NEW ZEALAND GREENSHELL MUSSEL SPAT STRATEGY - Aquaculture ...
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NEW ZEALAND GREENSHELL™ MUSSEL SPAT STRATEGY Photo credit: Cawthron Institute
Table of Contents
Executive summary ............................................................................................................................................ 2
Introduction ....................................................................................................................................................... 3
Projected spat requirements ............................................................................................................................. 4
Greenshell™ mussel spat ................................................................................................................................... 5
Strategic goals .................................................................................................................................................... 6
Goal 1: Securing and diversifying spat supply ................................................................................................... 7
Background to spat sources ............................................................................................................................... 9
Te Hiku (GLM 9) spat.................................................................................................................................. 9
Rope-caught wild spat ............................................................................................................................. 10
Hatchery spat ........................................................................................................................................... 11
Goal 2: Optimising spat use ............................................................................................................................. 12
Background to spat retention .......................................................................................................................... 14
Goal 3: Increasing hatchery production........................................................................................................... 17
Background to hatcheries ................................................................................................................................ 18
Breeding programmes ............................................................................................................................. 18
Pathway to a resilient spat supply ................................................................................................................... 20
Existing and future spat research and funding options ................................................................................... 21
References ....................................................................................................................................................... 23
1|P age
Executive summary
This spat strategy recognises the opportunity the New Zealand Greenshell™ mussel (GSM) industry has to
grow over the next decade, in a sustainable, resilient, productive and inclusive way; growth that will
contribute to the overall Government and aquaculture industry goal to exceed $3 billion by 2035 [1]. A
consistent and high-quality supply of GSM spat (juvenile mussels) will be critical in achieving this goal. This
strategy outlines the industry actions that can be taken and areas that will require targeted research and
development to optimise our spat resources.
A key step in achieving this goal is the development of this spat strategy that will underpin/guide our
research, innovation, and productive focus for the next decade. Through a working group process, the
industry has identified three strategic objectives that will guide industry, Government, and research
initiatives to pursue its goal:
1. Securing and diversifying spat supplies;
2. Optimising spat use; and
3. Increasing hatchery production to increase spat retention, resilience, and value.
Photo credit: SPATNZ
2|P age
Introduction
Spat supply underpins the New Zealand GSM industry, New Zealand’s most valuable seafood export at over
$336 m per annum in 2019-2020. Currently over 65-80 percent of the industry’s spat supply comes from
spat attached to drifting seaweed that washes up on Te Oneroa-a-Tōhē (90 Mile Beach). Another important
source of spat comes from wild-caught spat that attach to specially designed catching lines deployed at
dedicated spat-catching sites. These wild-catch sites, including areas on the North Island’s West and East
coasts, Banks Peninsula, Marlborough Sounds, and significant sites in Golden Bay, provide around 20-30
percent of the industry’s spat supply. The remaining spat supply is sourced from a state-of-the-art mussel
spat hatchery and nursery in Nelson, which is run by Shellfish Production and Technology NZ Limited (SPATNZ)
and is currently estimated to produce 10-20 percent of the industry’s spat. However, the percentage share
of each spat source fluctuates between years due to the variable nature of wild caught spat supplies.
The New Zealand GSM industry has potential to provide up to a third of the $3 billion goal that the New
Zealand Government has set for aquaculture in New Zealand by 2035. This increase in value will likely be
realised through development of consented space, faster turn-over of production cycles through hatchery
produced spat and breeding programmes, and market value (Table 1).
Table 1: Variables for estimated $1 billion value by 2035
Variable 2019 2035
Developed farm space (includes low 6,200 ha 17,000 ha
density open ocean farm space)
Production 93,000 t 140,000 t
Production cycle 18-20 months 12-14 months
Market value (frozen halfshell) $9.60 per kg $12.50 per kg
Faster production cycle gain (30% of 0 28,000 t
industry using hatchery spat)
Total production 93,000 t 168,000 t
Total market value $336 m $1 bn
3|P age
Projected spat requirements
To determine future spat requirements, we need to understand industry’s plans to develop additional new
farming space over the next decade. In September 2019, AQNZ surveyed the major mussel producers
regarding projected spat requirements for 2020, 2025, and 2035 horizons. The metric used was metres of
primary spat seeded, which relates to the metres of rope seeded with Te Oneroa-a-Tōhē and wild-caught
spat (Figure 1). In 2020, it is estimated that just over 5 million metres of primary spat will be seeded by the
industry. By 2025 the amount of primary spat is predicted to increase to 7.4 million metres, and by 2035 c.
