Small-scale Fisheries Research Articles

Innovative Machine Learning and Stakeholder Method to Assess Bycatch of Tursiops truncatus in the Southern Gulf of Mexico

The assessment and mitigation of bycatch, currently identified as the most significant threat to marine mammals, represents a substantial challenge for society. This issue is particularly acute in developing countries, where data on small-scale fisheries are scarce, and knowledge gaps exist regarding the distribution and abundance of various marine mammal species. Artisanal fisheries, particularly in developing countries, have been linked to significant mortality levels of marine organisms due to bycatch. The magnitude of this phenomenon reveals alarming figures. Notably, there is a high incidence of interactions between the bottlenose dolphin (Tursiops truncatus) and nearshore gillnets, where the overlap in their coastal distribution creates high-risk zones. The imperative to assess bycatch is driven not only by conservation principles but is also essential for sustainability in developing countries due to U.S. government regulations on imports of fishery products aimed at reducing bycatches worldwide. This study proposes an innovative methodology to investigate marine mammal bycatch in the southern Gulf of Mexico. This methodology is based on the development of artificial intelligence models, the integration of stakeholder input, and the use of habitat suitability models. This approach utilizes 11 years of sighting records and 1,654 spatial-temporal fishing effort data points collected through interviews with fishers. Additionally, the study develops artificial intelligence models, specifically Random Forest algorithms in Python, to enhance the analysis and prediction of bycatch risk. This research identified monthly variations in high-risk zones for marine mammal bycatch in the southern Gulf of Mexico, highlighting regions with a higher likelihood of interaction with gillnets. This pioneering work of applying artificial intelligence to marine mammal bycatch provides a complementary analysis for areas with limited economic and data resources.

Assessing fish assemblages on oil jackets off the Angolan coast: Implications for decommissioning decisions.

West Africa plays a significant role in global oil production. Much of the offshore infrastructure in this region is due for decommissioning. An understanding of the marine communities associated with the infrastructure is essential to predict the outcome of different decommissioning alternatives, such as leave-in-place or full removal. Using ROV inspection footage, we sampled nine jackets off Angola (Cabinda Province) to quantify the abundance and species composition of fish. Sixty-five species of fish were observed among jackets, including several taxa that are commercially important to the region, such as sardine (Sardinella spp.) and mackerel species (Trachurus spp.). We also observed taxa that are commonly targeted in small-scale (artisanal) fisheries in Angola, such as groupers (Epinephelidae) and snappers (Lutjanidae). Distinct fish assemblages were observed at each jacket, and attributed to differences in jacket location, depth, and infrastructure design. Time of day also affected the assemblage detected across jackets, although similar dominant families were present across day and night at a specific depth zone when pooled. Unlike patterns observed in other regions, there was not a clear depth zonation pattern at individual jackets, and only a weak depth zonation pattern was evident when all jackets were combined. Six species had not previously been recorded off Angola, suggesting that the jackets may either facilitate range extensions or highlight a paucity of fish studies in the region. Our results have important implications for evaluating decommissioning options, including addressing questions on jacket removal or reefing and implications for species of importance to fisheries.

Informing the spatial management of Silky Shark (Carcharhinus falciformis) in the Eastern Pacific Ocean

The Silky Shark (Carcharhinus falciformis) is highly vulnerable to population decline, yet leads shark bycatch in some of the world’s largest tuna fisheries. As such, this species provides an appropriate case study for regional fisheries management organizations—exemplified by the Inter-American Tropical Tuna Commission—to develop conceptual population assessment frameworks that integrate diverse data streams to elucidate population structure and dynamics of assessed species. Using genetic, movement, life history, and small- and large-scale fishery-dependent data from across much of the Silky Shark’s Pacific Ocean range, we found preliminary evidence for a three-stock model—southern, central, and northern—in the eastern Pacific Ocean (EPO). Length distributions of Silky Sharks varied with latitude and across fishery gears and strategies. The predominance of small juveniles, including neonates, caught on or near the continental shelf by small-scale fisheries and offshore by purse seines set on floating objects, including fish aggregating devices, suggested that Silky Sharks use both shelf-edge habitats and offshore areas as pupping and/or nursery areas. Finally, we showed that sex ratios favored females in oceanic and equatorial zones, where most Silky Shark bycatch in large-scale fisheries occurs. Our study serves as a roadmap to comprehensively understand spatial population dynamics of common bycatch species lacking a dispersive larval phase, such as elasmobranchs, by integrating genetic, biological, ecological, and fisheries data. Specifically, our work can inform stock assessments and management measures that may improve Silky Shark conservation in the EPO and elsewhere.

