Global Fish Research Articles

Predicting Skipjack Tuna Fishing Grounds in the Western and Central Pacific Ocean Based on High-Spatial-Temporal-Resolution Satellite Data

Skipjack tuna are the most abundant commercial species in Taiwan’s pelagic purse seine fisheries. However, the rapidly changing marine environment increases the challenge of locating target fish in the vast ocean. The aim of this study was to identify the potential fishing grounds of skipjack tuna in the Western and Central Pacific Ocean (WCPO). The fishing grounds of skipjack tuna were simulated using the habitat suitability index (HSI) on the basis of global fishing activities and remote sensing data from 2012 to 2015. The selected environmental factors included sea surface temperature and front, sea surface height, sea surface salinity, mixed layer depth, chlorophyll a concentration, and finite-size Lyapunov exponents. The final input factors were selected according to their percentage contribution to the total efforts. Overall, 68.3% of global datasets and 35.7% of Taiwanese logbooks’ fishing spots were recorded within 5 km of suitable habitat in the daily field. Moreover, 94.9% and 79.6% of global and Taiwan data, respectively, were identified within 50 km of suitable habitat. Our results showed that the model performed well in fitting daily forecast and actual fishing position data. Further, results from this study could benefit habitat monitoring and contribute to managing sustainable fisheries for skipjack tuna by providing wide spatial coverage information on habitat variation.

Scientific Methods to Understand Fish Population Dynamics and Support Sustainable Fisheries Management

Fisheries play a significant role in the livelihoods of the world population, while the dependence on fisheries is acute in developing countries. Fisheries are consequently a critical element for meeting the sustainable development (SDG) and FAO goals to reduce poverty, hunger and improve health and well-being. However, 90% of global marine fish stocks are fully or over-exploited. The amount of biologically unsustainable stocks increased from 10% in 1975 to 33% in 2015. Freshwater ecosystems are the most endangered ecosystems and freshwater fish stocks are worldwide in a state of crisis. The continuous fish stock decline indicates that the world is still far from achieving SDG 14 (Life Below Water), FAO’s Blue Growth Initiative goal and SDG 15 (Life on Land, including freshwater systems). Failure to effectively manage world fish stocks can have disastrous effects on biodiversity and the livelihoods and socio-economic conditions of millions of people. Therefore, management strategies that successfully conserve the stocks and provide optimal sustainable yields are urgently needed. However, successful management is only possible when the necessary data are obtained and decision-makers are well informed. The main problem for the management of fisheries, particularly in developing countries, is the lack of information on the past and current status of the fish stocks. Sound data collection and validation methods are, therefore, important. Stock assessment models, which support sustainable fisheries, require life history traits as input parameters. In order to provide accurate estimates of these life history traits, standardized methods for otolith preparation and validation of the rate of growth zone deposition are essential. This review aims to assist researchers and fisheries managers, working on marine and freshwater fish species, in understanding concepts and processes related to stock assessment and population dynamics. Although most examples and case studies originate from developing countries in the African continent, the review remains of great value to many other countries.

Planktivores as trophic drivers of global coral reef fish diversity patterns

One of the most prominent features of life on Earth is the uneven number of species across large spatial scales. Despite being inherently linked to energetic constraints, these gradients in species richness distribution have rarely been examined from a trophic perspective. Here we dissect the global diversity of over 3,600 coral reef fishes to reveal patterns across major trophic groups. By analyzing multiple nested spatial scales, we show that planktivores contribute disproportionally to the formation of the Indo-Australian Archipelago (IAA) marine biodiversity hotspot. Besides being "hotter" at the hotspot, planktivorous fishes display the steepest decline in species numbers with distance from the IAA when compared to other trophic groups. Surprisingly, we did not detect differences in diversification, transition, and dispersal rates in extant species phylogenies that would explain this remarkable gradient in planktivorous fish richness. Thus, we identify two potential complementary drivers for this pattern. First, exceptional levels of partitioning among planktivorous coral reef fishes were driven by temporally stable oceanographic conditions and abundant planktonic resources in the IAA. Second, extinctions of planktivores outside the IAA have been particularly pronounced during Quaternary climate fluctuations. Overall, our results highlight trophic ecology as an important component of global species richness gradients.