9 million metres. These estimations consider development of consented open ocean growing areas and
increasing efficiencies enabled by the introduction of hatchery spat.
This increase in metres of primary spat seeded equates to a 40 percent increase by 2025 and a 70 percent
increase in spat required by 2035 (Figure 2). These survey results have been used to inform a spat production
model, which forecasts spat requirements from the present day out to the year 2035. This model suggests
that at 168,000 tonnes of production, around 84 billion spat and 9 million metres of primary spat rope will
be needed (Table 2). If, for example, spat retention could be increased by one percent, it would reduce the
amount of spat required by 20 percent spat (c. 8 billion spat).
10000000
Metres of primary spat
8000000
6000000
4000000
2000000
0
2020 2025 2035
Figure 1. Projected GSM spat requirements (in metres of primary spat) for 2020, 2025, 2035
100
increase in spat
80
Percentage
required
60
40
20
0
% Increase 2020-2025 % Increase 2020-2035
Figure 2. Projected increase (%) in GSM spat requirements from 2020-2025 and 2020-2035
Table 2: Production model for primary spat rope and total number of spat using current methods
Production Adults Adults / m/kg Total adults Metres of Spat to Metres Spat Total
/ kg m (# / kg * total final / grow seed primary seed retention spat
(@6kg / kg production) rope conversion rope (proportion)
m) (m) (m)
90,000 25 150 0.167 2.25 bn 15,000,000 3:1 5,000,000 0.05 45 bn
168,000 25 150 0.167 4.2 bn 28,000,000 3:1 9,333,333 0.05 84 bn
4|P age
Greenshell™ mussel spat
Greenshell™, the trademarked name for Perna canaliculus (kuku or kūtai), is a mussel species endemic to
New Zealand. It is a filter feeding species that attaches to solid structures in the coastal environment and
thrives by feeding on the microscopic algae and organic matter that abound in local waters. They reproduce
by broadcasting sperm and eggs into the water column once they become sexually mature at around 12-18
months (Figure 3). After fertilisation eggs become zygotes and then develop into free swimming planktonic
larvae. Mussel larvae go through four stages of development (trochophore, D-larvae, veliger and pediveliger)
before finally settling onto seaweed or ropes as mussel spat after 3-4 weeks swimming in the water column.
Mussel spat that settle into less than optimal places will often migrate by sending up a mucus parachute to
drift and find a better settlement spot, going through a migration process called secondary settlement.
The mussel industry has three sources of spat: seaweed cast-up on beaches, rope-caught spat that settles
onto special spat-catching rope, and hatchery spat that is settled onto coir rope in a hatchery. In the New
Zealand mussel industry, spat are seeded onto the spat-catching rope with the aid of a biodegradable
stocking that holds the spat close to the spat rope in the hope that it will migrate across.
After 3-6 months, the so-called primary spat is removed from the rope and the process is repeated at a lower
seeding density (called "intermediate seeding"). This results in "secondary spat", which are spaced further
apart on the lines to reduce competition and to provide space to grow. The spat growing process takes 8-14
months before spat are removed and seeded onto final grow-out ropes as "final seed". Final seed mussels
typically take 12-14 months to grow to a harvest size of 90-100 mm, depending on growing conditions.
Settlement onto seaweed or ropes
→ Spat (3 - 4 weeks post-fertilisation)
(0.2 - 2 mm)
Migration and secondary
Free swimming (planktonic) larvae settlement
Trochophore → D-larvae→ Veliger Seaweed with spat or spat
→ Pediveliger (300µm) catching / hatchery rope
0.2 - 35 mm (3 - 6 months)
Fertilisation creates Intermediate seeding
zygotes 6 - 14 mm (8-14 months)
Removed from lines and re-seeded as
Adult mussels release final seed to grow-out
sperm and eggs 90 – 100 mm (12 - 14 months to harvest)
Figure 3: Greenshell™ mussel lifecycle from spawning through to harvest
5|P age
Strategic goals
Through the development of this strategy, the New Zealand Greenshell™ mussel industry has identified
three strategic goals that it sees as vital in the delivery of its aspirations to become a $1 billion mussel
industry by 2035.
