Main Commercial Species Research Articles

Fish stocks of Urophycis brasiliensis revealed by otolith fingerprint and shape in the Southwestern Atlantic Ocean

Brazilian codling Urophycis brasiliensis is one of the main commercial coastal fish species from the Southwestern Atlantic Ocean. Regardless of its economic relevance, its stock structure remains largely unknown. In this study, we used the otolith shape and the core/outer edge multi-elemental fingerprints (Li:Ca, Mg:Ca, Mn:Ca, Fe:Ca, Zn:Ca, Rb:Ca, Sr:Ca, and Ba:Ca ratios) to evaluate the spatial segregation of young (nursery areas) and adult (stocks) stages of fish from the coast of northern Argentina, Uruguay, and southern Brazil. Otolith edge chemistry showed that several elemental ratios were significantly different between catching areas. Permutational multivariate analysis of variance (PERMANOVA) (p < 0.05) and quadratic discriminant analysis (QDA), with jackknifed classification of 80.0 and 68.2% for otolith core and edge, respectively, were effective in discriminating between sampling sites considering young and adult life stages. PERMANOVA analysis of otolith shape revealed multivariate significant differences between Argentina and Brazil (p = 0.0001) individuals, whereas no differences were found between fish from Uruguay and Argentina (p > 0.05). QDA classification rates were relatively low for Uruguay (48.0%) and values of 66.7 and 70.0% were found for Brazil and Argentina, respectively. Our results not only show the presence of at least two fish stocks (Argentina and Brazil), with a third potential stock in Uruguay, but also suggest a strong spatial segregation during ontogeny.

Современное состояние популяции хамсы Engraulis encrasicolus (L.) (Pisces: Engraulidae), зимующей у побережья Восточного Крыма и Северного Кавказа

