Hasil untuk "Aquaculture. Fisheries. Angling"

Angelica R. Valdez, Mitchell P. Marabella, Jon‐Paul Bingham

ABSTRACT Settlement and metamorphosis are critical life stages for marine mollusks that transition larvae to their adult forms. Often acting as bottlenecks in aquaculture production, as it is the most difficult step in a hatchery due to the changes in anatomical structures, for example, loss of velum and gain of adult shell structures. With various methods for induction explored through the years, this review explores the use of synthetic compounds, endogenous neurotransmitters, native‐inducing compounds and genomics in larval settlement and metamorphosis. Synthetic compounds typically lead to higher mortality and reduced effectiveness than native compounds. However, they produce varied effects across many marine mollusks, serving as valuable tools for studying behaviour and morphology during this transition. In contrast, native‐inducing compounds from environmental factors have species‐specific effects, demonstrating high efficacy and low mortality. Although native larval inducers are often unknown, difficult to identify and highly specific to individual species, understanding trends in other organisms may provide insights into methodologies, especially with the increasingly significant role of genomics. Genomics has the potential to aid in identifying valuable life history information to streamline and increase the effectiveness of grow‐out techniques in production settings. This understanding has the potential to significantly influence aquaculture by exemplifying multidisciplinary strategies, refining future initiatives and encouraging similar research efforts.

C. Chan, N. Tran, S. Pethiyagoda et al.

Abstract Fish contribute to Africa's food and nutrition security, but future directions for the fish sector remain uncertain. Using a structural foresight modeling approach, this paper examines past, present, and future trends of fish supply and demand in Africa to highlight challenges and prospects of the fish sector's contribution to food security in the continent. If historical trends are maintained, growth of aquaculture and fisheries would be slow, resulting in declining per capita fish consumption. Alternative scenarios highlight the potential importance of African aquaculture development in addressing food security. Policies to promote sustainable aquaculture, reduce post-harvest losses, and facilitate fish trade are indispensable. Fish deserves more attention in food and nutrition policies due to its prominence in the African food basket.

Charlotte Flores, Christopher Bryant, Mohamed Bakr et al.

This study aimed to map the current status of farmers' knowledge, attitudes, and practices (KAPs) vis-à-vis animal welfare in the Egyptian tilapia farming sector. To this end, a survey was conducted of tilapia farmers across different regions, examining their level of training and knowledge as well as their farming practices including feeding, water changes and biosecurity measures.We found that just 11 % of the surveyed tilapia farmers had received any sort of training on the importance of animal welfare whilst 76 % said they could benefit from such training. Farmers perceived maintaining good water quality as the most important metric for achieving good tilapia welfare. However, they were significantly less willing and able to intervene on this factor compared to other factors such as changing feeding practices, minimising handling, and carrying out veterinary checks.In addition, we found evidence of better production outcomes for farmers that had received welfare training, with significantly fewer of them reporting high mortality rates and significantly lower reported frequency of poor growth. Most farmers expected the Egyptian tilapia production sector to continue to grow and intensify. This survey identified a need for establishing minimum animal welfare standards in Egyptian tilapia farming either through regulators or certification schemes. There is also a clear need for establishing training programmes that cover animal health and welfare aspects in aquaculture.

Kayleb Himiona, Andrew G. Jeffs, Bradley M. Skelton

ABSTRACT Nursery culture can improve the efficiency of mussel aquaculture by reducing the high losses of spat and overcoming inconsistencies in wild‐spat supplies. The success of nursery systems depends on the availability of unattached single or singulated spat, which requires the separation of spat from their associated settlement substrates (i.e., singulation). This study investigated whether sub‐lethal environmental stressors could facilitate the singulation of Greenshell mussels (Perna canaliculus) spat from their attachment to collector ropes. Segments of spat‐collector ropes were exposed to stressors consisting of either high (45 ppt) or low (25 ppt) salinity for 2 h, periods of emersion (air exposure) for 2 or 4 h, or combinations of reduced aeration and limited food availability for 12 h. Spat singulated from the collector rope were returned to clean seawater and reared for 24 h, after which their survival rates were measured. The results indicated that up to 80% of spat could be singulated from the ropes after a 12 h exposure to seawater with no aeration and no food (i.e., NA‐NF). However, although survival rates following singulation ranged from 60% to 90% across treatments, overall recovery of viable, unattached spat was lower, reaching a maximum of 65% relative to the initial number of settled spat. Singulation efficacy was influenced by treatment and spat size, with smaller spat (< 3.5 mm) more easily singulated than larger ones (> 5 mm). Variations in the spat responses to the stressors indicate a need for further research to optimise singulation techniques and better understand the mechanisms driving the attachment and detachment responses in the mussel spat. Regardless, the study demonstrates that up to 65% of viable spat can be effectively removed from collector ropes using environmental stressors, making them readily available for rearing in nursery systems and reducing spat losses from production.

