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1.
Mar Pollut Bull ; 202: 116364, 2024 May.
Article in English | MEDLINE | ID: mdl-38643586

ABSTRACT

Despite a growing literature on fishing grounds footprint, there is no study analyzing fishing footprint regarding spatial effects between neighboring countries. Thus, we explored whether the fishing grounds footprint of 156 countries is spatially correlated. For this purpose, we applied the dynamic spatial Durbin model to examine the direct and indirect effects of GDP per capita, biological capacity, trade openness, population, and urbanization on fishing grounds footprint in the short-term and the long-term during 2001-2021. The results revealed that: (1) there exists a positive and significant spatial dependence in fishing grounds footprint between countries; (2) inverted U-shaped environmental Kuznets curve hypothesis is valid in the short-term and the long-term; (3) fishing grounds footprint is negatively influenced by biocapacity and urbanization in neighboring countries, while population directly increases the fishing footprint. Finally, some suggestions were put forward to reduce fishing grounds footprint and to achieve a sustainable fisheries environment.


Subject(s)
Conservation of Natural Resources , Fisheries , Fisheries/statistics & numerical data , Urbanization , Models, Theoretical
2.
Biometrics ; 80(2)2024 Mar 27.
Article in English | MEDLINE | ID: mdl-38647000

ABSTRACT

Fish growth models are crucial for fisheries stock assessments and are commonly estimated using fish length-at-age data. This data is widely collected using length-stratified age sampling (LSAS), a cost-effective two-phase response-selective sampling method. The data may contain age measurement errors (MEs). We propose a methodology that accounts for both LSAS and age MEs to accurately estimate fish growth. The proposed methods use empirical proportion likelihood methodology for LSAS and the structural errors in variables methodology for age MEs. We provide a measure of uncertainty for parameter estimates and standardized residuals for model validation. To model the age distribution, we employ a continuation ratio-logit model that is consistent with the random nature of the true age distribution. We also apply a discretization approach for age and length distributions, which significantly improves computational efficiency and is consistent with the discrete age and length data typically encountered in practice. Our simulation study shows that neglecting age MEs can lead to significant bias in growth estimation, even with small but non-negligible age MEs. However, our new approach performs well regardless of the magnitude of age MEs and accurately estimates SEs of parameter estimators. Real data analysis demonstrates the effectiveness of the proposed model validation device. Computer codes to implement the methodology are provided.


Subject(s)
Computer Simulation , Fishes , Animals , Fishes/growth & development , Models, Statistical , Fisheries/statistics & numerical data , Biometry/methods , Likelihood Functions , Bias
3.
Rev. biol. trop ; 71(1)dic. 2023.
Article in Spanish | LILACS, SaludCR | ID: biblio-1514957

ABSTRACT

Introduction: Until today, the fishing effort by foreign fleets in the Costa Rican Pacific has not been analyzed. Objective: To determine the spatial distribution of the fishing effort of those fleets, variables that shape that distribution, and if they interact with management figures and highly fragile ecosystems. Methods: Using fishing effort data from 2012 to 2020, obtained from Global Fishing Watch, an Index of Fishing Effort (IEP) was calculated to apply geospatial and multivariate statistics, as well as multiple regression models. A grid with 55 905 cells of 0.10 degrees was used to apply Hot Spot Analysis, and another grid with 24 176 cell-year-month analysis units of 0.25 degrees was used to apply a Linear Regression Model. Results: The data reveals the fishing activity of international fleets associated with four types of fishing gear, and a wide coverage of a high IEP by two fleets throughout the nine years analyzed. The IEP is primarily associated with location and varies by month and year. There is also relative evidence that its influenced by the concentration of oxygen and nitrates. Conclusions: International fleets come into direct conflict with officially defined zones for national fleets and disrespect protected oceanic areas and a declared non-fishing zone to protect marine resources in the Costa Rican Pacific. Their activities in the Dome may affect a national yellowfin tuna fishery.


