Selectivity in a trawl codend during haul-back operation—An overlooked phenomenon

The selectivity of a 99 mm trawl codend was assessed using a codend cover fitted with a MultiSampler, which was acoustically triggered to take separate samples at three different phases of the haul. The first sample was collected during towing, the second during haul-up and the third at the surface. A total of 18 hauls were conducted with a commercial fishing vessel west of Scotland. It was demonstrated that escapes take place not only during the tow but also in the short period when the trawl is hauled back from the seabed and when the codend is at the surface. For haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus) and Norway lobster (Nephrops norvegicus), respectively, the mean percentages escaping at the surface were 16, 12 and 38% of the total escape while 17, 8 and 28% escaped during the haul-up phase. Compared to towing, the escape rate (no./min) increased for haddock by a factor 2.7 during haul-up and by a factor 1.7 at the surface, whereas the escape rates of whiting were similar for the three phases. The escape rate of Norway lobster increased by a factor of approximately 7 for both the haul-up and surface phases, compared to the towing phase. The selectivity parameters L50 (50% retention length) and SR (selection range = L75–L25) were estimated and compared for the three different phases and for the whole haul for haddock, whiting and Norway lobster. For all three species there was no significant (P > 0.05) difference in L50 between the three phases of the haul. There was also no significant difference for whiting and Norway lobster when comparing the SR of the three phases, whereas the SR was significantly lower for haddock when comparing the surface phase with towing and haul-up. The estimate of L50 when towing was about 6 cm lower for haddock and whiting and 9 mm for Norway lobster compared to the selection curve estimated conventionally for the whole haul. Finally, the effect of sea state, duration and codend catch on the selectivity parameters were estimated for the individual phases and for the whole haul. A significant effect of at least one variable was found in all phases.     

The end consumer’s choice of floorcovering in the Netherlands and the United Kingdom: a comparative pilot study of substitute competition

In order to understand the competitive situation of wood, it is essential to consider the end consumer of building materials. The knowledge of factors affecting the end consumers choice of building material for specific purposes, i.e., the mechanisms of substitute competition, is limited. Field studies of the British and Dutch floorcovering markets revealed that context, usage context as well as the general life situation, is of crucial importance in substitute competition. This contextual character severely limits the usefulness and adequacy of interviews with fixed-reply alternatives, as well as classical statistical methods of analysis. In this article, a qualitative approach to data gathering is combined with multivariate analysis. The results indicate that by using this methodology it is possible to determine which are the decisive predictors of material preferences, make cross-cultural comparisons, and apprehend the underlying motives or perspectives. The results further show that, unlike the other floorcovering materials studied, the determinant reasons for choosing wood appear to be exclusively nonfunctional in nature.     

Correction to: Nordic forest management towards climate change mitigation: time dynamic temperature change impacts of wood product systems including substitution effects

European Journal of Forest Research -     

Nordic forest management towards climate change mitigation: time dynamic temperature change impacts of wood product systems including substitution effects

European Journal of Forest Research - Climate change mitigation trade-offs between increasing harvests to exploit substitution effects versus accumulating forest carbon sequestration complicate...     

Fatty acid composition of 12 microalgae for possible use in aquaculture feed

Twelve algal strains representing the classes Cyanophyceae, Prymnesiophyceae, Bacillariophyceae, Rhodophyceae, Cryptophyceae, Chlorophyceae, Xantophyceae and Eustigmatophyceae were selected mainly from the culture collection of the Norwegian Institute for Water Research (NIVA). The algae were grown as continuous cultures in a 1.8 l. reactor, internally illuminated with an 11 W fluorescent tube. The retention time was adjusted in the range 2–4 days to fit the growth rate of the algae. The growth responses and fatty acid composition were analysed. The maximum production rate was obtained with Pseudokirchneriella subcapitata (0.63 g 1⁻¹ day⁻¹) and the lowest with Porphyridium cruentum 0.13 g 1⁻¹ day⁻¹. Arachidonic acid (AA) and eicosapentaenoic acid (EPA) were the dominating polyunsaturated fatty acids (PUFAs) in P. cruentum, while only EPA accumulated in Phaeodactylum tricornutum. Docosahexaenoic acid (DHA) was the major PUFA in Isochrysis galbana, while Pavlova sp. had both EPA and DHA. This is the first report on the fatty acid profiles of Nannochloropsis oceanica, Chroococcus sp., Synechococcus sp. and Tribonema sp.     

