Estimating Bycatch From Non-representative Samples (II): A Case Study of Pair Trawlers and Common Dolphins in the Bay of Biscay

Marine megafauna plays an important functional role in marine ecosystems as top predators but are threatened by a wide range of anthropogenic activities. Bycatch, the incidental capture of non-targeted species in commercial and recreational fisheries, is of particular concern for small cetacean species, such as dolphins and porpoises. In the North-East Atlantic, common dolphin (Delphinus delphis, Linné 1758) bycatch has been increasing and associated with large numbers of animals stranding during winter on the French Atlantic seashore since at least 2017. However, uncertainties around the true magnitude of common dolphin bycatch and the fisheries involved have led to delays in the implementation of mitigation measures. Current data collection on dolphin bycatch in France is with non-dedicated observers deployed on vessels for the purpose of national fisheries sampling programmes. These data cannot be assumed representative of the whole fisheries' bycatch events. This feature makes it difficult to use classic ratio estimators since they require a truly randomised sample of the fishery by dedicated observers. We applied a newly developed approach, regularised multilevel regression with post-stratification, to estimate total bycatch from unrepresentative samples and total fishing effort. The latter is needed for post-stratification and the former is analysed in a Bayesian framework with multilevel regression to regularise and better predict bycatch risk. We estimated the number of bycaught dolphins for each week and 10 International Council for the Exploration of the Sea (ICES) divisions from 2004 to 2020 by estimating jointly bycatch risk, haul duration, and the number of hauls per days at sea (DaS). Bycatch risk in pair trawlers flying the French flag was the highest in winter 2017 and 2019 and was associated with the longest haul durations. ICES divisions 8.a and 8.b (shelf part of the Bay of Biscay) were estimated to have the highest common dolphin bycatch. Our results were consistent with independent estimates of common dolphin bycatch from strandings. Our method show cases how non-representative observer data can nevertheless be analysed to estimate fishing duration, bycatch risk and, ultimately, the number of bycaught dolphins. These weekly-estimates improve upon current knowledge of the nature of common dolphin bycatch and can be used to inform management and policy decisions at a finer spatio-temporal scale than has been possible to date. Our results suggest that limiting haul duration, especially in winter, could serve as an effective mitigation strategy.

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Citizen science in the marine environment: A case-study estimating common dolphin densities in the north-east Atlantic

10.7287/peerj.preprints.27569 ◽

2019 ◽

Author(s):

James R Robbins ◽

Lucy Babey ◽

Clare B Embling

Keyword(s):

Citizen Science ◽

Common Dolphin ◽

Bay Of Biscay ◽

English Channel ◽

East Atlantic ◽

Science Data ◽

North East ◽

The North ◽

Celtic Sea ◽

Common Dolphins

Background. Citizen science is increasingly popular and has the potential to collect extensive datasets at lower costs than traditional surveys. Ferries have been used to collect data on cetacean populations for decades, providing long-term time series allowing for monitoring of cetacean populations. One cetacean species of concern is the common dolphin, which have been found stranded around the north-east Atlantic in recent years, with high numbers on French coasts being attributed to fisheries bycatch. We estimate common dolphin densities in north-east Atlantic and investigate the power of citizen science data to identify changes in marine mammal densities and areas of importance. Materials & Methods. Data were collected by citizen scientists on ferries between April and October in 2006 - 2017. Common dolphin sightings data from two ferry routes in the Bay of Biscay (n= 569), Celtic Sea (n= 260), and English Channel (n= 75) were used to estimate detection probabilities with detection functions. Density Surface Models estimated density across ferry routes, accounting for the influence of environmental (chlorophyll a, sea surface temperature, depth, and slope), spatial (latitude and longitude) and temporal terms (year and Julian day). Results. Overall detection probability was highest in the English Channel (0.384) and Bay of Biscay (0.348), and lowest in the Celtic Sea (0.158). Common dolphins were estimated to occur in higher densities in the Celtic Sea (0.400 per km) and the Bay of Biscay (0.319 per km), with low densities in the English Channel (0.025 per km). Densities in the Celtic Sea have been relatively stable on the ferry route since 2006 with a slight decrease in 2017. Densities peaked in the Bay of Biscay in 2013 with lower numbers since. The general trend in the English Channel is for increasing densities of common dolphins over time since 2009. Discussion. This study highlights the effectiveness of citizen science data to investigate the distribution and density of cetaceans. The densities and temporal changes shown by this study are representative of those from wider-ranging robust estimates. We highlight the ability of citizen science to collect data over extensive periods of time which complements traditional surveys. Such long-term data are important to identify changes within a population; however, citizen science data may, in some situations, present challenges. We provide recommendations to ensure high-quality data which can be used to inform management and conservation of cetacean populations.

