Financial comparisons of fishing gear used in Kenya's coral reef lagoons

The cost of fishing and the income earned by fishers using small and large traps, gill nets, beach seines, hand lines, and spearguns were assessed in the multigear fishery of southern Kenya to establish a financial rationale for fishing gear use. Direct observations and key-informant interviews with fish leaders and boat captains were used to gather data on fish catch, cost of fishing gear, boats, and the price of fish. Among the fishing gear used, spearguns had the lowest monthly cost (USD 1 mo(-1)) while big traps had the highest (USD 13 mo(-1)). Income was highest among capital cost beach seine fishers (USD 183 mo(-1)) and lowest among noncapital cost beach seine fishers (USD 20 mo(-1)). There was a direct positive correlation between income earned and profitability of gear. Correlation of the financial measure for each gear to four categories of damage to fish and habitats showed that low cost fishing gear were associated with the highest environmental damage indicating a trade-off between cost of gear and environmental health.     

Small-scale fisheries,population dynamics,and resource use in Africa: the case of Moree,Ghana

We consider population dynamics and sustainable use and development of fishery resources in Moree, a small-scale fishing and coastal community of 20,000 people in the Central Region of Ghana near Cape Coast. Moree suggests that relationships between population dynamics and fishery resources are more complex than the concept of Malthusian overfishing implies. Reasons include changing biophysical characteristics of the upwelling system along the coast of West Africa; qualitative as well as quantitative changes in fishing activity throughout the year; the market nature of fishing activity and nonlocal demands for fish; regular fishery migration; and institutions regulating fishery resource access at home and at migration destinations. Population and resource relationships in Moree may be the effects of fishery resource and economic changes on migration rather than population pressure on fishery resources. Fisheries management policies must take into account processes that lie beyond the influence of local fishermen.     

Lessons for resource conservation from two contrasting small-scale fisheries

Small-scale fisheries present challenges to management due to fishers’ dependency on resources and the adaptability of management systems. We compared social-ecological processes in the sea cucumber fisheries of Zanzibar and Mayotte, Western Indian Ocean, to better understand the reasons for resource conservation or collapse. Commercial value of wild stocks was at least 30 times higher in Mayotte than in Zanzibar owing to lower fishing pressure. Zanzibar fishers were financially reliant on the fishery and increased fishing effort as stocks declined. This behavioral response occurred without adaptive management and reinforced an unsustainable fishery. In contrast, resource managers in Mayotte adapted to changing fishing effort and stock abundance by implementing a precautionary fishery closure before crossing critical thresholds. Fishery closure may be a necessary measure in small-scale fisheries to preserve vulnerable resources until reliable management systems are devised. Our comparison highlighted four poignant lessons for managing small-scale fisheries: (1) diagnose the fishery regularly, (2) enable an adaptive management system, (3) constrain exploitation within ecological limits, and (4) share management responsibility.     

Patterns of catch and trophic signatures illustrate diverse management requirements of coastal fisheries in Solomon Islands

Coastal fisheries are a critical component of Pacific island food systems; they power village economies and provide nutritious aquatic foods. Many coastal women and men actively fishing in this region rely on multi-species fisheries, which given their extraordinary diversity are notoriously difficult to both characterize, and to manage. Understanding patterns of fishing, diversity of target species and drivers of these patterns can help define requirements for sustainable management and enhanced livelihoods. Here we use a 12-month data set of 8535 fishing trips undertaken by fishers across Malaita province, Solomon Islands, to create fisheries signatures for 13 communities based on the combination of two metrics; catch per unit effort (CPUE) and catch trophic levels. These signatures are in turn used as a framework for guiding suitable management recommendations in the context of community-based resource management. While a key proximate driver of these patterns was fishing gear (e.g. angling, nets or spearguns), market surveys and qualitative environmental information suggest that community fishing characteristics are coupled to local environmental features more than the market value of specific species they target. Our results demonstrate that even within a single island not all small-scale fisheries are equal, and effective management solutions ultimately depend on catering to the specific environmental characteristics around individual communities.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01690-z.     