Introducción: Hasta hoy, no ha sido analizado el esfuerzo pesquero por parte de flotas extranjeras en el Pacífico de Costa Rica. Objetivo: Determinar la distribución espacial del esfuerzo pesquero de esas flotas, variables que moldean esa distribución, y si las mismas interactúan con figuras de manejo y ecosistemas altamente frágiles. Métodos: A partir de datos de esfuerzo pesquero de 2012 a 2020, obtenidos de Global Fishing Watch, fue calculado un Índice de Esfuerzo Pesquero (IEP) sobre el cual fue aplicada estadística geoespacial y multivariada, así como modelos de regresión múltiple. Fue utilizada una cuadrícula con 55 905 celdas de 0.10 grados, para aplicar Análisis de Puntos Calientes, y otra cuadrícula con 24 176 unidades de análisis celdas-año-mes de 0.25 grados, para aplicar un Modelo de Regresión Lineal. Resultados: Los datos revelan la actividad pesquera de las flotas internacionales asociadas a cuatro tipos de artes de pesca, así como una amplia cobertura de alto IEP por parte de dos flotas a lo largo de los nueve años analizados. El IEP se asocia principalmente con la ubicación y varía según el mes y el año. También hay evidencia relativa de que está influenciado por la concentración de oxígeno y nitratos. Conclusiones: Las flotas internacionales entran en conflicto directo con zonas oficialmente delimitadas para las flotas nacionales e irrespetan las áreas oceánicas protegidas y una zona no pesquera declarada para proteger los recursos marinos en el Pacífico costarricense. Sus actividades en el Domo pueden afectar la pesquería de atún aleta amarilla.


Subject(s)
Animals , Marine Conservation Area , Fisheries/statistics & numerical data , Fishing Industry , Costa Rica
4.
Sci Rep ; 13(1): 15290, 2023 09 15.
Article in English | MEDLINE | ID: mdl-37714923

ABSTRACT

Most sophisticated stock assessment models often need a large amount of data to assess fish stocks, yet this data is often lacking for most fisheries worldwide, resulting in the increasing demand for data-limited stock assessment methods. To estimate fish stock status, one class of these data-limited methods uses simply catch time series data and, in other instances, life history information or fishery characteristics. These catch-only methods (COMs) built differently are known to make assumptions about changes in fishing effort and may perform differently under various fishing scenarios. As a case study, this paper used European anchovy (Engraulis encrasicolus) caught in the northwest African waters, though very economically and ecologically important, but still unassessed. Our study investigated the performance of five COMs under different fishing scenarios using as a reference the life-history information of the European anchovy captured in this region of the Atlantic. Hence, the present study developed a simulation approach to evaluate the performance of the five COMs in inferring the stock biomass status (B/BMSY) with consideration of different fishing scenarios under prior information true to anchovy. All five COMs mostly underestimated B/BMSY throughout the simulation period, especially under constant fishing mortality, and in the last five years of the simulation during all fishing scenarios. Overall, these COMs were generally poor classifiers of stock status, however, the state-space COM (SSCOM) generally performed better than the other COMs as it showed possibilities of recovering an overfished stock. When these methods were explored using actual anchovy catch data collected in the northwest African waters, SSCOM yielded results that were deferred from the other COMs. This study being the first to assess this species' stock in this area using a suite of COMs, presents more insights into the species stock status, and what needs to be considered before scientifically putting in place management measures of the stock in the area.


Subject(s)
Fisheries , Oceans and Seas , Animals , Biomass , Computer Simulation , Fisheries/statistics & numerical data , Hunting , Africa, Western , Fishes
5.
Nature ; 621(7978): 324-329, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37648851

ABSTRACT

Marine heatwaves have been linked to negative ecological effects in recent decades1,2. If marine heatwaves regularly induce community reorganization and biomass collapses in fishes, the consequences could be catastrophic for ecosystems, fisheries and human communities3,4. However, the extent to which marine heatwaves have negative impacts on fish biomass or community composition, or even whether their effects can be distinguished from natural and sampling variability, remains unclear. We investigated the effects of 248 sea-bottom heatwaves from 1993 to 2019 on marine fishes by analysing 82,322 hauls (samples) from long-term scientific surveys of continental shelf ecosystems in North America and Europe spanning the subtropics to the Arctic. Here we show that the effects of marine heatwaves on fish biomass were often minimal and could not be distinguished from natural and sampling variability. Furthermore, marine heatwaves were not consistently associated with tropicalization (gain of warm-affiliated species) or deborealization (loss of cold-affiliated species) in these ecosystems. Although steep declines in biomass occasionally occurred after marine heatwaves, these were the exception, not the rule. Against the highly variable backdrop of ocean ecosystems, marine heatwaves have not driven biomass change or community turnover in fish communities that support many of the world's largest and most productive fisheries.


