It may taste good, but is it good to eat? Recent chemical analysis of tissue samples from organisms living in environments that were once considered “pristine”, such as the far north or the open ocean, are showing worrying levels of accumulated toxins such as heavy metals. Is this an isolated phenomenon in a few isolated species, especially long-lived species, or is this a widespread environmental concern?
Inger Marie Tyssebotn
Masters / University of Bergen, Department of Chemistry and the National Institute of Nutrition and Seafood Research (NIFES).
”Metal content in deep water fish from the Mid Atlantic Ridge: Orange Roughy (Hoplostetus atlanticus)”
Masters’ student Inger Marie Tyssebotn is undertaking a fascinating research project to analyse the bioaccumulation of heavy metals and other environmental toxins in the flesh of a popular menu item in North America and New Zealand; the orange roughy.
Living far from land around seamounts and ocean ridges, the orange roughy was first commercially exploited in the 1970s, when concentrations were discovered and technology made the exploitation of such remote environments more economically feasible.
The fish quickly became a popular menu item because of its firm white flesh (that freezes well), mild flavour, and the fact that it is low in fat.
Today the fishery for orange roughy is conducted in many waters around the world, including on the mid-Atlantic Ridge, but the resource is limited and not very productive, so strict regulations have now been introduced in order to avoid the severe depletion of stocks observed in some areas.
Although Tyssebotn moved to the United States during her teens and completed a Bachelor’s degree in chemistry, with a major in environmental analytical chemistry there, she decided to return to Norway to do her Masters’ studies. Registered at the University of Bergen, she is taking advantage of the unique multidisciplinary collaboration between UiB’s Department of Chemistry and the National Institute of Nutrition and Seafood Research (NIFES).
The UiB-NIFES collaboration provides students with theory, training and practice from both institutions. According to UiB Chemistry Professor, Leif Sæthre, this collaboration has been working successfully for several years and a number of students have taken multi-disciplinary degrees with both institutions. In Tyssebotn’s case, he explains, the NIFES collaboration permitted Inger Marie to use the extensive and advanced laboratory resources at NIFES to conduct her analyses, in particular ICP-MS analysis or inductive coupled plasma mass spectroscopy analysis.
Orange roughy fisheries have been described as ‘boom and bust’ commercial phenomena. This is related to the orange roughy’s biology. Orange roughies are very slow growing, are long-lived (believed to be as long as 150 years, not being sexually mature until around 30) and they tend to aggregate to feed and breed. As a result they are vulnerable to over-fishing, particularly to modern commercial trawling.
Tyssebotn’s project, however, will investigate another aspect of this fishery, that of food safety. It may be that such a long-lived species can accumulate toxins to levels that are harmful for human consumption.
Tyssebotn is using orange roughies collected on the MAR-ECO Project’s 2-month research cruise along the northern mid-Atlantic Ridge summer 2004. There were not too many roughies in the collection, as this species while targeted proved difficult to sample in satisfactory numbers, however, the exploratory and multi-depth collection methods used meant that roughies from different age groups and of many different sizes were collected.
Sæthre explains that although there are relatively few fish being studied, Tyssebotn is undertaking analyses from a broader range of organs than is usual in this type of study including samples from muscle and bone and cartilage tissue, the liver, kidney, and gonads.
NIFES has long experience in food safety research. Tyssebotn will use their specially developed protocols to chemically analyse the roughy material to determine the presence of metals (manganese, cobalt, copper, zinc, molybdenum, cadmium, tin, mercury and lead), and non-metals (arsenic and selenium). When completed, the results will reveal valuable information about some food safety aspects of this vulnerable deep-sea fishery.
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