Levels of dioxins in fish and fishery products on the German market

In 1995-1998 the contents of polychlorinated dibenzodioxins and dibenzofurans of 184 pooled fish samples were analysed. Sampling focused on fish and fishery products with a market share of more than 1% and covered all fishing grounds important for the supply of the German market. Investigation included 15 different fish species, shrimp, mussel and squid samples and various fishery products, typically on the German market. Generally lean fish species like cod, saithe or Alaska pollock were less contaminated on fresh weight basis than fat fish species like herring, Greenland halibut and sardine. In herring the dioxin content is related to the fishing ground. Low concentrations were found in North Sea herring, high concentrations measured in samples from the Baltic Sea. Dioxin contents in fishery products did not differ significantly from the raw fish samples. Results allow an estimation of the daily intake of dioxins and furans via fish consumption in Germany. Based on a daily fish consumption of 20 g the average intake of dioxins via fish is 6.2 pg WHO-PCDD/F-TEQs per person and day.     

The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

Malaria is a serious global health issue, with around 200 million cases per year. As such, great effort has been put into the mass distribution of bed nets as a means of prophylaxis within Africa. Distributed mosquito nets are intended to be used for malaria protection, yet increasing evidence suggests that fishing is a primary use for these nets, providing fresh concerns for already stressed coastal ecosystems. While research documents the scale of mosquito net fisheries globally, no quantitative analysis of their landings exists. The effects of these fisheries on the wider ecosystem assemblages have not previously been examined. In this study, we present the first detailed analysis of the sustainability of these fisheries by examining the diversity, age class, trophic structure and magnitude of biomass removal. Dragnet landings, one of two gear types in which mosquito nets can be utilised, were recorded across ten sites in northern Mozambique where the use of Mosquito nets for fishing is common. Our results indicate a substantial removal of juveniles from coastal seagrass meadows, many of which are commercially important in the region or play important ecological roles. We conclude that the use of mosquito nets for fishing may contribute to food insecurity, greater poverty and the loss of ecosystem functioning.

     

Climate change,fisheries management and fishing aptitude affecting spatial and temporal distributions of the Barents Sea cod fishery

Climate change is expected to influence spatial and temporal distributions of fish stocks. The aim of this paper is to compare climate change impact on a fishery with other factors impacting the performance of fishing fleets. The fishery in question is the Northeast Arctic cod fishery, a well-documented fishery where data on spatial and temporal distributions are available. A cellular automata model is developed for the purpose of mimicking possible distributional patterns and different management alternatives are studied under varying assumptions on the fleets’ fishing aptitude. Fisheries management and fishing aptitude, also including technological development and local knowledge, turn out to have the greatest impact on the spatial distribution of the fishing effort, when comparing the IPCC’s SRES A1B scenario with repeated sequences of the current environmental situation over a period of 45 years. In both cases, the highest profits in the simulation period of 45 years are obtained at low exploitation levels and moderate fishing aptitude.     

Large-scale environmental degradation results in inequitable impacts to already impoverished communities: A case study from the floating villages of Cambodia

Cambodian subsistence communities within the Tonle Sap Great Lake area rely on resource extraction from the lake to meet livelihood needs. These fishing communities—many of which consist of dwellings floating on the lake—face potentially profound livelihood challenges because of climate change and changing hydrology due to dam construction for hydroelectricity within the Mekong Basin. We conducted interviews across five village communities, with local subsistence fisher people in the Tonle Sap in 2015, and used thematic analysis methods to reveal a fishery system that is undergoing rapid ecological decline, with local fishing communities increasingly experiencing reductions in available fish stocks. As a result, over 100 000 people living in these communities are experiencing a direct loss of well-being and livelihood. We discuss these losses and consider their implications for the future viability of Cambodian floating village communities.     