Trophic dynamics and ecosystem health of a young tropical reservoir in Northeast India.

Small reservoirs are recognised as the most productive man-made ecosystem inhabiting diverse flora and fauna, having a scope for small-scale fisheries to support food security, livelihood, and many other ecological services. This study aimed to determine the trophic structure and ecosystem functioning of the Maphou Reservoir, located in the Northeastern Hill region,India, using the Ecopath mass-balance modelling approach, to figure out the strategic scientific ecosystem-based fisheries management. Ten functional groups were identified, most of which were confined in trophic level II (low order primary consumer). Exotic fish was the most utilized group based on ecotrophic efficiency (EE = 0.782), followed by herbivorous fish (EE = 0.623), and carnivorous fish group arefound to be the keystone species. Based on the mixed trophic index (MTI), lowertrophic level functional groups(detritus and phytoplankton) had a positive impact on the higher trophic levels, manifesting a 'bottom-up control' ecosystem. The reservoir is a primary producer-driven ecosystem (transfer efficiency from primary producer, PP = 4.864%), and mean transfer efficiency is low (4.732%), indicating scope for enhancing the fish stock sizes. The total primary producer/total respiration (TPP/TR) (3.629) and total primary producer/total biomass (TPP/TB) (70.70) suggested that the reservoir is in immature and developing ecosystem with high resilience against external perturbations (Overhead = 63.25%). The reservoir shows a moderately complex food web structure (connectance index = 0.457). The study recommended management measures for stocking enhancement of detritivores (Cirrhinus mrigala, Cyprinus carpio) and phyto-planktivorous fishes (Hypophthalmichthys molitrix, H. nobilis) to improve ecosystem efficiency; both groups have fairly low EE (detritus EE = 0.105 and phytoplankton EE = 0.379). These findings will be an essential input for policy formulation and scientific management of the small reservoir ecosystems in the tropics.

OXPHOS genes analysis in the red mullet (Mullus barbatus Linnaeus, 1758)

Red mullet, Mullus barbatus Linnaeus, 1758, is a very important target species of high commercial value for small-scale fisheries in the Mediterranean Sea. The distribution of the species is wide encompassing the North-Eastern Atlantic (from Scandinavia to Senegal), the Mediterranean Sea and Black Sea. Climatic differences across its range could trigger specific bioenergetic demands due that ectothermic aquatic species exploit heat exchange with the external environment to regulate metabolic activities and adaptation. Mitochondrial OXPHOS (mtOXPHOS) genes are particularly involved in these processes and they have been studied in the last decades as a system that is subject to selection under determined environmental constraints. Based on the above considerations, the purpose of this work were to analyze the nucleotide sequences of the Cytochrome Oxidase I (COI) and Cytochrome b (Cytb) OXPHOS genes in seven Mediterranean populations of M. barbatus, living within a latitudinal range between the North Adriatic, the Strait of Sicily in the South, the Ionian Sea in the East and the Balearic Sea in the Western Mediterranean. The aims were to assess the genetic diversity in the studied populations and to detect the presence of positive selection on the two-target protein-encoded genes using tests of recombination and selection based on different models of evolution. The diversity indices indicated higher values of haplotype diversity in the Adriatic populations than in the remaining populations for both genes. Furthermore, a very high number of COI and Cytb private haplotypes was found in almost of populations. Signature of pervasive positive selection by FUBAR and episodic positive selection by MEME were exclusively detected in COI gene. Our results support the need to manage red mullet populations as separate sub-populations with distinct gene pools.