Subject(s)
Biomass , Extreme Heat , Fishes , Animals , Europe , Fisheries/statistics & numerical data , Fishes/classification , Fishes/physiology , Extreme Heat/adverse effects , North America , Biodiversity
6.
J Fish Biol ; 101(1): 213-225, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35575221

ABSTRACT

Manta and devil rays (collectively mobulids) belong to the monogeneric Mobulidae, which currently comprises 10 species, including a putative third manta ray species (Mobula cf. birostris). These large planktivorous rays are distributed throughout the tropical and subtropical oceans of the world. To date, six mobulid species are reported for the western Atlantic Ocean and the Caribbean Sea, three of which had previously been reported in Venezuela (Mobula birostris, Mobula tarapacana and Mobula hypostoma). A preliminary assessment of fishery landings and citizen science data was conducted to further the scientific knowledge of mobulid species in Venezuela. Fisheries landing data were collected at Margarita Island between 2006 and 2007, and again in 2014. Data mining of internet search engines and social media platforms spanning the past two decades was also conducted. A total of 117 individuals of five mobulid species were recorded: Mobula sp. (n = 27), M. birostris (n = 36), M. tarapacana (n = 3), Mobula mobular (n = 26), Mobula thurstoni (n = 14) and M. cf. birostris (n = 11). The latter three species are the first confirmation of these species in Venezuela. The authors found no records of the previously reported M. hypostoma during this study. Although the occurrence of M. hypostoma in Venezuela remains possible because of the broad regional range of this species, its current presence in Venezuela is invalidated given the repeated misidentifications which have occurred in previous publications. The results of this study increase the number of reported mobulid ray species in Venezuela to five (excluding M. hypostoma). The overall data from juvenile manta rays and pregnant M. mobular and M. thurstoni recorded in this study, combined with the occurrence of all but one species of mobulid ray found in the western Atlantic Ocean, suggest Venezuela provides important habitat for this threatened family of rays.


Subject(s)
Animal Distribution , Citizen Science , Skates, Fish , Animals , Fisheries/statistics & numerical data , Humans , Oceans and Seas , Skates, Fish/physiology , Venezuela
7.
Braz. j. biol ; 82: 1-13, 2022. map, tab, graf
Article in English | LILACS, VETINDEX | ID: biblio-1468520

ABSTRACT

Amazonian livelihoods are largely dependent on rivers, with local protein consumption mainly relying on several species of fish. The UJER (Upper Juruá Extractive Reserve - Reserva Extrativista do Alto Juruá) is located in the state of Acre, bordering Peru and several indigenous areas. Here we summarize the data we collected in 1993/1994 on the population living along the banks of the Juruá, Tejo, Bagé, Igarapé São João and Breu rivers on crop cultivation, animal husbandry, and use of game and fish resources. We interviewed 133 individuals (94 on the Juruá and Tejo, 16 on Bagé, 16 on Igarapé São João and 7 on Breu rivers). Our results include a comprehensive description on local livelihoods, including the most important fish species for local subsistence considering gender and seasonality, the main husbandry and game species, and the items cultivated on the local agriculture. Whenever more recent information was available in the literature, we compared changes in livelihoods over time in the same region and also with the recent patterns observed in the Lower and in the Middle Juruá River. We hope to provide useful information to understand temporal changes in local livelihoods, which can help adapt and shape the ecological management in the region.


Comunidades da Amazônia são amplamente dependentes dos rios, com o consumo local de alimentos baseado em várias espécies de peixes. A UJER (Reserva Extrativista do Alto Juruá - Reserva Extrativista do Alto Juruá) está localizada no estado do Acre, na fronteira com o Peru e com várias áreas indígenas. Aqui resumimos os dados que coletamos em 1993/1994 da população que vive às margens dos rios Juruá, Tejo, Bagé, Igarapé São João e Breu sobre cultivo, criação de animais e uso de recursos de caça e peixes. Foram entrevistados 133 indivíduos (94 nos rios Juruá e Tejo, 16 em Bagé, 16 em Igarapé São João e 7 no rio Breu). Nossos resultados incluem uma descrição abrangente dos meios de subsistência locais, incluindo as espécies de peixes mais importantes para a subsistência local, considerando gênero e sazonalidade, bem como as principais espécies de criação, de caça e os itens cultivados na agricultura local., Quando foi possível obter informações da literatura, comparamos as mudanças nos meios de subsistência ao longo do tempo na mesma região e também com os padrões recentes observados no Baixo e no Médio Rio Juruá. Esperamos fornecer informações úteis para o entendimento das mudanças temporais nos meios de subsistência locais, o que pode ser útil ao manejo ecológico da região.


