Sea Farming Research Articles

The environmental effectiveness of sea lice regulation: Compliance and consequences for farmed and wild salmon

Wild Atlantic salmon populations are declining. Since the 1970s, the proportion returning to Norwegian rivers has been almost halved, while Norwegian sea farming has undergone massive industrialization and expansion. As the proliferation of sea lice is an important part of the explanation for the decline in wild salmon, Norway has enacted increasingly stricter regulatory thresholds for the average number of lice per farmed fish at production sites. This study shows that setting stricter thresholds has led to declining lice-levels within sea farms, but that more frequent de-lousing measures to ensure compliance leads to farmed-salmon welfare problems and higher mortality rates. Compliance with stricter thresholds has not lessened the sea-lice infestation pressure on surrounding, wild salmonid populations. The environmental effectiveness of such regulation is thus limited. This raises the important question of whether a regulatory regime focused on minimizing the average number of sea lice per farmed fish may do more harm than good, unless accompanied by a broader set of regulatory instruments targeting other variables that affect sea-lice infestations in the wild salmon habitat. • This study evaluates the environmental effectiveness of sea-lice thresholds in salmon aquaculture. • Industry compliance with strict lice thresholds have reduced the average number of lice per fish within sea farms. • More frequent de-lousing action has led to declining fish welfare and higher mortality rates • Successful compliance with lice thresholds has no observable, positive effect on the infestation pressure on wild salmon • The environmental effectiveness of stricter thresholds is limited, and should be accompanied by complementary measures

Meaningful curriculum

The study took place at Maria Benedita Mota School, located in the coastal community of Perimirim, which is part of the Araí-Peroba Marine Extractive Reserve (RESEX-Mar) in the municipality of Augusto Corrêa-PA. The participants of the study are educational agents (principals, pedagogical coordinators, teachers and students) immersed in the context and who have knowledge related to local biodiversity, such as the sea, mangroves, small-scale fishery, crustaceans, and family farming. The aim of the study is to understand how the school develops the meaningful curriculum based on the local reality and to systematize the traditional knowledge through oral texts about the mangrove and preservation of the local ecosystem in order to reach students. The methodology is a participatory observation of qualitative nature, which allows the understanding of the object under study having as starting point its reality. The project developed at the school comprised a class trip to the mangrove, drawings, paintings, poetry, paper folding, research, paper cutting and collage, ending up with the presentation in the pedagogical projects exhibition of the school. The results show that the teaching and learning processes become pleasurable, relevant and meaningful for students when the curriculum is based on the reality of people, especially students.

Relationship of long weight between milkfish (Chanos chanos forsskal) and sea cucumber (Holothuria leucospilot) that are multi-trophic sea farming

Milkfish (Chanos chanos Forsskal) and sea cucumbers (Holothurians leucospilot), have high economic value, both to meet domestic and foreign consumption needs. This study examines the long-weight relationship of milkfish and sea cucumbers that are cultivated by multi tropic sea farming at the Tablolong Fish Seed Center in West Kupang District which has been conducted in October to December 2018. Sampling is done every 15 days with a maintenance period of 45 days showed that the milkfish and sea cucumbers have a negative algometric growth pattern based on a value of b which is lower than 3. The water quality parameters at the Balai Benih Ikan Pantai are still in the normal range to support the growth of milkfish and sea cucumbers.

Infectious Salmon Anemia and Farm-Level Culling Strategies.

Infectious salmon anemia (ISA) is an infectious disease, and outbreaks must be handled to avoid spread between salmon sea farms. Intensive culling at infected farms is an important biosecurity measure to avoid further spread but is also a costly intervention that farmers try to avoid. A lack of action, however, may lead to new outbreaks in nearby salmon sea farms, with severe impacts on both economy and animal welfare. Here, we aim to explore how a time delay between a detected outbreak and the culling of both infected cages and entire farms affects the further spread of the disease. We use a previously published model to calculate how many salmon sea farms were directly infected in each outbreak. To investigate the effect of culling on the further spread of disease, we use the number of months elapsed from the detected outbreak to (a) the first cage being depopulated, and (b) to the entire salmon sea farm being depopulated as predictors of how many new farms the virus was transmitted to, after controlling for contact between the farms. We show that the lapse in time before the first cage is depopulated correlates positively with how many new salmon sea farms are infected, indicating that infected cages should be culled with as little time delay as possible. The model does not have sufficient power to separate between culling of only cages assumed to be infected and the entire farm, and, consequently, provides no direct empirical evidence for the latter. Lack of evidence is not evidence, however, and we argue that a high probability of spread between cages in infected salmon sea farms still supports the depopulation of entire farms as the safest option.

