physical properties ofthe diet seems to be an underestimated area ofresearch, compared to studies on thenutritional properties of the diet. In thisstudy we used lanthanide markers as a tool inestimating diet preferences for examining theeffect of dietary moisture content on ingestionrates in juvenile cod (0.8 g). Fishmeal-baseddiets were produced with five levels of water,giving diets with 35, 42, 54, 65 or 95% dryweight. Each diet was marked with a smallamount of a lanthanide or yttrium oxide. Thefish were hand fed on a mixture of these fivediets. Ingestion rates where then estimated bykilling 1/2 of the fish after one day and therest after four days of feeding. The whole fishwith gut content was homogenized and markercontent was measured by ICP-MS. The amountingested of each of the five diets could thenbe calculated from these figures. Despite thehigh variation in diet selection betweenindividuals the results clearly indicate ahigher intake of moist feed. This could becaused by a better palatability or to a higheravailability caused by a lower sinking rate ofthe moist feed. 相似文献
5.
A Comparison of Three Different Hydroponic Sub-systems (gravel bed, floating and nutrient film technique) in an Aquaponic Test System 总被引：1，自引：1，他引：1
Murray Cod, Maccullochella peelii peelii (Mitchell), and Green Oak lettuce, Lactuca sativa, were used to test for differences between three hydroponic subsystems, Gravel Bed, Floating Raft and Nutrient Film Technique (NFT), in a freshwater Aquaponic test system, where plant nutrients were supplied from fish wastes while plants stripped nutrients from the waste water before it was returned to the fish. The Murray Cod had FCR's and biomass gains that were statistically identical in all systems. Lettuce yields were good, and in terms of biomass gain and yield, followed the relationship Gravel bed > Floating > NFT, with significant differences seen between all treatments. The NFT treatment was significantly less efficient than the other two treatments in terms of nitrate removal (20% less efficient), whilst no significant difference was seen between any test treatments in terms of phosphate removal. In terms of dissolved oxygen, water replacement and conductivity, no significant differences were observed between any test treatments. Overall, results suggest that NFT hydroponic sub-systems are less efficient at both removing nutrients from fish culture water and producing plant biomass or yield than Gravel bed or Floating hydroponic sub-systems in an Aquaponic context. Aquaponic system designers need to take these differences into account when designing hydroponic components within aquaponic systems. 相似文献
6.
Thomas D. Nickell Chris J. Cromey ngel Borja Kenneth D. Black 《Aquaculture (Amsterdam, Netherlands)》2009,295(3-4):226-237
A cod farm in Vidlin Voe, Shetland was at the time of the study the largest cod farm in Europe, and was started in 2003. Run according to organic principles, the farm consisted of 17 32 m diameter cages in the 3 km long sea loch (locally known as voe), which though extremely exposed at the mouth, is sheltered near the cages.Benthic macrofauna and physical/chemical sediment parameters were measured in the summer months of 2004, 2005 and 2006 as biomass increased in the growing cycle. A range of biotic indices showed the benthic environment was enriched at peak biomass of the farm, but by contrast, surficial CHN levels and organic matter were low and uniform. The commonly used sediment indicators redox, total organic carbon and total organic nitrogen did not correlate well with biotic indicators at this site. Predictions from a near-field particle tracking and resuspension model (CODMOD) and a simple nutrient enhancement box model of the voe system (Equilibrium Concentration Enhancement (ECE) model), were used to assess the assimilative capacity of the system. 相似文献
7.
Rotifers enriched with iodine,copper and manganese had no effect on larval cod (Gadus morhua) growth,mineral status or redox system gene mRNA levels 
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下载免费PDF全文 Sam Penglase Kristin Hamre Pål A Olsvik Espen Grøtan Andreas Nordgreen 《Aquaculture Research》2015,46(8):1793-1800
It currently remains unclear if rotifers contain sufficient mineral levels to meet larval fish requirements. In this study, rotifers were enriched with a commercial enrichment (control), or with additional iodine, iodine and copper, or iodine, copper and manganese, and the effects of feeding these rotifers to Atlantic cod (Gadus morhua) larvae from 3 to 18 days post hatch were investigated. Rotifer enrichment with minerals was successful, but Mn enrichment also increased rotifer zinc levels. No differences were observed between treatments in larval growth or survival, or in the mRNA levels in the majority of the redox system genes analysed. Only Zn levels increased in cod larvae in response to mineral enrichment of rotifers. Apart from Zn, little evidence was found to suggest that cod larvae require increased concentrations above the control rotifer levels of the essential elements studied here. 相似文献
8.
Influence of Different Pre-Storage Treatments on Resulting Shelf Life of Iced-Stored Barents-Sea Cod
《Journal Of Aquatic Food Product Technology》2013,22(3-4):187-200
Abstract Cod (Gadus morhua) was caught by bottom trawling in early summer 2000 (May/June) in the Barents Sea (217th cruise of FRV “Walther Herwig III”), treated in three different ways prior to iced storage and was subsequently iced-stored. Treatments were:
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none (whole ungutted, unbled)
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conventionally gutted (common practice)
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gill cut and bled but not gutted
9.
The global seafood industry, influenced by consumer demand, is closely linked to the global fishing industry, which determines the variety of fish available for consumption. The recently revealed issue of seafood mislabelling threatens to weaken this link by removing consumer power to influence patterns of fisheries exploitation through informed choice. Recognizing this, there is an urgent need to go beyond the mere documentation of the phenomenon and learn more about the origins of this problem and the nature of factors influencing its occurrence to develop solutions. In an attempt to understand seafood mislabelling more thoroughly in Europe, 226 cod products were purchased from Ireland and the UK, genetically identified using a DNA barcoding technique (COI barcoding gene), and species identification results were compared against product labels. Cod mislabelling proved more severe in Ireland than in the UK (28.4% vs. 7.4%). Moreover, whereas data show that in Ireland, cheaper species are sold as cod, in the UK, threatened Atlantic cod (Gadus morhua) may be sold as ‘sustainably sourced’ Pacific cod. Considering these countries operate under the same EU policies for seafood traceability and labelling, it is likely that this situation has been influenced by heightened consumer awareness in the UK, which has created an environment where mislabelling is discouraged. In addition to identifying samples, traceability information from packaged cod was used to trace products back to supplying companies. Although inconclusive in determining blame, this exercise has demonstrated that using traceability information can add explanatory power when attempting to determine responsibility for the occurrence of mislabelling. 相似文献
10.
Stavros Lalas Olga Gortzi John Tsaknis 《Plant foods for human nutrition (Dordrecht, Netherlands)》2006,61(2):93-102
The frying performance of Moringa stenopetala seed oil (extracted with cold press or n-hexane) was studied especially as regards repeated frying operations. The oils were used for intermittent frying of potato slices and cod filets at a temperature of 175 °C for 5 consecutive days (5 fryings per day). The chemical changes occurring in oils were evaluated. Free fatty acid content, polar compounds, colour and viscosity of the oils all increased, whereas the iodine value, smoke point, polyunsaturated fatty acid content, induction period and tocopherol content decreased. The effect of the oil on the organoleptic quality of these fried foods and the theoretical number of frying operations possible before having to discard the oil was also determined. The analytical and sensory data showed that the lowest deterioration occurred in cold press produced oil. 相似文献