Coastal Fisheries Management Research Articles

Leveraging deep learning and computer vision technologies to enhance management of coastal fisheries in the Pacific region

This paper presents the design and development of a coastal fisheries monitoring system that harnesses artificial intelligence technologies. Application of the system across the Pacific region promises to revolutionize coastal fisheries management. The program is built on a centralized, cloud-based monitoring system to automate data extraction and analysis processes. The system leverages YoloV4, OpenCV, and ResNet101 to extract information from images of fish and invertebrates collected as part of in-country monitoring programs overseen by national fisheries authorities. As of December 2023, the system has facilitated automated identification of over six hundred nearshore finfish species, and automated length and weight measurements of more than 80,000 specimens across the Pacific. The system integrates other key fisheries monitoring data such as catch rates, fishing locations and habitats, volumes, pricing, and market characteristics. The collection of these metrics supports much needed rapid fishery assessments. The system’s co-development with national fisheries authorities and the geographic extent of its application enables capacity development and broader local inclusion of fishing communities in fisheries management. In doing so, the system empowers fishers to work with fisheries authorities to enable data-informed decision-making for more effective adaptive fisheries management. The system overcomes historically entrenched technical and financial barriers in fisheries management in many Pacific island communities.

Practice of Territorial Use Rights in Fisheries in Coastal Fishery Management in China: A Case Study of the Island Reefs Fishery Lease Policy from Shengsi County in Zhejiang Province

Coastal fisheries are vital for food supply, employment, and social stability. However, overfishing is a common problem, often attributed to open access. Territorial Use Rights in Fisheries (TURFs) have gained popularity as a tool to improve the sustainability of coastal fisheries, but research on TURFs in China is limited. This paper examines the island reef fishery lease policy implemented in Shengsi County, Zhejiang Province, within the Ma’an Islands National Marine Special Reserve. The policy leases the use of island reefs to a collective, aiming to address overfishing and resource degradation by establishing fishing area boundaries and limiting the number of users and usage time. Technically, it is an application of TURFs, and it represents a shift from traditional fishing licenses to collective compliance. This experience has disrupted the existing top–down fishery governance structure and signifies a transition to a rights-based fishery management system in China. Through a comprehensive investigation and analysis of the policy’s implementation, this research identifies the factors contributing to its flaws. These include the inadequate provision of national and local government policies, insufficient support for policy implementation from fishery management authorities, and the limited involvement of fishermen’s organizations. To enhance coastal fishery management, we propose that the Chinese government should build upon existing foundations by clarifying fishing rights through central and local laws and policies. Additionally, there is a need to strengthen data monitoring of coastal fisheries, conduct multidisciplinary research to improve the allocation mechanism of fishing rights, adopt diverse fishery management approaches to enhance supervision capabilities, establish a collaborative governance mechanism, and foster coordination and cooperation between grassroots fishermen’s organizations and government departments.

Trophic effects of jellyfish blooms on fish populations in ecosystems of the coastal waters of China

Jellyfish play an important role in the material cycling and energy flow of food webs, and massive aggregations may have deleterious consequences for local fisheries; yet a theoretical framework of the trophic effects of jellyfish blooms on coastal fisheries is unclear. To address this knowledge gap, we assessed the trophic interactions between cooccurring bloom jellyfish and dominant fish groups (omnivorous fish and piscivorous fish) in the coastal waters of China (CWC) via stable isotope analysis; we subsequently discussed how jellyfish blooms may affect energy flow through coastal ecosystems. Our results indicate a considerable degree of trophic overlap (mean ratio > 65 %) between jellyfish and small omnivorous fish (< 10 cm), highlighting a similarity in feeding habits, while the overlap ratio decreased to <55 % of the large omnivorous fish group (> 10 cm). Relatively higher trophic levels and smaller overlaps of large omnivorous fish were found in the ecosystem with high jellyfish biomass, which suggested that they may reinforce the ontogenetic trophic shift pattern to alleviate the potential for resource competition with jellyfish under conditions of jellyfish explosion. The smallest trophic overlap (< 20 %) highlighted the strong trophic differentiation between jellyfish and piscivorous fish. Additionally, our study suggested that a massive aggregation of jellyfish can negatively influence zooplankton but may not transfer energy further up efficiently, implying a weak trophic coupling between jellyfish and upper-trophic levels in CWC ecosystems. Thus, we speculate that jellyfish play an important role in shaping pathways involved in the energy transfer of food webs and that large blooms may negatively affect fisheries through bottom-up control affecting prey availability. In general, these results hold strong potential to further improve the understanding of the trophic interactions between jellyfish and fish populations. Furthermore, this study provides valuable data for predicting the consequences of jellyfish blooms on ecosystems, and is crucial for ecosystem-based management of coastal fisheries.

