Boat­ies asked to stop slimy marine pest


As the weather warms up and the glis­ten­ing Hau­raki Gulf beck­ons, boat­ies are be­ing asked to clean their hulls to slow the spread of the in­va­sive sea squirt Eud­is­toma elon­ga­tum.

A na­tive of Aus­tralia, it was first spot­ted in oys­ter farms in Houhora Har­bour 12 years ago, and has now spread through­out the north.

Able to sur­vive be­ing out of the wa­ter be­tween tides also makes it is a sig­nif­i­cant nui­sance for mus­sel and oys­ter farm­ers.

While not poi­sonous or toxic, the squirt breeds in clus­ters of slimy white tubes that grow from five cen­time­tres to more than a me­tre long and from 5 mil­lime­tres to two cen­time­tres thick.

It ac­counts for about half of the marine waste on north­ern oys­ter farms dur­ing sum­mer, North­land Re­gional Coun­cil Biose­cu­rity Of­fi­cer, Cameron Bun­ton said.

Sand, mud, wharf piles - the fast grow­ing pest grows al­most any­where. It com­petes with na­tive species for space, and fil­ter feeds on the eggs and lar­vae of na­tive marine life.

Wark­worth marine bi­ol­o­gist Roger Grace spot­ted it at Sand­spit seven years ago.

He then raised con­cerns that dredg­ings, from the Sand­spit Ma­rina build, dumped near Cu­vier Is­land, could help spread the squirts in the gulf.

Found in Oakura Bay on Wai­heke Is­land last year, it is now in the Mahu­rangi Har­bour.

The tubes are in­cred­i­bly dif­fi­cult to con­trol or pick off, as they grow back and spread from bro­ken bits, Auck­land Coun­cil Marine Biose­cu­rity Ad­vi­sor Sa­man­tha Happy ad­vised.

It is a par­tic­u­lar risk to moored boats in mari­nas that may not get cleaned or taken out reg­u­larly, she said.

Some Sand­spit boats al­ready have the squirts on them, Grace said.

In an ef­fort to slow its spread in the Hau­raki Gulf, Auck­land Coun­cil is ask­ing boat­ies to check their boat hulls and keep them clean.

Pon­toons have also spread the pest in the north, Bun­ton said.

‘‘The pest will change our beau­ti­ful fore­shores as we know it, for­ever, and is nearly im­pos­si­ble to con­trol once it’s es­tab­lished,’’ Happy said.

Any­one who sees marine pests out­side of recorded sites can re­port it to the Min­istry for Pri­mary In­dus­tries on 0800 80 99 66.

For ad­vice, con­tact Auck­land Coun­cil biose­cu­rity on (09) 301 0101.


The marine pest Eud­is­toma elon­ga­tum has been found at Sand­spit and the Mahu­rangi Har­bour.

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