Hossam M. Hwihy, Amr F. Zeina, Mohamed Sh Abu Husein et al.

M. Shamsuzzaman, Mohammad Mojibul Hoque Mozumder, Sabrina Jannat Mitu et al.

Abstract Bangladesh possesses a large wetland area comprising diversified fisheries resources. Fish and fisheries are an integral part of Bangladesh and have earned its importance due to immense export and revenue potential. The objective of this study was to investigate the trend of fish production, export and import of Bangladesh during the last two decades. Several reviews of the literature were done, numerical data was obtained from the Ministry of Fisheries and Livestock (MoFL), Department of Fisheries (DOF), Bangladesh Bureau of Statistics (BBS). The results showed that fish production has increased in Bangladesh during the last two decades, starting from 17.81 lakh metric tons in 2000–01 and reaching up to 41.34 lakh metric tons in 2016–17. Due to the gradual decline in capture fishery, a significant percentage of total production comes from aquaculture. Hilsha (Tenualosa ilisha) is the largest single-species fishery in Bangladesh which makes the highest contribution to the country's total fish production. Exports of the fish commodity in terms of quantity and value has declined in recent years due to food quality and safety standards. This study has highlighted the contribution of fisheries production in Bangladesh and trade to the country's economy. By paying more attention to the fisheries sector, Bangladesh can boost up its economy.

Abigail E. Bennett, X. Basurto, J. Virdin et al.

The international development community is off-track from meeting targets for alleviating global malnutrition. Meanwhile, there is growing consensus across scientific disciplines that fish plays a crucial role in food and nutrition security. However, this ‘fish as food’ perspective has yet to translate into policy and development funding priorities. We argue that the traditional framing of fish as a natural resource emphasizes economic development and biodiversity conservation objectives, whereas situating fish within a food systems perspective can lead to innovative policies and investments that promote nutrition-sensitive and socially equitable capture fisheries and aquaculture. This paper highlights four pillars of research needs and policy directions toward this end. Ultimately, recognizing and working to enhance the role of fish in alleviating hunger and malnutrition can provide an additional long-term development incentive, beyond revenue generation and biodiversity conservation, for governments, international development organizations, and society more broadly to invest in the sustainability of capture fisheries and aquaculture.

L. Bernatchez, M. Wellenreuther, C. Araneda et al.

Best use of scientific knowledge is required to maintain the fundamental role of seafood in human nutrition. While it is acknowledged that genomic-based methods allow the collection of powerful data, their value to inform fisheries management, aquaculture, and biosecurity applications remains underestimated. We review genomic applications of relevance to the sustainable management of seafood resources, illustrate the benefits of, and identify barriers to their integration. We conclude that the value of genomic information towards securing the future of seafood does not need to be further demonstrated. Instead, we need immediate efforts to remove structural roadblocks and focus on ways that support integration of genomic-informed methods into management and production practices. We propose solutions to pave the way forward.

H. M. Abdel‐Latif, Mohamed M. Abdel-Daim, Mustafa Shukry et al.

Abstract The rapid expansion of the aquaculture industry, the global shortage of fish meal (FM) supplies from fisheries and the continuous demand for FM as a primary protein source in aquafeeds lead to increase the urgent necessity to find new FM alternatives. Plant protein sources have gained significant importance among aquaculture farmers and nutritionists because of their availability, eco-friendly, relative sustainability, environmentally safe, and relatively lower prices than FM protein. Extensive studies have been conducted to better assess the efficiency of plant protein sources as a partial or complete substitution of dietary FM in aquafeeds. From these sources, Moringa oleifera has been widely used. It is universally known as “the miracle tree” because of its high nutritional values and unique composition of phytochemicals, such as phenolic acids, flavonoids, carotenoids, alkaloids, tannins, lectins and terpenoids. These phytochemicals possess numerous advantageous properties such as antioxidant, hepatoprotective, antimicrobial and immune-stimulant characteristics. This review article describes the nutritional features of M. oleifera with a special emphasis on the current research findings on the possibility of including different forms of M. oleifera in diets to replace dietary FM protein in the diets of several fish species. It also evaluates its effects on the growth parameters, feed utilisation indices, and proximate body composition of fish. The haemato-biochemical parameters, hepato-renal functions, immune responses, and antioxidative capacity of fish fed M. oleifera-based diets are also assessed. The data will help to provide new perceptions and references for future research interests and aquaculture production.

