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

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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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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Scottish Inshore Fisheries Integrated Data System (SIFIDS): work package (2) final report WP2A: development and pilot deployment of a prototypic autonomous fisheries data harvesting system, and WP2B: investigation into the availability and adaptability of novel technological approaches to data collection

10.15664/10023.23443 ◽

2019 ◽

Author(s):

R. Ayers ◽

G.P. Course ◽

G.R. Pasco

Keyword(s):

Data Collection ◽

Economic Value ◽

Fishing Effort ◽

Final Report ◽

Executive Summary ◽

Fishing Activity ◽

Business Decisions ◽

Fishing Vessels ◽

Spatio Temporal ◽

Data Deficient

[Extract from Executive Summary] To enhance sustainability and foster resilience within Scotland’s inshore fishing communities an effective system of collecting and sharing relevant data is required. To support business decisions made by vessel owners as well as informing fisheries managers and those involved in marine planning it will be vital to collect a range of information which will provide a robust understanding of fishing activity, the economic value of the sector and its importance within local communities. The SIFIDS Project was conceived to assist in attaining these goals by working alongside fishers to develop and test technology to automatically collect and collate data on board vessels, thereby reducing the reporting burden on fishers. The project built upon previous research funded through the European Fisheries Fund (EFF) and was designed to deliver a step change in the way that inshore fisheries in Scotland could be managed in cooperation with the industry. The project focussed on inshore fishing vessels around Scotland, where spatio-temporal information on the distribution of vessels and associated fishing effort is data deficient. The whole project was broken down into 12 highly integrated work packages. This is the integrated report for work packages 2A and 2B, entitled’ Development and Pilot Deployment of a Prototypic Autonomous Fisheries Data Harvesting System’ (2A) and ‘Investigation into the Availability and Adaptability of Novel Technological Approaches to Data Collection’ (2B).

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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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Fishing Effort and Associated Catch per Unit Effort for Small-Scale Fisheries in the Mozambique Channel Region: 1950–2016

Frontiers in Marine Science ◽

10.3389/fmars.2021.707999 ◽

2021 ◽

Vol 8 ◽

Author(s):

Dirk Zeller ◽

Gabriel M. S. Vianna ◽

Matthew Ansell ◽

Angie Coulter ◽

Brittany Derrick ◽

...

Keyword(s):

Fishing Effort ◽

Small Scale ◽

Catch Per Unit Effort ◽

Important Species ◽

Small Scale Fisheries ◽

Mozambique Channel ◽

Fishing Vessels ◽

Unit Effort ◽

Fishing Capacity ◽

Channel Region

The Mozambique Channel region in East Africa has diverse marine ecosystems and serves as a migratory corridor for economically important species. Local and foreign industrial fisheries operate in the Mozambique Channel, but regional small-scale fisheries are the crucially important fisheries that provide food security, livelihoods, and economic opportunities for rural coastal communities. This study reconstructed and investigated trends in the fishing effort and catch per unit effort (CPUE) of small-scale marine fisheries in four Exclusive Economic Zones (EEZ) that constitute the Mozambique Channel, i.e., Union of Comoros, Madagascar, Mayotte, and Mozambique, from 1950 to 2016. Effective fishing effort for small-scale fisheries in the form of fishing capacity in kWdays (i.e., kilowatt days) was derived using the number, length, motorization (engine power) by fishing vessels, as well as an approximate human-powered equivalent for shore-based fishers without vessels, as well as days of fishing per year. Effective small-scale fishing effort in the Mozambique Channel increased by nearly 60 times from just over 386,000 kWdays in 1950 to over 23 million kWdays in 2016. Correspondingly, the overall small-scale CPUE, based on previously and independently reconstructed catch data declined by 91% in the region as a whole, from just under 175 kg⋅kWday–1 in the early 1950s to just over 15 kg⋅kWday–1 in recent years. All four EEZs showed the strongest declines in the small-scale CPUE in the earlier decades, driven by motorization and growth in vessel numbers impacting effective fishing effort. Increased motorization combined with a substantial growth in overall vessel numbers were the drivers of the increasing fishing effort and decreasing CPUE, and clearly suggest that continuing to increase the fishing capacity of small-scale fisheries in the absence of effective and restrictive management actions may exacerbate overexploitation risk.

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Trends in strandings and by-catch of marine mammals in north-west Spain during the 1990s

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315402005805 ◽

2002 ◽

Vol 82 (3) ◽

pp. 513-521 ◽

Cited By ~ 35

Author(s):

A. López ◽

M.B. Santos ◽

G.J. Pierce ◽

A.F. González ◽

X. Valeiras ◽

...