A dynamic energy budget model for black rockfish Sebastes schlegelii: Parameterization and application in marine ranching areas, Yellow Sea, China

Marine ranching has become a powerful tool for coastal habitat restoration, ecosystem conservation and stock enhancement. With increasing development of marine ranching in recent years, it has attracted wide attentions for fishery management and sustainability. The stock of black rockfish Sebastes schlegelii has undergone a serious decline due to overfishing in the past few decades, but has considerably recovered recently in marine ranching areas along the coasts of the Northwest Pacific. Appropriate management of the species is essential for marine ranching development. In this study, a dynamic energy budget (DEB) model of S. schlegelii was developed and applied in the Xixiakou, Changdao and Qiansandao marine ranching areas, Yellow Sea, China. The effects of food availability and water temperature on its growth and reproduction were quantified. The model was parameterised following the AmP procedure, which resulted in mean relative error of 0.123 and symmetric mean square errors of 0.134. The application of the model has showed that the model could reproduce the growth trajectories of both length and weight at each of the three marine ranching areas without site-specific calibration. The growth rates of S. schlegelii showed that Qiansandao > Changdao > Xixiakou in both length and weight. Temperature and food availability are the main contribution to the variations of growth amongst sites. In Qiansandao, the fast growth and maturation of the species correspond to relative high water temperature and sufficient food availability. Food availability limited growth and reproduction of S. schlegelii in Xixiakou, which indicated that the stock density in the areas might be close to the carrying capacity. The earlier maturation was a result of higher temperature and more food supply in Qiansandao than in Changdao and Xixiakou. Fishing and recapture in marine ranching areas should be adjusted to flexibly avoid spawning periods. The presented model is applicable to other marine ranching areas and coastal habitats. It provides an important component of ecosystem management approaches to estimate the ecological carrying capacities. This study provides information about the stock enhancement potential of coastal environments and a powerful tool for sustainable coastal fisheries management.

Sustainability Perspective of Minjiang Estuary Coastal Fisheries Management—Estimation of Fish Richness

Species richness is the most basic concept of diversity and is crucial to biodiversity conservation and sustainable fisheries. To understand the fish species richness of the Minjiang Estuary and its adjacent waters, eight documents and surveyed data were collected and compared from 1990–2021. To obtain suitable analysis data, the content of the data was compared and evaluated. Explore the suitability of data based on several criteria. Among them, the bottom trawling survey carried out in 2006–2007, and non-parametric estimation methods such as Chao 2, Jackknife 1, Jackknife 2 and Bootstrap were used to estimate the fish species richness. The results of this case show that a total of 153 species of fish were caught in the trawling survey in the fourth quarter, belonging to 14 orders, 57 families and 101 genera. The 2006–2007 cruise is more complete for studying species richness. The Estimable expectations of fish species richness are: 250 (Chao 2), 204 (Jackknief 1), 241 (Jackknief 2) and 174 (Bootstrap). The number of fish species was significantly higher in summer and autumn than winter and spring. To manage fishery resources and sustainability in the sea area of Fujian Province, biological information and stock assessment are required. This meaningful information, especially for endemic and economically important species such as can set a baseline. Once species change exceeds the baseline range, it provides decision-making basis for marine biodiversity conservation and fisheries management.