Хамса, или европейский анчоус, Engraulis encrasicolus (Linnaeus, 1758) ― один из наиболее массовых видов рыб в Азово-Черноморском бассейне. В данном регионе хамса является основным промысловым объектом, и в последние десятилетия доля её вылова достигает 80–85 %. Вид представлен двумя формами ― черноморской и азовской хамсой. Одна из актуальных задач современных исследований ― оценка состояния популяции хамсы и прогноз её возможных изменений при воздействии различных природных и антропогенных факторов. В данной работе приведены результаты изучения многолетней (2010/11–2017/18) динамики размерно-возрастной структуры и внутривидового состава хамсы, зимовавшей у побережья Восточного Крыма и Северного Кавказа, и дана оценка современного состояния её популяции. Материалом для исследований послужила хамса из траловых уловов промысловых судов. Собрано 138 проб; с точностью 0,1 см выполнены измерения общей и стандартной длины 44 202 экз. хамсы. Определён возраст у 1162 экз., составлен размерно-возрастной ключ. Установлена внутривидовая идентификация хамсы с помощью индекса отолитов (метод Сказкиной). В качестве показателей размерно-возрастной структуры изучены средняя и предельная длина, средний возраст, распределение (численное соотношение) представителей разных размерных групп и возрастных (годовых) классов. Установлены положительные тренды средней длины и среднего возраста хамсы, отражающие увеличение в составе популяции доли крупных (&gt; 9,5 см) особей ― представителей старших возрастных классов (трёх- и четырёхлеток). По многолетним наблюдениям, средняя длина хамсы увеличилась с 8,06 до 9,09 см, при этом относительная численность мелких (&lt; 7,5 см) особей сократилась почти в 4 раза (с 22,5 до 5,7 %), а доля крупных особей увеличилась почти в 6 раз (с 5,7 до 33 %). Средний возраст хамсы вырос с 1,64 до 1,98 года за счёт почти 3-кратного (с 7,1 до 2,6 %) сокращения относительной численности сеголеток (0+) и 1,5-кратного (с 72,6 до 47,7 %) — двухлеток (1+), а также за счёт 2,4- и 4,3-кратного увеличения относительной численности трёхлеток (2+) и четырёхлеток (3+). Непосредственной причиной этих изменений послужило появление урожайных поколений в 2013, 2014 и 2015 гг. Установлена внутривидовая принадлежность хамсы, идентифицированы азовская и черноморская формы. Показана многолетняя динамика количественного перераспределения хамсы в пользу черноморской формы. Так, в 2010/11–2013/14 гг. в составе смешанных зимовальных скоплений хамсы доминирующее положение занимала азовская форма; её доля составляла в среднем 58,5 %, варьируя от 55 до 63 %. Доля черноморской формы в среднем не превышала 41,5 %, варьируя от 37 до 45 %. В 2014/15 гг. численное соотношение азовской и черноморской форм изменилось на противоположное: доминирующее положение заняла черноморская хамса, доля которой увеличилась до 53 % и колебалась в последующие годы от 52 до 63 % (при среднем значении 56 %). Полученные результаты находятся в полном соответствии с предложенной нами ранее гипотезой перестройки внутривидовой структуры хамсы, вызванной изменением климатических условий (общим региональным потеплением). Гипотеза основана на результатах изучения многолетней (1999–2010) динамики внутривидовой структуры хамсы, зимовавшей у западного побережья Крыма. Согласно гипотезе, в зимовальных скоплениях в 1999–2004 гг. доминирующее положение занимала азовская хамса, доля которой составляла в среднем 66,7 % общей численности, варьируя в разные годы от 56 до 87 %. Доля черноморской хамсы в этот период не превышала 33,3 %, изменяясь в разные годы от 13 до 44 %. В 2005 г. соотношение численности двух форм изменилось на противоположное. Доминирующее положение заняла черноморская хамса, её доля в 2005–2010 гг. составила в среднем 76,7 % (с вариациями в разные годы от 57 до 88 %). Перестройку внутривидовой структуры популяции хамсы следует рассматривать как экологическую адаптацию данного вида, обеспечивающую его более совершенную приспособленность к изменившимся условиям среды, в частности к температуре воды, поскольку азовская и черноморская хамса являются «температурными расами», первая из которых устойчива к более низкой репродуктивной температуре, а вторая ― к более высокой. Учитывая произошедшие изменения в размерно-возрастной структуре, современное состояние популяции хамсы следует признать благополучным. Вместе с тем, принимая во внимание резкое сокращение относительной численности сеголеток в 2016 и 2017 гг., следует ожидать в ближайшие годы значительного омоложения популяции, и, соответственно, измельчания особей хамсы.

СОВРЕМЕННОЕ СОСТОЯНИЕ И ПЕРСПЕКТИВЫ ИСКУССТВЕННОГО РАЗВЕДЕНИЯ РЕДКИХ, ИСЧЕЗАЮЩИХ ВИДОВ РЫБ ДЛЯ СОХРАНЕНИЯ БИОРАЗНООБРАЗИЯ И ВОССТАНОВЛЕНИЯ ЧИСЛЕННОСТИ В ЕСТЕСТВЕННЫХ ВОДОЕМАХ ИЛЕ-БАЛКАШСКОГО БАССЕЙНА

This article presents materials on the current state of the native ichthyofauna of the Ile-Balkhash basin, affected by large-scale acclimatization works. Four species of the ichthyofauna composition are listed in the Red Book of Kazakhstan: spike ( Acipenser nudiventris Lovetsky, 1828), Aral barbel ( Barbus brachycephalus brachycephalus Kessler, 1872), Balkhash marinka ( Schizothorax argentatus argentatus Kessler, 1874), Balkhash perch ( Perca schrenkii Kessler, 1874). Due to the ineffectiveness of fish conservation measures, including the prohibition for catching of these fish species, which are not found anywhere except in the Ile-Balkhash basin, it is necessary to impose artificial reproduction, changes in the Fishery Rules and organization of commercial rearing. The work is based on research materials of 2001-2018 conducted in Lake Balkhash, the delta and the lower reaches of the Ile and the Tokraun. The status of spike populations ( Acipenser nudiventris Lovetsky, 1828), Aral barbel ( Barbus brachycephalus brachycephalus Kessler, 1872), Balkhash marinka ( Schizothorax argentatus argentatus Kessler, 1874) and Balkhash perch ( Perca schrenkii Kessler, 1874). The main reasons preventing the maintenance of a high number of endangered species have been established: small area of natural spawning grounds, death of fry in linmeshing fishing gear, large-scale poaching (spike); deterioration of conditions for the natural reproduction, mass mortality of young fishes in the irrigation system (Aral barbel); total elimination and food competition with pike perch (Balkhash marinka, Balkhash perch). The prospects for preservation of rare and endangered fish species have been considered, recommendations for breeding and replenishing populations of species listed in the Red Book have been given: measures for artificial reproduction and prevention of juvenile death, creating favorable conditions for fattening and reducing the pressure of trophic competition. Without taking adequate measures for reducing the anthropogenic impact on natural resources, including ichthyofauna, the number of main commercial fish species will decrease, rare species of fish will die out.