Keyword(s):

Marine Mammals ◽

Atlantic Coast ◽

Western Coast ◽

Common Dolphin ◽

North West ◽

The North ◽

By Catch ◽

Average Size ◽

Autumn And Winter ◽

Common Dolphins

Strandings of marine mammals on the north-western Spanish coast (Galicia) have been systematically recorded since 1990. A total of 1433 marine mammals belonging to 15 species was recorded from 1990 to 1999. The most frequently recorded species stranded were common dolphin (47%), bottlenose dolphin (11%) and harbour porpoise (7%). The number of strandings recorded increased annually over the study period, probably reflecting an increased observer effort. During 1996–1999, an average of 1·65 animals were stranded annually for each 10 km of coastline, the highest density of strandings recorded on the Atlantic coast of the Iberian Peninsula. More than 80% of the strandings were located on the western coast of Galicia, mainly in autumn and winter. During the study period, 42 proven incidental catches were recorded, although signs of by-catch were seen in a further 198 animals. The average size of stranded common dolphins and the proportion of males both increased towards the end of the calendar year.

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Behaviour of free-ranging short-beaked common dolphins (Delphinus delphis) in Gulf St Vincent, South Australia

Australian Journal of Zoology ◽

10.1071/zo12033 ◽

2013 ◽

Vol 61 (4) ◽

pp. 291 ◽

Cited By ~ 8

Author(s):

Nicole E. Filby ◽

Mike Bossley ◽

Karen A. Stockin

Keyword(s):

Group Size ◽

Water Depth ◽

Large Scale ◽

South Australia ◽

Population Level ◽

Common Dolphin ◽

Time Data ◽

Fishing Activity ◽

Delphinus Delphis ◽

Common Dolphins

Common dolphins are subject to large-scale fishing activity and tourism operations in South Australia; however, there is a paucity of data on this species. Understanding the behaviour of a population can contribute greatly to our knowledge of a species and how to manage potential population-level threats. This paper describes the behaviour of short-beaked common dolphins (Delphinus delphis) in Australian waters for the first time. Data were collected from 109 independent dolphin groups during boat-based surveys conducted in Gulf St Vincent, South Australia, between September 2005 and May 2008. Activity budgets were used to assess behaviour of common dolphins in relation to diel patterns, season, water depth, sea surface temperature (SST), group size and composition. Foraging (33.9%) and resting (2.8%) were the most and least frequently observed behaviours, respectively. Travelling (33.0%), socialising (20.2%) and milling (10.1%) accounted for the remainder of the activity budget. Diurnal differences were detected, with foraging (59.5%) and socialising (31.8%) groups most frequently observed from 10.00 to 11.59 hours. Behaviour did not vary seasonally or with water depth, SST, group size or composition. Behaviour varied significantly between single- and multispecies aggregations. Foraging was more frequent in multispecies aggregations, as 78.4% of all foraging behaviour observed for common dolphins occurred in the presence of other species. Multispecies aggregations were most frequently observed with flesh-footed shearwaters (Puffinus carneipes), which were present during 29.4% of common dolphin encounters. Behaviour varied significantly during aggregations with shearwaters, as 62.2% of foraging groups occurred in the presence of shearwaters. Resting, milling or socialising was rarely observed in the presence of any other species, indicating that the primary mechanism for aggregations is likely prey-related.

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A bioeconomic multispecies analysis of an estuarine small-scale fishery: spatial structure of biovalue

ICES Journal of Marine Science ◽

10.1016/s1054-3139(03)00096-1 ◽

2003 ◽

Vol 60 (4) ◽

pp. 721-732 ◽

Cited By ~ 6

Author(s):

Mario Rueda ◽

Omar Defeo

Keyword(s):

Risk Analysis ◽

Monte Carlo Analysis ◽

Fishing Effort ◽

Indicator Kriging ◽

Fish Abundance ◽

Economic Losses ◽

Small Scale ◽

Fishing Activity ◽

Spatial Allocation ◽

Spatial Risk

Abstract We estimated the spatial population structure by size and the economical potential (biovalue) of a multispecies fish resource in an estuarine lagoon in Colombia, based on fishery-dependent (catch and effort) and independent (seasonal fishing surveys) data. Model-based (geostatistics, kriging) estimations of such performance variables were used to quantify the uncertainty in abundance, individual price by size and variable costs per haul. Monte Carlo analysis was used to assess the status of the fishery. The spatial dimension of risk analysis was explored by indicator kriging, whereas effects of biovalue on the spatial allocation of fishing effort were evaluated using contingency tables. Fish abundance, individual sizes and biovalue were spatially structured, but the spatial patterns varied between seasons and species. Analysis of biovalue showed a moderate risk that fishers had economic losses derived from the fishing activity. Spatial risk analysis showed that no more than 30% of the total area from the lagoon registered profitable levels of fish abundance, which affected the spatial allocation of fishing effort. Management implications supported by our study suggest seasonal and spatial fishing closures to protect juveniles and spawning stock of fish species.

