Research Report

Record of Litter Ingestion by Cod (Gadus morhua) Collected from Masfjorden, Western Norway  

Laith A. Jawad1 , Odd-B. Humborstad2 , Per G. Fjelldal3
1 Flat Bush, Manukau, Auckland, New Zealand
2 Institute of Marine Research (IMR), Bergen, Norway
3 Institute of Marine Research (IMR), Matre Research Station, Matredal, Norway
Author    Correspondence author
International Journal of Marine Science, 2016, Vol. 6, No. 41   doi: 10.5376/ijms.2016.06.0041
Received: 26 Aug., 2016    Accepted: 10 Oct., 2016    Published: 19 Oct., 2016
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Jawad L.A., Humborstad O.B. and Fjelldal P.G., 2016, Record of Litter Ingestion by Cod (Gadus morhua) Collected from Masfjorden, Western Norway, International Journal of Marine Science, 6(41): 1-4 (doi: 10.5376/ijms.2016.06.0041)


We present the finding of a wild caught Atlantic cod (Gadus morhua) that had ingested a metal beverage can, common marine debris. The can was detected when the fish was radiographed alive as part of a scientific experiment. A possible cause for the death of the fish was the blockage of the digestive tract by the can. Due to paucity in marine debris monitoring programs and lack of impact studies of diverse marine debris in Norwegian waters it is not possible to assess the scale and extent of the effects of this type of pollution on cod and other species.

Pollution; Anthropogenic debris; Ingestion; Marine debris; Atlantic Cod (Gadus morhua)


Aquatic debris of anthropogenic origin has been paid attention internationally for some time (Miranda et al., 2016), and the aquatic environment has shown to be severely affected by the impact of these materials (Lusher et al., 2013).


Since the second half of the 20th century, there are many reports on ingestion of aquatic debris by different organisms all over the word (e.g. Kühnet al., 2015). Ingestion of aquatic debris can cause wounds, ulcerating sores, blockage of the digestive tract leading to starvation and death, reproductive inability, and failure to avoid predators (Oehlmann, 2009; Wright et al., 2013). In nature, fish are likely to come in contact with debris and get affected, but the likelihood is lower if compared with seabirds or turtles, where the prevalence of plastic ingestion is high (Van Franeker et al., 2011). So far, there are 18 species of rays/sharks, and 74 other fish species that have been found to ingest marine debris (Kühn et al., 2015). In the family Gadiedae, there are report on ingestion of marine debris (e.g. Foekema et al., 2013), and plastics (Rummel et al., 2015), such as plastic cups (Hoss and Settle, 1990).


Plastic materials are the most common debris that is ingested by fish and other aquatic animals (Van Franeker et al., 2011). Other materials with different sizes such as fishing net scraps, and pieces of wood and ropes have also been reported to be ingested by fish (Laist, 1997; Possatto et al., 2011). Much of the marine debris stems from consumer goods, and beverage cans, bottles and alike are one of the commonest marine debris found (Sheavly and Register, 2007). In Norway, there are several newspaper reports on different debris, including beverage cans in the stomach of Atlantic cod (Gadus morhua, Linnaeus, 1758), a commercially important species.


Except for the historical record by Gudger (1949) on a shark that had ingested a tin, there are no reports on such incidence. The aim of the present study is to report on this subject, which is an important aspect of sea pollution by debris, and its effect on marine organisms. It is about an unusual incident of a cod individual ingesting a beverage can and its potential impact.


1 Material and Methods

The 680mm (TL) and 2888g specimen used in this study was caught at depth of 4 meters in a fyke net in the inner part of Masfjorden, a narrow fjord in Western Norway, which is a relatively undisturbed area, with few people living there and very little boat traffic. The fyke net is a traditional fishing gear for costal cod in Norway, which consist of a leader connected to a funnel shaped trap. The fyke net was put out on 15th November 2013. The fyke net was collected on 21st November 2013. In total, 14 cod were caught. On the day of collection, the fish was radiographed with a Porta 100 HF (Eickemeyer Medizintechnik für Tierärzte KG, Tuttlingen, Germany) at 40kV and 10 mAs onto a 35x43cm image plate in a rigid cassette (Dürr Medical, Bietigheim-Bissingen, Germany) from 70cm above. The image plate was subsequently scanned with a CR 35 VET, Dürr Medical and converted into a digital TIFF file with Vet-Exam plus Software, version 4.14.0. The images were further processed using Adobe Photoshop, version CS2. During evaluation of the radiographs we detected the cod with the can inside the stomach. After the radiological examination all 14 fish were put at 40 meters depth inside a pot to study barotrauma effects in a separate study (Humborstad et al., 2016).


2 Results and Discussion

At the same day as the specimen was caught it was put at 40 meters depth inside a pot with 13 other cod. At this stage the fish was alive and active. Four days later a video record showed a motionless cod inside the trap. On 2nd December 2013, when the pot was brought to the surface, the fish was found dead inside the pot.


The fish had decomposed to a state where dissection was no longer possible. Neither had the radiographs been analyzed, so we did not know the presence of the can at this stage, and it was for that reason not retrieved. The can observed inside the stomach of the cod was not a full length can (344 mm), only the top of the can with a diameter of 67 mm was left, and it looked from the radiograph that the lower part was eroded away or chopped off (Figure 1).


Figure 1 Radiograph of a cod (Gadus morhua) with a beverage can in the stomach. Undigested bone (arrowhead) and beverage can (asterisk).


The presence of undigested bone in the front of the can (Figure 1) may suggest that the can was blocking the normal passage through the digestive tract. When trapped in fyke nets, cod often eat smaller fish that are also trapped inside the net (authors own observation). The cod in the present study may have had a reduced feeding capacity due to the ingestion of the relatively big can; being able to feed on easily caught prey inside the trap, the cod may have ingested more than it could handle with a blocked digestive tract. In addition to the blockage of the intestine by the beverage can, there might have been other factors that caused the death of this fish. Damage of the internal organs or tissues by the piece of litter such as can, the possible infection by germs transferred to the fish by the can, and the stress condition that the fish was in is all plausible reasons for the death of this fish.


The present finding of a tin can inside the stomach of a cod along with several newspaper reports on similar cases in Norway, especially in urban areas, sheds light on the ability of fish to ingest such hard and large materials on one hand, and it conveys a message to the decision makers to take extra measures to limit the amount of debris that finds its way to the aquatic environment.


The works of Van Franeker et al. (2011), Foekema et al. (2013) Trevail et al. (2015) and Herzke et al. (2016) showed that the coasts of Norway have different levels of pollution by marine debris, which in turn have impacts on the marine organisms in this part of the world.


Though significant advances in degradable materials are being developed, the preventive actions of avoiding marine debris in the first step should be strengthened. Prevention, reduction and control of marine debris should be obtained through an effective collaboration of education, legislation and innovation (Sheavly and Register, 2007).



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