Larval Spatiotemporal Distribution of Six Fish Species: Implications for Sustainable Fisheries Management in the East China Sea

The larval distributions of the small-sized fishes Omobranchus elegans, Erisphex pottii, Benthosema pterotum, Acropoma japonicum, Upeneus bensasi, and Apogonichthys lineatus in the East China Sea ecosystem are important due to their ecological and economic benefits. To date, however, there have been few studies describing their population distributions and dynamics. In the current study, ichthyoplankton surveys were carried out from April to July 2018 to analyze variations in the larval abundance, distribution, and development stages of these species. In addition, the spatiotemporal larval distribution was investigated in terms of measured environmental variables. It was found that larvae were mainly distributed at depths of 5.00–66.00 m, in areas with sea surface temperature of 4.40–29.60 °C, sea surface salinity of 16.54–34.60 psu, pH of 7.00–9.00, and dissolved oxygen concentration of 2.54–8.70 mg/L. Benthosema pterotum and A. lineatus migrated from 30.00–31.00° N 123.17–123.50° E in June to 30.00–32.50° N 122.22–123.50° E in July. The results of this study can help to preserve spawning and nursery grounds and contribute to sustainable coastal fisheries management.

Helping or hindering? The role of the public right to fish in the management of coastal fisheries

Managing coastal fisheries requires transitioning to sustainable exploitation of the marine environment. Set against this background, the public right to fish is often ignored or simply presented as a right to overfish or a hangover from more plentiful times, thus incompatible with sustainable fishing. However, the role of the public right to fish is not well understood, despite its extensive application in coastal waters around several common law countries. Through a case study focusing on coastal fishing within the Devon and Severn Inshore Fisheries and Conservation Authority district, the experiences and views of people involved in fishing were examined in order to build a picture of the role of the public right in the management of English coastal fisheries. Analysis reveals a right that is valued by society and that is viewed by many participants to be the foundation of management of the public fishery by Devon and Severn IFCA. Participants clearly recognized a wide public interest in the fishery and a need to understand the right as bringing with it attendant responsibilities on behalf of both fishers and the wider public. Embracing the public right to fish and the interest of the wider public in fishing is suggested as a route to more sustainable coastal fisheries. By focusing on this public interest, it is possible to address the challenge identified within the case study of a lack of agreement as to who fisheries management is for and how fisheries should be managed to achieve environmental and socioeconomic sustainability.

Is Diversity the Missing Link in Coastal Fisheries Management?

Fisheries management has historically focused on the population elasticity of target fish based primarily on demographic modeling, with the key assumptions of stability in environmental conditions and static trophic relationships. The predictive capacity of this fisheries framework is poor, especially in closed systems where the benthic diversity and boundary effects are important and the stock levels are low. Here, we present a probabilistic model that couples key fish populations with a complex suite of trophic, environmental, and geomorphological factors. Using 41 years of observations we model the changes in eastern Baltic cod (Gadus morhua), herring (Clupea harengus), and Baltic sprat (Sprattus sprattus balticus) for the Baltic Sea within a Bayesian network. The model predictions are spatially explicit and show the changes of the central Baltic Sea from cod- to sprat-dominated ecology over the 41 years. This also highlights how the years 2004 to 2014 deviate in terms of the typical cod–environment relationship, with environmental factors such as salinity being less influential on cod population abundance than in previous periods. The role of macrozoobenthos abundance, biotopic rugosity, and flatfish biomass showed an increased influence in predicting cod biomass in the last decade of the study. Fisheries management that is able to accommodate shifting ecological and environmental conditions relevant to biotopic information will be more effective and realistic. Non-stationary modelling for all of the homogeneous biotope regions, while acknowledging that each has a specific ecology relevant to understanding the fish population dynamics, is essential for fisheries science and sustainable management of fish stocks.

Spawning potential surveys in Fiji: A new song of change for small‐scale fisheries in the Pacific

AbstractCatastrophic overfishing of small‐scale coastal fisheries through the Pacific poses a major threat to regional food security and biodiversity. Globally, approaches to fisheries assessment and management that were developed for industrial fisheries, are failing small‐scale data‐poor fisheries. The Pacific Community has called for a complete rethink of fisheries methodologies for the region; a “new song” of change for small‐scale coastal fisheries. This article describes the application in Fiji of a new approach to facilitating coastal fisheries management reform. Spawning Potential Surveys (SPS) is a pragmatic multi‐disciplinary blend of sciences, that combines a new form of length‐based assessment and communication strategies informed by theories of behavior change, nudge and diffusion, that is initiated with programs of citizen science to inform policy development and catalyze broader societal change. Our project successfully coordinated Fiji‐based NGOs to work with the Ministry of Fisheries, communities, provincial government and supply chains, to collect the data needed to assess ~90% of the Fijian reef fish catch, conduct the analyses needed to develop new management policies, and build a broad consensus in society to support the ongoing reform process that has now been initiated by the Ministry. This project demonstrates the feasibility and effectiveness of the SPS methodology for informing and motivating coastal fisheries reform in the Pacific, as well as the necessity of a long term and multi‐disciplinary approach to achieve the societal change needed.