Securing and Increasing
Optimising spat
diversifying spat hatchery
use
supplies production
6|P age
Goal 1: Securing and diversifying spat supply
To secure a consistent, diverse, and high-quality supply of spat to support the industry’s productivity and
resilience goals
Challenges
• Unlikely to be any near term increases in the Te Hiku (GLM9) TACC • Biosecurity risks
• Unpredictable amounts and timing of wild spat • Climate change effects on spat
• Variable or unknown condition of wild spat • RMA challenges for critical spat catching sites
• The variable size and density of wild spat • Capital costs of hatchery
Goal: Securing and diversifying spat supply
Objective Action Responsible Party Timeframe
Hatchery spat
Establish additional hatchery spat capacity • Increase hatchery spat output options: capital for Industry 2020-25
additional facilities, scale up SPATNZ, or a combination Government
Te Hiku (GLM9) spat
Maintain productive and inclusive relationships with Te • Continue to support and participate in Te Oneroa-a- Industry Ongoing
Hiku Iwi/Hapu and the statutory appointed Te Oneroa- Tōhē working group Government
a-Tōhē Beach Management Board
Ensure sustainable spat collection techniques are used • Conduct research into current methods to determine Industry 2020-2025
impacts to beach fauna Researchers
• Update collector’s/industry code of practice
• Understand the biosecurity status of spat collecting
areas
Use TACC wisely and only utilise Te Hiku seaweed of the • Quality control spat prior to harvest Industry Ongoing
highest quality • Spat counts prior to harvest Researchers
7|P age
• Spat quality and count data are used to guide gathering
and end-use decisions
• Collect data on seasonality of spat quality/performance
Ensure spat collection season aligns with the best • Change GLM 9 fishing year window Government Ongoing
collection periods and promote transparency • Electronic monitoring of mechanical harvesting
Improve knowledge of larval and spat supply processes • Better understand natural variability and long-term Researchers 2020 –
change (e.g. climate change), effects on adult beds and ongoing
spat supplies
Identify and protect source beds and predict arrival of • Locate source adult mussel beds and seaweed beds and Government 2020 –
Te Hiku Spat work with government to protect spat sources Researchers ongoing
• Develop predictive tools to anticipate spat arrivals or Industry
absence of arrivals with confidence
Rope-caught wild spat
Protect and maintain existing and important wild spat • Work with local and central government to ensure the Industry 2020-2024
catching sites importance of these sites is recognised in planning Local Government
• Understand the biosecurity status of spat collecting Government
areas
• Identify and protect source populations
Identify potential reasons why some traditional spat • Research to understand potential environmental Researchers 2021-2026
catching sites are failing changes at these sites Government
• Identify source populations Industry
• Develop remote systems to record spat fall
Identify and apply for and develop new spat catching • Research to identify potential new spat catching sites Industry Ongoing
sites • Secure resource consents and develop new sites Researchers
Local Government
Government
Develop new and more efficient spat catching methods • Develop methods that ensure the most efficient Researchers 2021-2026
utilisation of spat catching areas and mitigate potential Government
ecological effects Industry
Advocate for permissible plan settings that allow for • Work with central and local government to ensure Industry 2020-2024
consenting of spat catching areas, including research regional plans allow for consenting of spat catching Local Government
sites areas and research sites Government
8|P age
Background to spat sources
Te Hiku (GLM 9) spat
Currently 65-80 percent of the industry’s spat supply comes from spat attached to drifting seaweed that
washes up on Te Oneroa-a-Tōhē (90 Mile Beach). Collection of beach-cast spat from Te Oneroa-a-Tōhē is
managed under the Quota Management System
(QMS). The current total allowable commercial Te Oneroa-a-Tōhē spat to seaweed ratio
catch (TACC) for this region (GLM9) is set at 135 In 2018, Fisheries New Zealand reduced the
tonnes per annum (at the assumed 25 percent ratio “spat ratio” used to apportion the combined
of spat to seaweed equates to 540 tonnes of weight of spat/seaweed material harvested at Te
material). Oneroa-a-Tōhē into the amount of spat and
seaweed harvested. The ratio was changed from
Spat is collected from Te Oneroa-a-Tōhē over
50 (spat): 50 (seaweed) to 25 (spat): 75
approximately 24-30 fishing days by licenced spat
(seaweed). The 25 % spat to 75 % seaweed ratio
collectors who operate under a code of practice to
reflected new research information that
ensure their activities are safe, sustainable and
indicated the actual ratio is 18% spat. To provide
minimize the impacts on the ecology, in particular
time for fishers to address concerns around the
toheroa and tuatua. Arrival of spat on seaweed at
effects of fishing, the Minister reduced the TACC
Te Oneroa-a-Tōhē, varies depending on the year and
from 180 tonnes to 135 tonnes. Consequently,
the climatic conditions that prevail. Seaweed
the amount of spat/seaweed material allowed to
covered spat can arrive at any time of the year but
be harvested increased from 360 to 540 tonnes.