RECENT CHANGES IN THE OKHOTSK SEA ECOSYSTEM (2008–2018)

Recent changes of the main oceanographic, chemical, and biological parameters of the Okhotsk Sea ecosystem are considered briefly for the last decades (2000–2010s), mostly on the data obtained in marine expeditions conducted by Pacific Fish. Res. Center (TINRO) annually. Since the mid-2000s, anomalous oceanographic conditions were formed there with prevailing heightened temperature in all layers of the sea and lowered ice cover caused by changes in the atmosphere circulation with northward shift of cyclones tracks in winter and weakening of winter monsoon. The ice cover was below the normal value every year since 2004. In the warmer winter conditions, producing of the high-density water on the northern shelf decreased from 3.2–7.8 . 103 km3 in 1998–2002 to 1.2 . 103 km3 on average in 2004–2015, and the water with density sq &gt; 26.8 was not formed at all in 2007–2009, 2011, and 2014–2015. As the result, winter convection, including the slope convection, became weaker and shallower and ventilated worse the water column, so dissolved oxygen content decreased in the lower portion of the intermediate layer, usually ventilated by slope convection. For the core of the intermediate layer (isopycnal surface 27.0 σθ), positive trend of temperature is estimated as +0.04…+0.16 o/decade, by areas, while the trend of dissolved oxygen content is negative: –0.07…–0.14 mL/L.decade, by areas. From the other hand, spring phytoplankton bloom became less intensive, presumably because of poorer upward flux of nutrients in conditions of weaker vertical mixing, and zooplankton biomass decreased, particularly for phytophages. However, these changes did not cause significant response in fluctuations of stocks for the main commercial fish and crab species. The largest stock of walleye pollock had cyclic fluctuations driven mostly by intra-population regulations, the stocks of pacific herring were rather stable, and the stocks of deep-water fish species, as flounders and halibuts had a slight tendency to growth, possibly because of better conditions for reproduction. Indeed, the densest aggregations of greenland halibut shifted from the depth of 600–700 m to 500–600 m that may be caused by de-oxygenizing of the lower portion of the intermediate layer. Crabs abundance also had positive dynamics obviously because of the effect of protective measures for red king crab in the 2009–2012, though its biomass continued to grow even after restoring the commercial landings. There is concluded that recent changes in the macroecosystem of the Okhotsk Sea correspond to the conception of the sub-polar ecosystems transformation under climate warming toward decreasing of their productivity and increasing of their functioning efficiency that was proposed earlier for the Japan Sea. Thus, from position of commercial exploitation of marine biological resources, the modern reconstruction of the Okhotsk Sea ecosystem under the climate change impact could be considered as a positive process.

Methods for predicting Sitka spruce natural regeneration presence and density in the UK

