a blueprint for mussel farm design - … 04.pdf · issue 04 march/april 2005 $5.00 a blueprint for...

ISSUE 04 ■ MARCH/APRIL 2005 $5.00

A blueprint for mussel farm design

Looking at diseasesin aquaculture

Shellfishbreeding a first LINES IN THE WATER

– a history of greenshell mussel farming

A blueprint for mussel farm design

LINES IN THE WATER– a history of green

shell mussel farming

AQUACULTURE mar/apr 05 13/2/05 9:23 PM

2 ■ NZ AQUACULTURE MAR/APR 05

EDITOR: Keith Ingram

MANAGER: Vivienne Ingram

EDITORIAL ASSISTANT:Mark Barratt-Boyes

CONTRIBUTORS:Andrew Morgan, Ian Horne,Peter Stevens, Amanda Steenhart,Michelle Hollis, Ben Dingles, Craig Stevens, Bob Spigel

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3 EDITORIALThe strength of unity should never be squandered, says guest editor Peter Stevens

4 NEWSA look at what’s happening in the industry

5 GRASS CARP CLEAR EXOTIC WEEDSAs well as controlling weeds, Chinese grass carp are featuring on restaurant menus

6 PROACTIVE APPROACHES TO DISEASE PROBLEMS INAQUACULTUREDisease prevention should be an important part of a business plan

8 A BLUEPRINT FOR BETTER MUSSEL FARM DESIGNWaves are the biggest hurdle facing offshore mussel farmers

10 BOOK REVIEWThinkers and tinkerers started the mussel industry

11 LIFE IN THE FREEZERA New Zealand project has achieved success in cryopreservation

14 ANIMAL HUSBANDRY AND MATURATION IN THE HATCHERYA good understanding of systems biology is important

CONTENTS

5 8 11

ISSN 1176-5402 ISSN 1176-8657 (web)

ON THE COVER:Lady Marie

harvesting a line forthe Marlborough

Mussel Co. PhotoCourtesy NZMFA

AQUACULTURE mar/apr 05 13/2/05 9:13 PM

Positive is elusive and like democracy has to becontinually nurtured in order to survive. Negative, onthe other hand, is always just around the corner and

needs no invitation to visit.As someone who has written and reported a fair bit about the

aquaculture industry over past years, I have come to the pointwhereby I have to confess that it’s getting harder to write aboutthe industry, in the sense that it’s becoming impossible to avoidrepetition by covering the same old territory.

You know the sort of thing.Why aren’t we realising thepotential of the industry? Why isn’t officialdom doing more toremove the barriers? Why are we lagging behind other countriesin getting behind our marine farmers? Why have the necessarylegislative requirements always been relegated to the back burner?

There are far too many negatives, and there is a natural limit asto how many times one can repeat them without fosteringdepression and creating an unproductive aura of gloom and doom.

At various stages right from the small beginnings of theaquaculture industry, various governments have declared thatthey will fix things once and for all and assist the industry tomove forward. On each of those occasions I’m sure that those inthe industry have breathed a sigh of relief and looked forward toa positive future with renewed confidence.At long last, theywould have thought, someone is listening and taking notice.

However, their hopes have ended up being dashed on therocky shores of the sea of procrastination, bogged down in theswamp of political maneuvering or tangled in webs ofbureaucratic red tape.The latest “fix it once and for all” moveseems now to be the granddaddy of them all, and the light at theend of the tunnel has almost flickered out. Not for those alreadyestablished, of course, but it must be remembered that many, ifnot all, had a hard row to hoe in order to get their operation upand running.They will have to maintain the status quo for some,and it’s to be hoped that they will, instead of taking their capitaland expertise offshore.

I don’t think that it is entirely a one-way street in terms of theproblems facing the industry, and many participants shouldshoulder some of the blame. It’s no secret that on manyoccasions industry participants have opposed progress, if notexactly overtly then at least covertly.

Some farmers have opposed development out of fear thattheir market opportunity would be eroded. In taking thatstance they ignore the rules and benefits of critical mass.They seem to ignore the actual size of the potential market,

which is not domestic but global.The industry didn’t really move until production reached a

certain critical mass and developed the ability to fill orders withvolume and certainty.There are those who have opposed thesiting of new farms in locations near their own out of the fearthat their farm may suffer from reduced plankton flow-by.That isa genuine concern of course where farms have been sited inareas of low nutrient production and/or bad flow, but that, moreoften than not, is not necessarily the case.

When an industry is divided on issues, and that divisionbecomes evident to policy makers and officials, everybody in theindustry pays a price.The strength of unity, both in terms ofpurpose and numbers, is a priceless asset that should never besquandered.The organisations that oppose marine farming areheeded because they can claim large numbers - numbersincidentally, that they work hard to maintain, in the certainknowledge that without them they have no clout whatsoever.

Personally, I am of the opinion that the mussel industry, giventhe right backing and encouragement, could have (dare I sayshould?) been producing $1 billion worth of product by now.Youhave no idea how mixed the reactions are when I voice thatopinion in aquaculture circles.

Impossible is one retort - we’d never market that much in amillion years.Well, I think (but don’t say), the seafood industrywent from $25 million to $1.5 billion in something like 25 years.Others say we’d never get enough space. I think, hell, it wouldonly take four times the space currently under production - noteven as much in total as a large sheep or cattle farm.

Others who are still happy with the cottage farming lifestyleshiver at the thought, and probably think - who brung him? Therest say, you’re dead right.We could and should, and given theright breaks we certainly would!

I am still certain that the mussel farming industry will reachthat level of production at some future time and perhaps evenexceed it.The pity of it, in my estimation, is that it could havebeen raised significantly towards that level or up to it by now, andthe benefits realised both in confidence and fiscal return.

As it now stands, the costs of litigation and the legal expensesassociated with space applications will increasingly erode a largeproportion of the working capital required for essentials such asropes, floats, anchors, machinery and vessels.