Subject(s)
Food Supply/economics , Biodiversity , Hunting/statistics & numerical data , Fisheries/statistics & numerical data
8.
PLoS One ; 16(12): e0260944, 2021.
Article in English | MEDLINE | ID: mdl-34855922

ABSTRACT

Enrichment of rearing environment with natural elements has been suggested to improve the welfare and post-release survival of cultured fish. We studied the combined effects of shelter structures, periodical water flow and water level changes on pre- and post-release performance of critically endangered landlocked Atlantic salmon (Salmo salar m. sebago). Relative to standard (plain) rearing tanks, provision of enrichment improved fish condition factor and survival during the first year of rearing when most mortality was attributable to parasitic and bacterial infections. The consequent higher density in enriched tanks probably induced greater growth variation and more dorsal fin damages than found in fish of standard tanks. Possibly this was partly due to the applied changes in water level. Experimentally determined smolt migration tendency at age 3 did not differ, on average, between the rearing groups, but enriched-reared fish showed clearly less variation in total movement activity than standard-reared fish. Experimental angling in earthen ponds did not suggest divergent vulnerability between the differentially reared fish at age 3, but decreased condition during the preceding growth season increased vulnerability to fishing. Based on long-term post-stocking tag returns in large-lake fisheries, fish length at release but not rearing method affected the capture rates of fish released at age 2. When released at age 3 the fish grown in enriched environment had a higher risk to be captured with stationary gears and earlier by hook and line gears compared to standard-reared conspecifics. Earlier time of maximal smolt migration activity was associated with an increased risk of being captured. We suggest that environmental enrichment may modulate growth- and behavior-related qualities that indirectly increased the vulnerability to fishing in natural conditions but not in experimental setting. The favorable effects of enrichment on early survival encourages adopting enriched rearing practices in supportive breeding of landlocked salmon.


Subject(s)
Animal Husbandry/methods , Animal Migration , Environment , Fisheries/statistics & numerical data , Reproduction , Salmo salar/physiology , Animals , Seasons
9.
Nat Commun ; 12(1): 6492, 2021 11 11.
Article in English | MEDLINE | ID: mdl-34764244

ABSTRACT

The COVID-19 pandemic caused unprecedented cancellations of fisheries and ecosystem-assessment surveys, resulting in a recession of observations needed for management and conservation globally. This unavoidable reduction of survey data poses challenges for informing biodiversity and ecosystem functioning, developing future stock assessments of harvested species, and providing strategic advice for ecosystem-based management. We present a diversified framework involving integration of monitoring data with empirical models and simulations to inform ecosystem status within the California Current Large Marine Ecosystem. We augment trawl observations collected from a limited fisheries survey with survey effort reduction simulations, use of seabird diets as indicators of fish abundance, and krill species distribution modeling trained on past observations. This diversified approach allows for evaluation of ecosystem status during data-poor situations, especially during the COVID-19 era. The challenges to ecosystem monitoring imposed by the pandemic may be overcome by preparing for unexpected effort reduction, linking disparate ecosystem indicators, and applying new species modeling techniques.


Subject(s)
COVID-19/epidemiology , Conservation of Natural Resources/methods , Fisheries/statistics & numerical data , SARS-CoV-2/pathogenicity , Animals , Biodiversity , COVID-19/transmission , COVID-19/virology , Databases, Factual , Ecosystem , Environmental Monitoring/methods , Fishes , Food Chain , Models, Statistical , SARS-CoV-2/isolation & purification
10.
PLoS One ; 16(9): e0256146, 2021.
Article in English | MEDLINE | ID: mdl-34499686