Effects of the 1998 coral morality event on Kenyan coral reefs and fisheries

Data were collected in southern Kenya on coral reef ecosystems and fisheries to assess the influence of the 1998 coral bleaching and mortality event. We compared benthic cover, sea urchin and fish abundance in unfished marine parks and fished reefs and the reef-associated fisheries 3 years before and after 1998. Hard and soft coral decreased while coralline algae increased in both management areas. Turf increased in marine parks and sponge and fleshy algae increased in the fished reefs. Sea urchin grazer biomass was unchanged over this period and the fish community changed less than benthic cover. In general, butterflyfish, damselfish and wrasses were negatively influenced while surgeonfish and a few uncommon families were positively influenced by the substratum change. There was a 17% increase in fishing effort as measured by fishermen per day at each landing site and the total demersal catch declined by 8% and the catch per man declined by 21% after 1998. The decline in the total catch and CPUE combined with the increase in effort suggest an overexploited fishery and this makes it difficult to distinguish changes caused by coral mortality or fishing effort. The price of fish increased over this period and this caused an 18% increase in the total value of the fishery but no difference in the net income of individual fishermen.     

Satisfaction with fishing and the desire to leave

Predicting who may leave a fishery is an important consideration when designing capacity reduction programs to enhance both ecological and economic sustainability. In this paper, the relationship between satisfaction and the desire to exit a fishery is examined for the Queensland East Coast Trawl fishery. Income from fishing, and changes in income over the last 5 years, were key factors affecting overall satisfaction. Relative income per se was not a significant factor, counter to most satisfaction studies. Continuing a family tradition of fishing and, for one group, pride in being a fisher was found to be significant. Satisfaction with fishing overall and the challenge of fishing were found to be the primary drivers of the desire to stay or leave the fishery. Surprisingly, public perceptions of fishing, trust in management and perceptions of equity in resource allocation did not significantly affect overall satisfaction or the desire to exit the fishery.     

Understanding non-compliance in small-scale fisheries: Shark fishing in Myanmar’s Myeik Archipelago

Achieving fisheries compliance is challenging in contexts where enforcement capacity is limited and the incentives for rule-breaking are strong. This challenge is exemplified in Myanmar, where an active shark fishery exists despite a nationwide ban on targeted shark fishing. We used the Kipling method (5W1H) to gather a complete story of non-compliance in five small-scale fishing communities in the Myeik Archipelago. Among 144 fishers surveyed, 49% were aware of the nationwide ban. Shark fishers (24%) tended to be younger individuals who did not own a boat and perceived shark fishing to be prevalent. Compliant fishers were motivated by a fear of sharks and lack of capacity (equipment, knowledge), whereas food and income were cited as key motivations for non-compliance. The results of our study emphasize that in resource-dependent communities, improving compliance for effective shark conservation may require addressing broader issues of poverty, food security and the lack of alternatives.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01400-1) contains supplementary material, which is available to authorized users.     

Fishing for Prawn Larvae in Bangladesh: An Important Coastal Livelihood Causing Negative Effects on the Environment

Freshwater prawn (Macrobrachium rosenbergii) farming in Bangladesh has, to a large extent, been dependent on the supply of wild larvae. Although there are 81 freshwater prawn hatcheries in the country, a lack of technical knowledge, inadequate skilled manpower, and an insufficient supply of wild broods have limited hatchery production. Many thousands of coastal poor people, including women, are engaged in fishing for wild prawn larvae along the coastline during a few months each year. On average, 40% of the total yearly income for these people comes from prawn larvae fishing activity. However, indiscriminate fishing of wild larvae, with high levels of bycatch of juvenile fish and crustaceans, may impact negatively on production and biodiversity in coastal ecosystems. This concern has provoked the imposition of restrictions on larvae collection. The ban has, however, not been firmly enforced because of the limited availability of hatchery-raised larvae, the lack of an alternative livelihood for people involved in larvae fishing, and weak enforcement power. This article discusses the environmental and social consequences of prawn larvae fishing and concludes that, by increasing awareness among fry fishers, improving fishing techniques (reducing bycatch mortality), and improving the survival of fry in the market chain, a temporal ban may be a prudent measure when considering the potential negative impacts of bycatch. However, it also suggests that more research is needed to find out about the impact of larvae fishing on nontarget organisms and on the populations of targeted species.     

Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic

In this contribution, we propose fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic. Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km² kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970 s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods and fleet. These fish were important predators on urchins and the reduction coincided with the urchin bloom. From this circumstantial evidence, we hypothesize that coastal predatory fish were important in regulating sea urchins, and that a local population dynamics perspective is necessary in management of coastal ecosystems.     