Fishery Stock Assessments in the Min River Estuary and Its Adjacent Waters in Southern China Using the Length-Based Bayesian Estimation (LBB) Method

The Min River Estuary and its adjacent waters, connecting to the East China Sea, is one of the most important fishing grounds in Fujian Province, southern China; however, the stock assessments have not yet been conducted. In the present study, the length-based Bayesian estimation (LBB) method was applied for the first time to assess 20 fishery single-species stocks in the region. Catches of 8 fishes from the Class Actinopterygii and 12 shrimps from the Class Malacostraca were obtained from two commercial demersal trawlers, operated in the Min River Estuary and its adjacent waters in February, May, August and November of 2017 and 2018, covering all four seasons. The results showed that 8 species were overexploited with the estimated B/BMSY (i.e., the current exploited biomass relative to the biomass producing the maximum sustainable yield) 1.2). The results revealed that some commercially important food fishes are overexploited in the region, and small-sized, non-commercial food species can also be overexploited. There is an urgent need for local and national fisheries authorities to focus on coastal fishery management.

Governance and Power Dynamics in a Small-Scale Hilsa Shad (Tenualosa ilisha) Fishery: A Case Study from Bangladesh

This paper considers the hilsa shad (Tenualosa ilisha) fishery of southern Bangladesh as a case study regarding governance and power dynamics at play in a small-scale fishery, and the relevance of these for the sustainable management of coastal fisheries. Qualitative methods, involving in-depth individual interviews (n = 128) and focus group discussions (n = 8) with key stakeholders in the hilsa fishery, were used to capture multiple perspectives on governance from those in different positions in the relative power structures studied, while facilitating insightful discussions and reflections. The analysis here is based on a power cube framework along three power dimensions (levels, spaces, and forms) in Bangladesh’s hilsa fishery. The study displays an imbalance in the present hilsa governance structure, with some stakeholders exercising more power than others, sidelining small-scale fishers, and encouraging increasing illegal fishing levels that ultimately harm both the fisheries and those dependent on them. To overcome this, we propose a co-management system that can play a vital role in equalizing power asymmetry among hilsa fishery stakeholders and ensure effective hilsa fishery governance. Our results suggest that recognizing analyzed power dynamics has substantial implications for the planning and implementation of such co-management and the long-term sustainability of the hilsa fishery.

Rapid winter warming could disrupt coastal marine fish community structure

Marine ecosystems are under increasing threat from warming waters. Winter warming is occurring at a faster rate than summer warming for ecosystems around the world, but most studies focus on the summer. Here, we show that winter warming could affect coastal fish community compositions in the Mediterranean Sea using a model that captures how biotic associations change with sea surface temperature to influence species’ distributions for 215 fish species. Species’ associations control how communities are formed, but the effect of winter warming on associations will be on average four times greater than that of summer warming. Projections using future climate scenarios show that 60% of coastal Mediterranean grid cells are expected to lose fish species by 2040. Heavily fished areas in the west will experience diversity losses that exacerbate regime shifts linked to overexploitation. Incorporating seasonal differences will therefore be critical for developing effective coastal fishery and marine ecosystem management. The rate of warming in many marine ecosystems is faster in winter than in summer. Winter warming will impact fish species’ associations in the Mediterranean more than summer warming, and this has implications for how communities form and for future biodiversity, particularly in heavily fished areas.