Abstract: Natural regeneration is crucial for silvicultural approaches based on the continuous presence of a forest cover, or Continuous Cover Forestry (CCF). Sitka spruce (Picea sitchensis) is the main commercial species in the United Kingdom (UK), and its potential for CCF has been demonstrated in various studies. However, there are no quantitative models available to predict its natural regeneration in the country. We describe models for Sitka spruce seedlings presence and density under canopy cover in the UK forests, to be used as a substitution of a regeneration survey. Using a natural regeneration dataset comprised of 340 plots, a Generalized Linear Mixed Model (GLMM) was calibrated to estimate the likelihood of regeneration presence at plot level. Seedling density was simulated in a subsequent step using only the subset of data with regeneration presence (138 plots): we compared methods based on GLMMs calibrated to the observed seedling density, and the simple generation of random numbers similar in distribution to the observed values. We validated the models with a cross-validation method using the calibration dataset and with an independent dataset of 78 plots collected in forests already in the process of transformation to CCF. The best GLMM for regeneration presence included age of the plantation, time after last thinning, favourable ground cover and basal area. After the cross-validation, 73% of the plots were correctly estimated (76% for presence of regeneration and 71% for the absence). After the independent validation process, 82% of the plots were correctly estimated, although 100% for presence of regeneration and only 12% for the absence. Both methods for estimating seedling density had a poor performance, both with the cross-validation and independent validation. The results showed that the tools here described are appropriate for estimating regeneration presence in traditional Sitka spruce plantations. However, alternative methods are required for forests already in an advanced stage of transformation to CCF systems.

Modelling the effects of more selective trawl nets on the productivity of European hake (Merluccius merluccius) and deep-water rose shrimp (Parapenaeus longirostris) stocks in the Strait of Sicily

Single-species Gadget models were used to assess the effects of using a sorting grid mounted on the traditional trawl net used by Sicilian trawlers to exploit the deep-water rose shrimp in the Strait of Sicily. The main commercial by-catch species of this fleet is the European hake (Merluccius merluccius), often caught at sizes well below the minimum conservation reference size. Selectivity curves based on the results of an experimental survey carried out in the area using a commercial trawler equipped with an ad hoc-designed sorting grid were incorporated into single-species Gadget models to forecast the effects of changing fishery selectivity on the performance of the two stocks in terms of catch and biomass. The models included catch data from the Italian, Tunisian and Maltese fleets as well as MEDITS trawl survey data for the period 2002-2016. Several scenarios were defined to simulate the effect of the Italian trawlers’ adopting the sorting grid under different stock-recruitment assumptions. The results obtained, when compared with status quo simulations of fishing without a sorting grid mounted on the trawl net, indicated a beneficial effect for both stocks in terms of an increase in biomass and for the fleets in terms of the amount and size composition of annual landings.

Recruitment in tuna RFMO stock assessment and management: A review of current approaches and challenges

We review recent approaches and challenges in monitoring and estimating recruitment for the main commercial tuna species managed under the auspices of the five tuna Regional Fisheries Management Organizations (tRFMOs), including: (i) the stock assessment and management context, (ii) fisheries-independent recruitment monitoring successes, failures and future options, (iii) recruitment estimation methods within statistical population models and (iv) recruitment in projections for traditional stock assessment and management strategy evaluation. Despite the diversity in tuna populations and tRFMO scientific processes, there are many common recruitment themes, including: (i) fisheries-independent recruitment monitoring is difficult and rare (the aerial surveys for juvenile southern bluefin tuna, Thunnus maccoyi, and juvenile eastern Atlantic bluefin tuna stocks, T. thynnus, are the only time series used in assessments), (ii) most statistical models estimate lognormal recruitment deviations around a stationary Beverton-Holt relationship using a penalized likelihood approach, (iii) the degree of compensation in the stock-recruitment relationship and the variance is difficult to estimate (steepness is usually fixed at 0.7 ≤ h ≤ 1.0, and the CV is most often fixed with σR = 0.6 for lognormal recruitment deviations), and (iv) estimated recruitment time series often deviate systematically from the mean relationship, but it is unclear the extent to which this reflects reality (e.g. environmental change) or estimation artefacts (e.g. incorrect model assumptions or biased data). There is a trend toward the use of model ensembles to represent recruitment (and other sources of) uncertainty, both in the context of traditional assessments and management strategy evaluation. Recommendations include: i) continued development of fisheries-independent recruitment monitoring methods, including adopting emerging technologies (e.g. genetics-based mark-recapture or abundance monitoring with a network of acoustic FADs), and (ii) the management paradigm should be designed to be robust to future recruitment uncertainties (e.g. recognize that recruitment compensation might be much lower than model-based estimates or assumptions, and be prepared to respond to substantial serially-correlated recruitment deviations, e.g. regime shifts). Following a history of over-exploitation and difficulties in reaching international scientific and management consensus, the CCSBT now provides a leading example of how tuna recruitment issues might be addressed through innovative monitoring, comprehensive modelling of uncertainty, and management with simulation-tested management procedures.