HafsAuga MobileEM: mobile electronic monitoring for fisheries management and research

Electronic monitoring (EM) using video cameras is valuable for documenting fisheries catch and bycatch, but it remains challenging to implement in small-scale fisheries. Current barriers include high costs, technical installation needs and limited power supply on small vessels. In addition, as most EM systems on the market are difficult to quickly move between vessels, they do not allow for random data collection, which may be required to obtain reliable estimates of bycatch across a fleet. Basic EM systems available, designed for use in small-scale fisheries, are image-based, have low frame rates and are not always capable of recording in high enough video quality to identify species with high precision. The Swedish small-scale fishery consists of over 700 boats (under 12 m length), with key target species including cod, herring, sprat and flatfish. To meet monitoring requirements and to gather sufficient data for machine-learning applications, we created the HafsAuga MobileEM: a low-cost mobile multi-camera, GPS and remote data offload system for recording data on fisheries catch, bycatch and effort. It records video (up to 60 fps), is compact (~ 2 kg) and deployable in under 30 minutes. Designed to be simple to operate and install, it is modifiable and allows users to connect to a vessel's 12v power or to an internal battery to record high-quality video footage continuously for over a week. This system is ideal for use in small-scale fisheries and also well-suited to situations where fleets need to be randomly sampled by quickly moving EM systems between vessels. Here, we describe the HafsAuga MobileEM system and outline its use in Sweden, where it has been in use since 2020. To date, twenty Swedish vessels have had mobile systems mounted on them and over 1000 fishing days have been successfully recorded. The HafsAuga MobileEM provides an innovative new EM tool with potential applications in fisheries in other regions.

The contributions of coastal small-scale fisheries toward the sustainable development goals: a Kenyan Case Study

The contributions of coastal small-scale fisheries toward the sustainable development goals: a Kenyan Case Study

Progress and challenges of multi-habitat marine restoration in the eastern Aegean Sea, Türkiye

Ecological restoration is an increasing global priority and is critical to reverse ecosystem decline caused by anthropogenic impacts. We outline the approach to marine restoration in Gökova Bay, Türkiye and present observations from lesser to more highly assisted restoration interventions and trials, including enforcing multi-habitat No Fishing Zones (including Posidonia oceanica, macroalgae and rocky reef) within a wider Marine Protected Area network. We consolidate evidence from ecological monitoring, small-scale fisheries catch data, marine patrol threat monitoring and a macroalgae trial intervention. It remains difficult to decipher interactions in this system where anthropogenic threats persist and change is not linear but we observe that areas of restoration (No Fishing Zones) demonstrated a lower proportion of Non Indigenous Species compared to fished areas. This work provides a new case study of the progression of multi-habitat interventions and the potential for marine ecosystem recovery in the eastern Mediterranean Sea, informing restoration at scale.

Disentangling the entangled in productive ways: modelling social–ecological systems from a process-relational perspective

Process-relational perspectives have been proposed as new ways of conceptualising, analysing and engaging with social–ecological systems (SES) that are capable of dealing with intertwinedness and complexity. The application of PR perspectives in SES research, however, remains challenging and largely conceptual. We explore the possibilities of combining process-relational thought with agent-based modelling as a methodology for thinking with and exploring the becoming/emergence of SES. We call it relation-based modelling (RBM) and develop it through modelling the emergence/becoming of a virtual small-scale fishery. RBM focuses attention towards the apparatus, i.e. the material and discursive practices that shape the model structure which then provides the conditions for the emergence of fishery assemblages in a virtual, simulated world. Our attempt to produce a model from a process-relational perspective supported critical reflection of our assumptions about fisheries and agent-based modelling, particularly with respect to questioning common ways of dissecting the world that hinder understanding their intertwinedness and dynamism. Analysis of simulation results and our reflections about the apparatus together reveal how organisation at different levels, from the arrangement of practices that shape the design of the model to the arrangements of elements in the virtual world of the simulation influence the emergence of a virtual fishery. We reflect on the tensions we encountered when disentangling the entangled and formalising process-relational ideas and conceptualisations in the model and the learning and transformations that occurred through this process. A process-relational practice of modelling can open up possibilities to think differently about SES and change the way we theorise and act within them.