Mud crab fishery in climate vulnerable coastal Bangladesh: an analysis towards sustainable development

Developing countries are far more vulnerable to climate change impacts than industrialised countries. Most of the world’s poor live in South Asia where they have limited livelihood options that have become even narrower in recent years, indicating a need for alternative income-generating options. Mud crabs (Scylla spp.) are considered to have promising prospects in different parts of the world including Bangladesh, a well-known region for its vulnerability to climate change. At present, this fishery has become a growing venture in coastal Bangladesh, primarily due to the potential of the export market and availability of seed locally. This study included a calculation of the Human Development Index linked to mud crab fishery (HDIMCF) and a strengths, weaknesses, opportunities and threats (SWOT) analysis to clarify the present status of and strategic directions for the mud crab fishery, for the first time. Results revealed an intermediate level of development of mud crab aquaculture, indicating potential alternative livelihood opportunities for vulnerable coastal communities. The SWOT analysis revealed that positive factors, both internal (strengths) and external (opportunities), predominate over negative factors (weaknesses and threats) and that the fishery can be an alternative livelihood option for vulnerable coastal communities. Despite noticeable diversification of the mud crab fishery, dependence on wild seedstock and possible over-exploitation in the wild appear to constrain sustainable development of the fishery. This study’s findings suggest undertaking immediate wild crab stock assessment for determining current status of wild populations. Moreover, modification of the Government of Bangladesh’s existing mud crab policy is needed to better meet growing demand and sustainability of the fishery. Recommendations of this study may be of help in guiding responsible integrated coastal fisheries management and policy.

Long-Term Fishing Catch and Effort Trends in the Republic of the Marshall Islands, With Emphasis on the Small-Scale Sectors

Small-scale fishing has been an important element of the livelihood and food security in Pacific Island countries throughout history; however, such catches have been under-reported in the official fisheries data. Here, we reconstruct the total domestic catches and fishing effort of the Republic of the Marshall Islands (RMI) by fishing sectors for 1950-2017. Reconstructed total catches were estimated to be 27% higher than the data officially reported by the Food and Agriculture Organization of the United Nations on behalf of the RMI. Catches of the truly domestic, but export-oriented, industrial tuna sector accounted for 84% of the total catch, dominating catches since the early 2000s. The subsistence component contributed 74% of total small-scale catches, of which 92% was deemed unreported. The remaining 26% of small-scale catches were artisanal, i.e., small-scale commercial, in nature, of which 45% was deemed unreported. Trends suggested steady growth in small-scale catches from 1,100 t·year-1 in the early 1950s to a relatively stable level of 4,500 t·year-1 since the 1990s. However, over the 2009-2017 period, there was a gradual reduction of 2% per year in subsistence fishing, which was paralleled by a concomitant increase in artisanal catches of 3% per year. This gradual shift from predominantly non-commercial to commercial small-scale fisheries may be related to efforts to commercialize small-scale fisheries in the past decades. Small-scale fishing effort increased approximately 13-fold from the early 1980s to the late 2000s, stabilizing at around 401,000 kWdays since then, while catch-per-unit-of-effort displayed an inverse pattern, declining 8-fold between the 1980s and 1990s, and stabilizing around 15 kg∙kWdays-1 in recent decades. These findings may assist sustainable coastal fisheries management in the RMI, which is particularly important given the increasing impacts of climate change on local stocks.

Self-Assessment Scheme to Improve the Management of Coastal Fisheries:

Self-Assessment Scheme to Improve the Management of Coastal Fisheries:

Noncompliance a Major Threat in Fisheries Management – Experience from the Artisanal Coastal Fisheries of Bangladesh

Non-compliance with regulation is a major problem that undermines the effectiveness of the coastal fisheries management in Bangladesh. The result of non-compliance with regulation is over fishing, resource depletion, habitat degradation and resource use conflicts. From a management perspective, it is important to examine the level and causes of non-compliance and explore policies for encouraging or securing compliance. An attempt has been made in this study to investigate these issues in the case of the marine fisheries of Bangladesh. The specific area of interest is the mesh size regulation. Result showed an absolute violation of the mesh size regulation. The study found that the opportunity of getting higher catches and economic returns, weak enforcement, influence of the social environment, ignorance about the law and limited livelihood opportunities are the main causes behind the noncompliance of the fishers with respect to mesh size regulation.

Juvenile fish habitat across the inner Danish waters: Habitat association models and habitat growth models for European plaice, flounder and common sole informed by a targeted survey

The management of coastal fisheries and coastal marine areas both require information on the use and importance of coastal marine habitats for marine species. This information is certainly pertinent for exploited species dependent on these coastal habitats for specific life-history stages. This study uses two different measures of habitat suitability to build Habitat Association Models (HAMs) and Habitat Growth Models (HGMs) for juveniles of three commercially and recreationally important fish species (Pleuronectes platessa, Platichthys flesus, and Solea solea) of the Inner Danish Waters (IDW). A large scale, one-off juvenile survey was used to collect juvenile fish and directly observed environmental data. The survey informed Generalised Linear (Mixed) Models (GLMs and GLMMs), which were fit and run through repeated random sub-sampling cross-validation before being utilised to build interpolative maps of both prediction and model uncertainty. The limitations of this approach are discussed in reference to the future works required to complement and improve such static habitat suitability maps. These results can be used to inform marine spatial planning and future work into the role of juvenile habitats in supporting fishery species.