Julee Stewart, Carmen Kotowich, Jacob Ulrich et al.

The lake cisco (Coregonus artedi) is not often caught by recreational anglers in open‐water in western Canada but becomes a common component of catch‐and‐release ice fisheries in the winter. Little is known about the composition of recreational cisco fisheries or factors that affect the success of winter catch and release. We examined the size and body condition of 555 cisco caught by anglers in four interconnected lakes in southern Saskatchewan, Canada. We also examined the influence of length on the probability of hooking injuries and determined the age of a subset of angled fish. Cisco caught by anglers ranged in total length from 24 to 48 cm and 110 to 1370 g mass; however, 60.2% of cisco caught ranged from 37 to 40 cm and 470 to 560 g. The scale ages of cisco caught by anglers ranged from 4 to 10 years, with the most common ages caught being 6–8 years; however, scales likely underestimated age beginning around 8 years. Overall, cisco from our four study lakes had lower body conditions compared to Lake Superior populations based on standard weight comparisons. The length, mass, age and body condition of cisco caught by anglers varied significantly among our four study lakes, following a west‐to‐east productivity gradient. Of the 555 cisco assessed, 54 (9.7%) experienced gill bleeding and 21 (3.8%) had other visible hooking injuries. Longer cisco had a significantly increased probability of gill bleeding, but length did not affect the probability of other injuries. Cisco are relatively slow growing in our study area and warrant more consideration from a catch‐and‐release angling perspective.

Prince Ofori-Darkwah, Prince Ofori-Darkwah, Daniel Adjei-Boateng et al.

High larval and fry mortality has been a major challenge to the commercial culture of the African bony-tongue (Heterotis niloticus). Research indicates inadequate feeding to be a possible cause of the high mortality rates of larvae/fry grown in captivity. An experiment was conducted to first describe the developmental stages of H. niloticus eggs and larvae until schooling, 6 days after hatching (DAH), at 26°C. The morphological development, survival, growth (weight gain and length), and swimming behavior of the larvae were monitored. A follow-up feeding trial was conducted with H. niloticus fry from 6 to 27 DAH involving four treatments: feeding with Artemia nauplii; a combined feed of 50% Artemia nauplii and 50% rotifers (w/w); feeding with rotifers; and no feeding. The activities of three digestive enzymes (trypsin, lipase, and amylase) were assessed in fry exposed to the live feed treatments. At hatching, the larvae had a large, vascularized yolk sac filled with yolk platelets, which occupied approximately one-third of the total body length of the abdominal cavity. Yolk platelet reabsorption started at 1 DAH and was complete at 6 DAH. Metamorphosis was completed at 6 DAH, and schooling behavior was observed. For the feeding trial, the fry that received Artemia nauplii underwent the fastest development until 27 DAH. Similarly, the survival rate was considerably higher in fry fed with Artemia nauplii than in those that received a combination of Artemia nauplii and rotifers or only rotifers. Overall, the survival rates for fry fed with Artemia nauplii and larvae co-fed were 72.7% ± 0.9% and 41.2% ± 3.3%, respectively. Fry did not survive until 27 DAH in the rotifer-fed and unfed treatment groups. Digestive enzyme activity differed significantly (p&lt; 0.05) between treatments and sampling dates. All digestive enzymes were detectable at the onset of mouth opening (5 DAH) and fluctuated through the 7 and 9 DAH. Lower enzyme activity was observed when the fry were subjected to starvation or the rotifer treatment. Results indicate that Artemia nauplii is the best live feed organism for H. niloticus larviculture.

Keisuke Himeno, Masakazu Teragaito

Twisted right-angled Artin groups are defined through presentation based on mixed graphs. Each vertex corresponds to a generator, each undirected edge yields a commuting relation and each directed edge gives a Klein bottle relation. If there is no directed edge, then this reduces to an ordinary right-angled Artin group. There is a characterization of right-angled Artin groups which can be embedded in knot groups by Katayama. In this paper, we completely determine twisted right-angled Artin groups embedded in knot groups.

