M4 AM Endocrine Disruption in Fish
Monday, 14 November 2005: 8:00 AM - 11:40 AM in Ballroom 4

(SCO-1116-518416) Evidence for estrogenic endocrine disruption in the open sea.

Scott, A¹, Hylland, K², Katsiadaki, I¹, Witthames, P³, Thain, J⁴, ¹ Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Weymouth, Dorset, UK² NIVA, Oslo, Norway³ Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Lowestoft, Suffolk, UK⁴ Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Burnham-on-Crouch, Essex, UK

ABSTRACT- In 2002, CEFAS started to look for evidence of estrogenic endocrine disruption in the Atlantic cod (Gadus morhua), a species that lives its entire life cycle in the open sea. Collections of cod have now been made from several areas on the continental shelf. In at least three of these areas (off Iceland, the Shetland Box and the southern North Sea) male cod have been found with elevated levels of VTG. Furthermore, elevated VTG levels in males show a strong positive correlation with the size of the fish. These findings raise several questions, the main ones being: are elevated VTG levels a sign of endocrine disruption or of a natural aging process in males? is endocrine disruption a problem for the cod (perhaps being linked to the sharp decline of this species in the North Sea)? is it a problem for the consumer? The synthesis of VTG by the liver requires estrogen stimulation. Thus, if VTG in males were a natural process, we would expect to find elevated estradiol concentrations in the plasma of those males that also have elevated VTG. This we have not found (and nor have we found any of these males to be intersex). It thus seems probable that the causative agent is of external origin. We hypothesise that large cod pick up estrogenic compounds via the food chain. This hypothesis is based upon the fact that the size of fish at which VTG levels rise sharply (ca. 5 kg) is also the size at which cod change their diet from mainly nektonic (free-swimming) to benthic (bottom-living) organisms. We acknowledge the financial support of CEFAS and DEFRA.

Key words: Cod, Gadus morhua, endocrine disruption, vitellogenin, xenoestrogens in cod, endocrine disruption, marine environment, endocrine disruption in the open sea