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Citizen science in the marine environment: A case-study estimating common dolphin densities in the north-east Atlantic

10.7287/peerj.preprints.27569v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

James R Robbins ◽

Lucy Babey ◽

Clare B Embling

Keyword(s):

Citizen Science ◽

Common Dolphin ◽

Bay Of Biscay ◽

English Channel ◽

East Atlantic ◽

Science Data ◽

North East ◽

The North ◽

Celtic Sea ◽

Common Dolphins

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Prey preferences of adult sea bass Dicentrarchus labrax in the northeastern Atlantic: implications for bycatch of common dolphin Delphinus delphis

ICES Journal of Marine Science ◽

10.1093/icesjms/fss200 ◽

2013 ◽

Vol 70 (2) ◽

pp. 452-461 ◽

Cited By ~ 29

Author(s):

J. Spitz ◽

T. Chouvelon ◽

M. Cardinaud ◽

C. Kostecki ◽

P. Lorance

Keyword(s):

Dicentrarchus Labrax ◽

Sea Bass ◽

Common Dolphin ◽

Bay Of Biscay ◽

Predator Species ◽

Delphinus Delphis ◽

Prey Preferences ◽

Common Dolphins ◽

Trawl Fisheries ◽

Northeastern Atlantic

Abstract Spitz, J., Chouvelon, T., Cardinaud, M., Kostecki, C., and Lorance, P. 2013. Prey preferences of adult sea bass Dicentrarchus labrax in the northeastern Atlantic: implications for bycatch of common dolphin Delphinus delphis – ICES Journal of Marine Science, 70: 452–461. In the northeastern Atlantic, adult sea bass (Dicentrarchus labrax) is one of largest fish living on the shelf, and this species has important commercial value. However, pelagic trawl fisheries that target sea bass have negative operational interactions with common dolphins (Delphinus delphis). Our goal was to determine the diet of adult sea bass in the Bay of Biscay from stomach-content and stable-isotope analyses, and explore the dietary overlap between sea bass and common dolphins. We found that sea bass primarily target small pelagic fish, most notably mackerel (Scomber scombrus), scads (Trachurus spp.), anchovy (Engraulis encrasicolus), and sardine (Sardina pilchardus). These four species also dominated the diets of common dolphins. This overlap in feeding preferences could increase the risk of dolphins being caught by trawl fisheries while feeding among sea bass, and may be an underlying mechanism to explain the high rate of common dolphin bycatch observed in the pelagic trawl fishery for sea bass in the Bay of Biscay. Understanding the foraging ecology and trophic interactions of predator species is an essential step for identifying and resolving management issues in the northeastern Atlantic and other marine ecosystems.

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In the Wrong Place at the Wrong Time: Identifying Spatiotemporal Co-occurrence of Bycaught Common Dolphins and Fisheries in the Bay of Biscay (NE Atlantic) From 2010 to 2019

Frontiers in Marine Science ◽

10.3389/fmars.2021.617342 ◽

2021 ◽

Vol 8 ◽

Author(s):

Helene Peltier ◽

Matthieu Authier ◽

Florence Caurant ◽

Willy Dabin ◽

Pierre Daniel ◽

...

Keyword(s):