V. Sbragaglia, R. Arlinghaus, D. Blumstein et al.

Recreational spearfishing is a fishing method that occurs globally, yet receives considerably less attention in the scientific literature relative to other recreational fishing methods, such as angling. Lack of scientific information on spearfishing may negatively affect the development and management of marine recreational fisheries. We conducted a systematic review of 102 peer-reviewed papers published between 1967 and 2022 pertaining to marine recreational spearfishing. Based on this literature review, we provide an overview of key insights across social, economic, and ecological dimensions of marine recreational spearfishing. While spearfishers represent less than 5% of marine recreational fishers, the participants are younger and may differ from recreational anglers in their motivations, with suggestions of increased well-being generated from a close connection with the sea during underwater fishing. Recreational spearfishers mostly target species of moderate to high levels of vulnerability that are mid to high trophic level carnivores. Though spearfishers can deliberately target larger individuals of exploited populations, this is not a generalizable pattern. Despite a growing body of research on the ecological impacts of marine recreational spearfishing, there is limited knowledge of these effects and their mechanisms across biological levels of organization (e.g., individual, population, community and ecosystem) compared with those of other fishing methods. Recreational spearfishers can contribute to advances in marine ecological knowledge, and inclusive participatory management could represent a key step towards transformative sustainable development of marine recreational spearfishing. Throughout the review, we identify gaps in the research and areas where future research is needed to better inform the socio-economic importance, ecosystem impacts and future management of marine recreational spearfishing.

Mayada H. Ahmed, Abdulaziz M. Abdullah, Noori AN. Nasir

Water is one of the most important natural sources for sustaining life, as human life and various activities depend on it. The current study dealt with knowing the effect of organic pollution on physical and chemical properties in  Garmat Ali river, which was represented in  two stations, the first station called Al-Mashab, and the second Al-Sindbad. Water and sediment samples were collected monthly during the period from August, 2016 to July, 2017. Numbers of physical and chemical variables were measured during this period (water temperature, light penetration, pH, Salinity, dissolved oxygen, biological demand oxygen, chemical demand oxygen, total nitrogen, total phosphorus and total organic carbon in sediment). The results of the study was showed that water temperature were ranged between 13.2-31.3°C for the first station and 13.4-33.1°C  for the second station. The light penetration values were ​​ranged between 20.6-58.5 cm for the first station and 35-65 cm for the second station. The pH values were ​​ranged between 7.5-8.6 for the first station and 7.5-8.5 for the second station. Salinity values were ​​ranged between 1.58-3.16 g/l for the first station and 0.92-2.13 g/l for the second station. Dissolved oxygen values were ​​ranged between 4.66-10.8 mg/l for the first station and 11.85-6.26 mg/l for the second station. The values ​​of BOD5 were ​​ranged between 1.1-4.26 mg/l for the first station and 0.75-4.06 mg/l for the station. The values ​​of the COD were ranged between 8-120 mg/l for the first station and 8-61 mg/l for the second station. Total nitrogen values were ​​ranged between 2.8-29.4 mg/l for the first station and 2.4-33.6 mg/l for the second station. The total phosphorus values were ​​ranged between 1.11-19.6 mg/l for the first station and between 1.24-19.98 mg/l for the second station. Total organic carbon values were ​​ranged between 0.36-2.19% for the first station and 0.32-2.94% for the second station. The two stations were recorded a little increased in organic pollution levels during summer months and first station (Al-Mashab) was most affected.

Ardiba R. Sefrienda, Jasmadi Jasmadi, Hilda Novianty et al.

Highlight Research • Proximate of Ulva lactuca after cooking treatments were analyzed. The cooking treatments carried out in this study were roasted and boiled-roasted • Protein quality such as in-vitro digestibility, protein solubility, and amino acids composition of Ulva lactuca after cooking treatments were analyzed • The result showed that boiled-roasted samples had the highest protein content, amino acid score and essential acid index, and predicted-protein efficiency ratio   Abstract Plant-based protein has been increasingly demanded as a sustainable protein source. Sea lettuce (Ulva lactuca) is one of the potential sources as plant protein due to its high protein content. During processing, the sea lettuce is exposed to heat which might affect its nutrition, particularly the protein quality. This study aimed to evaluate two different cooking processes on the nutritional quality of the sea lettuce based on the proximate and protein quality analyses. The samples were raw, roasted, and boiled-roasted sea lettuce. All treatment using temperature 100°C. The protein quality was assessed by in-vitro protein digestibility, solubility, and amino acid profiles. The result showed that boiling treatment followed by roasting treatment had significantly higher protein content, amino acid score and essential amino acid index, and predicted-protein efficiency ratio compared with the value of roasting treatment only. It resulted in protein content of 18.87% (dry basis), amino acid score of 37.96%, essential amino acid index of 79.41% and predicted-protein efficiency ratio of 2.58. Therefore, boiling followed with roasting process is recommended to maintain the nutrition quality of sea lettuce.