I sincerely hope that the industry can hold together and thatthe future provides some really positive aspects uponwhich to comment.

MAR/APR 05 NZ AQUACULTURE ■ 3

WHAT PRICE POSITIVE?BY PETER STEVENS

EDITORIAL

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AQUACULTURE mar/apr 05 12/2/05 6:51 AM


BRAKES COME OFFAQUACULTUREINDUSTRYThe $1 billion-a-year potential of NewZealand’s aquaculture industry can now berealised with the passing of the AquacultureReform Bill, says Fisheries Minister DavidBenson-Pope.The bill passed its final readingon December 15 by 83 votes to 36.

In November 2001 a moratorium wasplaced on the issuing of new consents formarine farms to allow for the creation of anew management regime.This was inresponse to the “gold rush” for space thathad developed within the industry.

The act had created a new regime underthe Resource Management Act, and enabledcouncils to effectively manage aquacultureand encourage the aquaculture industry todevelop in a sustainable way, he said.

“While it has taken time to reach thispoint, I am confident we have come up with aworkable solution that will take us into afuture that will see the exciting potential ofthe marine farming industry realised.

“We have acted to protect the coastlinefor all users.The whole purpose of thereform is to provide clarity and certainty tousers, which was not there before.”

Benson-Pope said the aquaculture industry

would provide many regions of New Zealandwith new employment opportunities, andrepresented an important economic driver,especially in rural coastal areas where growthand job opportunities were needed most.

“This new legislation has created a soundand well thought out platform from whichstrong future development can take place. I’mconfident that it balances economicdevelopment, environmental sustainability,Treaty obligations and community concerns.”

Maori interests in commercial marinefarming space had also been addressed byproviding iwi, where possible, with 20 percentof marine farming space allocated since 1992,and 20 percent of any future new space, theminister said.

“This is an important step. Settlingcontemporary commercial claims removes amajor impediment to progress and certainty.This is consistent with the 1992 FisheriesSettlement - aquaculture being the unfinishedbusiness of that legislation.”

PARTY SAYS REFORMSCAUSE CONCERNThe National Party says it is still opposedto the new Aquaculture Reform Act,though it acknowledges that the SelectCommittee process has changed significant

aspects, says the party’s spokesperson forfisheries, Phil Heatley.

Heatley said the allocation of up to 40percent of new marine farming space to beset aside for Maori addressed what isreferred to as “the unfinished business” ofthe 1992 Fisheries Settlement. “We calledfor, but have not received, any historicdocumentary evidence that proves therewas such unfinished business, despiteassurances that such evidence existed.”

Under the terms of the act, the Crown isto use marine farming applications put “onhold” by the moratorium to settlecontemporary Maori claims. “That anapplicant’s space can be re-allocated tosomeone else is unfair; the settlement ofone grievance will create another,” he said.

Most Maori submitters did notacknowledge this action as a “settlement”,as there was no negotiation.There was nodeed of settlement to point to, unlike withthe 1992 Fisheries Settlement. He said theNational Party saw the Treaty Settlementapproach, which gave preferential tenderingrights for aquaculture space, was asatisfactory way of addressing aquacultureclaims that have merit.

“Such settlements with iwi should beaddressed on a case-by-case basis and besolely between the Crown and Maori, notinvolving or interfering with theoperations of current or future marinefarmers.”

National was still concerned that theundue adverse effects test and associatedprocesses might not fully solve the conflictbetween commercial fishing and marinefarming. It also had concerns over regionalcouncil’s abilities to quantify and qualifyaquaculture’s other effects on fishingbesides access issues, such as spawning andstock development.

An incumbent marine farmer should havepriority over a newcomer due to their pre-existing investment. Marine farmers shouldask for a right of first refusal to providecertainty, and it was vague and subjectivethat incumbents had to manage their farmsaccording to “industry good practice” togain renewal.

Further, regional councils were able tore-tender out occupied space if theydeemed it “necessary”. “We havereservations over whether theserequirements and tests are sufficientlyrobust to provide the certainty thatensures ongoing investment in thisvital industry.”

NEWS

NATIONAL BIOSECURITY CENTRE PLANNEDThe government has approved in principle the establishment of a National Centre forEmerging Diseases and Biosecurity at Wallaceville, Upper Hutt.

The new centre would add significantly to the country’s ability to safeguard human andanimal health and to protect the economy. It combines state-of-the-art EnvironmentalScience and Research laboratories and new staff with the existing facilities at the Ministryof Agriculture and Forestry National Centre for Disease Investigation and AgriQuality.

Biosecurity Minister Jim Sutton said on November 26 that the proposal would enhanceNew Zealand’s ability to provide animal health protection and biosecurity services. It wouldalso enable an enhanced proactive, national response to human diseases such asmeningococcal and influenza epidemics.

“Biosecurity is extremely important to New Zealand, and the government takes itsresponsibilities to ensure that foreign pests and diseases don’t establish in New Zealandseriously,” Sutton said.

The Minister for Crown Research Institutes, Pete Hodgson, said the addition of new ESRpersonnel and facilities would boost New Zealand’s ability to monitor and respond to new andemerging human and animal health disease threats, such as SARS and avian influenza variants.

“It would be a very significant move. It would concentrate our best scientists in the fieldin a single place where they can all work together using the very best facilities.”

Aquaculturalists will find the costs of business compliance should drop significantly withthe passing of the Fisheries Amendment Act, says the Ministry of Fisheries.The act, whichintroduced many new species into the quota management system, removed many of theextensive rules, constraints and limitations that had previously been necessary.

One example was that fishers wanting to harvest mussel spat from Ninety Mile Beachhad previously required two sets of exemption permits because of moratoriums onharvesting seaweed and spat around the beach. As from October 1, if they wish to catchspat, they use their annual catch entitlement or pay the deemed value. ac


Chinese grass carp are a freshwater herbivore, native toChina.While they are proven to be an efficient weedcontroller in New Zealand, more recently they have beencommercially bred and are developing a market niche in therestaurant trade.