Community structure of the deep sea fishes in the northern Gulf of Aqaba, Red Sea (Osteichthyes and Chondrichthyes)

The aim of this study was to investigate the community structure of deep sea fishes in the northern Gulf of Aqaba. Deep fish traps, short lines and long lines were deployed at depth ranges from 60 to 700 m between June 2014 and May 2015. A total of 369 fish individuals belonging to 37 species in 21 families were collected. The most abundant family observed in deep fish traps and short line was the commercially important family Sparidae, whereas the most abundant family in long line catch was the commercially unimportant fish family Muraenidae. The most abundant fish species sampled by deep fish traps and shortline was Blueskin Seabream, Polysteganus coeruleopunctatus. The most abundant species in long line catch White-spotted Moray, Gymnothorax johnsoni. In fish traps and with short line, the most commonly caught species was Blueskin Seabream. White-spotted Moray was the most common long line catch. Depth distribution for 37 deep fish species and GIS maps for the two main commercial fish species Blueskin Seabream and Bigeye Hound Shark, Iago omanensis were documented.

Modification of the phyllosphere bacterial biocoenosis by Pseudomonas syringae pv. actinidiae infection

In Italy, since 2008, kiwifruit growing has been widely affected by the bacterial pathogen Pseudomonas syringae pv. actinidiae (Psa), the causative agent of bacterial canker. Although the role played by phyllosphere bacteria in protecting hosts against pathogen infection is known, to our knowledge, no studies aimed at characterizing the bacteria living on the aerial parts of the kiwifruit have been performed to date. In the present study, the bacterial communities harbored by flowers of Actinidia chinensis and Actinidia deliciosa are described at both qualitative and quantitative levels. The microbiota of the two kiwifruit species were analyzed in healthy plants and plants infected with Psa. To achieve this goal, a metagenomic approach was adopted, based on deep sequencing of DNA from epiphytic bacteria followed by the amplification of the V3-V4 region of the 16S rRNA gene. In this study, we describe (i) the different composition of the biocoenosis associated with the two main commercial species of Actinidia, (ii) the influence of Psa population on the composition of the epiphytic biocoenosis, and (iii) the abundance and persistence of non-pathogenic bacterial species of interest.

Assessing ecological and fisheries implications of the EU landing obligation in Eastern Mediterranean

Discards are of primary target for the European Union policy and concerns have been expressed on the consequances that the landing obligation may have on the fisheries resources and other ecosystem components. In this context, we used an ecosystem modelling approach based on a previously constructed food web model for the Greek Ionian Sea to explore changes in food web components and fisheries due to the application of the landing obligation. Time series were also used to tune the trophic relationships during a hindcast period (1998–2014) and six scenarios were explored after 2015 simulating the current policy; a partial and a total discard ban (implemented after 2017) under both constant and decreasing fishing effort. Results indicated that, under constant fishing effort, changes in the management of unwanted catches (from discarding to landing them) had a significant consequences on certain functional groups, especially on marine birds which were even more adverse in the scenario tuned for the total discard ban. However, the new management practices seem pointless for the sustainability for most of the stocks, because there were no changes in the main commercial fish species apart from few exceptions (e.g. flatfish, deep water shrimps, continental shrimps) in which biomass changes were generally low. In contrast, simulations of declining fishing effort affected to higher extent more groups, whereas additionally representing changes in discarding policies had little effect. The model presented here is intended to shed light in the importance of discards in the food-web structure and subsequently to incentivize the practices to avoid producing discards in the first place.