Quantification of anthropogenic debris from small-scale fisheries and community-based aquaculture in marine and coastal ecosystems of Southwestern Madagascar.

Quantification of anthropogenic debris from small-scale fisheries and community-based aquaculture in marine and coastal ecosystems of Southwestern Madagascar.

Productivity changes and management systems in small-scale fisheries

Productivity changes and management systems in small-scale fisheries

Impacts of the invasive blue crab Callinectes sapidus on small-scale fisheries in a Mediterranean lagoon using fishery landing data.

Human activities have introduced numerous non-native species beyond their natural habitats, leading to their establishment in new regions. Among them, the Atlantic blue crab (Callinectes sapidus) has significantly impacted biodiversity and fisheries in the Mediterranean Sea. This study investigates the recent population increase of C. sapidus associated changes of small-scale fisheries in one Mediterranean lagoon, the Sacca di Goro lagoon within the Po River Delta. We analysed the influence of environmental factors and C. sapidus biomass on trends in landings of commercially important species, using multivariate analysis, including principal component analysis (PCA) and redundancy analysis (RDA), as well as variance partitioning, linear regression and change point analysis on fishery landings data. Our results suggest that the spread of C. sapidus coincides with a decline in several commercial species, such as the European flounder (Platichthys flesus), the big-scale sand smelt (Atherina boyeri), the European eel (Anguilla anguilla) and the Mediterranean green crab (Carcinus aestuarii), suggesting a strong ecological and economic impacts of the blue crab invasion. The main mechanisms by which C. sapidus could drive this trend likely involve predation and competition, although further investigation is needed for confirmation. Annually averaged environmental variables (i.e., water temperature, salinity, nitrate and chlorophyll-a concentrations) were not significant predictors of commercial species trends, suggesting that the changes in landings cannot be primarily attributed to environmental factors. This study is the first to provide a comprehensive analysis of the potential effects of C. sapidus on the relative abundance of key fisheries species in Mediterranean Sea, suggesting a potential link between the rapid increase in its abundance and observed fish landing trends. The results highlight the need for integrated management strategies, including promoting market opportunities for C. sapidus and consideration of ecosystem-based management to control its abundance such as the protection of native local predators.

Leveraging Collective Action for Reinvestment in Small-Scale Fisheries by Women in Blue Economic Space of Homa-Bay County, Kenya

Can collective action drive reinvestment in small-scale fisheries by women? Given the increasing demand for quality livelihood, food and nutritional security, and poverty alleviation, there are calls for reinvestment in small-scale fisher enterprises by women. However, given the rapidly growing number of women players in the sector, and their accumulated expertise in the recent past, the study's objective is to leverage collective action by women for the reinvestment in small-scale fisheries in the blue economic space of Homa-bay County. Borrowing from social capital theory and applying a mixed method approach study design, data from a sample size of 330 from small-scale women fishers was scientifically obtained and analysed. Focus on common business challenges, participatory dialogue, beach management units, and affirmative action, were dimensions of collective action used in the analysis. The null hypothesis was put to the test. Findings were anchored on parametric and thematic analyses on the influence of collective action on the reinvestment of women-owned small-scale fisheries in the blue economic space of Homa-bay County. It was established that collective action had a statistically significant influence on reinvestment in the sector. Collective action explained 17.1% (R2=.171) variability in the reinvestment of small-scale fisheries, the model significance was reported by F (1,328) 67.752, p<0.05, and β= .272, p<0.05 which implied that a unit increase in collective action results into .272 units change in reinvestment. Small-scale fisheries space in the blue growth trajectory in the Lake-Victoria region of Homa-bay County in Kenya is scientifically established and therefore concluded that collective action has the potential to enhance reinvestment in the sector, improve household livelihood and address the women's poverty challenges.

