Update and information about the dead spermwhales, stranded in the german north-sea in the beginning of 2016
As we reported earlier this year (february) during winter 2015/2016 lots of young spermwhale-bulls stranded at the german north sea.
Meanwhile, investigative results about their autopsy (Stiftung Tierärztliche Hochschule in Hannover; GEOMAR Kiel; u.a.) were published. According to the report, the marine mammals died during their stranding as a result of a collapse of their cardiovascular system. Probably the animals got into the shallow north sea shore, when they followed their prey. If big whales touch the ground, then it is often impossible for them to reverse. Because of their body weight, they then get crushed to death. The weight of the stranded whales was in average 12-18 tons. Which is a normal weight, so it can be assumed, that the animals were sufficient nurtured.
Stranded whales can provide many kind of informations. Tissue samples offer valuable clues of different parameters. With the help of teeth, experts can determinate age and due to the condition of the whales inner ears, they can see, if the animals suffered from acustic traumata (military manoever with sonar testing; explosions, etc.). Especially the contents of their stomachs informs about what they had eaten and maybe in indirectly way also, from which area they came.
During the dissection of the spermwhale carcass, the scientists found a big amount of plastic in the stomaches of some animals. Amongst other things, they found a big fishing-net, which is used in the shrimpfishing industry. It is clear, that such kind of stomach content is not a very healthy one. Eventhough, it is not the reason for their strandings, the affected animals would have received certainly health problems in the future. So again, the discovery of plastic inside of marine animals shows, again, the poor conditions of our oceans. This awareness is not a new one. Already 25 years ago, we could read about perished albatross, which had fed their chicks with plastic parts. They starved to death with a filled belly of plastic.
Meanwhile the “plastic waste” – topic is disscused regulary in the public. Especially the small plastic parts, the so called “microplatic” (smaller than 5 mm), which has reached enormous quantities in the ocean, is dangerous. Small marine organisms absorb the microparts (mistake them for plancton) and accumulate the plastic in their bodies. Thats how plastic is entering the marine food web, up to the edible fish on our plates. And even worse, at the surfaces of the micro plastic parts, toxic substances (which floats in the oceans anyway) enrich. So with the plastic, also chemical pollutants reach the foodweb. Finbackwhales, which lives in certain parts of the mediteranean sea, were monitored (collection of skin biopsy samples) and showed higher concentrations of poisonous substances in their bodies. Most probably, these whales have an higher impact on the plastic-chemical pollution because they are filter-feeders (eating small parts, planctonic organisms). According to investigations of an italian institute, more than 76 % of the collected microplatic parts originated from packaging material like plastic bags and bottles.
by Astrid Haas
Copyright pictures: Stiftungtierärztliche Hochschule Hanover