A Sea Change in the Environmental Humanities

As we are living through a transformative response to a viral pandemic, this think piece suggests a reimagining of the environmental humanities in the open-ended inventories of feminist posthumanities and the low trophic registers of the oceanic. Sea farming of low trophic species such as seaweeds and bivalves is still underexplored option for the mitigation of climate change and diminishing species diversity in the warming oceans of the world. The affordances of low trophic mariculture for coastal life and for contributing to society’s transition into climate aware practices of eating, socializing and thinking is here considered, and showcased as an example of the practical uses of feminist environmental posthumanities.

A Sea Change in the Environmental Humanities

As we are living through a transformative response to a viral pandemic, this think piece suggests a reimagining of the environmental humanities in the open-ended inventories of feminist posthumanities and the low trophic registers of the oceanic. Sea farming of low trophic species such as seaweeds and bivalves is still underexplored option for the mitigation of climate change and diminishing species diversity in the warming oceans of the world. The affordances of low trophic mariculture for coastal life and for contributing to society’s transition into climate aware practices of eating, socializing and thinking is here considered, and showcased as an example of the practical uses of feminist environmental posthumanities.

Comparison of machine learning methods for mapping sea farms with high spatial resolution imagery

ABSTRACT In general, sea farms are classified into two types depending on their locations, seawater depths, and cultivation species: underwater and above water farms. This study compared the machine learning techniques (random forest, a supervised learning technique, and K-means, an unsupervised learning technique) for mapping both underwater and above water farms using the high-resolution satellite image acquired in the sea farming areas of the South Sea of South Korea through the following steps. First, each machine learning algorithm was separately used in the given high-resolution satellite image to generate a sea surface map. Then underwater and above water farms were detected from each sea surface map. Finally, the accuracy of both the underwater and above water farms detected from the different sea surface maps was assessed. The experimental results led to the following conclusions. First, random forest, a supervised learning technique, has better performance than K-means, an unsupervised learning technique, for detecting both underwater and above water farms from the given high-resolution satellite image. Second, only a few misclassification errors occurred in both the underwater and above water farms detected by the random forest algorithm in the given image, with the underwater farms misclassified as having above water features, or vice versa.

Insights into life cycle patterns, spore formation, induction of reproduction, biochemical and molecular aspects of sporulation in green algal genus Ulva: implications for commercial cultivation

The green algal genus Ulva (Ulvophyceae) has been recently perceived as a model organism, due to its tractability for genetic analyses. This biomass is drawing considerable attention as a potential feedstock for energy security, including emerging applications in functional foods, bio-fuels and energy, pharmaceutical, biotechnological industries, etc. Nevertheless, unlike other commercially farmed seaweeds where clonal propagation is practiced, this genus solely relies on motile reproductive cells (zoospores or gametes) for seeding or seedling production. The culture practices encompass photobioreactor, land-based and open sea farming. The knowledge of reproduction is pivotal for efficient seeding technologies, selecting and domesticating fast growing varieties as well as genetic improvement. The successful induction of reproduction in Ulva spp. is being achieved through external environmental stimuli as well as by manipulating sporulation and swarming inhibitor concentration. However, comprehensive biochemical and molecular evidences are underdeveloped and further knowledge is imperative to improve aquaculture practice. This mini-review provides comprehensive insights into life cycle, spore formation, mechanisms for the induction of reproduction, biochemical and molecular aspects of sporulation besides advances in the farming of Ulva spp. with future prospective. The existing commercial trade of Japan about 1500 t dry annum−1 is poised to become the leading industry with focus on niche, high-value products in the coming decade.

Experimental evaluation of the effect of water velocity on the development of string-attached kelp seedlings (Laminariales) with implications for hatchery and nursery production

Abstract Kelp sea farming is performed using seedlings (early stage of sporophyte development) attached to string, known as seedling string, which are produced from an indoor culture under controlled environmental conditions. However, very little is known about the influence of water movement and the optimal growth level of early kelp sporophytes on string. Thus, the present study evaluated the development of string-attached kelp seedlings (Undaria pinnatifida) simultaneously exposed to simulated seawater velocities in an indoor tank. The experiment was conducted using string that had seedlings approximately 2 mm in length, whose growth was measured after 28 and 56 days of culture. Seawater velocity level was found to significantly influence both the rates of increase in total biomass (dry weight) and in length of kelp seedlings on string. Seedling growth rates increased up to a water velocity range of 15.8–17.1 cm s−1 beyond which it declined. This pattern is similar for the two time periods explored during the experiment, although both growth rates were significantly higher during the first 28 days of culture than after 56 days of culture. This difference is related to the increase in kelp seedling size throughout the experiment, and this increase could affect the requirements and/or optimal environmental conditions for their growth. In addition, comparatively, the rate of total biomass increase for seedlings was significantly higher than the rate of length increase for seedlings, indicating seawater velocity favours greater biomass productivity over length increase. Based on these results, suitable seawater velocities are recommended that would be the most productive for kelp seedling growth on strings in hatchery and nursery phases.

