scholarly journals Fishery observers address arctic fishery discards

2020 ◽  
Vol 15 (9) ◽  
pp. 0940c4
Author(s):  
Hunter T Snyder ◽  
James T Erbaugh
Keyword(s):  
Fishery Discards

scholarly journals Fishery discards do not compensate natural prey shortage in Northern gannets from the English Channel

2019 ◽  
Vol 236 ◽  
pp. 375-384 ◽  
Author(s):  
Tangi Le Bot ◽  
Amélie Lescroël ◽  
Jérôme Fort ◽  
Clara Péron ◽  
Olivier Gimenez ◽  
...  
Keyword(s):  
English Channel ◽  
Natural Prey ◽  
Fishery Discards

scholarly journals Suitability of artisanal fishery discards as feed for juvenile tub gurnard (Chelidonichthys lucerna L.) reared in sea bottom cages in the mid Adriatic Sea

2016 ◽  
Vol 17 (3) ◽  
pp. 644
Author(s):  
A. RONCARATI ◽  
F. MARIOTTI ◽  
A. FELICI ◽  
M. MELIGRANA ◽  
P. MELOTTI
Keyword(s):  
Adriatic Sea ◽  
Survival Rates ◽  
Condition Index ◽  
Conversion Ratio ◽  
Feed Conversion Ratio ◽  
Artisanal Fisheries ◽  
Artisanal Fishery ◽  
Feed Conversion ◽  
Sea Bottom ◽  
Fishery Discards

The suitability of using discards from artisanal fisheries as feed for wild-caught Chelidonichthys lucerna (L.) reared in submerged cages in the Adriatic Sea was investigated. Three-hundred juvenile tub gurnard (72.9 ± 11 g, 18 ± 1 cm) were captured and separated into four circular 35.3 m3 submerged cages. Two stocking densities were used: two cages contained 60 fish each (1.7 fish m-3; CG-L) and two cages contained 90 fish each (2.55 fish m-3; CG-H). Growth performance and survival rates were recorded over a 240 day period during which tub gurnard were fed with a variety non-target fishery discards, including common crab, sardine, Atlantic chub mackerel, anchovy, and salema. The survival rate was approximately 90% in both groups (CG-L = 91% and CG-H = 90%), with final stocking densities of 0.32 kg m-3 and 0.49 kg m-3 for the CG-L and CG-H groups, respectively. There were no significant differences in final mean body weight or length between the CG-L group (206 ± 23 g, 24.6 ± 2 cm) and the CG-H group (215.5 ± 32 g, 24.8 ± 2 cm). The condition index was similar between the two groups (1.38 and 1.42 for CG-L and CG-H, respectively). The feed conversion ratio was high in both the CG-H (2.39) and CG-L (2.32) cages. These results demonstrate that viable growth rates of tub gurnard may be obtained by feeding recycled fishery discards and rearing in cages placed on the seabed, which allows for the natural benthic behavior of this species.

Parasitic fauna of a yellow-legged gull colony in the island of Escombreras (South-eastern Mediterranean) in close proximity to a landfill site: potential effects on cohabiting species

2015 ◽  
Vol 60 (2) ◽  
Author(s):  
Sandra Hervías Parejo ◽  
Carlos Martínez-Carrasco ◽  
Julia I. Diaz ◽  
Lidia Chitimia ◽  
Juana Ortiz ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Physical Contact ◽  
Helminth Community ◽  
Intermediate Hosts ◽  
Parasitic Fauna ◽  
Waste Landfill ◽  
Close Proximity ◽  
Larus Michahellis ◽  
Fishery Discards

AbstractWe identified the ectoparasites and helminth fauna of yellow-legged gulls (Larus michahellis michahellis), breeding near to a solid waste landfill, and compared infection levels with those of other yellow-legged gull colonies. Moreover, we analysed correlations between parasites and sex and body condition of yellow-legged gulls, co-infections and the helminth community structure in order to propose the role of this species as reservoir of certain parasites. We also discuss the potential transmission of parasites between the yellow-legged gull and the endangered Audouin’s gull, because interactions between these two species, such as kleptoparasitism and predation, occur frequently around colonies. The following species were recorded: Ornithodorus capensis (Arthropoda); Cosmocephalus obvelatus, Paracuaria adunca, Eucoleus contortus, Tetrameres skrjabini and Contracaecum sp. (Nematoda); Tetrabothrius cylindraceus (Cestoda); Acanthotrema armata, Cardiocephaloides longicollis and Ornithobilharzia intermedia (Digenea). Tetrabothrius cylindraceus, A. armata and O. capensis are new parasite records for this host. The dependence of yellow-legged-gulls on fishery discards is supported by the dominance of parasites transmitted through marine intermediate hosts with interest to fisheries in the study area. However, the shift in diet from natural resources to food derived from human activities seems not to affect the parasitic fauna of yellow-legged gull. Besides of direct physical contact between individuals in nesting and resting habitats, the high availability of fishery discards could increase the risk of Audouin’s gulls to be infected by common parasites of yellow-legged gull.