Atlantic Coast ◽

Sea Bass ◽

Fishing Effort ◽

Small Scale ◽

Common Dolphin ◽

Bay Of Biscay ◽

The European Union ◽

Fishing Activity ◽

Fishing Vessels ◽

Common Dolphins

The first Unusual Mortality Event (UME) related to fishing activity along the Atlantic coast recorded by the French Stranding Network was in 1989: 697 small delphinids, mostly common dolphins, washed ashore, most of them with evidence of having been bycaught. Since then, UMEs of common dolphins have been observed nearly every year in the Bay of Biscay; unprecedented records were broken every year since 2016. The low and unequally distributed observation efforts aboard fishing vessels in the Bay of Biscay, as well as the lack of data on foreign fisheries necessitated the use of complementary data (such as stranding data) to elucidate the involvement of fisheries in dolphin bycatch. The aim of this work was to identify positive spatial and temporal correlations between the likely origins of bycaught stranded common dolphins (estimated from a mechanistic drift model) and fishing effort statistics inferred from Vessel Monitoring System (VMS) data on vessels >12 m long. Fisheries whose effort correlated positively with dolphin mortality areas after 2016 included French midwater trawlers, French Danish seiners, French gillnetters, French trammel netters, Spanish bottom trawlers, and Spanish gillnetters. For the French fleet only, logbook declarations, sales, and surveys carried out by Ifremer were integrated into fishing effort data. Six fleets were active in common dolphin bycatch areas at least twice between 2016 and 2019: gillnetters fishing hake, trammel netters fishing anglerfish, bottom pair trawlers fishing hake, midwater pair trawlers fishing sea bass and hake, and Danish seiners fishing whiting. Except for changes in hake landings in some fisheries, there were no notable changes in total fishing effort practice (gear or target species) based on the data required by the ICES and Council of the European Union that could explain the large increase in stranded common dolphins recorded along the French Atlantic coast after 2016. Small scale or unrecorded changes could have modified interactions between common dolphins and fisheries, but could not be detected through mandatory data-calls. The recent increase in strandings of bycaught common dolphins could have been caused by changes in their distribution and/or ecology, or changes in fishery practices that were undetectable through available data.

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Abundance, distribution and behaviour of common dolphins, Delphinus spp., off north-eastern Venezuela: implications for conservation and management

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s002531540999097x ◽

2009 ◽

Vol 90 (8) ◽

pp. 1623-1631 ◽

Cited By ~ 4

Author(s):

Lenin Oviedo ◽

María Alejandra Esteves ◽

Romina Acevedo ◽

Noemi Silva ◽

Jaime Bolaños-Jiménez ◽

...

Keyword(s):

Trophic Ecology ◽

Coastal Upwelling ◽

Current Status ◽

Eastern Coast ◽

Line Transect ◽

North East ◽

The North ◽

Wide Range ◽

North Eastern ◽

Common Dolphins

The north-eastern coast of Venezuela hosts a high diversity of megafauna, particularly related with high productivity due to coastal upwelling. This area is mainly characterized by the existence of the primary fisheries in Venezuela, mostly supported by a great abundance of small pelagic species. This would explain why the area supports a wide range of marine top predators, including cetaceans. The current status of cetacean populations off north-eastern Venezuela is uncertain, mainly because research efforts have been very sparse. There are still many gaps of information in cetacean biology to establish a solid baseline that can be used for management decisions. Common dolphins (Delphinus spp.) are widely dispersed over the whole north-east basin, including waters off Araya and Paria Peninsula and around Margarita, Coche and Cubagua Islands. Areas of higher densities for Delphinus spp. coincide with the focal location of sardine fisheries and the most-active upwelling on the north-eastern coast. Therefore, a scheme of management should consider the areas of major productivity along the coast as potential critical habitat for the species. Further data collection is recommended, increasing aspects such as trophic ecology and the continuity of behavioural sampling, paired with systematic line transect estimation.

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Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores

PeerJ ◽

10.7717/peerj.4285 ◽

2018 ◽

Vol 6 ◽

pp. e4285 ◽

Cited By ~ 6

Author(s):

Maria João Cruz ◽

Miguel Machete ◽

Gui Menezes ◽

Emer Rogan ◽

Mónica A. Silva

Keyword(s):

Negative Binomial ◽

Negative Impact ◽

Mitigation Measures ◽

Small Scale ◽

Common Dolphin ◽

Ratio Estimation ◽

Related Factors ◽

Significant Negative Impact ◽

Common Dolphins ◽

Tuna Fishery

Small-scale artisanal fisheries can have a significant negative impact in cetacean populations. Cetacean bycatch has been documented in the pole-and-line tuna fishery in the Azores with common dolphins being the species more frequently taken. Based on data collected by observers on ∼50% of vessels operating from 1998 to 2012, we investigate the influence of various environmental and fisheries-related factors in common dolphin bycatch and calculate fleet-wide estimates of total bycatch using design-based and model-based methods. Over the 15-year study dolphin bycatch occurred in less than 0.4% of the observed fishing events. Generalized additive modelling results suggest a significant relationship between common dolphin bycatch and duration of fishing events, sea surface temperature and location. Total bycatch calculated from the traditional stratified ratio estimation approach was 196 (95% CI: 186–205), while the negative binomial GAM estimated 262 (95% CI: 249–274) dolphins. Bycatch estimates of common dolphin were similar using statistical approaches suggesting that either of these methods may be used in future bycatch assessments for this fishery. Our work shows that rates of common dolphin bycatch in the pole-and-line tuna fishery in the Azores are low, despite considerable variations between years. Dolphins caught were released alive although the fate of these individuals is unknown. Continued monitoring will provide a better understanding of dolphin bycatch and more accurate estimates essential in the development of potential mitigation measures.