How do fishery resources enhance the development of coastal fishing communities: Lessons learned from a community-based sea farming project in Taiwan

Abstract Taiwan government proposes a national level Coastal Blue Economy Growth (CBEG) program to promote ocean-linked industries based on the concept of sustainable development. Sea farming development is considered an important aspect that needs to be promoted for the CBEG program. Generally, sea farming relies on artificial technologies, environmental improvement and resource management to increase fishery resources and to enhance fisheries productivity. Developing sea farming could contribute to the transformation of capture fisheries; it integrates the concept of Blue Economy into sustainable economic development so as to improve economic activities in fishing communities. In line with this, the Taiwan government launched the Community-Based Sea Farming (CBSF) project in 2015. The CBSF project aims to establish sea farming zones to help fishing communities achieve sustainable development. In this paper, the development process of sea farming and site selection of the CBSF project were described and the needs of local people in fishing communities around sea-farming demonstration zones were also assessed. According to findings, a framework for sea farming development is proposed. In this framework, several new sea farming-based industries can serve as the driving force to accelerate the development of fishing communities. The driving forces include developing a community-based tourism recreational industry, strengthening localized marketing of featured seafood products, combining local ecological landscapes and cultures of the fishing village to develop recreational fishery activities, and integrating seafood products with recreational tourism activities. Overall, CBSF are important tasks that warrant continuous attention for enhancing the fishing community development. The experiences and framework of promoting the Taiwan CBSF project would provide beneficial information and foundation for decision makers and natural resources managers in other areas.

Trophic dynamics of anadromous brown trout and Arctic charr in NW Iceland and their correlation to salmon lice infection

Anadromous Arctic charr Salvelinus alpinus and sea trout Salmo trutta are commonly found in marine, estuarine and freshwater habitats across the Northern Hemisphere. The marine phase varies between populations but often involves summer foraging in nearshore waters while spawning and overwintering occur in freshwater. The dependence of anadromous salmonids on nearshore habitats makes them vulnerable to increased industrial activity, such as aquaculture developments, that may increase the risk of salmon lice Lepeophtheirus salmonis, infection. Lice infection in wild salmonids depends on farmed fish density but can also be correlated to environmental factors, including foraging ecology. In the current paper we examine niche use and trophic variation of co-occurring Arctic charr and sea trout in northwest Iceland, using stomach contents and stable isotope values of δ13C, δ15N and δ34S. We then test if these factors correlated to salmon lice infection. The salmonid species differed in niche use, for example, in time of marine foraging, with Arctic charr having a longer marine phase than was expected, and in the level of piscivory between both species. Moreover, we show that both environmental factors and individual trophic use are related to salmon lice infection in sea trout. This information may be useful in evaluating the risk and spatial management of sea farming.

Oyster Tourism in Postdisaster Japan: Towards an Understanding of Human-Mollusk Relations in the Miyagi Prefecture

This article is a qualitative, ethnographically informed exploration of the relations between the Miyagi Oysters (Crassostrea gigas) and the diverse social actors of northeastern Japan (Tōhoku), namely local sea farmers, domestic immigrants, and tourists, in the aftermath of the 2011 “triple disaster” (the 2011 earthquake, tsunami, and related nuclear plant meltdown). I contend that the processes of post-disaster reconstruction have been significantly informed by the specific frames of human-oyster relations as they are developed in the sea farming bays of the municipality of Ishinomaki (Miyagi Prefecture). Individuating four fields of interest (environmental purity, experientiality, emic timeframes, and authenticity), I analyze the ongoing transformations prompted by the disaster on discourses of locality and self-representation and the interactions among local producers and non-local actors (visitors, volunteers, entrepreneurs) with the cycle of life of the Crassostrea. Within the interactions between locals and non-locals, the discursive characteristics of oyster sea farming in Miyagi are negotiated, shared, and contested through instances of transformative resilience during the progressive shift from “classic” modes of production towards the economies of domestic tourism, and the overlapping of local, bottom-up initiatives with organized top-down structures.