First introduced into New Zealandby the University of Auckland in1966, grass carp should not to beconfused with their distant cousin,koi carp, “the possum of thewaterways”. Grass carp are abeneficial fish stock, introduced as abiological weed control agent andassisting in clearing exotic weedfrom farm drainage channels anddams.

LETTERSOCEAN RANCHINGDear Sir

Congratulations on the first two editions of this new Aquaculture magazine. Pleasing to see some of the range of articles - hopefully weshould be able to contribute to these in the future.

One of the difficulties with a periodical such as this is timing, and many of our stories reflect very much the immediacy of an issue.Therewill continue to be things about the Resource Management Act which will be topical if not controversial.There are some greenish elementswho believe what they read on the web from their fellow antagonists, and translate contentions or allegations as fact in New Zealand(especially when they were not facts in the first place) - it is always a struggle to get balance in these things, as negativity sells first!

I notice in your latest editorial the suggestion that ocean ranching would be a boom. Unfortunately, not only was it not successful in NewZealand in the 1980s but it has since died an economic death throughout the globe as margins have got finer and finer for the big industrialgrowers in the northern hemisphere.We have looked at this carefully and it simply does not work on any scale.

So, best wishes for 2005 and with NZ Aquaculture.Paul Steere, Chief Executive,The New Zealand King Salmon Co Ltd

Thanks Paul for your comments on the viability of ocean ranching of salmon.While salmon have proved uneconomic, I still believe we have a numberof species that would be viable. Paua is an obvious example. Ed...

However, as their reproductive cycle is extremelycomplicated, they cannot naturally reproduce in this country.An early breeding programme by the National Institute forWater and Atmospheric Research was not commerciallyviable, and did not survive the 1990s government researchscience reshuffles.

Crown negotiations resulted in the entire brood stock of 11fish being taken over by New Zealand Waterways RestorationLtd, a private company which remains the country’s only grasscarp suppliers.

So, as they are unable to reproduce in the wild, every kiwigrass carp is born at the same place - Warkworth, the home ofthe Mahurangi Technical Institute.The aquaculture tertiaryeducation provider is a partner in the grass carp breedingprogramme with NZ Waterways Restoration.

The two key figures behind New Zealand grass carp are themanaging director of NZ Waterways Restorations, GrayJamieson, and the director of the Mahurangi TechnicalInstitute), Paul Decker.

There may be something to be said for the success of privateenterprise’s entrepreneurial approach versus governmentresearch, though Paul points out that without the earlier NIWAdata, the Warkworth success wouldn’t have happened.

“Grass carp require considerable manipulation of watertemperature, light and water quality to come into egg, andthat’s only the start of it,” he says.

Grass carp are highly rated as a table fish among NewZealand’s Asian community, with many stating that the NewZealand fish has better texture and flavour than thoseproduced in China.

This January, NZ Waterways Restoration completed a jointventure farming and marketing project with Lake OmapereTrustees to supply live fish from Lake Omapere (40,000fish stocks) to the Auckland restaurant trade.

GRASS CARP CLEAR EXOTIC WEEDSBY AMANDA STEENHART

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Dr Tagried Kurwie

monitoring theincubators

AndrianPaarman witha fine example

of a chinesegrass carp


When any species of aquatic animal is farmed, butparticularly if a new species is being farmed forthe first time, there is a huge learning curve

that inevitably includes a number of husbandry-related challengesfor aquaculturalists to overcome.

Under any circumstances when husbandry conditions aren’tideal, the door is left open for disease problems to emerge.

But even when farming established species for which thehusbandry requirements are well known, unforeseencircumstances can result in a disease outbreak in stock whichcould affect bottom-line profitability.

When a logical, structured approach is undertaken to diagnoseand manage disease problems, in hindsight what initially may haveappeared to be a disaster waiting to happen can turn out to be avaluable lesson.

However, this sort of reactive approach towards dealing withdisease issues makes aquaculture is inherently risky. Fish andshellfish often respond slowly to disease treatments, resulting inmortality, morbidity and lost production. In aquaculture, diseaseprevention is the key, and prevention requires a proactiveapproach to addressing disease problems before they occur.

The idea of promoting prevention rather than cure whentalking about disease in aquaculture is not new or revolutionary.However, in my experience, many aquaculturalists look upondisease as a taboo subject.

Certainly the prospect of stock developing a disease whichcould adversely affect the bottom line never seems to bementioned in business plans and prospectuses sent to potentialinvestors.While it is understandable to want to paint anaquaculture opportunity in the best possible light, acknowledgingthe real possibility of a disease outbreak at some stage during theproduction cycle can make aquaculturalists begin to think aboutmaking disease prevention an important component of theirbusiness plan.

This can be used to show potential investors that allcontingencies have

been considered during the design of the project and, hopefully,that risk mitigation procedures are in place.

For example, a hypothetical marine finfish farm may beexperiencing unusual mortalities in a population of snapper dueto some type of unknown gill disease. Often under thesecircumstances the first disease-related decision the aquaculturemanager is forced to make is a choice between whether to letthe status quo remain, or to try and locate expert advice andinitiate an investigation to determine the cause of the mortalities.This is a completely avoidable situation.

A professional and well-planned approach towardsdevelopment of the original business plan would have alreadyaddressed the possibility of a disease outbreak occurring byexamining the range of disease agents already known in theculture of snapper and other closely related species.

This process of disease risk assessment benefits the business ina number of ways. Firstly, by identifying the disease agents likelyto be encountered, a better informed decision can be made onthe inherent biological risks involved with the project.

Secondly, once the range of disease risks is known, thisknowledge can be incorporated into the design of the projectfrom the outset, ensuring that appropriate infrastructure,resources, mitigation and contingency procedures are in placefrom the very beginning to minimise the risk of diseasesemerging and/or causing significant damage to stock and thefarm’s bottom line.