Spatio-temporal variations of fish assemblages in seagrass ecosystem of Karang Congkak Island, Kepulauan Seribu

Seagrass are globally known as an essential habitat for marine fishes. The study of fish assemblages in seagrass ecosystem is needed as the first base to select the most suitable coastal fisheries management. The study aims to reveal the composition of fish assemblages both seasonally and spatially in Karang Congkak Island, Kepulauan Seribu. Sampling was performed six times in NW monsoon (March), first transitional monsoon (April-May) and SE monsoon (Juni, August, September) 2018. Fish were sampled at four sites at seagrass ecosystem of Karang Congkak Island, namely eastern, southern, western, and northern by using beach seine net. The differences of juvenile fish assemblages were analyzed using One-Way ANOSIM. A total of 6,326 fish were collected belonging to 78 species, 31 families and 10 orders in which Labridae was the most diverse family. The result indicates strong spatial and temporal variation in fish composition. Fish compositions were dominated by juvenile both spatially and temporally. The most common species that inhabits seagrass beds of the Karang Congkak Island as temporary resident such as Gerres oyena and Siganus canaliculatus, and regular visitor namely Halichoeres argus. Cannonical correspondence analysis indicated strong correlation between several fish species and environmental variables.

Fishers’ Local Ecological Knowledge (LEK) on Connectivity and Seascape Management

In developing countries where data and resources are lacking, the practical relevance of Local Ecological Knowledge (LEK) to expand our understanding of the environment has been highlighted. The potential roles of the LEK varies from direct applications such as gathering environmental information to a more participative involvement of the community in the management of resources they depend on. Fishers’ LEK could therefore be useful in order to obtain information to advance management of coastal fisheries. Many targeted fish species migrate between habitats to feed, spawn or recruit, connecting important habitats within the seascape. LEK could help provide answers to questions related to this connectivity and the identification of fish habitat use and migrations for species and areas where such knowledge is scarce. Here we assess fishers’ LEK on connectivity between multiple habitats within a tropical seascape, investigate the differences in LEK among fisher groups and the coherence between LEK and conventional scientific knowledge (CSK). The study was conducted in Zanzibar, Tanzania, a tropical developing country, in 2017. One hundred and thirty-five semi-structured interviews were conducted in six different locations focusing on fish migrations, and matching photos of fish and habitats. Differences between fisher groups were found, where fishers travelling further, exposed to multiple habitats, and fish with multiple gears had a greater knowledge on connectivity patterns within the seascape than those that fish locally, in single habitats and with just one type of gear. A high degree of overlap in LEK and CSK was found, highlighting the potential benefits of collaboration between scientists and fishers and the use of LEK as complementary information in the management of small-scale fisheries.

The Spanish Mediterranean Fishing Guilds (Cofradías): An Example of Collaborative Management with a Key Role in Sustainable Fisheries

The management of Spanish coastal fisheries is based on a mixed model where the centralised action of the government is combined with the self‐organisation of fishers in cofradías (guilds). These institutions have economic and political functions, intermediating between the State and the fishing sector and mediating in the conflicts that may occur. They also have welfare and mutualist tasks. This original and traditional co‐management model is part of the social capital of traditional Spanish fishing. The aim of this article is to explore the possibilities of these Spanish fishers’ organisations in order to improve the legitimacy of the fishery system and the sustainability of fisheries. Our hypothesis is that updating and adapting some aspects of the cofradías model could produce efficient forms of collaborative management and lead to improvements in the sustainability of fisheries. To validate this hypothesis the study analysed 69 face‐to‐face interviews in 21 Spanish–Mediterranean guilds. The analysis focused on three core aspects: the control of fishing resources; the integration of fishing knowledge in the management system; and, finally, the guilds contribution to the legitimacy of the system in the eyes of the fishers.