is most frequently collected in spring (Aug–Dec),
and to a lesser extent, autumn (May–Jun).
The seaweed and spat are mainly brought ashore
under easterly winds and low swell conditions, and
generally travel northwards along the beach. There
also appears to be a relationship between storm
events and spat arrival. The quantity of spat on the
seaweed is highly variable, ranging from hundreds
to millions per kilogram of seaweed. In 2018-2019,
the Te Hiku (GLM 9) seaweed/spat harvest was 592
tonnes, which is sold in 10 kg bags at a cost to
industry of approximately $8 million. The amount of
spat caught in 2018-19 equates to approximately 40
billion individuals, and from that number
approximately 2 billion adult mussels are produced
each year (c. 90,000t). The ratio of spat seeded to
final product harvested suggests that conversion of Photo credit: Brad Skelton – University of Auckland
spat to final product is approximately five percent,
but due to uncertainty around the density of spat on seaweed this number could be significantly lower or
higher. Beach-cast spat, while providing a relatively low-cost source of spat, has the inherent challenge of
being variable in supply quantity and quality.
9|P ageIn 2019, AQNZ coordinated the establishment of a Te Oneroa-a-Tōhē Spat Working Group (SWG) to
progress the industry’s commitment to ensuring the spat collecting activity on Te Oneroa-a-Tōhē (90 Mile
Beach) is supported by Government, the Te Hiku o Te Ika Iwi and the Northland community. The SWG
comprises representatives of the Te Hiku Iwi, spat collectors, the mussel industry, Te Ohu Kaimoana, and
Fisheries New Zealand (MPI). Among a range of initiatives, the group is developing a code of practice for
spat collectors, and an ongoing review process. These will be overseen by a management board and will
be closely aligned with the work of the broader Te Oneroa-a-Tōhē Beach Management Plan.
Rope-caught wild spat
In several coastal regions of New Zealand, wild GSM mussel spat are aggregated by oceanic currents. If the
timing is right and appropriate settlement substrata are available (e.g. spat catching ropes), spat will settle
and attach. Spat catching sites, where specially designed fibrous spat-rope is suspended off long lines for
the specific purpose of catching wild spat, provide up to 30 percent of the industry’s spat requirements.
Regionally important existing wild spat catching sites include Wainui (Golden Bay), Aotea Harbour, Kawhia
Harbour, Opotiki, and traditionally, Pelorus Sound. The Wainui spat catching sites are due for reconsenting
in 2024 and are critically important to the industry as the spat they provide enable different and extended
harvest windows. A recent economic assessment of the expected economic losses if these sites are not
available to provide industry with spat suggests losses of over $44 million, and 232 jobs [2]. Additional wild
spat catching sites are being investigated in open ocean environments along the west coast of the North
Island and on the east coast of Coromandel Peninsula. Once wild spat has settled on spat catching ropes,
they are transferred within regions to on-grow spat. In some cases, rope caught spat are intermediate
seeded at 6-14 mm, but in others they are kept on ropes until they are 30-55 mm in length and are stripped
into bags and sold as final seed. One benefit of wild-caught spat is that it can provide a relatively cost-
effective source of spat. However, as is the case for Te Hiku spat, the timing, quantity and quality of spat
is variable and unpredictable.