Molecular markers associated with antigen presentation process in Atlantic salmon during outbreaks of Piscirickettsia salmonis at sea farming centers

Molecular markers associated with antigen presentation process in Atlantic salmon during outbreaks of Piscirickettsia salmonis at sea farming centers

Implementation of lyapunov method to analyze the stability of pompano, cantang growth and nutrition dynamical systems

This study aims to determine the analysis stability of dynamical model of pompano, cantang growth, and nutrition on the Integrated Multi-Trophic Aquaculture (IMTA) systems by using the Lyapunov method. The analytical analysis was given to discuss the dynamic behavior of this model. Global stability analysis was performed based on the Lyapunov theory, i.e., construction the function V (x) that is a definite positive scalar function and the derivative of V (x) is defa inite negative. As a verification of the Lyapunov method, we conducted numerical simulations with data taken from IMTA systems in Sea Farming region, Kepulauan Seribu, Indonesia.

Growth, survival and byssal attachment of the blacklip pearl oyster Pinctada margaritifera (Linnaeus 1758) spat exposed to different salinities

The influence of salinity on growth, survival and byssal fibre attachment of the blacklip pearl oyster, Pinctada margaritifera spat was assessed. P. margaritifera enjoys a coastal distribution in the intertidal reef flats of Andaman and Nicobar Islands, with maximum density at 5 -10 m depth, where drastic changes in environmental parameters such as salinity, temperature and turbidity occur. Spat showed comparatively good growth in terms of instantaneous growth rates (IGRs) of dorso-ventral measurement (DVM), antero-posterior measurement (APM) and total weight (TWT) in a wide range of test salinities from 19 to 37 psu; IGRs were drastically decreased in spat reared at lower and higher salinities outside of this range. The highlight of the present study was better growth performance and 100% survival of P. margaritifera spat at lower salinity levels (22-28 psu) than in the ambient salinity (31 psu). The study also showed that sudden exposure to a higher salinity (above 40 psu) will be helpful for detachment of P. margaritifera spat from settlement tanks in the hatchery to facilitate stress-free spat transfer to sea farming systems. This will be useful in adopting the Japanese technique on post-operative culture for producing high quality pearls from P. margaritifera.

Stable and unstable equilibrium states in a fishery–aquaculture model

AbstractWe study interactions between fishery and aquaculture using a 3D generalized Lotka–Volterra model, where we assume that the aquaculture production may affect the growth rate in the fish stock and the productivity in harvesting. In addition, input demands from both marine industries may result in effort competition. We identify conditions for the coexistence of a unique equilibrium state inside the first octant of the phase space and equilibrium states on its boundary. Conditions for stability and instability of these states are also given, thus showing the possibility of having bistability. The equilibrium point inside the first octant is stable if the growth impact on fishery from sea farming is below the potential productivity in harvesting. In the complementary case, we have an unstable interior equilibrium, and we may then end up in stable equilibrium states on the boundary, where either the fishery or the aquaculture is wiped out.Recommendations for Resource Managers More empirical and theoretical research is needed to reveal types of interrelations between fisheries and aquaculture, and their importance for long run stability between the sectors. When designing policies for the aquaculture industries, managers should in particular be aware of possible long‐term harmful effects from aquaculture to fisheries. Increased areas for sea farming reduce the relative profitability of the fishery, and if the area increases above a certain level, this could wipe out the fishery.

Potensi Pengembangan Komoditas Teripang Pasir (Holothuria scabra Jaenger) secara Berkelanjutan dengan Model Integrasi Sea Farming di Kepulauan Padaido Kabupaten Biak Numfor

Sea cucumber is one of high value economic commodity due to not only having a fairly completed nutrition, but also used as the raw material for production of drugs, cosmetics and others. Therefore it becomes one of the highly potential export commodities. However, the target of catching sea cucumbers community intensively will give a negative impact on its sustainability. Sea cucumber has long been recognized and protected by the people in Padaido islands known as sasisen or sasi system. Although it has been conserved through sasisen system, but tends decline recently. This happen due to the high fishing activities by fisherman. Sea farming methods is a sea fisheries development concept in shallow waters such as the merger between aquaculture and capture fisheries by utilizing leading commodity in potential cultivation area. Sea farming is a system of utilization of marine ecosystem-based marine culture with the ultimate goal to improve the stock of fish (fish resources enhancement) to the sustainability of fisheries and other marine-based activities such as ecotourism. This paper will discuss the development opportunities of sea farming system that is integrated with the prevailing of local wisdom in Padaido Islands, Biak Numfor Regency, Papua, namely sasisen. This system works in conserving sea cucumber resources and increasing incomes of local communities in Padaido island through the creation of alternative livelihoods specifically in sea cucumber cultivation. Therefore, these models and approaches can be considered to manage coastal and marine resources in a sustainable way in Padaido Islands, Biak Numfor Regency.Key words: Sea cucumber, sustainable management, sasisen, Padaido Islands.