Total-and NO3-nitrogen level in different parts of the potato haulm as an index of nutritional status

Summary Changes in total- and NO₃-nitrogen ratios in different plant parts, due to fertilizer rates and stage of development are shown. The importance of considering the stage of development when pioposing critical levels, is emphasized. A fairly strong relationship between nitrogen ratio and yield was found for the total-nitrogen ratio of petioles and leaflets of upper leaves at mid-season (stage of flowering). A weaker, but still significant relationship, was obtained for NO₃-nitrogen in corresponding samples. At late season, about 20 days after mid-season, the relationship between yield and nitrogen ration was weaker. A comparison was made between the critical levels for potato petioles proposed earlier, and results obtained in the present study.

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Zusammenfassung In Feldversuchen wurden die Ver?nderungen im Gesamtstickstoff- und im NO₃-Stickstoff-Verh?ltnis (in Prozent der Trockensubstanz) in verschiedenen Teilen des Kartoffelkrautes und bei verschiedenen Düngergaben studiert. Der Zweck der Versuche war, die M?glichkeit einer Anwendung von Pflanzenanalysen für Ern?hrungsstudien bei der Kartoffel abzukl?ren. Die Angaben über die verwendeten Düngermengen und das Alter der Pflanzen anl?sslich der Probenentnahme sind in den TABELLEN 1 und 2 zusammengestellt. Aus den TABELLEN 3 und 4 ist zu ersehen, welche Pflanzenteile für die chemischen Analysen gebraucht wurden. Der Bereich der Stickstoffwerte war im Leitgewebe gew?hnlich gr?sser als in den Blatteilen. Die Düngungsstufen kamen-vom Ende der Vegetationszeit abgesehen-in allen analysierten Pflanzenteilen deutlich zum Ausdruck (TABELLEN 3 und 4). Grosse Ver?nderungen im Gesamtstickstoff- und NO₃-Stickstoff-Verh?ltnis wurden w?hrend kleinen Zeitintervallen gefunden (TABELLE 5), was die Notwendigkeit einer kurzen und genau umschriebenen Zeitperiode für die Probenentnahme hervorhebt. Eine ziemlich gute Relation zwischen Stickstoff-Verh?ltnis und Ertrag wurde für das Gesamtstickstoff-Verh?ltnis in Blattstielen und Bl?ttchen der oberen Bl?tter in der Mitte der Vegetationsperiode (zur Blütezeit) ermittelt. Eine weniger deutliche, aber immer noch signifikante Relation wurde für NO₃-Stickstoff in den entsprechenden Mustern gefunden (TABELLE 6). Gegen Ende der Vegetationsperiode, ungef?hr 20 Tage nach der Mitte dieser was die Relation zwischen Ertrag und Stickstoff-Verh?ltnis weniger ausgepr?gt. Zwischen früher vorgeschlagenen kritischen Werten und den in den vorliegenden Untersuchungen erhaltenen Ergebnissen wurden Vergleiche angestellt. Daraus ergab sich der Hinweis, dass unter Berücksichtigung der Wachstumsbedingungen, die w?hrend der geschilderten Versuche herrschten, die früher angegebenen kritischen Werte unn?tig hoch sind.

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Résumé L’auteur a étudié dans des expériences au champ les changements dans les proportions d’azote total et d’azote nitrique (en pourcent de matière sèche) dans les différentes parties de la fane avec différented quantités de fertilisants. La recherche visait à déterminer la possibilité d’utiliser l’analyse des plantes comme moyen d’études de la nutrition de la Pomme de terre. Les TABLEAUX 1 et 2 résument les données sur les quantités de fertilisants utilisés et sur l’age des plantes au moment des prélèvements d’échantillons. Un examen des TABLEAUX 3 et 4 montre quelles parties des plantes ont été utilisées pour les analyses chimiques. Les valeurs en azote sont habituellement plus élevées dans les tissus conducteurs que dans les parties de feuille. Sauf à la fin de la période de végétation, les quantités de fertilisants appliqués sont clairement marquées dans toutes les parties de la plante analysées (TABLEAUX 3 et 4). On trouve (TABLEAU 5) de grands changements dans les proportions d’azote total et d’azote nitrique pendant de courtes périodes de temps, ce qui met en évidence le besoin d’une brève période bien définie de prélèvement d’échantillons. On trouve une assez bonne corrélation entre la proportion d’azote total et la production pour ce qui concerne la proportion d’azote total dans les pétioles et les folioles des feuilles supérieures au moment de la pleine végétation (floraison). Une corrélation plus faible mais encore significative se constate pour l’azote nitrique dans les échantillons correspondants (TABLEAU 6). A la fin de la période de végétation, quelque 20 jours après la pleine végétation, la corrélation entre production et proportion d’azote est plus faible. L’auteur fait une comparaison des valeurs critiques antérieurement proposées et des résultats obtenus dans la présente étude. Il obtient des indications que sous les conditions de croissance rencontrées dans les présentes expériences, les quantités critiques proposées antéricurement sont inutilement élevées.