The Meridionally Averaged Model of Eastern Boundary Upwelling Systems (MAMEBUSv1.0)

Abstract. Eastern boundary upwelling systems (EBUSs) are physically and biologically active regions of the ocean with substantial impacts on ocean biogeochemistry, ecology, and global fish catch. Previous studies have used models of varying complexity to study EBUS dynamics, ranging from minimal two-dimensional (2-D) models to comprehensive regional and global models. An advantage of 2-D models is that they are more computationally efficient and easier to interpret than comprehensive regional models, but their key drawback is the lack of explicit representations of important three-dimensional processes that control biology in upwelling systems. These processes include eddy quenching of nutrients and meridional transport of nutrients and heat. The authors present the Meridionally Averaged Model of Eastern Boundary Upwelling Systems (MAMEBUS) that aims at combining the benefits of 2-D and 3-D approaches to modeling EBUSs by parameterizing the key 3-D processes in a 2-D framework. MAMEBUS couples the primitive equations for the physical state of the ocean with a nutrient–phytoplankton–zooplankton–detritus model of the ecosystem, solved in terrain-following coordinates. This article defines the equations that describe the tracer, momentum, and biological evolution, along with physical parameterizations of eddy advection, isopycnal mixing, and boundary layer mixing. It describes the details of the numerical schemes and their implementation in the model code, and provides a reference solution validated against observations from the California Current. The goal of MAMEBUS is to facilitate future studies to efficiently explore the wide space of physical and biogeochemical parameters that control the zonal variations in EBUSs.

A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes

About half of all vertebrate species today are ray-finned fishes (Actinopterygii), and nearly all of them belong to the Neopterygii (modern ray-fins). The oldest unequivocal neopterygian fossils are known from the Early Triassic. They appear during a time when global fish faunas consisted of mostly cosmopolitan taxa, and contemporary bony fishes belonged mainly to non-neopterygian (“paleopterygian”) lineages. In the Middle Triassic (Pelsonian substage and later), less than 10 myrs (million years) after the Permian-Triassic boundary mass extinction event (PTBME), neopterygians were already species-rich and trophically diverse, and bony fish faunas were more regionally differentiated compared to the Early Triassic. Still little is known about the early evolution of neopterygians leading up to this first diversity peak. A major factor limiting our understanding of this “Triassic revolution” is an interval marked by a very poor fossil record, overlapping with the Spathian (late Olenekian, Early Triassic), Aegean (Early Anisian, Middle Triassic), and Bithynian (early Middle Anisian) substages. Here, I review the fossil record of Early and Middle Triassic marine bony fishes (Actinistia and Actinopterygii) at the substage-level in order to evaluate the impact of this hiatus–named herein the Spathian–Bithynian gap (SBG)–on our understanding of their diversification after the largest mass extinction event of the past. I propose three hypotheses: 1) the SSBE hypothesis, suggesting that most of the Middle Triassic diversity appeared in the aftermath of the Smithian-Spathian boundary extinction (SSBE; ∼2 myrs after the PTBME), 2) the Pelsonian explosion hypothesis, which states that most of the Middle Triassic ichthyodiversity is the result of a radiation event in the Pelsonian, and 3) the gradual replacement hypothesis, i.e. that the faunal turnover during the SBG was steady and bony fishes were not affected by extinction events subsequent to the PTBME. Based on current knowledge, hypothesis three is favored herein, but further studies are necessary to test alternative hypotheses. In light of the SBG, claims of a protracted diversification of bony fishes after the PTBME should be treated with caution.

Microplastics in fish and fishmeal: an emerging environmental challenge?

Microplastics are contaminants of emerging concern; they are ingested by marine biota. About a quarter of global marine fish landings is used to produce fishmeal for animal and aquaculture feed. To provide a knowledge foundation for this matrix we reviewed the existing literature for studies of microplastics in fishmeal-relevant species. 55% of studies were deemed unsuitable due to focus on large microplastics (> 1 mm), lack of, or limited contamination control and polymer testing techniques. Overall, fishmeal-relevant species exhibit 0.72 microplastics/individual, with studies generally only assessing digestive organs. We validated a density separation method for effectiveness of microplastic extraction from this medium and assessed two commercial products for microplastics. Recovery rates of a range of dosed microplastics from whitefish fishmeal samples were 71.3 ± 1.2%. Commercial samples contained 123.9 ± 16.5 microplastics per kg of fishmeal—mainly polyethylene—including 52.0 ± 14.0 microfibres—mainly rayon. Concentrations in processed fishmeal seem higher than in captured fish, suggesting potential augmentation during the production process. Based on conservative estimates, over 300 million microplastic particles (mostly < 1 mm) could be released annually to the oceans through marine aquaculture alone. Fishmeal is both a source of microplastics to the environment, and directly exposes organisms for human consumption to these particles.