Incidental capture of Myliobatis goodei and Myliobatis ridens in artisanal fishing in southern Brazil

2017 ◽  
Vol 98 (7) ◽  
pp. 1793-1800 ◽  
Author(s):  
Priscila Rocha Vasconcelos Araújo ◽  
Juliano César Marangoni ◽  
Gonzalo Velasco
Keyword(s):  
Rio Grande ◽  
Species Level ◽  
Southern Brazil ◽  
Artisanal Fishing ◽  
Beach Seine ◽  
Incidental Capture ◽  
Pregnant Females ◽  
Disc Width ◽  
Gill Net ◽  
Fishery Discards

This study described the myliobatids caught in artisanal beach seine fisheries in southern Brazil. Fieldwork was carried out from spring 2012 to winter 2014 in Cassino Beach (Rio Grande, Brazil). Both retained and discarded specimens were identified to species level, and sex, maturity and disc width (DW in cm) were recorded. A total 359 specimens of Myliobatis spp. were recorded, of which 43.4% were from fishery discards, 31.5% from beach seine and 25.1% from drifting gill-net (‘lance de praia’, a fishery that has developed recently in the study area). Catches of myliobatids were higher in the spring and autumn. A total of 94 Myliobatis goodei (24 males, 69 females (eight pregnant) and one unsexed), and 179 Myliobatis ridens were recorded (24 males, 148 females (17 pregnant) and seven unsexed). Myliobatis goodei ranged in size from 45.0–65.0 cm DW (males) and 43.3–115.0 cm DW (females). Myliobatis ridens were 45.0–59.0 cm DW (males) and 41.2–98.0 cm DW (females). Both beach seine and gill-net fisheries operated in potential nursery areas for these myliobatid rays, as indicated by the proportionally high number of mature females (including pregnant females) and juveniles found in this study. The rays probably feed and give birth during the warmer seasons of the year (spring and summer) in these areas.

scholarly journals How fishing intensity affects the spatial and trophic ecology of two gull species breeding in sympatry

2018 ◽  
Vol 75 (6) ◽  
pp. 1949-1964 ◽  
Author(s):  
Diana M Matos ◽  
Jaime A Ramos ◽  
Joana G Calado ◽  
Filipe R Ceia ◽  
Jessica Hey ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Habitat Preferences ◽  
Isotope Analysis ◽  
Demersal Fish ◽  
Trophic Niche ◽  
Isotopic Niche ◽  
Temporal Segregation ◽  
Fishery Discards ◽  
Individual Tracking ◽  
South Portugal

Abstract Fisheries produce large quantities of discards, an important resource for scavenging seabirds. However, a policy reform banning discards, which is soon to be implemented within the EU, will impose a food shortage upon scavengers, and it is still largely unknown how scavengers will behave. We studied the diet (hard remains), trophic (stable isotope analysis), and foraging (individual tracking) ecology of two gull species breeding in sympatry: Audouin’s gull Larus audouinii (AG) and yellow-legged gull Larus michahellis (YLG), in South Portugal, under normal fishery activity (NFA; work days) and low fishery activity (LFA; weekends), over two consecutive years. We established a pattern of dietary, spatial, and temporal segregation between the two gull species. Under LFA, yellow-legged gulls reduced their time spent at-sea, thus foraging more in alternative habitats (e.g. refuse dumps) and widening their isotopic niche (i.e. generalist behaviour). Contrastingly, Audouin’s gull had a narrower trophic niche (i.e. specialist behaviour), foraging exclusively at-sea, reducing the amount of demersal fish and increasing the amount of pelagic fish in their diet. Under NFA, both species foraged mostly at-sea, feeding almost exclusively on fish, with increased consumption of demersal species (i.e. fishery discards). In general, yellow-legged gull had a broader trophic niche (i.e. generalist behaviour) when compared with the narrower isotopic niche of Audouin’s gull (i.e. specialist behaviour). Overall, both gull species relied heavily on fishery discards. However, there was visible dietary, spatial, and temporal segregation between the two species, associated with their dietary and habitat preferences that could be attributed to the availability of anthropogenic resources, such as fishery discards.

scholarly journals Mediterranean fishery discards: review of the existing knowledge

2013 ◽  
Vol 71 (5) ◽  
pp. 1219-1234 ◽  
Author(s):  
K. Tsagarakis ◽  
A. Palialexis ◽  
V. Vassilopoulou
Keyword(s):  
Resource Use ◽  
Environmental Gradients ◽  
Analytical Techniques ◽  
Ecosystem Approach ◽  
Small Scale ◽  
Small Scale Fisheries ◽  
The Mediterranean ◽  
Spatio Temporal ◽  
Legal Constraints ◽  
Fishery Discards

