Structure in a sea of sand: fish abundance in relation to man-made structures in the North Sea

2018 ◽  
Vol 77 (3) ◽  
pp. 1206-1218 ◽  
Author(s):  
Serena R Wright ◽  
Christopher P Lynam ◽  
David A Righton ◽  
Julian Metcalfe ◽  
Ewan Hunter ◽  
...  
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Oil And Gas ◽  
Generalized Additive Models ◽  
Strong Association ◽  
Additive Models ◽  
Artificial Structures ◽  
Habitat Alterations ◽  
The North ◽  
The North Sea

Abstract Artificial structures in the marine environment may have direct and/or indirect impact on the behaviour and space use of mobile foragers. This study explores whether environmental and physical features in the North Sea—including artificial structures (wrecks, wind turbines, cables, and oil and gas structures) were associated with local abundance of three fish species: cod (Gadus morhua), plaice (Pleuronectes platessa), and thornback ray (Raja clavata). Generalized additive models (GAMs) were used to compare distributions between data collected by fisheries surveys and electronic tags. Distributions of cod, plaice, and ray were correlated with environmental variables including temperature, depth, and substrate, matching findings from previous studies. All species showed seasonal increases in their abundance in areas with high densities of artificial structures, including oil and gas platforms and wrecks. Independent of whether fish purposefully associate with these features or whether structures happen to coincide with locations frequented by these populations, the strong association suggests that greater consideration needs to be given to regulation of habitat alterations, including decommissioning.

Diel variation of stomach contents of North Sea cod (Gadus morhua) during a 24-h fishing survey: an analysis using generalized additive models

2000 ◽  
Vol 57 (12) ◽  
pp. 2363-2367 ◽  
Author(s):  
Sara A Adlerstein ◽  
Henny C Welleman
Keyword(s):  
North Sea ◽  
Stomach Content ◽  
Gadus Morhua ◽  
Generalized Additive Models ◽  
Stomach Contents ◽  
Additive Models ◽  
Large Prey ◽  
Diel Variation ◽  
The North ◽  
The North Sea

Results show that the weight of cod (Gadus morhua) stomach contents sampled in the North Sea varies significantly within 24 h. To determine whether feeding varied with time, over 1100 cod stomachs were collected around the clock between 7 and 18 May 1984 in two areas in the central North Sea thought to be representative for feeding studies. Here we investigate temporal feeding patterns based on the analysis of stomach-content data, using generalized additive models (GAMs). Results show significant variation of content weight and indicate morning and evening peaks. The relative peak importance differed between and within areas. We propose that differences are due to diet composition, namely, prey size and diel availability. Cod fed primarily on molluscs, mainly ocean quahog (Cyprina islandica), crustaceans, sandeels (Ammodytes spp.), haddock (Melanogrammus aeglefinus), herring (Clupea harrengus), and several flatfish species. In one area, the diet was dominated by fish, relatively large prey that perform diel vertical migration, and in the other by invertebrates, smaller prey that are digested faster. The diel pattern was more pronounced where invertebrate prey were dominant. Generalisation of results and implications for predation-mortality estimates based on data from the North Sea Stomach Content Database, used to implement multispecies models in the region, are discussed.

Recruitment of North Sea cod (Gadus morhua) and Norway pout (Trisopterus esmarkii) between 1992 and 2006: the interplay between climate influence and predation

2009 ◽  
Vol 66 (4) ◽  
pp. 633-648 ◽  
Author(s):  
Alexander Kempf ◽  
Jens Floeter ◽  
Axel Temming
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Generalized Additive Models ◽  
Additive Models ◽  
The North ◽  
Time Period ◽  
Spawning Stock ◽  
The Status ◽  
Temperature Ranges ◽  
The North Sea