The fish farm of origin is assigned by the element profile of Atlantic salmon (Salmo salar L.) scales in a simulated escape event

Abstract The Norwegian aquaculture management authorities require that the sea farm of origin for escaped salmon can be identified. As a contribution to develop a reliable and feasible method for tracing escaped salmon to their sea cage of origin the proof-of-concept of the case-based red alert method ‘FarmSalmTrack’ is demonstrated through a simulated escape event. The ‘FarmSalmTrack’ method uses the trace element distribution in the scale hydroxyapatite, HAP-layer, to discriminate between groups of salmon. The case-based approach can primarily be used for larger escapes and preferably where the escaped fish are caught relatively soon after the time of escape. The method is dependent on baseline data being available from all sea farm cages potentially responsible for the escape. Classification of the escapees towards the baseline material collected from nearby sea cages holding salmon of same age and size is done in a three-step process; (1) analysis of the Sr/Ba ratio which reveals if seawater or salt are added to the hatchery tanks, (2) analysis of element profiles in the juvenile section of the scale and (3) analysis of trace element profile of the scale HAP-layer formed in seawater. Step (1) reduced the number of suspected sea cages by one half, step (2) identified the escapees’ hatchery of origin and step (3) identified the sea cage of origin. The classification was based on the concentration of the elements B, Ba, Li, Mg, Mn, Na, S, Sr, U and Zn along selected sclerites. Barium was the most important element for correct classification using the elemental profile of the juvenile section of the scale, while Zn showed the strongest influence on the classification using the seawater section of the scale. Improved understanding of the incorporation of non-essential life elements and essential life elements into the bio-mineralised structures of the fish scale HAP-layer would be highly beneficial for further development of the ‘FarmSalmTrack-method’.

Marine macroalgal nursery: A model for sustainable production of seedlings for large scale farming

Abstract Innovative technologies in seaweed aquaculture are the need of the hour for sustaining the emerging global market demands. The supply of seedlings for year-round sea farming has remained as a major challenge for large-scale production of seaweeds. This study describes a simple innovative model integrating the designing of a prototype with an effective protocol for seedling production and their propagation for the continuous production of seedlings from seaweeds. The novelty of this model includes its design enabling maximum seedlings production and demonstration of reusability of enzyme employed for protoplast (seedlings) production for five times without compromising over the protoplast yield and viability. The laboratory test trials conducted to assess the effectivity of this model in the production of seedlings from protoplasts with Ulva yielded seedling biomass of 0.25 kg fresh wt. (>200 folds of initial biomass) in 44 days culture period over 0.33 m2 surface area. The present prototype is simple, scalable and facilitates a consistent production of a large number of quality seedlings from relatively a small sample size. A concept layout for scale-up production of seedlings in an outdoor facility is also proposed based on prototype tested in this study. The findings reported in this study collectively not only promote the concept for establishing the macroalgal nursery for large-scale production of quality seedlings suitable for extraction of pharmaceutical and nutraceutical grade products but also provide an option for rapid restoration of species, if found under threat.

The integrated impacts of natural processes and human activities on groundwater salinization in the coastal aquifers of Beihai, southern China

Salinization in coastal aquifers is usually related to both seawater intrusion and water–rock interaction. The results of chemical and isotopic methods were combined to identify the origin and processes of groundwater salinization in Daguansha area of Beihai, southern China. The concentrations of the major ions that dominate in seawater (Cl−, Na+, Ca2+, Mg2+ and SO 4 2– ), as well as the isotopic content and ratios (2H, 18O, 87Sr/86Sr and 13C), suggest that the salinization occurring in the aquifer of the coastal plain is related to seawater and that the prevailing hydrochemical processes are evaporation, mixing, dissolution and ion exchange. For the unconfined aquifer, groundwater salinization has occurred in an area that is significantly influenced by land-based sea farming. The integrated impacts of seawater intrusion from the Beibuwan Gulf and infiltration of seawater from the culture ponds are identified in the shallowest confined aquifer (I) in the middle of the area (site BBW2). Leakage from this polluted confined aquifer causes the salinization of groundwater in the underlying confined aquifer (II). At the coastal monitoring site (BBW3), confined aquifer I and lower confined aquifer II are heavily contaminated by seawater intrusion. The weak connectivity between the upper aquifers, and the seaward movement of freshwater, prevents saltwater from encroaching the deepest confined aquifer (III). A conceptual model is presented. Above all, understanding of the origin and processes of groundwater salinization will provide essential information for the planning and sustainable management of groundwater resources in this region.