ABSTRACT

Sharks and rays are at risk of extinction globally. This reflects low resilience to increasing fishing pressure, exacerbated by habitat loss, climate change, increasing value in a trade and inadequate information leading to limited conservation actions. Artisanal fisheries in the Bay of Bengal of Bangladesh contribute to the high levels of global fishing pressure on elasmobranchs. However, it is one of the most data-poor regions of the world, and the diversity, occurrence and conservation needs of elasmobranchs in this region have not been adequately assessed. This study evaluated elasmobranch diversity, species composition, catch and trade within the artisanal fisheries to address this critical knowledge gap. Findings show that elasmobranch diversity in Bangladesh has previously been underestimated. In this study, over 160000 individual elasmobranchs were recorded through landing site monitoring, comprising 88 species (30 sharks and 58 rays) within 20 families and 35 genera. Of these, 54 are globally threatened according to the IUCN Red List of Threatened Species, with ten species listed as Critically Endangered and 22 species listed as Endangered. Almost 98% juvenile catch (69-99% for different species) for large species sand a decline in numbers of large individuals were documented, indicating unsustainable fisheries. Several previously common species were rarely landed, indicating potential population declines. The catch pattern showed seasonality and, in some cases, gear specificity. Overall, Bangladesh was found to be a significant contributor to shark and ray catches and trade in the Bay of Bengal region. Effective monitoring was not observed at the landing sites or processing centres, despite 29 species of elasmobranchs being protected by law, many of which were frequently landed. On this basis, a series of recommendations were provided for improving the conservation status of the elasmobranchs in this region. These include the need for improved taxonomic research, enhanced monitoring of elasmobranch stocks, and the highest protection level for threatened taxa. Alongside political will, enhancing national capacity to manage and rebuild elasmobranch stocks, coordinated regional management measures are essential.


Subject(s)
Conservation of Natural Resources , Ecosystem , Endangered Species/statistics & numerical data , Fisheries/statistics & numerical data , Sharks/physiology , Skates, Fish/physiology , Animals , Bangladesh , Climate Change , Oceans and Seas , Population Dynamics , Sharks/classification , Skates, Fish/classification
11.
Proc Natl Acad Sci U S A ; 118(39)2021 09 28.
Article in English | MEDLINE | ID: mdl-34544851

ABSTRACT

Across publicly owned natural resources, the practice of recovering financial compensation, commonly known as resource rent, from extractive industries influences wealth distribution and general welfare of society. Catch shares are the primary approach adopted to diminish the economically wasteful race to fish by allocating shares of fish quotas-public assets-to selected fishing firms. It is perceived that resource rent is concentrated within catch share fisheries, but there has been no systematic comparison of rent-charging practices with other extractive industries. Here, we estimate the global prevalence of catch share fisheries and compare rent recovery mechanisms (RRM) in the fishing industry with other extractive industries. We show that while catch share fisheries harvest 17.4 million tons (19% of global fisheries landings), with a value of 17.7 billion USD (17% of global fisheries landed value), rent charges occurred in only 5 of 18 countries with shares of fish quotas primarily allocated free of charge. When compared with other extractive industries, fishing is the only industry that consistently lacks RRM. While recovering resource rent for harvesting well-governed fishery resources represents a source of revenue to coastal states, which could be sustained indefinitely, overcharging the industry might impact fish supply. Different RRM occurred in extractive industries, though generally, rent-based charges can help avoid affecting deployment of capital and labor to harvest fish since they depend on the profitability of the operations. Our study could be a starting point for coastal states to consider adapting policies to the enhanced economic condition of the fishing industry under catch shares.


Subject(s)
Conservation of Natural Resources , Ecosystem , Fisheries/statistics & numerical data , Fishes/physiology , Models, Biological , Population Dynamics , Animals , Fisheries/economics , Internationality
12.
Nat Commun ; 12(1): 5384, 2021 09 10.
Article in English | MEDLINE | ID: mdl-34508079

ABSTRACT

Antimicrobial resistance (AMR) is a growing threat to human and animal health. However, in aquatic animals-the fastest growing food animal sector globally-AMR trends are seldom documented, particularly in Asia, which contributes two-thirds of global food fish production. Here, we present a systematic review and meta-analysis of 749 point prevalence surveys reporting antibiotic-resistant bacteria from aquatic food animals in Asia, extracted from 343 articles published in 2000-2019. We find concerning levels of resistance to medically important antimicrobials in foodborne pathogens. In aquaculture, the percentage of antimicrobial compounds per survey with resistance exceeding 50% (P50) plateaued at 33% [95% confidence interval (CI) 28 to 37%] between 2000 and 2018. In fisheries, P50 decreased from 52% [95% CI 39 to 65%] to 22% [95% CI 14 to 30%]. We map AMR at 10-kilometer resolution, finding resistance hotspots along Asia's major river systems and coastal waters of China and India. Regions benefitting most from future surveillance efforts are eastern China and India. Scaling up surveillance to strengthen epidemiological evidence on AMR and inform aquaculture and fisheries interventions is needed to mitigate the impact of AMR globally.