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Citizen science in the marine environment: estimating common dolphin densities in the north-east Atlantic

PeerJ ◽

10.7717/peerj.8335 ◽

2020 ◽

Vol 8 ◽

pp. e8335

Author(s):

James R. Robbins ◽

Lucy Babey ◽

Clare B. Embling

Keyword(s):

Citizen Science ◽

Quality Data ◽

Common Dolphin ◽

Bay Of Biscay ◽

English Channel ◽

East Atlantic ◽

Science Data ◽

North East ◽

The North

Background Citizen science is increasingly popular and has the potential to collect extensive datasets at lower costs than traditional surveys conducted by professional scientists. Ferries have been used to collect data on cetacean populations for decades, providing long-term time series for monitoring of cetacean populations. One cetacean species of concern is the common dolphin, which has been found stranded around the north-east Atlantic in recent years, with high numbers on French coasts being attributed to fisheries bycatch. We estimate common dolphin densities in the north-east Atlantic and investigate the ability of citizen science data to identify changes in marine mammal densities and areas of importance. Materials and Methods Data were collected by citizen scientists on ferries between April and October in 2006–2017. Common dolphin sightings data from two ferry routes across three regions, Bay of Biscay (n = 569); south-west United Kingdom to the Isles of Scilly in the Celtic Sea (n = 260); and English Channel (n = 75), were used to estimate density across ferry routes. Two-stage Density Surface Models accounted for imperfect detection, and tested the influence of environmental (chlorophyll a, sea surface temperature, depth, and slope), spatial (latitude and longitude) and temporal terms (year and Julian day) on occurrence. Results Overall detection probability was highest in the areas sampled within the English Channel (0.384) and Bay of Biscay (0.348), and lowest on the Scilly’s route (0.158). Common dolphins were estimated to occur in higher densities on the Scilly’s route (0.400 per km2) and the Bay of Biscay (0.319 per km2), with low densities in the English Channel (0.025 per km2). Densities on the Scilly’s route appear to have been relatively stable since 2006 with a slight decrease in 2017. Densities peaked in the Bay of Biscay in 2013 with lower numbers since. Densities in the English Channel appear to have increased over time since 2009. Discussion This study highlights the effectiveness of citizen science data to investigate the distribution and density of cetaceans. The densities and temporal changes shown by this study are representative of those from wider-ranging robust estimates. We highlight the ability of citizen science to collect data over extensive periods of time which complements dedicated, designed surveys. Such long-term data are important to identify changes within a population; however, citizen science data may, in some situations, present challenges. We provide recommendations to ensure high-quality data which can be used to inform management and conservation of cetacean populations.

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Fitness of Herbicide-Resistant Weeds: Current Knowledge and Implications for Management

Plants ◽

10.3390/plants8110469 ◽

2019 ◽

Vol 8 (11) ◽

pp. 469 ◽

Cited By ~ 5

Author(s):

Vila-Aiub

Keyword(s):

Life History ◽

Herbicide Resistance ◽

Management Practices ◽

Current Knowledge ◽

Resistance Management ◽

Fitness Cost ◽

Plant Fitness ◽

Resistance Mutations ◽

Fitness Costs ◽

Wide Range

Herbicide resistance is the ultimate evidence of the extraordinary capacity of weeds to evolve under stressful conditions. Despite the extraordinary plant fitness advantage endowed by herbicide resistance mutations in agroecosystems under herbicide selection, resistance mutations are predicted to exhibit an adaptation cost (i.e., fitness cost), relative to the susceptible wild-type, in herbicide untreated conditions. Fitness costs associated with herbicide resistance mutations are not universal and their expression depends on the particular mutation, genetic background, dominance of the fitness cost, and environmental conditions. The detrimental effects of herbicide resistance mutations on plant fitness may arise as a direct impact on fitness-related traits and/or coevolution with changes in other life history traits that ultimately may lead to fitness costs under particular ecological conditions. This brings the idea that a “lower adaptive value” of herbicide resistance mutations represents an opportunity for the design of resistance management practices that could minimize the evolution of herbicide resistance. It is evident that the challenge for weed management practices aiming to control, minimize, or even reverse the frequency of resistance mutations in the agricultural landscape is to “create” those agroecological conditions that could expose, exploit, and exacerbate those life history and/or fitness traits affecting the evolution of herbicide resistance mutations. Ideally, resistance management should implement a wide range of cultural practices leading to environmentally mediated fitness costs associated with herbicide resistance mutations.