Is community-based management of small-scale fisheries in Sierra Leone the answer to their problems?

With increasing decline in global fish stocks and the possibility of extinction of many small-scale fisheries (SSF) partly because of over-fishing by large-scale industrial fishers (both licensed and unlicensed) and partly because of harmful fishing gear used by small-scale fishers themselves, researchers are focusing on alternatives to the prevailing top-down systems of fisheries management. One such alternative that is receiving attention is the community-based approach to the governance of SSF, which maintains that small-scale or artisanal fishers have a special attachment to their geographical area which makes them better managers of their fish resources. This study investigates the viability of this approach in Sierra Leone’s Tombo and Goderich fishing communities. Fieldwork was carried out during 2017 and 2019 when a total of 51 key informant (KI) and 14 telephone interviews (TI) were conducted, and 200 survey questionnaires (SQ) were distributed in the two communities. The main finding is that although several community fisheries organisations (CFO) try to manage coastal stocks, they have no power to curb industrial over-fishing, and their power to stop artisanal fishers using harmful gear is compromised by government interference and by conflicts between CFOs. The study concludes that both top-down (governmental) and bottom-up (communitarian) approaches to SSF management have flaws, and each side needs to acknowledge its flaws, and work together with the other side to eliminate them.

DNA Barcoding of Fish in Mischief Reef—Fish Diversity of a Reef Fish Community From Nansha Islands

Development of effective conservation and management strategies requires assessments of ecosystem biodiversity status, especially in understudied hotspots of global fish diversity. Coral reefs are important habitats for fishes, with biodiversity hotspots known globally. We present the first data on molecular diversity of fishes of Mischief Reef, the largest atoll in the Nansha Islands. Partial sequences (650 bp) of mitochondrial COI gene (Cytochrome c oxidase subunit I) are used to identify 209 individuals, representing 101 species, referable to 62 genera, 27 families, 8 orders, and 1 class. The most abundant orders are the Perciformes (176 specimens, 84.21%), Tetraodontiformes (13 specimens, 6.22%), and Beryciformes (13 specimens, 6.22%). Mean Kimura 2-Parameter genetic distances within genera, families, and orders are 4.51, 13.90, and 17.63%, respectively. We record Monotaxis heterodon from this region for the first time—a species that may previously have been misidentified as M. grandoculis. In addition, we recognized possible cryptic species of Lethrinus olivaceus based on significantly diverging barcode sequences. Barcode data provide new insights into fish diversity of Mischief Reef, important for developing further researches on this fauna, and for its conservation.

Periodic pattern mining from spatio-temporal database using novel global pollination artificial fish swarm optimizer-based clustering and modified FP tree

Periodic pattern mining from spatio-temporal database using novel global pollination artificial fish swarm optimizer-based clustering and modified FP tree