Photo credit: Cawthron Institute
10 | P a g eHatchery spat
SPATNZ are currently New Zealand’s only producer of hatchery reared mussel spat, but there is significant
potential to increase the supply of hatchery spat to enable sustained industry productivity and resilience.
SPATNZ currently produce up to 20 percent of the industry’s spat supply. During their seven-year PGP
project that finished in late 2019, SPATNZ made significant advances in hatchery production and nursery
care of GSM spat. Developing rearing systems to optimise the resilience of spat, targeting nursery
technology to optimise the size and nutritional status of spat, and targeted spat rearing sites. SPATNZ have
increased hatchery spat retention to over 20 percent and growth rates are up to double those of wild
caught spat [3]. There are also significant benefits and efficiencies that come from hatchery spat through
consistency of supply and consistency of size and shape at processing.
Photo credit: SPATNZ
11 | P a g eGoal 2: Optimising spat use
To increase on-farm retention of spat for greater production performance
Challenges:
• Improving spat harvesting and handling to increase subsequent performance
• Assessing spat quality, spat numbers, and seeding densities
• Understanding the seeding environment and what makes a good and bad spat retention site
• Uncertainty around the feasibility of nursery systems at a commercial scale to boost spat condition prior to seeding
• Industry heavily invested in current systems, making changes potentially disruptive and costly to implement
• Lack of methods to reduce predation by fish
Goal: Increase on-farm retention of spat
Objective Action Responsible Party Timeframe
All Spat Sources – Te Hiku, Rope-caught wild spat, Hatchery
Improved spat handling practices • Review existing research Industry 2020 –
increase subsequent spat • Optimising spat handling and shipping methods Researchers ongoing
performance • Framework to monitor spat size and subsequent retention by growing Government
area
• Develop management options for spat behaviour and triggers of
secondary settlement
Improved assessments of spat • Develop rapid field-based methods for quality control of spat prior to Researchers 2020 –
condition and quantity prior to seeding Industry ongoing
seeding increases retention • Develop rapid field-based methods to count spat prior to seeding Government
• Spat condition and count data are used to guide seeding decisions
Improved understanding of seeding • Environmental monitoring at good and poor retention sites Researchers Ongoing
environment at good versus poor • Environmental and retention data are used to identify the best sites Government
retention sites • Only the best retention sites are used for seeding spat Industry
• Environmental monitoring of biofouling
12 | P a g eCommercial scale nursery systems • Develop near commercial-scale methods to remove spat from Te Hiku Researchers 2020 –
are used to boost spat quality prior weed or spat catching ropes and settle spat onto a standard substrate Industry ongoing
to seeding • Develop near commercial-scale nursery systems to boost spat quality Government
and size prior to seeding
• Determine spat hardening / acclimatisation protocols for nursery spat
• Determine the optimal spat transfer protocols
• Use research data to inform a cost/benefit analysis for a commercial-
scale nursery system for spat
Efficient methods are used to strip • Develop efficient stripping or ‘milking’ methods and systems to reduce Industry 2020-2025
intermediate spat and increase time costs and increase conversion rates from primary to secondary Researchers
conversion rates seed
Methods are developed that reduce • Develop commercial scale methods for reducing the effects of Researchers Ongoing
predation effects on spat predation on spat Industry
Government
13 | P a g eBackground to spat retention
One of the issues facing the industry is the inefficient use of spat in the early stages of production due to
poor spat retention. Currently, it is estimated that approximately five percent of seeded spat are retained
through to grow-out, leading to a harvest of over 2.2 billion adult mussels (c. 90,000 t). The industry goal
for 2035 is to increase spat retention to greater than five percent, which will deliver more efficient
production and certainty around spat supplies. Achieving this goal will require a greater understanding of
the quality and numbers of spat that are being seeded, better knowledge of spat biology and behaviour,
the environment into which spat are seeded, methods to increase spat quality before seeding, and
techniques to reduce the effects of predation.