Acoustic target strength measurement of striped goatfish (Upeneus vittatus)

The Striped Goatfish (Upeneus vittatus) is a demersal species of significant ecological and economic value, particularly for small-scale fisheries in Aceh Province. Accurate biomass estimation and species identification in hydroacoustic surveys rely heavily on precise target strength (TS) reference values. This study aimed to establish reference TS values for U. vittatus by examining the relationship between TS and fish morphology. Specimens collected from northern Aceh waters were measured for total length (TL: 17.3–28.3 cm) and weight (W, g). TS measurements were conducted using a single-beam echosounder (Simrad EK15) operating at 200 kHz with a pulse duration of 0.16 ms in a controlled water-tank environment. This approach enabled the assessment of TS variability across specimens with different TLs. A robust relationship between TL and weight revealed positive allometric growth (b = 3.2932, R² = 0.94) in the study. Furthermore, TS analysis demonstrated a logarithmic increase with TL (R² = 0.6459), in alignment with theoretical predictions. These findings contribute to more accurate biomass estimation and support sustainable management strategies for U. vittatus populations in northern Aceh, Indonesia. Future research should encompass a broader range of fish sizes and incorporate additional biological variables to refine TS prediction models further.Keywords:GoatfishAcehLWRTSMullidae

Co-management of small-scale fisheries in the Eastern Mediterranean: Insights and lessons from Türkiye’s Gökova MPA

Overfishing poses a critical threat to marine ecosystems and local coastal communities worldwide. Designation of Marine Protected Areas, particularly those incorporating No-Fishing Zones, act as refuges from the effects of climate and fishing, serve as valuable biodiversity conservation tools for more resilient social-ecological systems. Nevertheless, to be successful in long-term conservation these areas have to be monitored, and rules must be enforced. In this study, we examine collective action efforts for sustainable management of fisheries in Gökova Bay Marine Protected Area, Türkiye by utilizing semi-structured interviews and participant observation. Drawing upon Elinor Ostrom’s social-ecological systems framework and design principles, we put emphasis on the challenges and advantages of co-management in a social setting, as well as its potential to enhance marine conservation efforts. Our findings underscore the unsuitability of centralistic, command-and-control type of resource management for Gökova Bay. We highlight the significance of adaptive governance approach among small-scale fishers, government bodies, and non-governmental organizations. However, drawing from the Gökova Case, we assert that effective co-management hinges upon political commitment, alongside the provision of incentives by government authorities to fisheries and development of appropriate government institutions at the local level.

Integration of Renewable Energy in the Electrical System of Small-Scale Fishing Vessels: A Sustainable Marine Solution

This research explores the integration of renewable energy into the electrical system of small-scale fishing vessels as a sustainable solution for coastal communities. The study develops a solar-powered electrical system with battery storage to reduce dependence on fossil fuels and enhance energy reliability at sea. A prototype system was designed and installed on a traditional fishing boat and tested over a two-week operational period. Data on energy generation, consumption, and battery performance were collected and analyzed. The results demonstrate that the system provides sufficient power for lighting, navigation, and refrigeration needs during fishing trips. This study contributes to the development of green maritime technologies and offers a scalable model for sustainable electrification in the small-scale fisheries sector

Helminth parasites and epizoites in common dolphins (genus Delphinus) from coastal Peru and Ecuador