With a disease mitigation and contingency framework alreadyin place, the aquaculture manager’s decision-making processwhen confronted with diseased stock becomes better focused,improving the chances of a positive outcome.

As another bonus, rather than being scared off by unknownsand unmentionables, investors may feel more confident investingin businesses which present realistic business plans completewith disease risk assessments, and with mitigation and

contingency procedures in place.Of course, even when all due care and consideration has

been exercised during the planning process, Murphy’s Lawoften dictates that unforeseen problems arise.With welldeveloped disease mitigation and contingency plans in place,however, well prepared fish farmers are better positionedto make the best of the situation, because they knowwhom to contact and how to collect the samples requiredto allow aquatic animal health experts to achieve anaccurate diagnosis.

When new diseases emerge, this diagnostic process cantake time, which is a luxury few can afford in thesecircumstances. Clearly, it helps to know who are themost appropriate local aquatic animal health specialists,and more importantly, how to contact them quickly ifthe need arises.

PROACTIVE APPROACHES to disease problems in aquaculture

BY BEN DIGGLES OF DIGSFISH SERVICES

Prevention isthe key to

husbandry-related

problemssuch as thisshell disease

in a rocklobster



In New Zealand, the Ministry of Agriculture and Forestry’sNational Centre for Disease Investigation is responsible forpreventing, detecting and controlling exotic diseases.

MAF considers exotic disease to also include any new andemerging diseases which are not known to occur in NewZealand, regardless of their origins. Under such situations, thediagnostic service provided by the NCDI is free of charge.Aquaculturalists are encouraged to freephone 0800 809 966 if anoutbreak of a new or exotic disease is suspected in their stock.

If the disease is already known to exist in New Zealand, or it issuspected that the disease outbreak is related to management,water quality or environmental factors, the best approach is foraquaculture managers to contact their regular aquatic animalhealth specialist.

A classic example of the emergence of a new disease agent inNew Zealand aquaculture (which would nowadays require thefull involvement of the NCDI), was the detection of a newhaplosporidian parasite in cultured paua (Haliotis iris) in thesummer of 1999/2000.This parasite caused heavy systemicinfections (figure 1) and was responsible for mortalities of 90percent of the juvenile paua in that facility (Diggles et al 2002,Hine et al. 2002).

While this disease agent was new, it was also related to otherhaplosporidian parasites of oysters in the northern hemispherethat the world animal health organisation Office International desEpizooties or OIE) lists as notifiable diseases of molluscs (Reeceand Stokes 2003).

A disease risk assessment undertaken prior to developing thepaua culture facility would have considered haplosporidians,because they cause diseases listed by the OIE. It’s possible,therefore, that disease mitigation recommendations (resultingfrom a risk assessment) designed to prevent infection byhaplosporidians (eg by filtration of the incoming water) wouldhave excluded the parasite from this facility.

While all efforts made in the name of disease preventionshould be supported, if a problem arises there remains a needfor guidance in the disease control decision-making process. Inmy opinion, one aspect of fish health management which has yetto be fully explored is the area of aquatic animal healtheconomics.

The tools used to assess the economic performance of aresponse to a disease outbreak vary from measures as simple asthe cost of treatment per fish, cost-benefit analysis and break-even point analysis, to more applied tools such as decision treeanalysis and systems simulation.

By employing these tools and others, we can evolve fromsimply treating diseased aquatic animals to effect a cure, tochoosing the most appropriate treatment which will optimise the

economic outcome given acertain set of circumstances.

DigsFish Services it is working with industrypartners in the northern hemisphere to develop and trial anaquatic animal health economic software package which we hopeto eventually make available to aquaculturists so they canimprove their decision-making processes and maximise theupside of any disease problems they may experience.See www.digsfish.com


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FIGURE 1.Histology of numerous

multinucleate haplosporidianplasmodia in the gills of paua

heavily infected with a newspecies of haplosporidian

Scale bar = 106 µm

Gas bubble disease in snapper. Even when all due care andconsideration has been exercised during planning, Murphy’s Law

often dictates that unforeseen problems arise

A cultured paua with heavymudworm infection and

shell erosion. Bothproblems can be easilyprevented by changing

husbandry practices and system design

A cultured paua with heavymudworm infection and

shell erosion. Bothproblems can be easilyprevented by changing

husbandry practices and system design

acREFERENCESDiggles B K, J Nichol, P M Hine, S Wakefield, N Cochennec-Laureau,R D Roberts and C Friedman 2002. Pathology of cultured paua(Haliotis iris Martyn, 1784) infected by a novel haplosporidianparasite, with some observations on the course of disease. Dis.Aquat. Org. 50: 219-231Hine P M, S Wakefield, B K Diggles,V L Webb and E W Maas 2002.The ultrastructure of a haplosporidian containing Rickettsiae,associated with mortalities among cultured paua Haliotis iris. Dis.Aquat. Org. 49: 207-219Reece, K S and N A Stokes 2003. Molecular analysis of ahaplosporidian parasite from cultured New Zealand abalone(Haliotis iris Martyn, 1784). Dis.Aquat. Org. 53: 61-66


As mussel farms near the shore face increasingspace constraints, people are beginning toconsider new developments further offshore. But

it’s not a matter of simply “beefing up” the design of aninshore mussel farm.

The National Institute of Water and Atmospheric Researchhas been working with the University of Canterbury and theUniversity of New Hampshire in the United States to improvemussel farm design.

It all comes down to “drag”.When water flows past an objectlike a mussel dropper, it tries to drag the object along with it. Indoing so, the water flow loses energy to turbulence. If enoughenergy is lost, the waves and currents will change.As someproposed mussel farms contain 1000km or more of rope,predicting the likely drag and its effects will help in farm design,site selection, consideration of nutrient requirements, assessmentof environmental effects and preparation of permit applications.

The main findings of the research to date are:❚ Designs can’t simply be scaled up. If a farm is hit by waves

twice as big, it’ll have to withstand more than twice theamount of drag, especially if there are reasonable currents.