The interplay between temperature-related processes and predation in determining age-1 recruitment strength between 1992 and 2006 was analysed for North Sea cod ( Gadus morhua ) and Norway pout ( Trisopterus esmarkii ). For this purpose, an predation impact index (PI) was calculated out of survey data. PI was assumed to depend on the abundance of the predators and on the spatial overlap between predator and prey populations. Generalized additive models (GAMs) were created with spawning stock biomass (SSB) and sea surface temperature (SST) in the respective spawning and nursery areas and PI as explaining variables. SSB had no significant impact on recruitment during this time period for both species. SSTs during spring and PI explained the interannual variability in recruitment strength to a large extent (88% of the total variance for cod and 68% for Norway pout). The SST during spring determined the overall level of recruitment. At SSTs above a certain level, however, the effect on recruitment was no longer significant. In these temperature ranges, predation was the dominant effect. Therefore, the fate of North Sea cod and Norway pout stocks under global-warming conditions will be strongly influenced by the status of the North Sea food web.

An "experiment" on effort allocation of fishing vessels: the role of interference competition and area specialization

2007 ◽  
Vol 64 (2) ◽  
pp. 304-313 ◽  
Author(s):  
Jan-Jaap Poos ◽  
Adriaan D Rijnsdorp
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Seasonal Pattern ◽  
Interference Competition ◽  
Catch Rate ◽  
The North ◽  
Closed Area ◽  
Fishing Vessels ◽  
The North Sea

A temporarily closed area established to protect spawning Atlantic cod (Gadus morhua) in the North Sea allowed us to study the response of the Dutch beam trawl fleet exploiting common sole (Solea solea) and plaice (Pleuronectes platessa). A number of vessels left the North Sea 1 month earlier than the normal seasonal pattern. The vessels that continued fishing in the North Sea were concentrated in the remaining open areas. In the first week after the closure, the catch rate decreased by 14%, coinciding with an increase in crowding of 28%. Area specialisation affected the response of individual vessels because vessels without prior experience in the open areas showed a larger decline in catch rate compared with vessels that previously fished in these open areas and were more likely to stop fishing during the closed period. The decrease in catch rate in response to the increase in competitor density allowed us to estimate the strength of the interference competition.

scholarly journals A prospective observational study of why people are medically evacuated from offshore installations in the North Sea

BMJ Open ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. e037558
Author(s):  
Anne Waje-Andreassen ◽  
Øyvind Østerås ◽  
Guttorm Brattebø
Keyword(s):  
Observational Study ◽  
North Sea ◽  
Prospective Observational Study ◽  
Oil And Gas ◽  
Record System ◽  
The North ◽  
Transport Services ◽  
Offshore Installations ◽  
Severity Scores ◽  
The North Sea

ObjectivesFew studies have described evacuations due to medical emergencies from the offshore installations in the North Sea, though efficient medical service is essential for the industrial activities in this area. The major oil- and gas-producing companies’ search and rescue (SAR) service is responsible for medical evacuations. Using a prospective approach, we describe the characteristics of patients evacuated by SAR.Design and settingA prospective observational study of the offshore primary care provided by SAR in the North Sea.MethodsPatients were identified by linking flight information from air transport services in 2015/2016 and the company’s medical record system. Standardised forms filled out by SAR nurses during the evacuation were also analysed. In-hospital information was obtained retrospectively from Haukeland University Hospital’s information system.ResultsA total of 381 persons (88% men) were evacuated during the study period. Twenty-seven per cent of missions were due to chest pain and 18% due to trauma. The mean age was 46.0 years. Severity scores were higher for cases due to medical conditions compared with trauma, but the scores were relatively low compared with onshore emergency missions. The busiest months were May, July and December. Weekends were the busiest days.ConclusionThree times as many evacuations from offshore installations are performed due to acute illness than trauma, and cardiac problems are the most common. Although most patients are not severely physiologically deranged, the study documents a need for competent SAR services 24 hours a day year-round. Training and certification should be tailored for the SAR service, as the offshore health service structure and geography differs from the structure onshore.

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