Using Vessel Monitoring System Data to Improve Systematic Conservation Planning of a Multiple-Use Marine Protected Area,the Kosterhavet National Park (Sweden)

When spatial fishing data is fed into systematic conservation planning processes the cost to a fishery could be ensured to be minimal in the zoning of marine protected areas. We used vessel monitoring system (VMS) data to map the distribution of prawn trawling and calculate fishing intensity for 1-ha grid cells, in the Kosterhavet National Park (Sweden). We then used the software Marxan to generate cost-efficient reserve networks that represented every biotope in the Park. We asked what were the potential gains and losses in terms of fishing effort and species conservation of different planning scenarios. Given a conservation target of 10 % representation of each biotope, the fishery need not lose more than 20 % of its fishing grounds to give way to cost-efficient conservation of benthic diversity. No additional reserved area was needed to achieve conservation targets while minimizing fishing costs. We discuss the benefits of using VMS data for conservation planning.     

Assessment of Blue Mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> Fisheries and Waterbird Shellfish-predator Management in the Danish Wadden Sea

We assessed the blue mussel Mytilus edulis fishery management scheme introduced in 1994 in the Danish Wadden Sea that regulate fishing vessels, fishery quota, set-aside for mussel-eating birds and established zones closed to mussel fishery. The results showed (i) a reduction in the blue mussel biomass and mussel bed areas in zones closed to fishery, (ii) decrease in eiders Somateria mollissima numbers and increase or stable numbers for oystercatcher Haematopus ostralegus and herring gull Larus argentatus and (iii) that energy estimations based on ecological food requirements for the mussel-eating birds should be at least three times larger, than the amount set-aside in the mussel management scheme. It is concluded that the mussel management scheme had been unable to stabilize or increase the blue mussel stocks and to secure stable or increasing numbers for all target bird species. Thus, it is recommended to revise the present blue mussel management scheme in the Danish Wadden Sea, to continue and improve mussel stock and bird surveys, and to consider novel studies of the mussel-eating birds’ energetics for improved set-aside estimates and future assessments.     

Bioconcentration of trichlorfon insecticide in pacu (Piaractus mesopotamicus)

Pacu (Piaractus mesopotamicus) is one of the most representative fish species of Brazilian fish culture, produced in most Brazilian States due to its importance for food diet and sport fishery. This research work investigated the bioconcentration of trichlorfon [phosphonic acid, (2,2,2-trichloro-1-hydroxyethyl)-dimethyl ester] insecticide in pacu under fish ponds culture conditions and a first-order kinetic insecticide dissipation in the water. Trichlorfon was applied at a rate of 4.62 x 10(4) mg to each of three nurseries containing 4.2 x 10(5)l of water. The fish ponds were built on the soil and supported 60 young pacus fishes. The concentrations of trichlorfon fitted to an equivalent non-linear kinetic type model, allows estimate the values of trichlorfon concentration in the water and fishes. These estimations together with the bioconcentration factor determined in the fishes, allowed establishing theoretical reference limit values for human consumption of fishes produced under cultivation systems with trichlorfon. This information will contribute to enlarge the database on pesticide use in Brazilian commercial fish farming, especially about the use of trichlorfon as chemotherapy for the control of fish ectoparasites.     

Assessing the Impacts of Establishing MPAs on Fishermen and Fish Merchants: The Case of Lyme Bay,UK

Shortly after the implementation of a marine protected area (MPA) in Lyme Bay in 2008, inside which scallop dredging and bottom trawling is prohibited, a socio-economic impact assessment was initiated. This article presents the initial findings from this study. The aim was to understand the costs and benefits to fishermen and fish merchants of establishing the MPA. These were assessed using a combination of primary and secondary data. The results indicate that the impacts of the closure differ according to the gear type and the fishing location used by the fishermen. Static gear fishermen who fish inside the closed area have seen changes in terms of increased fishing effort, mostly because they have been able to increase the number of crab and whelk pots they deploy. The effects of the closure on static gear fishermen who fish outside the closed area has been reported in terms of increased conflicts with towed gear fishermen who now fish regularly in their traditional grounds. Fishermen using towed gear on the other hand have been impacted through displacement effects as they have been forced to look for other fishing grounds outside the closed area. Most fish merchants and processors initially claimed that they were heavily impacted by the closure but when they were interviewed 1 year after the closure they suggested a more stable picture. Preliminary analyses of landings data indicate that the introduction of the MPA has so far had minimal impacts on the average incomes and financial profits of fishermen and fish merchants. This conclusion, however, reflects a short-term view as the impacts of the closure of Lyme Bay are likely to be felt for a long time to come.     