❚ Surface longlines can be hit directly by waves, but evensubmerged backbones experience significant loading in oceanswell.

❚ Large farms affect the waves, currents and mixing of wateraround them.The environmental effects might not be bad,but they still need to be understood and quantified.

WAVE DAMAGEWaves are the biggest hurdle faced by offshore farmers.Theybuffet the farm, creating constant acceleration and deceleration.When waves and currents combine, the whiplash effects can bedevastating. Existing large farms in areas such as Golden Bayand the Firth of Thames are relatively sheltered, but it is muchmore difficult to build farms on less sheltered coastlines.

Computer modelling is the best way to test how the musselfarm will cope with waves. Models can show how alteringaspects of the farm design, such as the stretchiness of therope, float buoyancy and longline length, reduce or enhancethe impact of wavy conditions.

Over the past decade, the open-ocean aquaculture group atthe University of New Hampshire has developed acomplicated computer model called Aquafe that shows howfish cages move in large ocean waves. Scientists from NIWAand the University of Canterbury have been working withthem to convert the model into one which deals with longlinemotion and loading.

The goal is to create a blueprint for better farm designwithin the next two years.This will improve the ability ofmussel farms to survive wave loading and reduce their effecton currents.

Why are waves and currents important formussel aquaculture?The research is being funded by the Foundation for Research,Science and Technology, and the Royal Society ISAT LinkagesFund. It has three main purposes. Firstly, to understand theproductivity of any mussel farm, we need to know the amountof pre-existing nutrients being removed from the water.Thisrequires knowledge of how the water moves through the farm.

Secondly, it is important to understand what effects changesin waves and currents will have on the local environment, suchas beach erosion. Lastly, as future developments move offshore,it is vital that farm structures are strong enough to survive theharsh conditions.

WATER MOTIONStudies of kelp forests show that a large amount of drag canreduce water motion.The same is true for large musselfarms.The longer it takes for a “blob” of water to pass


A BLUEPRINT FOR better mussel farm designBY CRAIG STEVENS AND BOB SPIGEL OF NIWA, DAVID PLEW OF THE UNIVERSITY OF CANTERBURY, AND DAVID FREDRIKSSON OF THE UNIVERSITY OF NEW HAMPSHIRE

A mussel farm longline is a complexcollection of masses, floats and ropes (Craig Stevens, NIWA)

NIWA scientists attach sensors to floats, droppers and mooring lines to obtain measurements (Murray Smith, NIWA)

Measuring mussel float motion by radar. The radar is equivalentin operation to having 30 police traffic radars monitoring

different points on the water surface. It also providesinformation about the speed of the water (Craig Stevens, NIWA)


through a mussel farm, the more nutrients the mussels filterout of that water.

To estimate this rate of nutrient depletion before a farm isbuilt, we need to know the rate at which the mussels feed andthe speed of the water flow.We already know about feedingrates from previous studies, and existing models andmeasurements can predict tide and wind-driven coastalspeeds.The problem is that these current estimates do notinclude the effect of the farm itself.

Finding out what effect a farm has on flow is not easy.Even if we could instantly install and remove a farm (thefoolproof method), conditions in the ocean are constantlychanging.We’ve had to use a number of other approaches,including field measurements, laboratory experiments andcomputer modelling.

As well as traditional oceanographic measurements such ascurrent speed and direction, temperature and salinity, we aremeasuring water turbulence and farm structure motion.Theinstruments we use to measure turbulence capture the smalleddies created as water moves past the mussel lines.This tellsus the energy lost from the main flow, and from the flowaround the mussels themselves.

One feature we did not expect to see was the strongaffect of drag from mussel farms on water stratification.Thisdiscovery could help us to develop more reliable estimatesof nutrient depletion and productivity, and betterunderstand how brackish plumes from rivers spreadthrough a farm.

Mussel farms influence the environment away from the farmas well. For example, if a large farm slows down currents, it willalso reduce the height of waves.A change in the currents andwaves on a coastline will probably affect the movement ofsediment.This is why it is important to try and gauge theeffect of the farm on waves and currents, as well as the effecton the environment as a whole.

These factors are not just an issue for large, offshore farms.Presently, the changes to flow caused by farms can only bereliably measured near large farms because they have a clear,strong effect on the flow.This does not mean that small farmsdo not have an effect.The effect of a small farm is oftenhidden, because water movement close to the coast is sohighly variable anyway.

Also, it takes a good computer model to distinguish aparticular farm’s contribution from the cumulative effects ofseveral small farms in a bay. Studies on large farms can provideclues as to how to design both large and small farms tominimise their impact on the local ecology.


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This model of alongline riding awave showshow thestructure isbuffeted about.The surfacefloats are shownas black circlesand the musseldroppers asgreen. The redline representsthe backboneand mooringline. The bluearrows showthe watercurrent (CraigStevens, NIWA)

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Lines in the Water - a history ofGreenshell mussel farming in NewZealandWhat do old washing machines, cracked milk

bottles and a toy knitting machine have in common?Thirty years ago they each played a vital part in developing

the Greenshell mussel industry, according to a new booklaunched on December 10. Lines in the Water - a history ofGreenshell mussel farming in New Zealand (River Press,$79.95), tells how the industry developed from mussel rafts tolonglines, how pioneer mussel farmers developed thetechnology to grow and harvest mussels, and how the firstentrepreneurs set out to create a market for New Zealand’sunique Perna canaliculus.

Commissioned by the New Zealand Marine FarmingAssociation Inc, Lines in the Water, written by Carol Dawber, isinformal and anecdotal in style, using the voices andphotographs of those in the industry to record the way itdeveloped. Scientists, fishermen, teachers and business peoplebecame mussel farmers, often working long nights in theirworkshops and weekends in the Marlborough Sounds whilethey kept their day jobs to finance the new venture.