A significant decrease in spat losses throughout the farming system, from initial seeding to grow-out, will
be required to reach over five percent retention. This starts with using methods that keep spat in a cool,
humid environment during transfer from spat collection areas to farms, as studies have found that spat
that are less stressed and more likely to have higher retention [4]. Research has also shown that over 40
percent of seeded spat can be lost to the environment within minutes of deployment [5]. Unlike oyster
spat, mussel spat are highly mobile and settlement is not permanent. Spat naturally undertake post-
settlement migrations from one settlement site to another, but the triggers of these migrations are poorly
understood [6]. Triggers for migration are thought to include: the size of the spat, the overcrowding of
spat, the health and nutritional status of the spat, environmental conditions at the time of seeding, the
amount of food available, settlement substrata preferences, biofouling, chemical cues, handling and on-
farm practices. Better knowledge of all factors that trigger migration will be necessary to increase spat
retention.
The current method of seeding mussel spat requires them to migrate from the seeding substrate (either
Te Hiku seaweed, rope-caught wild spat, or coir rope from the hatchery) to specially designed fibrous rope.
Mussels also undergo migrations as they are removed from spat catching lines, either as intermediate seed
(6-15mm) or as final seed (30-55mm) and are reseeded against grow-out rope using biodegradable
stocking. In some cases, spat migrate to the stocking that surrounds the rope, and then either back to the
rope or are lost into the environment as the stocking degrades. Each migration comes at an energetic cost
to the mussel [7], so spat that are less stressed by migrations are likely to be in better condition and
demonstrate better growth in the long term. Novel methods for encouraging spat to migrate directly to
the ropes could significantly increase spat retention and long-term performance.
A recent mussel spat working group identified four knowledge gaps that affect the ability of the industry
to increase spat retention:
Condition of spat
Historically there have been two methods developed for understanding and assessing the condition of spat.
Cawthron developed a behavioural /survival method in 2006 [8], and NIWA developed a nutritional
condition method in 2011 [9]. Unfortunately, neither of these methods have been used to great effect by
industry as spat supply has been so limited that growers have had to use any available spat, regardless of
condition, in the hope that some will survive. More recently, gene expression and oxidative stress markers
have been used to show that that spat that are less stressed are better able to deal with additional stressors
14 | P a g elike high temperatures [10], and larger spat that are in better nutritional condition also have better
retention [11].
A small number of spat counts are taken by collectors to provide farmers with an estimate of the average
size and quantity of spat on Te Hiku seaweed. However, these small samples do not necessarily reflect the
size and number of spat in the whole 10 kg bag and take additional time. Rope-caught spat are either
stripped from lines and re-seeded or moved on spat catching rope based on spat size and count estimates
per metre. While basic count estimates are made at re-seeding, this is not done consistently. As such,
there is currently no effective way of benchmarking spat performance on farms as there is no standard
count data collected, either at primary or secondary stages. An effective method for counting and sizing
will be necessary to truly understand the performance of each spat source under different seeding
conditions.
Size and number of spat
Te Hiku spat are delivered to mussel farmers in 10 kg bags, which were traditionally seeded at 10 kg per
200-250 m of spat rope. Te Hiku spat ranges in size from 0.76 mm to 3 mm [12]. Periodic poor retention
of Te Hiku spat has, however, driven an increase in the seeding density by industry to 10 kg of Te Hiku
seaweed per 100-150 m. Production statistics suggest that this increase in seeding density has not led to
an increase in production. Recent research funded by industry through the Sustainable Farming Fund has
shown that increasing the seaweed density at seeding does not convert to an increase in survival and
density at secondary seeding [13]. The research suggests that a seeding density of c.11,000 spat per metre
of rope appears optimal for maximising Te Hiku spat retention. However, a lack of Te Hiku spat density
and size distribution data makes this difficult to achieve, and farmers are more likely to reduce the seeding
density of weed per metre of line.
