Kerry MacKay takes a deep dive into the food chain , and how our lethal dependence on plastic has affected environment on a molecular level
ENVIRONMENT
Plastic in your fish supper ?
Kerry MacKay takes a deep dive into the food chain , and how our lethal dependence on plastic has affected environment on a molecular level
To me , diving and a fish supper are synonymous with a successful club trip , but at the same time , BSAC ’ s surveys show that members are concerned about overfishing . To that end , this month I ’ m considering how we divers can have our fish , and eat them too .
The Marine Conservation Society have a Good Fish Guide in which you can check how sustainable different types of fish are to eat . www . mcsuk . org / goodfishguide / Sadly most chippy staff don ’ t know where the fish was sourced from , but we can at least ask ; then retailers will get the message that customers want to know .
Back to the title then . Is there really plastic in your fish supper ? Before I go and scare you too much , I would like to say that I myself still enjoy the occasional bit of seafood . In fact , it ’ s still recommended to eat two portions of seafood per week for a healthy , balanced diet .
Scarily though , plastic is indeed found in the fish we eat . A review study found that 60 % of fish investigated globally contain microplastics . More disturbingly , microplastics are found in the parts of the fish we actually eat !
Plastic isn ’ t the only thing we should be concerned about . Plastic particles act like tiny magnets , attracting all sorts of other nasty chemicals in the environment . This process is called ‘ adsorption ’; it means that almost every particle of plastic consumed by a sea creature comes with a bonus dose of toxins .
These chemicals come in many forms , with some of the more notorious being mercury , PCBs ( banned toxic chemicals ) and DDT ( a toxic insecticide and organic pollutant , long banned but still present in soils and rivers ). Let ’ s not forget the chemicals in the plastic itself , which leach out chemicals such as BPA , an industrial chemical used in plastic manufacturing , linked to a number of health issues Some species are safer than others – it ’ s all to do with what they eat . Imagine a shellfish filter feeding and consuming a piece of plastic with a little bit of toxin adsorbed to it . A hungry predator comes along
“ A review study found that 60 % of fish investigated globally contain microplastics ”
and eats 10 of those shellfish . This predator now has 10x the dose of toxins . Then a bigger fish comes along and eats 10 of those , now it ’ s 100 times the dose ... and so on up the food chain .
While each microplastic particle carries only a tiny dose of toxin , over time these doses add up . This build-up is called bioaccumulation . Carnivorous fish near the top of the food chain ( such as tuna ), have more microplastics and toxins than many other fish .
Guess who ’ s considered top of the food chain in many cases ? Yup , that ’ s right , humans . I hate to break it to you , but your fish supper does indeed come packed with bonus nasties .
Let ’ s take a slightly less personal case study . Meet Lulu the Orca . Lulu lived as part of the only resident pod of Orca here on the west coast of Scotland . She was at least 20 years old when she got tangled in fishing ropes and drowned . She was found washed up on Tiree in 2016 .
Terrible as that is , here ’ s the really scary part . Scientists took the opportunity to study Lulu . They found PCB chemical levels in Lulu over 100 times the level at which they start having serious health implications !
It is assumed the whole pod is suffering from similar PCB levels . Infertility is a known effect of PCBs and this is thought to be the reason they have been unsuccessful in having a calf . The pod is now down to less than ten individuals .
PCBs , you ’ ll be glad to hear , are now banned . However , their legacy still haunts our oceans . I find it scarier that new chemicals are being released every day into our seas and we usually have no idea how harmful they are .
To put things into perspective , you consume more microplastics in bottled water than from your fish supper . But choose your fish wisely . You can pay Lulu a visit at the Natural History Museum in Edinburgh , where her skull is on display . �
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