Captura incidental en nasas del pez león Pterois volitans (Scorpaeniformes: Scorpaenidae) en el Caribe colombiano

Incidental catch in traps of the lionfish Pterois volitans (Scorpaeniformes: Scorpaenidae) in the Colombian Caribbean. Since 2011, small-scale fishermen from Taganga Bay (Colombian Caribbean) have been catching lionfish in traps in the Tayrona National Natural Park, which had caused them to believe that the lionfish is the cause of the decrease in overall fishing. In order to determine the changes in the species captured and to know the abundance of the lionfish in this fishing method, we analyzed the historical landings in traps between 1993 and 2014, as well as the landing of three fishing units between March 2012 and July 2014. The historical analysis showed that the decline in species and kilograms landed has been occurring since 2000. A total of 4 913 specimens were landed between March 2012 and July 2014, of which 85 % were species of commercial interest, and the rest were used by fishermen for consumption. Landings between 2012 and 2014 were conditioned by climatic conditions, where the co-occurrence between Pterois volitans and the main commercial species and self-consumption did not provide evidence of the lionfish affecting its abundance. This confirms the presence of the lionfish as a new member in the landings in traps the Taganga Bay.

Assessing the Inter-Relations Between Fish Health and Stock Status of the Main Commercial Fish Species

Abstract This paper aims to show the importance of knowing the health status of fish populations in their natural environment and its influence on fish stocks at the Romanian coast. To assess the interrelationship between fish health status and the state of stocks, the following fish species: turbot, sprat, anchovies and horse mackerel were analysed from the pathological point of view. Pathological analyses performed between 2015 and 2017 revealed the presence of infections caused by bacteria of the genus Aeromonas and Vibrio and parasitic diseases Trichodinosis, Botriocephalosis and Nematodosis. The presence of these diseases in natural fish populations may represent a real danger to the state of existing stocks, but also to their evolution.

In vitro regeneration of triploid plants from mature endosperm culture of commercial passionfruit ( Passiflora edulis Sims)

Abstract Due to the triploid nature of endosperm, an embryonic reserve tissue, in vitro culture of endosperm tissues has been considered a direct method for production of polyploids. In the present study, we report the establishment of an in vitro regeneration system from endosperm culture for production of triploid Passiflora edulis plants, the main commercial species of passionfruit. Surface-sterilized endosperms were cultured in MS medium with different concentrations of benzyladenine (BA), thidiazuron (TDZ), and kinetin (KIN). The cultures were maintained in a growth chamber under controlled conditions, for 60 days. Thidiazuron was the only type of cytokinin that induced shoot production in the endosperm tissues; the highest number of shoots was produced in the presence of 4.5 and 9.0 μM TDZ. Flow cytometry and chromosomal analysis confirmed that endosperm-derived plants were triploid. The internal standard, Pisum sativum, and the diploid control, seed-derived Passiflora edulis plants (2n = 2× = 18), showed average DNA quantities of 9.09 and 3.35 pg respectively. Endosperm-derived P. edulis plants showed an average DNA content of 5.10 pg and a chromosome count of 27 (3n = 3× = 27), the same ploidy level as the endosperm (triploid). Our data open new prospects for breeding of passionfruit by means of a stable and reproducible regeneration system from endosperm culture leading to generation of triploid plants.

A socio-ecological approach to the declining Catalan clam fisheries

The world demand for marine bivalves continuously increased from 1980 to 2014. Their fisheries landings in the Mediterranean Sea also increased, until they began to drop in the last decade. This trend was particularly intense in the western Mediterranean Sea, where landings dropped from 4046 t (1996) to 425 t (2012). Since then, they have never recovered. We examined the status of the main commercial clam species in Catalonia (NW Mediterranean) one of the main productive areas of the western Mediterranean Sea, and analyzed the social and ecological context of the different small scale clam fisheries as an example of the Mediterranean as a whole to detect the possible causes of this negative trend. Our results reveal the critical status of all clam fisheries along the entire coast, where most clam stocks are currently collapsed or close to collapse. This trend mirrors the evolution of bivalve fisheries in the western Mediterranean. Many management failures and factors inhibiting the sustainability of clam fisheries over time were detected (i.e. the nearly absence of resource monitoring or control of rules enforcement; lack of conflict resolution mechanisms among fishermen and other coastal users; the incongruence between appropriation and provision regulations, and deficient nested enterprises), suggesting that inadequate and incongruent management is largely to blame for the precarious present situation. However, our results also suggest that undetermined additional factors (e.g. pathologies, pollution, climate change etc.) have also affected what were already highly stressed populations.

