SEALS AND SEAL PROTECTION - A PRESENTATION OF A SWEDISH RESEARCH-PROJECT

A 4-year research project, Seals and Seal Protection, is presented. The background and the organization of the multidisciplinary project is summarized. The study aim was to investigate the possible effects of contaminants on seal populations in Swedish waters. Contaminants in Swedish waters are similar to those found in waters all over the world and the contaminant problems are thus of international concern. The project included population studies on three different species, namely harbor seal (Phoca vitulina), grey seal (Halichoerus grypus) and ringed seal (Phoca hispida). Studies on seal-skull collections have been carried out in order to study changes over time in the prevalence of skull-bone lesions. Tissue concentrations of 17 metals and non-metal elements and various organohalogen compounds have been determined to disclose differences in contaminant concentrations related to species, geographical areas, age, sex and health status. Experimental studies have been carried out investigating biological effects on mink (Mustela vison) exposed to commercial PCB and PCB fractions. Fractions have been selected on the basis of number of chlorine atoms in ortho-position of the biphenyl bond and contaminants in the mixture such as polychlorinated dibenzofurans and naphthalenes. Comparative studies on various species studying the toxicity of methylsulfonyl metabolites of DDT have also been carried out.