A twenty-five year old dataset of parasites in long-beaked and short-beaked common dolphins (Delphinus spp.), using fisheries as an opportunistic platform of access, registered seven species of helminths and one epizoite, being a unique dataset for the Southeast Pacific. Sampling was conducted in 1985-2000 at six fishing ports in Peru and Ecuador where cetaceans were landed from interactions with small-scale fisheries. From a total of 473 common dolphins examined, we identified helminths including three species of Trematoda: Nasitrema globicephalae, Pholeter gastrophilus, and Braunina cordiformis; three species of Nematoda, including Anisakis spp., Crassicauda spp., and Halocercus sp.; and two cestodes, Tetrabothrius forsteri and Clistobothrium delphini. No acanthocephalans were observed. No statistically significant sexual and ontogenetic variation in helminth prevalence was detected, after which samples were pooled. The highest prevalences in the long-beaked common dolphin (n = 440) were observed for N. globicephalae (87.9%, 29 infested/33 sampled) in cranial sinuses, Crassicauda sp1. (80%, 4/5) in mammary glands, followed by Cl. delphini (28.6%, 2/7) in the blubber, and P. gastrophilus (23%, 26/113) in the pyloric stomach. Although comparative testing was unfeasible due to minimal samples of short-beaked common dolphin (n = 33), several of the same helminth species were found; but not N. globicephalae nor B. cordiformis. No cyamids were encountered while pseudo-stalked barnacles Xenobalanus globicipitis were common. Although no new (global) helminth host records were revealed for common dolphins, this study presents a first checklist of parasites separately for the Southeast Pacific long-beaked and short-beaked common dolphins. Future work should include exhaustive laboratory-based necropsies, enhanced sampling of the short-beaked form, review data from recent parasite collections, focus on intermediate hosts and parasitic pathology, including potential human health impact from consumption of small cetaceans.

Reconsidering Child Labour as a Psycho-Social Dynamic and Form of Child Rights Violation

Abstract The issue of child labour is widely researched and debated, and is well addressed in different laws, policies and forums of governments; yet child labour remains intractable in both developed and developing countries. This intractability is often explained differently, such that international child rights conventions often attribute child labour to a lack of protection for children against harmful work, while econometric studies typically blame household poverty as the factor driving families to expose their children to work that harms their sound growth and development and right to education. There are also socio-cultural debates in which child labour is correlated with normative practices that are unable to separate harmful from non-harmful child work. Focusing on Ghana’s small-scale fisheries, this article draws on the socio-cultural debates as it observes stronger ties between child labour and normative constructions of childhood. The paper concludes with reflections on both debates and research and policy considerations.

Exploring the impacts of global change on small-scale fisheries: expanding the use of I-ADApT as a decision support tool

Exploring the impacts of global change on small-scale fisheries: expanding the use of I-ADApT as a decision support tool

Bangladeş Kalni Nehri'ndeki balıkçıların sosyo-ekonomik koşullarının değerlendirilmesi ve küçük ölçekli balıkçılığın sürdürülebilirliği

Small-scale fisheries play a vital role in the economy of Bangladesh, especially in providing livelihood to fishers and foreign exchange. A study on the socio-economic assessment of small-scale fishing and fish availability in the Kalni River in Habiganj district was conducted for four months from May to August 2023. A total of 58 fishers were randomly selected and interviewed for information gathering and pre-checklisting in focus group discussions (FGDs). Of these, 93% were male and the mean age was 36.89 ± 6.43 years. The results showed that the monthly income of fishers ranged from 10,000-20,000 BDT, 20,000-30,000 BDT, and less than 10,000 BDT. The study collected information on various aspects including the type of fishing gear used and the availability of small indigenous fish (SIS). The main fishing method, 'Ber jal' gear, accounted for 80% of the catch, while 'Dhormo jal' gear accounted for the remaining 20%. During this period, 1-3 types of Puti (Puntius sp.) and (Nandus nandus) Gobiidae family is the most abundant species. Various SISs were caught in the river; some rare species were also identified. Community-based management approach and management of fish sanctuaries, as well as public awareness of fishery resources, could be effective in minimizing anthropogenic impacts on fishers’ livelihood.