Knot attributes of Korean pine plantation based on mixed effect model.

Based on 1534 knot data from 60 sample trees in a Korean pine plantation in Mengjiagang Forest Farm, Heilongjiang Province, China, mixed effect model of knot attributefactors (knot diameter, sound knot length, year of death of knot and knot angle) of Korean pine plantation was established using NLMIXED and GLIMMIX procedures of SAS software. The prediction accuracy of models was compared using evaluation statistics, such as Akaike information criterion (AIC), Bayesian information criterion (BIC), -2Log likelihood(-2LL), and likelihood ratio test (LRT). Results showed that all of the mixed effect models that considered tree effect performed better than conventional fixed-effect models. For knot diameter models, the model with random parameter combination of b1, b2 had the best performance. For sound knot length models, the model with random parameter combination of b1, b3 had the best performance. For the models of year of death of knot, the model with random variables of knot diameter was proved to be the optimal generalized linear mixed model. For the models of knot angle, the model with randomvariables of intercept, knot diameter, sound knot length was proved to be the optimal generalized linear mixed model. Mixed effect model was more effective than conventional fixed-effect model for describing knot attributes. The combination of knot attributes models and reasonable prunning schemes could improve timber quality of Korean pine which is one of the main commercial tree species in Northeast China.

Diets and trophic niches of the main commercial fish species from the Celtic Sea.

The characterization and quantification of diets of nine commercially important Celtic Sea fish species (black-bellied angler Lophius budegassa, blue whiting Micromesistius poutassou, Atlantic cod Gadus morhua, haddock Melanogrammus aeglefinus, European hake Merluccius merluccius, megrim Lepidorhombus whiffiagonis, European plaice Pleuronectes platessa, common sole Solea solea and whiting Merlangius merlangus) was undertaken November 2014 and November 2015 to gain a better understanding of fish feeding strategies, prey preferences, competition for resources and, more generally, increases knowledge of marine ecosystem functioning. Prey were classified into 39 taxonomic groups. A feeding overlap index and multivariate analyses were used to classify the fishes into four main trophic groups where interspecific competition for resources may be important: piscivorous species, omnivorous species, planktivorous species and invertebrate benthic feeders. Ontogenetic changes in diet were also considered for L. budegassa, G. morhua, M. aeglefinus, M. merluccius and M. merlangus through partitioning into size classes. This revealed an important shift in the diet of M. merluccius from omnivory to piscivory, whereas M. aeglefinus exhibited no significant ontogenetic change in diet, remaining an invertebrate benthic feeder. Feeding strategies of these species were also investigated using the Shannon niche-breadth index and other descriptors, such as the total number of taxonomic groups of prey and the mean number of prey in gut contents.

Influence of different concentrations of jasmonic acid on in vitro development of Catasetum fimbriatum Lindl. (Orchidaceae)

In vitro seeding constitutes an indispensable tool for propagation of the main commercial species of orchids. This study aimed to analyze the in vitro development of Catasetum fimbriatum under different concentrations of jasmonic acid in Murashige & Skoog culture medium compound of ½ macronutrients. After 180 days of cultivation, concentration of 0.25 and 0.50 μL • L-1 caused a significant increase in number of roots and leaves. The concentration of 1.00 μL • L-1 showed the best result for the length of longest root and largest leaf, the total length of seedling, and the total fresh and dry masses. Nevertheless, the use of this plant regulator on in vitro culture media still requires further investigations to determine the optimal concentration in order to obtain desirable phytotechnical characteristics in different orchid species.