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Transfer of Plasmid DNA to Clinical Coagulase-Negative Staphylococcal Pathogens by Using a Unique Bacteriophage

Applied and Environmental Microbiology ◽

10.1128/aem.04190-14 ◽

2015 ◽

Vol 81 (7) ◽

pp. 2481-2488 ◽

Cited By ~ 19

Author(s):

Volker Winstel ◽

Petra Kühner ◽

Bernhard Krismer ◽

Andreas Peschel ◽

Holger Rohde

Keyword(s):

Plasmid Dna ◽

Genetic Manipulation ◽

Current Knowledge ◽

Virulence Determinants ◽

Coagulase Negative Staphylococci ◽

Reliable Technique ◽

Content Type ◽

Research Activities ◽

Wide Range ◽

Genetic Barriers

ABSTRACTGenetic manipulation of emerging bacterial pathogens, such as coagulase-negative staphylococci (CoNS), is a major hurdle in clinical and basic microbiological research. Strong genetic barriers, such as restriction modification systems or clustered regularly interspaced short palindromic repeats (CRISPR), usually interfere with available techniques for DNA transformation and therefore complicate manipulation of CoNS or render it impossible. Thus, current knowledge of pathogenicity and virulence determinants of CoNS is very limited. Here, a rapid, efficient, and highly reliable technique is presented to transfer plasmid DNA essential for genetic engineering to important CoNS pathogens from a uniqueStaphylococcus aureusstrain via a specificS. aureusbacteriophage, Φ187. Even strains refractory to electroporation can be transduced by this technique once donor and recipient strains share similar Φ187 receptor properties. As a proof of principle, this technique was used to delete the alternative transcription factor sigma B (SigB) via allelic replacement in nasal and clinicalStaphylococcus epidermidisisolates at high efficiencies. The described approach will allow the genetic manipulation of a wide range of CoNS pathogens and might inspire research activities to manipulate other important pathogens in a similar fashion.

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Molecular Subtyping of Blastocystis sp. Isolated from Farmed Animals in Southern Italy

Microorganisms ◽

10.3390/microorganisms9081656 ◽

2021 ◽

Vol 9 (8) ◽

pp. 1656

Author(s):

Simona Gabrielli ◽

Marialetizia Palomba ◽

Federica Furzi ◽

Emanuele Brianti ◽

Gabriella Gaglio ◽

...

Keyword(s):

Current Knowledge ◽

Pcr Amplification ◽

Epidemiological Studies ◽

Fallow Deer ◽

Small Subunit ◽

Zoonotic Transmission ◽

Ssu Rrna ◽

Molecular Approaches ◽

Wide Range ◽

Blastocystis Sp

Blastocystis is a common intestinal protist distributed worldwide, infecting humans and a wide range of domestic and wild animals. It exhibits an extensive genetic diversity and, so far, 25 distinct small subunit ribosomal RNA (SSU rRNA) lineages termed subtypes (STs)) have been characterized; among them, 12 have thus far been reported in humans. The aims of the present study were to detect and genetically characterize Blastocystis sp. in synantropic animals to improve our current knowledge on the distribution and zoonotic transmission of Blastocystis STs in Italy. Samples were collected from N = 193 farmed animals and submitted to DNA extraction and PCR amplification of the SSU rRNA. Blastocystis was detected in 60 samples (31.08%) and successfully subtyped. Phylogenetic analysis evidenced that the isolates from fallow deer, goats, and pigs (N = 9) clustered within the ST5; those from pheasants (N = 2) in the ST6; those from chickens (N = 8) in the ST7; those from sheep (N = 6) in the ST10; and those from water buffaloes (N = 9) in the ST14 clade. The comparison between the present isolates from animals and those previously detected in humans in Italy suggested the animal-to-human spillover for ST6 and ST7. The present study represents the widest Blastocystis survey performed thus far in farmed animals in Italy. Further epidemiological studies using molecular approaches are required to determine the occurrence and distribution of Blastocystis STs in other potential animal reservoirs in Italy and to define the pathways of zoonotic transmission.

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