Abstract A considerable amount of the existing knowledge of discards in the Mediterranean Sea is presented. Discarding highly varies along the basin both geographically and among the different fishing gears with bottom trawls being responsible for the bulk of discards, since they are characterized by high discards ratios. Midwater trawls, purse-seines, and small-scale fisheries, despite their less proportion of discards per se, produce overall high discards quantities, since they are responsible for the majority of the landings. Based on the collected information, a rough Mediterranean-wide estimate of discards around 230 000 t or 18.6% (13.3–26.8%) of the catch is produced. Discarding in the Mediterranean is regulated by market demands rather than by legal constraints, and marketable bycatch may constitute an important supplemental source of income. A pattern in resource use related to socio-cultural characteristics is apparent, with welfare communities discarding more in terms of percentages. Natural conditions (e.g. environmental gradients) and fishers' strategies also substantially affect discarding. Mitigation tools mainly comprise selectivity improvement and spatio-temporal closures. Despite the progress in studying discards, needs are evident to expand monitoring schemes, apply analytical techniques, and establish objectives of the discards issue under the framework of ecosystem approach to fisheries.

scholarly journals How shearwaters prey. New insights in foraging behaviour and marine foraging associations using bird-borne video cameras

2021 ◽  
Vol 169 (1) ◽  
Author(s):  
Lucie Michel ◽  
Marco Cianchetti-Benedetti ◽  
Carlo Catoni ◽  
Giacomo Dell’Omo
Keyword(s):  
Prey Type ◽  
Foraging Strategy ◽  
Foraging Strategies ◽  
Fine Scale ◽  
Video Cameras ◽  
Natural Prey ◽  
Trade Offs ◽  
Calonectris Diomedea ◽  
Fishery Discards ◽  
The Impact

Abstract Conventional bio-logging techniques used for ethological studies of seabirds have their limitations when studying detailed behaviours at sea. This study uses animal-borne video cameras to reveal fine-scale behaviours, associations with conspecifics and other species and interactions with fishery vessels during foraging of a Mediterranean seabird. The study was conducted on Scopoli's shearwaters (Calonectris diomedea) breeding in Linosa island (35°51′33″ N; 12°51′34″ E) during summer 2020. Foraging events were video recorded from a seabirds' view with lightweight cameras attached to the birds' back. Foraging always occurred in association with other shearwaters. Competitive events between shearwaters were observed, and their frequency was positively correlated to the number of birds in the foraging aggregation. Associations with tunas and sea turtles have been frequent observations at natural foraging sites. During foraging events, video recordings allowed observations of fine-scale behaviours, which would have remained unnoticed with conventional tracking devices. Foraging events could be categorised by prey type into “natural prey” and “fishery discards”. Analysis of the video footage suggests behavioural differences between the two prey type categories. Those differences suggest that the foraging effort between natural prey and fishery discards consumption can vary, which adds new arguments to the discussion about energy trade-offs and choice of foraging strategy. These observations highlight the importance of combining tracking technologies to obtain a complete picture of the at-sea behaviours of seabirds, which is essential for understanding the impact of foraging strategies and seabird-fishery interactions. Graphical abstract

scholarly journals Favorites and leftovers on the menu of scavenging seabirds: modelling spatiotemporal variation in discard consumption

2016 ◽  
Vol 73 (9) ◽  
pp. 1446-1459 ◽  
Author(s):  
Jochen Depestele ◽  
Marie-Joëlle Rochet ◽  
Ghislain Dorémus ◽  
Pascal Laffargue ◽  
Eric Willem Maria Stienen
Keyword(s):  
Large Scale ◽  
Benthic Communities ◽  
Mitigation Measures ◽  
Spatial And Temporal Variation ◽  
Bay Of Biscay ◽  
Modelling Framework ◽  
Fishing Vessels ◽  
Fisheries Policy ◽  
Seabird Ecology ◽  
Fishery Discards

Fishery discards subsidise the food supply of a large community of scavenging seabirds, thus substantially influencing seabird ecology. Seabird preference for certain types of discards determines the number and composition of discards available for non-avian marine scavengers. To quantify both portions of discards temporally as well as spatially, we have used a modelling framework that integrates the spatial and temporal variation in seabird distribution, seabird attraction to fishing vessels, and discard distribution. The framework was applied to a case study in the Bay of Biscay, where a wide variation in discard consumption was observed across seabird foraging guilds, discard types, periods, and locations. Seabirds removed about one-quarter of the Bay of Biscay discards. The remaining sinking discards have limited potential to subsidize scavenging benthic communities on a large scale, but they may contribute substantially to scavenger diets on a local scale. Changes in food subsidies caused by discard mitigation measures, such as the “landing obligation” in the European Common Fisheries Policy, are likely to have ecosystem effects on both scavenging seabirds and non-avian marine scavengers.

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