Genetic variation of growth and log end-splitting in second-generation Eucalyptus grandis in Sri Lanka

ABSTRACTEucalyptus grandis is one of the main commercial forest plantation species in the highlands of Sri Lanka. An E. grandis genetic improvement program was initiated in 1995 with the establishment of a first-generation provenance-family trial cum seedling seed orchard (SSO), and several seed production areas (SPAs) using seeds from natural stands in Australia. In 2007 a second generation was initiated, comprising a seed-source/family trial with 132 families from plus-trees selected in Sri Lanka: 72 families from the first-generation SSO, 28 families from two of the first-generation SPAs, and 32 families from plus-trees selected in local plantations. Diameter at breast height (DBH) and tree height measurements were taken at ages 2, 5 and 7 years. Trees from a first thinning conducted just after the 5-year assessment were used for assessment of log end-splitting. Significant differences between seed sources and families within seed sources were observed for individual tree volume but not for log end-splitting. The seed source with the highest 7-year tree volume was the SSO, and the second and third best seed sources were the SPAs. Heritabilities for individual tree volume ranged from 0.04±0.05 at age 2 years (all trial families) up to 0.27±0.12 at age 7 years (subset of the 72 SSO families). Heritabilities for end-splitting were close to zero across all trial families and 0.16±0.15 for the subset of 72 SSO families. Phenotypic and genetic correlations between tree volumes across different ages were positive (favourable) with genetic correlations ranging from 0.39±0.38 to 1.00±0.40. The phenotypic and genetic correlations between individual tree volumes at ages 2 and 5 years with end-splitting at age 5 years were generally positive (unfavourable), with the former ranging up to 0.70 and the latter ranging up to 0.90±0.95. This correlation between tree volume and end-splitting could make simultaneous improvement of these traits difficult. Options for further tree improvement work with E. grandis in Sri Lanka are discussed.

Long-term stability of Sphyrion lumpi abundance in beaked redfish Sebastes mentella of the Irminger Sea and its use as biological marker.

The main commercial fish species in the Irminger Sea, the beaked redfish Sebastes mentella, is commonly infected with the copepod Sphyrion lumpi. This ectoparasite is often used as a biological marker for stock discrimination to evaluate the still-debated metapopulation structure of beaked redfish. Nevertheless, it is still not understood whether parasite abundances and communities vary over longer time periods. In the present study, we investigated the abundance of S. lumpi in S. mentella of the pelagic zone of the Irminger Sea and adjacent waters. Our analyses revealed that live S. lumpi abundance remained constant during summer over a sampling period from 2001 to 2015, which confirms its validity as a biomarker. As S. mentella forms dense aggregations during mating, our results suggest that host densities are, regardless of a fishery-induced decrease in host biomass, large enough to facilitate the direct transmission of S. lumpi. After correcting for covariate effects, two stock units could be differentiated, which supports a continuation of the current fishery management strategy.

Monitoring demersal scalefish populations in the Browse Basin region: accounting for spatial variability and detecting change in key fish populations

One of the objectives of the Applied Research Program (ARP), funded by Shell and the INPEX-operated Ichthys LNG Project, was to establish the basis for evaluating the effects of any potential oil spill from the Prelude or Ichthys fields on populations of commercially important demersal fishes in the Northern Demersal Scalefish Managed Fishery. The ARP has delivered improved baseline understanding of the status and spatial variability in populations of commercially and ecologically important finfish of the Browse Basin region, in the vicinity of the Prelude and Ichthys fields, using both commercial-style fish traps and baited remote underwater videos (BRUVs) as sampling methods. We used available environmental-data layers and fish-distribution data, in combination with modelled plume projections, to design a study such that sites were balanced with respect to fish habitat and likely affected and unaffected zones. The sampling-design employed was statistically effective with power to show changes in fish assemblages, and relative abundance of as little as 30% could be detected with 80% certainty in the main commercial species, goldband snapper (Pristipomoides multidens), using BRUVs. For the second-most important species, red emperor (Lutjanus sebae), a larger decline of 50% would have to occur for this change to be determined with the same level of confidence. Traps were a more powerful tool for sampling L. sebae, allowing a 40% change to be detected; however, for all other species BRUVs were more powerful. Sampling of the demersal-fish assemblages surrounding the Prelude and Ichthys fields by using both fish traps and BRUVs demonstrated the feasibility of detecting change in the relative abundance of the fish assemblage as well as in the key commercial species.