The book tells of the “Cook Strait cowboys” who carriedmussel floats illegally across Cook Strait, the heartache of losingcrops in a storm, the never-ending battles with bureaucracy, and

the families who harvested their mussels by hand and soldthem at fairs and market days to keep their businesses viable.

Today Greenshell mussel farms are scattered along the NewZealand coast, but the industry started in the MarlboroughSounds and is still largely based there. Modern musselharvesters are purpose-built, highly sophisticated processingunits crewed by trained and qualified career people. It’s a far cryfrom the Fordson tractor that was tied securely onto a bargeand towed into Kenepuru Sound to lift the first mussel ropesfrom the water in 1972.

As for the washing machines, milk bottles and knittingmachine - wringer washing machines set up on small boats andwork rafts were used to separate the clumps of immaturemussels grown from seed on single drop ropes.The musselshad to be thinned and re-attached to growing ropes.

Cracked milk bottles, tin cans and other small containerswere filled with cement and sand to make weights to hang thedrop ropes from. And a plastic toy knitting machine designedfor making dolls’ clothes was adapted to make the firstbiodegradable mussel stocking. The book is about Kiwiingenuity, and the story of an industry that took an indigenousproduct and sold it to the world.

Lines in the Water is 320pp,hard cover,with more than 400photographs. It is available from the NZMFA (Ph 03 578 5044or email [email protected]) and bookshops.

BOOK REVIEW

Lines in the Water,a History of Greenshell

Mussel Farmingin New Zealand

Retailing for $79.95, the book is 320 pages, hard cover,with more than 400 colour photographs.

Available fromThe NZ marine Farming Association Inc, PO Box 86, Blenheim,

Ph 03 578 5044, Fax 03 578 5046, e-mail [email protected] from all good bookshops

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THINKERS AND TINKERERS STARTED MUSSEL INDUSTRY

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algal species that contain chemicals important for biotoxinresearch or their pharmaceutical potential.

TOOLS OF THE TRADEThe primary driver behind the cryopreservation research is toprovide a powerful tool for selective breeding. Cawthronscientist Nick King says it is all about time travel.“As a shellfishbreeder, I’d love to be able to cross any parents, any place, anytime - even beyond the lifespan of the shellfish.That’s theultimate in breeding control, but it hasn’t been achieved forany animal, anywhere in the world, so far.With our progress


Cryopreservation used to be the stuff of sciencefiction - chilling life forms in storage until they’reneeded. Now the future is here, and the ability to

store live sperm and embryos indefinitely at ultra-lowtemperatures is a technique that is routinely used to help withhuman reproduction and livestock breeding.

Until fairly recently, when structured selective breedingprogrammes began to be developed, cryopreservation hadn’tbeen used in aquaculture.A research programme led by theCawthron Institute is changing that, and has broken newground in cryopreservation for shellfish.

The Cryopreservation for Aquaculture project began in1998. It covers the eggs, sperm and larvae of Greenshellmussels, Pacific oysters and paua. Pacific oyster spermcryopreservation is fully commercial, and mussel and pauasperm freezing are also well advanced.

In a major breakthrough, the project has achieved successwith cryopreservation of eggs.This has never before beenachieved for any fish or shellfish, and it has not becomeroutine for any terrestrial animal either.

“We first reared oysters from cryopreserved eggs in 2003,and recently demonstrated that our techniques can producethe numbers required for selective breeding,” says researchleader Rodney Roberts.

Mussels have proven more difficult, although they lookpromising, while paua eggs are still a long way off, he says.Larval freezing is also looking good, but the team has nowdiverted its attention to eggs, as they’re much more useful forselective breeding.

“Sperm is traditionally regarded as being much easier tocryopreserve than eggs, but our egg freezing is now moresuccessful in terms of proportion surviving than our spermfreezing,” says Roberts.

The majority of eggs survive and develop in goodtreatments, whereas the fertility of sperm is reduced by 10 to1000-fold by freezing.This is the case for spermcryopreservation in all species, and implies that most spermare compromised by cryopreservation.

“For many animals you can get away with such losses simplybecause they produce so many sperm - about 200 billion in alarge male oyster. But when we’re aiming for commerciallyrobust protocols, the numbers matter, so we need to minimisethe loss of fertility.”

The project is also developing techniques to cryopreservemicroscopic plants. It has been successful with several key speciesused as feeds in bivalve hatcheries. Cryopreserved samplesprovide a stable backup that is not subject to the “genetic drift”that occurs in live cultures.The next cryopreservation target is

LIFE IN THE FREEZER - how Kiwi science is creating aworld-first shellfish breeding toolBY LINDA MORRIS

CONTINUED ON NEXT PAGE

Cryopreservation is the storage of living things at temperatures so low that allbiological activity is suspended. Live organisms can be held indefinitely in liquid nitrogen- the tricky bit is to freeze and thaw the material without causing lethal damage

Colour-codedstrawscontaining livesperm arestored in liquidnitrogen at atemperature of -196° Celsius


on freezing eggs, as well as sperm, we’re very close toachieving that for the first time.

“One of our strengths is that we’re developingcryopreservation and selective breeding in concert, so thecryopreservation transfers seamlessly into its primaryapplication.We’ve already used sperm cryopreservation in ouroyster and mussel breeding programmes.”

Cryopreservation comes with swag of other advantages. Itcan provide a year-round supply of juveniles for aquaculture,and avoid the unpredictability and costs of conditioningbroodstock. It can be used to maintain genetic diversity orpreserve particular strains, and allows transport without riskof spawning, and with reduced disease/biosecurity issues.

Breeding programmes around the world wantcryopreservation techniques to reduce the cost of maintainingnumerous family lines over long periods. Cawthron has alsohad enquiries from people wanting cryopreserved shellfish fortoxicity bioassays or as food for larval finfish.