Subject(s)
Anti-Bacterial Agents/adverse effects , Bacteria/drug effects , Drug Resistance, Bacterial/drug effects , Fish Diseases/drug therapy , Fisheries/trends , Animals , Anti-Bacterial Agents/administration & dosage , Asia , Bacteria/isolation & purification , Fish Diseases/epidemiology , Fish Diseases/microbiology , Fish Products/microbiology , Fisheries/statistics & numerical data , Fishes/microbiology , Prevalence
13.
Parasit Vectors ; 14(1): 431, 2021 Aug 28.
Article in English | MEDLINE | ID: mdl-34454593

ABSTRACT

BACKGROUND: In Norway, x-cell parasites associated with disease in farmed salmonids have been known as a rare phenomenon for two decades. These parasites cause systemic infections in farmed rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar), but have so far not been characterized and described. METHODS: The x-cells from several cases of diseased fish were studied using light and electron microscopy, and by phylogenetic analysis based on small subunit ribosomal RNA (SSU rRNA) gene sequences. RESULTS: We describe here the x-cell parasite as a new species in a new genus, Salmoxcellia vastator n. gen., n. sp. Phylogenetic analyses placed Salmoxcellia n. gen. together with Gadixcellia among the xcelliids, a group of perkinsozoan alveolates. The new genus and species were found to have vacuolate plasmodial x-cells filled with lipid droplets, and an electron-dense alveolar pellicle. Electron-dense cytoplasmic inclusions, which are characteristic of the other xcelliid genera Xcellia and Gadixcellia, are lacking in Salmoxcellia n. gen. These x-cell plasmodia divide by plasmotomy and occur as aggregates in the host tissues, particularly in blood-rich tissues such as those of the kidney, red musculature, heart and liver. Host reaction and the refractive lipid droplets in the x-cells result in S. vastator n. gen., n. sp. aggregates appearing as white patches in the tissues. CONCLUSIONS: We describe a new genus and species of xcelliid protist parasites from two very important farmed fish species and provide molecular methods for detection. The new parasite is associated with disease, but more importantly it has a spoiling effect on farmed salmonid fillets, rendering them unsuitable for sale. Consequently, this parasite represents a threat to the aquaculture industry.


Subject(s)
Fish Diseases/parasitology , Fisheries/statistics & numerical data , Oncorhynchus mykiss/parasitology , Parasites/classification , Parasites/genetics , Phylogeny , Salmo salar/parasitology , Animals , Aquaculture , Base Sequence/genetics , Norway , Parasites/isolation & purification
14.
PLoS One ; 16(7): e0253914, 2021.
Article in English | MEDLINE | ID: mdl-34288940

ABSTRACT

The northern shrimp (Pandalus borealis Krøyer) population in the Gulf of Maine collapsed during an extreme heatwave that occurred across the Northwest Atlantic Ocean in 2012. Northern shrimp is a boreal species, and reaches its southern limit in the Gulf of Maine. Here we investigate proximate causes for the population collapse using data from fishery-independent surveys, environmental monitoring, and the commercial fishery. We first examined spatial data to confirm that the decline in population estimates was not due to a major displacement of the population, and then tested hypotheses related to fishing mortality and shifts in predation pressure. Fishing mortality may have contributed but could not explain the magnitude of the decline or the disappearance of pre-exploitable size individuals. Stomach contents analysis and biomass trends revealed no new fish predators of shrimp. However, longfin squid (Doryteuthis pealeii Lesueur) was unique among all species in showing time-series biomass peaks during spring, summer and fall of 2012, and spatial overlap with northern shrimp was unusually high in 2012. Longfin squid is a voracious and opportunistic predator that consumes crustaceans as well as fish. We hypothesize that the warmer temperatures of 2012 not only led to expansion of longfin squid distribution in Gulf of Maine, but had differential effects on migration phenology that further increased spatial overlap with northern shrimp. The weight of our evidence suggests that longfin squid predation was likely a significant factor in the collapse of northern shrimp in the Gulf of Maine.