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The status and trends of small cetacean landings at Dixcove artisanal fishing port, western Ghana

10.7287/peerj.preprints.27749v1 ◽

2019 ◽

Author(s):

Patrick K Ofori-Danson ◽

Joseph Debrah ◽

Koen Van Waerebeek

Keyword(s):

Coastal Waters ◽

Bottlenose Dolphins ◽

Fishing Effort ◽

Humpback Whales ◽

Small Scale ◽

Catch Per Unit Effort ◽

Western Africa ◽

Republic Of Benin ◽

Lagenodelphis Hosei ◽

Common Dolphins

One of the largest documented takes of small cetaceans in western Africa occurs in Western regional coastal waters of Ghana. This temporally coincided with steadily decreasing catches of finfish, especially small pelagics (sardinellas, anchovies, mackerel) over the past decades, attributed to both climate change and indiscriminate exploitation methods. Dixcove, a key fishing port for cetacean landings was surveyed during 96 days between 12 September -17 December 2018. Our goal was to update insights from our earlier surveys, especially on catch rates, catch per unit effort and species composition. A total of 57 delphinids of 10 species were observed landed: Stenella attenuata (28.1%), Stenella clymene (17.5%), Lagenodelphis hosei (10.5%), Steno bredanensis (10.5%), unidentified stenellids (8.8%), Grampus griseus (3.5%), Delphinus sp. (3.5%), Pseudorca crassidens (3.5%) and single specimens of Tursiops truncatus, Stenella longirostris and Stenella frontalis. The observed cetacean catch per diem (cpd =0.59) at Dixcove was low compared to earlier rates for this port (e.g. cpd =2.82, in 2013-2014). However, fishing effort, measured as the number of canoes landing per diem (range 0-25; mean= 8.82 ± 6.05; n=22) was also reduced. Poor fish catches forced many canoes to remain in port. The prevalence in landings of common bottlenose dolphins and common dolphins has significantly decreased in the period 2000-2018. The prevalence of Fraser's dolphins and false killer whales increased. Indications are that a higher proportion of cetacean carcasses may be utilised offshore as shark bait. Hooks baited with cetacean parts are deployed in auxiliary longlines set longside large-mesh drift gillnets with a shark aggregating purpose, a first report in Africa. Shore-based incidental sightings of humpback whales suggest the potential for small scale whale-watching ecotourism in Ghanaian coastal waters, as pertains in the nearby waters of the Republic of Benin.

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A rapid assessment of trends in the multispecies small-scale fishery of Palamós (Catalonia, Spain)

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv149 ◽

2015 ◽

Vol 72 (9) ◽

pp. 2638-2649 ◽

Cited By ~ 1

Author(s):

Caterina Dimitriadis ◽

Alvar Carranza ◽

Raúl Vilela ◽

Margarida Casadevall

Keyword(s):

Rapid Assessment ◽

Ecosystem Approach ◽

Fishing Effort ◽

The State ◽

Economic Consequences ◽

Small Scale ◽

Limited Information ◽

The European Union ◽

Fisheries Policy ◽

Aichi Biodiversity Targets

Abstract Monitoring small-scale fisheries (SSFs) is challenging due to the limited information available and their underlying socioeconomic characteristics. This constitutes a serious impediment to assess the compliance level of Aichi Biodiversity Targets (ABT). The European Union has committed itself to include an Ecosystem Approach to Fisheries Management (EAFM) in its Common Fisheries Policy. EAFM depends on suites of indicators that track the pressure exercised, the state of the ecosystem, and the socio-economic consequences of management objectives. Therefore, The Living Planet Index (LPI) is proposed here for describing the performance of SSF towards the ABT. We show that the LPI can be reformulated to track trends in Fishing Effort (LPIFE), trends in Fish Populations (LPIFP), and both the state and trends related to the contribution of fisheries to broader society (LPIDEB). The implementation of the LPI in SSF applies several principles of the EAFM, including decentralization, fishers participation, and consideration of local knowledge. In this paper, we used 10-year daily data from the Cofradía at Palamós port, Catalonia - Spain. This is a multi-species SSF landing ca. 130 species, from which 10.9% are of special interest, being listed by the IUCN or in agreements by regional conventions. We observe a decreasing trend in the LPIFP, the LPIFE, and in the LPIDEB, including 36 species or groups, accounting for 90% of total landings, suggesting an overall decrease in the sustainability of this SSF. We conclude that use of the LPIFP is especially well suited to standardize the reporting of information for multispecies fisheries using a wide array of fishing strategies, and results strongly suggest the feasibility of using the LPI methodology to standardize reporting of any given agreed fisheries indicator in order enhance management towards the ABTs.

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