RESEARCH PARTNERSCawthron has teamed up with AgResearch and the University ofOtago for this project, and the combination of cryopreservation

and shellfish experts has proven to be highly effective.Robin Tervit pioneered embryo-freezing techniques for goats

and sheep in the 1980s before leading the AgResearch RuakuraReproductive Technologies group.“When Cawthron rang me andsuggested collaborating on shellfish cryopreservation, I told themthat we don’t do shellfish. But fortunately they didn’t see that as aproblem, and the partnership has worked out extremely well.”

AgResearch offered a lot of cryopreservation knowledge andCawthron had all the facilities and expertise on the shellfish side.

Tervit says there are pros and cons in relation to workingwith shellfish.“The limited past work on shellfish, and theirtotally different living environment, mean that we are justabout starting from scratch in some respects. But the numbersof gametes we have to work with is wonderful. In livestockwork, you are lucky if you get a dozen eggs or embryos towork with. I could hardly believe it when told that a singleshellfish could give us fifty million eggs!”

INDUSTRY SUPPORTThis vital research has huge support from the industry, whichhas recognised the importance of cryopreservation as a tool inselective breeding.The New Zealand Mussel Industry Council


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■ Local Launch Operator■ Inshore Launch Master

MOBILE SKIPPER’S COURSES

Darcy Ranger Ph/fax 07 866 8276Email dranger @wave.co.nz.

WE WILL COME TO YOU!

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Oysters from cryopreserved eggs are aworld first for any aquatic organism

CONTINUED FROM PREVIOUS PAGE



contributes funding, while various private companies sourceand donate ripe broodstock for the project.

The executive officer of the council, Lorna Holton, isenthusiastic about the role of cryopreservation and selectivebreeding.“We need research like this to stay ahead of thecompetition,” she said.“We see the potential for selectivebreeding to take our industry to a whole new level ofsophistication where the best mussels are grown naturallyfrom the best parents.”

Aquaculturalists already know the benefits ofcryopreservation. New Zealand’s leading paua farm, OceaNZBlue, is one of those who are keen to apply cryopreservationin their breeding programme.

“We’ve already had Cawthron staff on site showing us themethods for sperm preservation.We’ll preserve sperm fromstud males, and also want to preserve genes from places likethe Three King’s Islands, where paua might not be available in afew years,” said the general manager, Jimmy Miller.

THE FUTURE Much of the future work on the cryopreservation projectwill focus on ensuring that the techniques are commerciallyuseful. Roberts says too much science gets left at theexperimental stage.“We could stop when we havedemonstrated success in the lab, but our goal is to make surethat the technology is robust enough to be applied forindustry.”

Roberts is grateful for long-term funding from theFoundation for Research Science and Technology.“The easygains happen early in the research, but the tough stuff takestime. For commercial application, we need to improvemethods to the point that they still work on the bad days.Thisrequires in-depth research to figure out what makes oneshellfish good for cryopreservation, while another is poor.”Roberts says they hope to have further successes within thenext 18 months.

If you have any questions please email Rodney Robertsat Cawthron - [email protected] ac

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Newly metamorphosedoyster spat reared

from cryopreservedeggs. No genetic

engineering, just goodbreeding!


Iwould like to share some experiences in working with andbreeding marine organisms over the past 10 years. In partbecause there are often a number of similarities in working

with different animals across different species, but mainly becauseof the shared enthusiasm for working with and understandingthe life cycles of animals.

Although common scientific principals underpin the breedingof following organisms and it is an area that I work a lot in, I willfocus on the practical aspects, as these have been interesting andvery rewarding experiences.

In terms of the practicalities of breeding I have seen someinteresting ways in which species such as pipis, scallops, mussels,sea slugs, sea urchins, sea cucumbers, crabs, prawns, Moreton baybugs, flatfish and snapper have been exploited in captivity toenable successful breeding.

In some circumstances this hasbeen achieved from pure trialand error, in others from triedand proven methods, and stillothers from more rigorousfundamental research, or infact any combination of these.

For instance, seacucumbers are sensitivecreatures in captivity and donot like to be disturbed.Perhaps the most criticalkey to breeding them is astable environment withno interruptions toestablished routines,combined with carefulhandling.

I have found that they

are easily disturbed both before and during spawning, which canfrustrate efforts to breed them. However, exploiting their naturalcycle of maturation and spawning, their spawning behaviour, andthen augmenting it has proven to be very successful.

By trial and error and then by rigorous experimentation I foundthat these guys are “sparked off” to do their thing by a romanticfull moon during the reproductive season, although they tend tobe less enthusiastic about the whole process later in the season.

Having an understanding of an organism’s interaction with theenvironment and sound knowledge of whole-organism biology isa great tool to exploit in aquaculture practices. Once theseprocesses are understood I feel more fundamental processes canthen be exploited in organismic biology at the biochemical andperhaps the molecular level.

These days, a good understanding of systems biology or multi-level processes is important. How everything relates, from thelevel of the cell to the whole organism, provides a betterunderstanding of why things are the way they are.

After all, knowledge of cellular processes is difficult to translateinto knowledge of how an organism interacts with itsenvironment, or how its behaviour is related to the processesgoing on that enable it to reproduce successfully.

Sea urchins are perhaps one of the most basic animals in termsof breeding to work with in captivity and gain insight into someof these processes. Because of the manner in which they goabout producing gametes and spawning them, they are easy toexploit to gain an understanding of reproductive processes.

Consequently, the induction of spawning by injection is a simpleand effective process.There is no need for the more complexunderstanding of reproductive processes needed for otherorganisms such as sea cucumbers in order to successfully breedthem in captivity. So sea urchins are an ideal organism to use ingaining an understanding of some basic principals in breeding.

It was interesting working with sea urchins as part ofundergraduate teaching at the Leigh marine laboratory. Basicallywe collected a bunch of urchins during the summer months andbrought them into the laboratory on trays.

We injected them and obtained male and female gametes foruse in fertilisation assays.We investigated factors such as spermconcentration versus polyspermy of embryos, and the numbersof embryos undergoing normal cell division.