Migration and fishing in Indonesian coastal villages

The coastal ecosystems in Southeast Asia are under increased pressure from local and global change. This paper examines human migration and the use of marine resources in coastal villages in the Minahasa district of North Sulawesi, Indonesia. Primary data were collected through interviews with village leaders, focus groups, and a sample survey of 600 fishing households. Migration is responsible for at least one quarter of the total growth during the past decade. All groups of fishermen report falling productivity of the nearshore fisheries. Econometric analysis is used to examine the weekly fish catch of the artisanal fishing sector. Migration status and socioeconomic variables seem to have no systematic effect, while fishing effort (labor, boat, and gear), the degree of specialization, and the remoteness of villages are found to be positively related to weekly fish catches.     

Impact of metal pollution,food availability,and excessive fishing on <Emphasis Type="Italic">Rhabdosargus haffara</Emphasis> stock (family: Sparidae) in Timsah lake

The lakes’ fisheries play an important role in Egyptian economy. In 1980s, they provided more than 50 % of harvested fish in Egypt but now their contribution to the Egypt fish production decreased to only 12.5 % in 2012. Lake Timsah, one of the Suez Canal lakes, faced many challenges that lead to serious changes in its water and fish quality, fish production, as well as the catch composition. The present work investigated the impact of pollution, food availability, and excessive fishing mortality on the haffara production in lake Timsah. The distribution of four heavy metals (Pb, Zn, Ni, and Fe) was detected seasonally in water and in muscles, gills, and livers of Rhabdosargus haffara, during 2012 through 2013. Fe and Zn were presented by high values in liver, while Pb and Ni in gills. Generally, the lowest concentrations of all metals were found in muscles. The recorded crustacean organisms (the main food of haffara) decreased from 12 species and 32,079 organisms?m² in 2012 to only 7 species and 7290 organisms?m² in 2013 while the amphipods completely disappeared. This serious change was due to the severe pollution in the lake. A logistic surplus production model was fitted to the catch per unit effort indices, to estimate the maximum sustainable yield and the optimum level of fishing effort. The results revealed that haffara stock at lake Timsah is overfished, and the estimated precautionary target reference points advised the reduction of fishing effort by about 30–50 %.     

Energy,food, and land — The ecological traps of humankind

Humans’ superiority over all other organisms on earth rests on five main foundations: command of fire requiring fuel; controlled production of food and other biotic substances; utilization of metals and other non-living materials for construction and appliances; technically determined, urban-oriented living standard; economically and culturally regulated societal organization. The young discipline of ecology has revealed that the progress of civilization and technology attained, and being further pursued by humankind, and generally taken for granted and permanent, is leading into ecological traps. This metaphor circumscribes ecological situations where finite resources are being exhausted or rendered non-utilizable without a realistic prospect of restitution. Energy, food and land are the principal, closely interrelated traps; but the absolutely decisive resource in question is land whose increasing scarcity is totally underrated. Land is needed for fulfilling growing food demands, for producing renewable energy in the post-fossil and post-nuclear era, for maintaining other ecosystem services, for urban-industrial uses, transport, material extraction, refuse deposition, but also for leisure, recreation, and nature conservation. All these needs compete for land, food and non-food biomass production moreover for good soils that are scarcer than ever. We are preoccupied with fighting climate change and loss of biodiversity; but these are minor problems we could adapt to, albeit painfully, and their solution will fail if we are caught in the interrelated traps of energy, food, and land scarcity. Land and soils, finite and irreproducible resources, are the key issues we have to devote our work to, based on careful ecological information, planning and design for proper uses and purposes. The article concludes with a short reflection on economy and competition as general driving forces, and on the role and reputation of today’s ecology. Updated version of the keynote lecture presented at the EcoSummit 2007 in Beijing, China, May 24. The article is gratefully dedicated to the memory of my late colleague and friend Frank B. Golley.