Seaweeds: A potent source of antimicrobial drugs for aquaculture industry

The purpose of this review is to elucidate the antimicrobial effect of seaweed extracts as a dietary supplement in aquatic animals. Aquaculture, a future of food producing sector, plays an important role in global food security, elimination of mal nutrition, and provides livelihood and employment over 59 million people around the world. Though, one side global food fish production and consumption shows an increasing trend, on the other side due to the over exploitation of available marine resources and emergence of deadly bacterial and viral disease in culture practices, the sector is leading to a great adversity which can bridge a gap between fish production and consumption. Nowadays there are several chemicals and drugs have been used to treat the diseased aquatic animals. Antibiotic usage in aquaculture practices, to mitigate the pathogenic intruders, is unsustainable and its application makes the bacteria to evolve resistance and their consumption leads to food vulnerability in human and animal. Presently, the global fish production sector is moving towards the sustainable and eco-friendly solutions to mitigate the emerging deadly intruders. However, there are many sustainable alternatives in practice such as, bacteriophage therapy, vaccine, RNA interference, use of short-chain fatty acids and polyhydroxyal kanoates to inhibit the growth of bacterial intruders, use of immune stimulants, probiotics, prebiotics, symbiotics, quorum sensing inhibition, and also the use of seaweed extract in the place of antibiotics and chemicals considered as an effective and sustainable alternative in fighting against the diseases in aquatic animals. Extracts derived from seaweeds, exerts numerous benefits over the cultivable aquatic animal which includes, promotion of growth and enhancement of the immune and other physiological performances. The present review gives an insight to the use of bio-active compounds derived from seaweeds and its beneficial effects to improve the production and immune status in aquatic animals.

An overview of most commonly used methods for detection of fish mislabeling

The increase of global fish consumption brings with it the problem of fish mislabeling, which leads to economic losses for consumers or may even result in consumers’ health risk. Thus, continuous development of methods used in identification of exact fish species is essential. There are numerous modern identification methods, which use DNA or specific fish proteins as biomarkers, but they all come with various benefits and drawbacks. Protein-based methods include electrophoretic methods, ELISA, HPLC and MALDI-ToF Mass Spectrometry, while the methods that use DNA as a biomarker include PCR-RFLP, SSCP, qPCR, RAPD, FINS, DNA microarray, DNA barcoding, pyrosequencing and metabarcoding. There is a continuous development of new or improved methods. Most of the methods display a much better performance when analyzing raw or lightly processed fish, such as chilled or frozen, while heat treatment often leads to changes in the biomarker molecules, making the species identification difficult. The ideal method does not yet exist, but methods such as DNA barcoding, MALDI-ToF Mass Spectrometry and metabarcoding are the ones that show most potential.

Aquaculture Over-Optimism

The recent rapid growth in aquaculture production reported by the United Nations Food and Agriculture Organization has resulted in what we denote here as aquaculture over-optimism. An extreme form of which is the notion that we need not worry about depleting wild fish because we can meet the global need for seafood through farming. Here we investigate, whether the recent growth in aquaculture production can be maintained and compare aquaculture production projections with the future need for fish to find out whether aquaculture optimism is justified. We find that aquaculture growth rates in all the cases studied have already reached their peak and have begun declining. Also, our results suggest that for aquaculture alone to supply the projected total global fish demand between 2025 and 2030, it would have to grow by between 11% and 19% per year, rates that are outside the range that been possible to date.

Benefits of Agricultural R&D International Spillovers: The case of aquaculture

International spillovers from research and development (R&D) arise when technology developed in one geopolitical region is adopted by another region, resulting in a divergence between social and private benefits from the technology. Applying this concept to aquacultural R&D, study results based on a partial equilibrium model of the global fish market suggest the magnitude of spillovers depends crucially on where the R&D occurs. When the R&D occurs in the developing world and assuming the cost savings to the developed world from the technology transfer equals half the cost savings experienced by the developing world, spillover effects are shown to be negligible. A basic reason is that developing countries account for over 90% of the global production of farmed fish. Consequently, technology “leakages” to the developed world have a modest effect on the global supply of farmed fish, and thus on the price and welfare effects of the technology transfer. In contradistinction, spillovers associated with technology leakages in the other direction, namely from the developed to the developing world, are shown to be both large and economically important. When spillover effects are taken into account the global annual gain ($4.9 billion) from a 2.5% import tax used to fund aquacultural R&D in the developed world is estimated to be 4.9 times larger than the domestic annual gain ($1.0 billion).