This is a key factor in the aquaculture industry, and is one ofthe factors that was critical in cracking the commercial-scalehatchery production of mussels.A number of other featuresuseful in aquaculture include sperm and egg age post-spawning,contact times and sperm-to-egg ratios.

Hands-on experience in working with sea urchin gametesenables a greater appreciation of the complex issues involved inhatchery production of animals and breeding success in thenatural environment.


BY DR ANDREW MORGAN

ANIMAL HUSBANDRY and maturation in the hatchery

Broodstocksea

cucumbersplaced inindividual

containers withmesh screens

in a flow-through

seawater bathfor conditioningin preparationfor spawning

A lobster ripe with a broodready to be spawned


The ability to obtain gametes from sea urchins on demandduring the reproductive season means that gametes can be usedto model fertilisation kinetics both in situ and in vitro.Thisenables an understanding of the basic principals of fertilisation.

From this I feel a foundation can be built on whereby morecomplex issues can be addressed, such as gamete quality and itseffect on fertility. In using sea urchins as a model system, theprincipals of reproductive endocrinology can be highlighted.Thisenables the linking of whole-organism biology with biochemistryand molecular biology in what is now the proteomic era.

Without a good understanding of reproductive behaviour andhow it relates to reproductive physiology and its interaction withthe environment, shellfish can also be a real problem to workwith in captivity. In this case a lot of techniques have beendeveloped through trial and error and then exploited moresystematically in commercial production.

I remember we used to collect pipi from the beach to chop upand feed to Moreton bay bug nauplii.These pipi were broughtback to the research centre and kept in 200-litre tubs.The tubswere aerated vigorously and filled with a thick culture ofphytoplankton to enrich the pipi.

During their peak reproductive season they often spawnedspontaneously in these tanks, which resulted in millions ofgametes everywhere.

Scallops have also been observed to spawn spontaneously aftervigorous agitation of the water they have been contained in. Evenabalone have been observed to do this. I also remember that atcurtain times during the summer months sea slugs, anothermollusc, that had settled in our grow-out ponds would producelarge amounts of spiralling egg masses on the tank walls.

It seems to me that across species the subtle play of gametematurity and its interaction with environmental variables, and theunderlying physiological limits on breeding, are common and inprincipal very similar.

However, you cannot say “Eureka!” and vigorously agitate aspecies to make it spawn during the reproductive season. Itshould be remembered that the process is more complex thanthat and aspects are species specific.

For instance, chemical communication likely plays a key role inthe success and synchrony of maturation and spawning. Inmussels, scallops and sea cucumbers it is beneficial to keepindividuals in separate tubs in the hatchery prior to inducingand/or augmenting spawning behaviours.

However, mesh screens are often used to allow mixing ofwater which in some instances has been proven to allowsynchronisation of gamete maturation. I have done this with seacucumbers to some degree of success.

Once these animals are going to spawn it is not necessary tohave mesh screens, which is great for spawning as it allows morecontrol over selective breeding. Unless you are conditioninganimals over a long period of time in the hatchery this is notalways successful either.

Factors such as gamete age, whether animals have alreadyspawned in the wild, and the timing of spawning during thereproductive season when animals are being exploited allcontribute to gamete viability and the success of breeding.

Similar trial and error methods or perhaps methods that havebeen stumbled on have been developed for other species. Interms of Moreton bay bugs, crabs and prawns, the process of


maturation and spawning is well understood.Eyestalk ablation is often used in combination with continuous

dim light, resulting in constant access to mature, reproductivelyripe animals for gametes. I remember with mud crabs that the eggclutch could be observed as it matured after mating, and the timingof spawning predicted to within days using a qualitative index.

A similar condition index formaturation has also beendeveloped for a number of speciesof prawn to predict spawning afterbeing held in captivity underconsistent conditions.

Not that crustaceans are anyeasier to breed, but thephysiological processes andhormonal pathways involved arebetter understood. In fact, in termsof the whole organism, they arealso more accessible, thus thesuccess of using eyestalk ablation. Ifyou tried to do the same inmolluscs you would have to cut atiny nerve near a small ganglionaround the oesophagus.

In echinoderms it would benearly impossible to achieve thesame without killing the animal. In fact, in both phyla the wholereproductive endocrine process is more of a “black box”.

I remember walking into the dark maturation room containing16-tonne holding tanks that were being supplied with filteredseawater at a constant temperature and a dim light source.Wewould shine a torch into the tanks to spot the prawns, and the lightfrom the torch would show up their gonad or roe as it ripened.Wethen recorded on a whiteboard an index of how ripe they were.

Close to spawning time we would be in there every day, as oncea drop in the condition index was observed we knew that theyhad done their thing.Then it was a matter of shining the torch onthe water as the hatched larvae were positively phototactic andswam towards it,making it easy to sieve them out of the tanks.

Dealing with mud crabs was a little different, as close tospawning, which we knew by the development of an eye spot inthe egg clutch embryos, the female crab and her babies weretaken to a large, conical tank containing a plastic cage tocomplete spawning of hatched larvae.

So, as you can see, it is amazing to see the similaritiesunderpinning the successes in working with various species, andit is very rewarding to be able to identify the subtle differencesbetween species, both within and among phyla that enable moresuccess in hatchery production.

A key aspect of this is understanding how features ofreproductive endocrinology underlying maturation remainconserved across species. Being able to exploit this in captivity isachieved by recognising key features at the level of the wholeorganism that differentiate how they respond to theirsurrounding environment.This is expressed as reproductivebehaviours that differ between species and phyla, that through aprocess of trial and error, development of methodologies andthen more rigorous experimental testing, enables thecommercial exploitation of species in the hatchery.

A gonadtubule(0.6mmdiameter)filled with ripesperm asevidenced bythe presenceof spawningchannels

A gonadtubule(0.6mmdiameter)filled with ripeoocytes(unfertilisedeggs) ready tobe spawned

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