Subject(s)
Animal Distribution , Climate Change , Decapodiformes/physiology , Fisheries/statistics & numerical data , Pandalidae , Predatory Behavior , Animals , Atlantic Ocean , Hot Temperature , Maine , Models, Theoretical , Population Dynamics , Seasons
15.
Proc Natl Acad Sci U S A ; 118(30)2021 07 27.
Article in English | MEDLINE | ID: mdl-34282013

ABSTRACT

Seismic surveys are used to locate oil and gas reserves below the seabed and can be a major source of noise in marine environments. Their effects on commercial fisheries are a subject of debate, with experimental studies often producing results that are difficult to interpret. We overcame these issues in a large-scale experiment that quantified the impacts of exposure to a commercial seismic source on an assemblage of tropical demersal fishes targeted by commercial fisheries on the North West Shelf of Western Australia. We show that there were no short-term (days) or long-term (months) effects of exposure on the composition, abundance, size structure, behavior, or movement of this fauna. These multiple lines of evidence suggest that seismic surveys have little impact on demersal fishes in this environment.


Subject(s)
Acoustics/instrumentation , Ecosystem , Fisheries/statistics & numerical data , Fishes/growth & development , Population Dynamics , Animals , Environmental Monitoring , Remote Sensing Technology , Western Australia
16.
PLoS One ; 16(6): e0252391, 2021.
Article in English | MEDLINE | ID: mdl-34061860

ABSTRACT

An understanding of the effects of fishing on marine ecosystems relies on information about the conserved state of these environments. Non-conventional approaches such as the use of historical data and local ecological knowledge can provide information and help adjust our references of changes in the environment. Also, the combination of different types of data can indicate a fisheries trend that would be undetectable when evaluated separately. Here we investigated changes in fisher's perceptions regarding overexploited and new target species in artisanal fisheries in a secular fishing village of the subtropical, southeastern Brazilian coast. We identified temporal changes in landings and in the mean trophic level (MTL) of high trophic level species (≥ 3.5 and >4) over 16 years. Fishers' knowledge revealed shifts in perception associated with years of fishing practice. More experienced fishers recognized a greater number of overexploited and new target species than fishers in the beginning of their careers. Landing data has revealed declining trends of 72% for five mesopredators species. Due to the overfishing of mesopredators, there was a shift in target species, towards fish that were previously discarded. Temporal changes in landings and in the MTL metric are concordant with previous reports on the overexploitation of species caught by local fishers. Our work reveals that multiple sources of information can be combined to establish historical baselines and improve the detection of change in marine ecosystems.


Subject(s)
Fisheries/statistics & numerical data , Brazil , Food Chain
17.
Adv Mar Biol ; 88: 39-89, 2021.
Article in English | MEDLINE | ID: mdl-34119046

ABSTRACT

Skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tuna are the target species of tropical tuna fisheries in the Indian Ocean, with high commercial value in the international market. High fishing pressure over the past three decades has raised concerns about their sustainability. Understanding life history strategies and stock structure is essential to determine species resilience and how they might respond to exploitation. Here we provide a comprehensive review of available knowledge on the biology, ecology, and stock structure of tropical tuna species in the Indian Ocean. We describe the characteristics of Indian Ocean tropical tuna fisheries and synthesize skipjack, yellowfin, and bigeye tuna key life history attributes such as biogeography, trophic ecology, growth, and reproductive biology. In addition, we evaluate the available literature about their stock structure using different approaches such as analysis of fisheries data, genetic markers, otolith microchemistry and tagging, among others. Based on this review, we conclude that there is a clear lack of ocean basin-scale studies on skipjack, yellowfin and bigeye tuna life history, and that regional stock structure studies indicate that the panmictic population assumption of these stocks should be investigated further. Finally, we identify specific knowledge gaps that should be addressed with priority to ensure a sustainable and effective management of these species.


