It’s a tricky task turn­ing lar­vae into rock lob­sters

The Weekend Australian - Review - - Research Round - Up - Bren­dan O’Keefe

CHI­NESE din­ers in 2017 tuck­ing into a suc­cu­lent Tas­ma­nian rock lob­ster may have Arthur Ri­tar to thank for the treat.

It is a dis­tant sce­nario in more ways than one, but that is the way with long- range re­search. Ri­tar, a se­nior re­search fel­low and leader of the Univer­sity of Tas­ma­nia’s rock lob­ster aqua­cul­ture group, is work­ing on get­ting the lob­sters from the egg, through a dif­fi­cult lar­val stage and out the other end where they start look­ing like lob­sters.

The lar­val stage, at six to 12 months, is much longer than any other aqua­cul­ture species. In the wild it is as long as two years.

The lob­sters grow from a 1mm egg into 2mm lar­vae, end­ing as 40mm ju­ve­niles be­fore they un­dergo a meta­mor­pho­sis in which they ‘‘ be­come ob­vi­ously lob­sters’’.

‘‘ Un­til then they are a strange shape, like a flat spi­der,’’ Ri­tar says. ‘‘ We’re try­ing to de­fine the con­di­tions that are best to get them through the meta­mor­pho­sis and not die in large num­bers. We’re try­ing to de­velop cul­ture sys­tems where we can pro­duce large num­bers of ju­ve­niles in a hatch­ery. The ob­vi­ous prob­lem with lots of an­i­mals in one small vol­ume is dis­ease.’’

Ri­tar de­scribes the lar­val stage as a bot­tle­neck. With­out giv­ing away too many trade se­crets, he says he is work­ing on de­vel­op­ing the tech­nol­ogy to im­prove wa­ter qual­ity, min­imise dis­ease and im­prove the nu­tri­tion for de­vel­op­ing lar­vae. ‘‘ All our ef­forts are fo­cused on this time,’’ he says.

A com­mer­cial fish­ery could be up to 10 years away. ‘‘ We work on a long time frame and the peo­ple in­ter­ested re­alise there’s a long time scale,’’ Ri­tar says.

Very lit­tle is known about the lob­sters’ de­vel­op­ment in the wild ex­cept that they dis­perse and go through meta­mor­pho­sis, then swim back to shore and settle on rocky reefs.

There is no Aus­tralian cul­tured rock lob­ster in­dus­try but Ri­tar says there is po­ten­tially a good mar­ket for it.

‘‘ The size of the fish­ery is lim­ited and the de­mand for lob­sters is in­creas­ing world­wide,’’ he says.

Viet­nam’s cul­tured lob­ster in­dus­try pro­duces about 2000 tonnes a year but grow­ing caught ju­ve­niles from 0.5g to 1kg is a boomor- bust propo­si­tion that de­pends on nat­u­ral breed­ing fluc­tu­a­tions.

The approach at the univer­sity’s Tas­ma­nian Aqua­cul­ture and Fish­eries In­sti­tute is to go for the eggs.

‘‘ One breed­ing fe­male can lay more than 100,000 eggs and you don’t need many to sup­ply a hatch­ery,’’ Ri­tar says.

The like­li­est busi­ness model is hatch­eries for rear­ing lar­vae to ju­ve­nile stage for sale to farm­ers, who then grow them to a mar­ketable size for sell­ing them to the big ta­bles in China.

Cul­ture war­rior: Arthur Ri­tar and a friend

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