Comparison and optimization of a novel larval rearing method for bighead carp Hypophthalmichthys nobilis

Bighead carp Hypophthalmichthys nobilis is a species that is widely cultured throughout Asia, currently ranking 5th in overall global fish production. Despite the prevalence of this species culture it is considered invasive in North America and a threat to local fish communities. Investigations into the early life environmental requirements and optimization of intensive larval rearing have been limited. The present study attempts to establish most desired larval rearing conditions of bighead carp by investigating a novel static rearing method utilizing continuous light, salinity (2 parts per thousand; ppt), algal turbidity, and continuous food availability as compared to traditional recirculating culture system methods. Increased levels of salinity (3 and 5 ppt) were also examined in the novel rearing environment. A 2x2x3 full factorial ANOVA design was implemented to compare the main effects of larval rearing system, feeding regime, and stocking density (12.5, 25, and 50 fish L−1) and the interactions between the main effects on survival, biomass, length, weight, proportion of large fish (measure of heterogeneity), and specific growth rate over twenty days of feeding. A desirability function was then constructed to maximize survival (%), biomass (g L−1) and proportion of large fish to optimize larval rearing for diet nutritional requirement studies. Mortalities recorded in the experiment primarily occurred within the first ten days of feeding and leveled off during the second ten days of feeding. The desirability function identified the novel static rearing method, at high initial stocking density (50 fish L−1), and feeding with Artemia nauplii from inception as having the maximum desirability (0.733) for the selected variables. The predictions for biomass, survival and proportion of large fish from the desirability function were 2.38 g L−1 (95% CI, 2.14–2.62), 70.3% (95% CI, 60.1–80.6), and 0.768 (95% CI, 0.696–0.841) respectively. Elevated salinity, 3 and 5 ppt, was found to increase survival (51.3 ± 3.5 and 64.3 ± 10.1%, respectively) and proportion of large fish (0.76 ± 0.08 and 0.82 ± 0.02, respectively) i.e. decreased heterogeneity, as compared to 2 ppt (33 ± 3% and 0.63 ± 0.03) in the novel static rearing environment. This indicates that current results may further be improved if bighead carp are reared at higher salinities (3–5 ppt). The optimization methodology which was utilized in the current study could potentially be applied to any larval rearing program to select for treatments which meet specific desired outcomes.

Adapting to climate change in small-scale fisheries: Insights from indigenous communities in the global north and south

Climate change is having a significant influence on global fish production as well as on small-scale fishers’ livelihoods, nutrition, and food security. We compared two climate-sensitive small-scale fisheries (SSFs) – an Inuit community in the Canadian Arctic and the Coastal-Vedda in Sri Lanka – to broaden our understanding of how fisheries-dependent Indigenous communities respond and adapt to climate change impacts. We used three steps to achieve this comparative study. To do this, we developed a resilience-based conceptual framework to empirically assess adaptations in two SSF communities, based on a literature review. Using the proposed framework and collecting qualitative field data over three years (2016–2019) to investigate how different remote SSFs experience and respond to climate change, we assessed Inuit and Coastal-Vedda case studies. The framework provided the structure for data analysis and conceptual guidance for two empirical assessments and the comparative analysis. Finally, we carried out the comparative analysis across the case studies using content analysis, identifying adaptive strategies, sources of resilience, and characteristics of successful adaptation. Additionally, we used discourse analysis to develop sources of resilience and characteristics of successful adaptation. Two key adaptive strategies emerged in common across the two communities – diversification and adaptive co-management. Eight sources of resilience that underpin adaptive capacity: i) use of diverse kinds of knowledge; ii) practice of different ways of learning; iii) use of community-based institutions; iv) efforts to improve human agency; v) unique worldviews; vi) specific cultural attributes that keep up with adaptation; vii) effective social networks; and viii) a high level of flexibility. Definitive characteristics that need to promote successful community adaptation: continuous learning through knowledge co-production; capacity-building to improve human agency; a place-specific nature (rootedness); collective action and partnerships through community-based institutions; and flexibility.

Vulnerability to Viability (V2V) Global Partnership for building strong small-scale fisheries communities

Small-scale fisheries (SSF) support over 90 percent of the 120 million people engaged in capture fisheries globally (FAO, 2015). They also contribute two-thirds of the global fish catch destined for direct human consumption, and provide critical contributions to food security, poverty alleviation, and local and national economies (FAO, 2015). Most SSF communities are economically marginalised, increasingly vulnerable to climate and environmental changes, and, until recently (Berkes, 2015), they have remained largely invisible in global and national policy debates. However, the prognosis is not all negative. SSF possess certain strengths and forms of resilience upon which to build viable solutions to combat food insecurity and poverty (Bundy et al. , 2016; Bavinck et al. , 2018; Nayak and Armitage, 2018)