Subject(s)
Fisheries/statistics & numerical data , Tuna , Animals , Fishes , Indian Ocean
18.
PLoS One ; 16(5): e0251638, 2021.
Article in English | MEDLINE | ID: mdl-34043656

ABSTRACT

Rockfish are an important component of West Coast fisheries and California Current food webs, and recruitment (cohort strength) for rockfish populations has long been characterized as highly variable for most studied populations. Research efforts and fisheries surveys have long sought to provide greater insights on both the environmental drivers, and the fisheries and ecosystem consequences, of this variability. Here, variability in the temporal and spatial abundance and distribution patterns of young-of-the-year (YOY) rockfishes are described based on midwater trawl surveys conducted throughout the coastal waters of California Current between 2001 and 2019. Results confirm that the abundance of winter-spawning rockfish taxa in particular is highly variable over space and time. Although there is considerable spatial coherence in these relative abundance patterns, there are many years in which abundance patterns are very heterogeneous over the scale of the California Current. Results also confirm that the high abundance levels of YOY rockfish observed during the 2014-2016 large marine heatwave were largely coastwide events. Species association patterns of pelagic YOY for over 20 rockfish taxa in space and time are also described. The overall results will help inform future fisheries-independent surveys, and will improve future indices of recruitment strength used to inform stock assessment models and marine ecosystem status reports.


Subject(s)
Animal Distribution , Ecological Parameter Monitoring/statistics & numerical data , Fisheries/statistics & numerical data , Perciformes/physiology , Seasons , Animals , California , Conservation of Natural Resources/statistics & numerical data , Food Chain , Spatio-Temporal Analysis
19.
PLoS One ; 16(4): e0249725, 2021.
Article in English | MEDLINE | ID: mdl-33857188

ABSTRACT

While there is substantial literature about the socio-cultural characteristics and values associated with recreational and commercial fisheries in the U.S., studies directed at those who 'fish for food'-those who depend on consuming their catch to various degrees-are relatively sparse. Using qualitative data collected through 80 semi-structured interviews with fishers in the summer and fall of 2018 in Carteret County, North Carolina, this study aims to better understand the group of recreational fishers who consume their catch by describing social and cultural dimensions and values associated with fishing for food, examining the role of infrastructure in facilitating access to benefits associated with this activity, and considering how knowledge of existing licensing regulations surrounding subsistence license waivers affect this fishing community. Interviews conducted at free public fishing structures in the region revealed that fishers derive a variety of values and benefits from fishing at these sites, including access to recreation, nutrition, a social community, and mental health benefits, which were found to be negatively impacted by Hurricane Florence in September 2018. We also found an informal economy of sharing catch on- and off-site that extends the reach and benefits facilitated by public infrastructure to people beyond those using it directly. Overall, we call for conceptualizations of 'fishing for food' that include aspects that go beyond traditional definitions of 'subsistence' or 'recreational' fishing such as food security, access, and less obvious social and cultural motivations behind the activity. These findings are a compelling rationalization for the creation and maintenance of formal and informal fishing places locally and, by extension, in other coastal areas, given the array of benefits provided by access to these types of locations.


Subject(s)
Conservation of Natural Resources/methods , Ecosystem , Fisheries/statistics & numerical data , Food Supply/statistics & numerical data , Seafood/supply & distribution , Adolescent , Adult , Animals , Female , Humans , Male , Middle Aged , North Carolina , Recreation , Surveys and Questionnaires , Young Adult
20.
PLoS One ; 16(4): e0249173, 2021.
Article in English | MEDLINE | ID: mdl-33882056

ABSTRACT

This study develops a definition of what mangrove-fisheries can encompass, incorporating a broad range of their possible characteristics. A detailed case study was conducted to develop a typology of mangrove-fishing in the Perancak Estuary, Bali, Indonesia, using interview surveys to investigate the fishing activities associated with mangroves. This case study demonstrated the complexity that a mangrove-fishery can entail, where fishing is connected to the mangrove forest by fishers of multiple sectors, functions, locations and temporal scales. Through a comparison with other mangrove-fishing communities in Bali, it also highlighted that mangrove-fisheries are variable even when in close proximity. With particular reference to this case study, a framework was developed as a flexible tool for identifying the multiple dimensions of a mangrove-fishery in a local context. Following this framework should encourage researchers and managers to look outside of the groups of fishers traditionally expected to benefit from mangrove fishing. This will enable the development of a broader definition of mangrove-fisheries in a site specific way. Identifying the full scope of fishers that contribute to or benefit from a mangrove-fishery is the first step towards building management measures that reflect the interests of groups of fishers that may otherwise remain under-represented. This is in line with international efforts for sustainability, especially in promoting small-scale fishers' access to sustainable resources under the UN Sustainable Development Goals.


Subject(s)
Biodiversity , Fisheries/statistics & numerical data , Wetlands , Estuaries , Fisheries/economics , Humans , Indonesia , Workforce/statistics & numerical data
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