فاطمه کیاپور, عبدالمجید حاجی مرادلو, رسول قربانی et al.

این مطالعه با هدف بررسی تاثیر سطوح مختلف هورمون تیروکسین در آب پرورشی و جیره غذایی بر فاکتورهای رشد در مراحل اولیه رشد ‌ماهی قزل‌آلای رنگین‌کمان انجام شد. آزمایش در سه مرحله تخم چشم‌زده تا تفریخ کامل تخم، لارو تفریخ شده تا زمان تغذیه فعال و زمان تغذیه فعال تا وزن‌گیری حدود 1 گرم بچه‌ماهی انجام شد. در هر مرحله، آزمایش در سه غلظت محلول تیروکسین (03/0، 06/0 و 09/0 میلی‌گرم در لیتر) به همراه گروه شاهد (فاقد هورمون تیروکسین) با 3 تکرار انجام گردید. تیروکسین در مراحل اول و دوم، به آب و در مرحله سوم به غذا اضافه گردید. در انتهای مرحله سوم، شاخص‌های رشد مورد بررسی قرار گرفت. نتایج نشان داد که بالاترین وزن و طول نهایی در تیمار 9 به ترتیب برابر با 04/0±53/1 و 31/0±85/5 سانتی‌متر به دست آمد. شاخص‌های درصد افزایش وزن بدن و ضریب رشد ویژه در مقایسه با سایر تیمارها تفاوت معنی‌داری از خود نشان داد (05/0>p) و به ترتیب برابر با 32/18±45/872 و 04/0±05/5 بود. بیش‌ترین ضریب تبدیل غذایی و ضریب چاقی نیز در گروه شاهد برابر با 004/0±78/0 و 07/0±14/1 بود مشاهده گردید. بر اساس مطالعه حاضر، هورمون تیروکسین منجر به اثرات مثبت بر فاکتورهای رشد در بچه‌ماهی قزل‌آلای رنگین‌کمان گردیده است.

Alexander Dranishnikov, Satyanath Howladar

We prove that the universal covering $\Wi M$ of an $n$-dimensional closed spin PSC manifold $M$ whose fundamental group $π_1(M)$ is a right-angled Artin group has macroscopic dimension $\dim_{mc}\Wi M\le n-2$. This confirms Gromov's conjecture in the case of right-angled Artin groups.

Welington de Oliveira, Valentina Sessa, David Sossa

This paper addresses the numerical computation of critical angles between two convex cones in finite-dimensional Euclidean spaces. We present a novel approach to computing these critical angles by reducing the problem to finding stationary points of a fractional programming problem. To efficiently compute these stationary points, we introduce a partial linearization-like algorithm that offers significant computational advantages. Solving a sequence of strictly convex subproblems with straightforward solutions in several settings gives the proposed algorithm high computational efficiency while delivering reliable results: our theoretical analysis demonstrates that the proposed algorithm asymptotically computes critical angles. Numerical experiments validate the efficiency of our approach, even when dealing with problems of relatively large dimensions: only a few seconds are necessary to compute critical angles between different types of cones in spaces of dimension 1000.

Yajuan Cheng, Zheyong Fan, Tao Zhang et al.

We report a local minimum in thermal conductivity in twisted bilayer graphene (TBG) at the angle of 1.08$^\circ$, which corresponds to the 'magic angle' in the transition of several other reported properties. Within the supercell of a moiré lattice, different stacking modes generate phonon scattering sites which reduce the thermal conductivity of TBG. The thermal magic angle arises from the competition between the delocalization of atomic vibrational amplitudes and stresses on one hand, and the increased AA stacking density on the other hand. The former effect weakens the scattering strength of a single scatterer while the latter one increases the density of scatterers. The combination of these two effects eventually leads to the apparition of the highlighted irregularity in heat conduction. The manifestation of a magic angle, disclosing new thermal mechanisms at nanoscale, further uncovers the unique physics of two-dimensional materials.