Factors affecting consumers´ preferences for products from aquaculture

Fish is an essential component of a balanced and healthy diet and the present demand for fish cannot be sustained by capture fisheries. Consequently, aquaculture is currently the fastest growing food production industry in the world, contributing to more than half of the global fish production intended for human consumption. Although the image of aquaculture is not necessarily negative per se, consumers around the world still have a greater preference for wild fish. Therefore, the aim of this review is to critically evaluate some of the factors which may affect consumer preferences: socio-demographic characteristics of consumers, quality and safety perception of products from aquaculture, price of aquaculture products and socio-economic aspects of aquaculture, and concerns about the negative impact of aquaculture on the environment and about the sustainability of the production method. A literature review confirmed that age is the most influential sociodemographic variable. Being younger, female or having higher income and a higher education level can result in greater preference for aquaculture products. The image of farmed fish suffers from a perception of lower quality in terms of taste, health and nutritional value and, in some cases, even from low safety perceptions. On the other hand, farmed fish is believed to have lower prices and greater availability. Additionally, economic benefits are one of the main advantages of aquaculture. Mixed results emerge, however, with regard to the environmental impact of aquaculture, but sustainable production may compensate for possible environmental concerns and drive preference for farmed fish. Depending on how consumers weigh up the advantages and disadvantages of both aquaculture and its products, this will result in a preference for wild or farmed fis

Systematic Mapping of Research on Farm-Level Sustainability in Finfish Aquaculture

The sustainability of future finfish aquaculture needs to be improved to meet global environmental challenges. Global fish aquaculture production has expanded significantly recently, due to the increased demand for fish for human consumption. Therefore, it is important to mitigate challenges to the sustainability of the sector, such as pollution and depletion of natural resources. In this study, we systematically mapped the scientific literature on farm-level sustainability in fish aquaculture. The concept of sustainability was considered holistically, covering its economic, environmental and social dimensions, each consisting of a range of different aspects that may contradict or reinforce each other. Literature published between January 2000 and August 2020 with the geographical focus on Europe, Northern America and Australia–New Zealand was included. The search resulted in a total of 287 hits, but after the exclusion of articles that did not match the scope, only 17 papers remained for the systematic mapping. Of these, five papers covered all three dimensions of sustainability. Economic sustainability was addressed in 10 papers, environmental sustainability in 13 papers and social sustainability in 12 papers. This systematic mapping provides an important foundation for discussions and prioritisations of future actions to increase knowledge on farm-level sustainability in finfish aquaculture.

Thought of Alternate Aquafeed: Conundrum in Aquaculture Sustainability?

The exponential growth of human population and their ever-increasing demands have challenged the aquaculture sector with respect to its growth, sustainability and environmental well-being. Due to the rapid intensification, aquaculture’s share of global fishmeal and fish oil consumption has more than doubled over the past decade with limited availability and high prices. Hence, the key concern of aquaculture in recent times is to reduce the environmental footprint while feeding the farmed fish with nutritionally balanced, economic and environmentally sustainable feed. But the changes in feed systems are dependent on several potential drivers, including environmental, political, economic, cultural, technological and demographic ones. The use of compound feeds formulated with a great variety of ingredients was a major step in the development of the worldwide aquaculture industry in the last century. However, the main challenges are the availability and cost of alternate feed resources, their competitiveness with other sectors, demand-supply consort with the environmental quality, social acceptability and economic growth. This review is an attempt to assess the present scenario of conventional aquafeed with an understanding of the gaining importance of alternate aquafeed along with their trade-offs addressing the principal issues of sustainability for future policy making.

COVID-19, instability and migrant fish workers in Asia.

This paper seeks to establish how COVID-19 is impacting migrant fish workers through focusing on two global fish hubs, Thailand and Taiwan. Through a careful review of the news reports, social media, and NGO reports and press releases, three significant themes emerged: employment disruptions due to seafood system instabilities; travel or mobility restrictions; and poor access to services such as health care or social programs. We unpack each theme in turn to spotlight the impacts COVID-19 is having on yet another vulnerable worker population, fish workers. We further reflect on what this pandemic reveals about unacceptable work in industrial fisheries and consider if the pandemic may be producing opportunities to advocate for better working conditions.