     

Effect of precooling at 5 or −1°C on shoot growth,flowering and carbohydrate metabolism in tulip bulbs

Precooling of dry tulip bulbs at ?1°C may be advantageous, compared with precooling at 5°C. Increasing the duration of precooling enhanced the growth of the shoots after planting, improved flower quality, and reduced the number of days to flower. The positive benefit of a stepwise precooling (5°C for 3 weeks, then ?1°C) was evident.Shoot elongation was promoted, and number of days to flower was reduced when the bulbs were precooled at ?1°C for less than 12 weeks. Extension of precooling beyond 12 weeks, however, was more effective with 5°C precooling. With few exceptions, sufficient precooling at either 5 or ?1°C gave a high percentage of flowering plants with first-quality flowers. Short durations (6–8 weeks) of precooling sometimes promoted flower blasting.Precooling at 5 or ?1°C had a similar effect upon the carbohydrate interconversion in scales and shoots of the bulbs, which as a rule is more pronounced at the lower temperature. The shoots accumulated sucrose, and to some extent fructosyl sucroses, during the 15 weeks precooling. Starch was also accumulated, the highest concentration being obtained at 5°C. The amount of starch was reduced in the scales during precooling, while the concentration of sucrose and fructosyl sucroses increased to a maximum value and then slowly diminished after about 9 weeks of precooling. The monosaccharides, glucose and fructose showed very small variations.     

Condensed tannins from Sesbania sesban and Desmodium intortum as a means of Haemonchus contortus control in goats

Two experiments were conducted to determine whether the proanthocyanidin (condensed tannin)-containing forage legumes Desmodium intortum cv Greenleaf and Sesbania sesban (accession 15019) could be integrated into a feeding management strategy as a means of Haemonchus contortus control in goats. The anthelmintic effects of condensed tannin extracts from the two legumes on H. contortus L₃ larvae were studied in an in vitro larval migration inhibition system. The extracts inhibited larval migration in a dose-dependent manner, and at concentrations from 1,000???g/ml condensed tannin, the extract from D. intortum caused a significantly higher inhibition of larval migration than did the corresponding concentrations of the S. sesban extract (P?<?0.01). Prolonged feeding of tanniniferous forage legumes showed that animals receiving D. intortum had the lowest total worm burden, the lowest female to male parasite ratio, the lowest number of eggs in the uterus of each female worm and the lowest per capita fecundity (P?<?0.01). However, there was no change in the performance (weight gain) of parasite-infected goats probably due to incomplete removal of the parasite or prolonged confinement of goats in small pens, which calls for further investigation. However, since there is no single efficient method in control of parasites, based on the obtained data from this experiment, integrated feeding of D. intortum with other suitable method of parasite control is thus suggested.     

Changes in trimethylamine oxide and trimethylamine in muscle of wild and farmed cod (Gadus morhua) during iced storage

Trimethylamine oxide (TMAO) is found at high levels in wild Atlantic cod. Trimethylamine oxide is reduced to trimethylamine (TMA) during iced storage. In this study, the levels of TMAO and TMA in wild and farmed cod and the impact of storage, gender and season on these levels were investigated. Wild cod had higher levels of TMAO than farmed cod. Wild cod also had higher levels of TMA after 15 days of iced storage. Farmed cod were found to have levels of TMA‐N <5 mg/100 g after 15 days of iced storage, which is below the maximum permitted level for fresh fish. Therefore, TMA appears to be an unsuitable measure of freshness in farmed cod. Female farmed cod had higher levels of TMAO than male farmed cod; no such difference between genders was found in wild cod. Female and male farmed cod had similar levels of TMA after post‐mortem iced storage. The hepatosomatic index (HSI) of female farmed cod was higher than that seen in male cod and this may be the underlying reason for the differences in muscle TMAO. Levels of TMAO in male farmed cod were higher during the autumn and were correlated with a larger HSI during the same period.     

THE RUSSIAN SEAFOOD REVOLUTION: SHIFTING CONSUMPTION TOWARDS AQUACULTURE PRODUCTS

A food consumption revolution is taking place in Russia. After decades of severe constraints on food consumption options under the communist regime Russian consumers are now adopting new food products—including seafood products – at a high pace. Since Russian consumers have previously had very limited seafood consumption choices, the market can be seen as an interesting laboratory for investigating consumer responses to products that have previously not been available. Among imported seafood products are both wild and farmed species. Furthermore, Russian imports include both traditional species such as herring, and ‘new’ species such as pangasius. We analyze market integration among seafood products using Russian monthly import prices from 2002 to 2007 on several products, such as herring, salmonids and pangasius. We find that pangasius compete in the white fish segment, and is a price leader. In the salmonids market, farmed salmon trout appears to be the price leader, both in the fresh and frozen market segment.