Retention of spat differs between size-classes, with spat between 1.5-5 mm and between 8-10 mm having
a greater likelihood of retention than smaller or larger size-classes [11], so there may be benefits in
stripping and intermediate seeding spat at a smaller size (e.g. 10-12 mm), or using nursery systems (e.g.
floating upwelling systems, FLUPSYs, dedicated nursery farms, or land-based facilities) to grow smaller spat
to larger size-classes before seeding onto grow-out lines. Regardless of source, nurseries provide an
opportunity to boost spat condition through the addition of high-quality feed prior to farm transfer, which
may reduce their propensity to migrate off lines. Additional research is also required to determine the best
ways to ‘harden’ (acclimatise) or ‘condition’ (fatten or tolerate stress) spat prior to transfer. The transfer
step from nursery to farm is likely to be an important determinant of survival / retention of spat and will
require additional refinement for spat that has been brought in from the wild.
A common industry metric is that the industry expects, as a minimum, to seed 3 m of grow-out rope for
every 1 m of primary seeded rope (a 3:1 ratio). Preliminary industry studies have shown that despite
coming at an additional time and cost, stripping and secondary seeding spat at 10-12 mm can double
retention and increase this ratio to 6:1. The development of new methods for achieving this process quickly
and efficiently will likely be necessary to provide the retention needed to achieve the industry goal.
Research has also shown that the different seaweed materials that the Te Hiku spat arrive on can negatively
affect the survival of spat through to secondary seeding [14]. As such, there may be significant benefits in
15 | P a g eremoving spat off this material, sorting into different size classes, and settling onto a standard rope
substrate for use in nursery systems, or for delivery straight to good spat retention sites.
The seeding environment
Industry has identified what appear to be good spat retention sites and poor spat retention sites, and that
there is variability in the retention of spat within farms. However, the environmental attributes of the best
spat retention sites have not been well defined, and there is no metric to indicate when a site has the right
conditions (be they food type, quantity, or quality, or physical water column properties, or combinations
of both), for good spat retention. Recent work by SPATNZ has shown that hatchery produced spat retention
rates can be more than doubled simply by only seeding spat to better retention sites [3]. Biofouling has
also been shown to affect spat retention [15, 16]. In recent years, predictive models have been developed
to enable better manage the risks of blue mussel over settlement, which can affect yield by up to 10 percent
[17]. With additional environmental and retention data, similar predictive models could be developed to
manage spat nursery sites.
Predation
Predation by fish and other mobile predators (e.g. decorator crabs) has also been identified as an important
factor affecting the retention of spat in some areas. There is a need to better understand the role that
predation plays in spat loss and how this might be managed or mitigated for better retention outcomes.
SPAT CONDITION, SEEDING AQUACULTURE INCREASED SPAT
SIZE, AND NUMBER ENVIRONMENT PRACTICE & RETENTION (> 5 % TO
PREDATION INTER-SEEDING)
16 | P a g eGoal 3: Increasing hatchery production
To enable greater spat supply, productivity, value, and resilience
Challenges
• Capital and operating costs
• Requires land-based hatcheries in more than one region to reduce risk
• Requires access to optimal sea-based nursery areas
• Optimal settlement substrata, densities, feeding regimes in land-based nursery systems
• Optimal transport from nursery to farm
• Seasonal production cycles
• High maintenance costs for breeding programme
• Access to specialist knowledge and suitably trained staff
Goal: Breeding programmes, hatcheries enable greater productivity, value,
retention, and resilience
Objective Action Responsible Timeframe
Party
Hatchery Spat
Multiple hatcheries • Support proposals for additional Industry 2020 – ongoing
based in more than hatcheries in other regions Researchers
one region, • Hatchery spat supports field- Government
collectively provide based retention experiments
over 30 percent of • Ensure access to optimal sea-
industry spat based nursery space
requirements
Industry increasingly • Explore the potential for triploid Researchers 2020 – ongoing
use a breeding spat – for nutraceutical uses Industry
programme for • Assess the interaction between Government
advantage wild and hatchery produced
mussel populations
• Explore potential to select for
families that enable farming in
marginal areas
• Explore potential to select for
genetic / epigenetic traits
underlying better retention
• Explore potential to breed for
high value components – e.g.
nutraceuticals
17 | P a g eBackground to hatcheries
By 2035, industry have set a goal to have more than 30 percent of all spat supplied by hatcheries.
Hatcheries will lead the industry toward a resilient and smart farming future. SPATNZ is currently New
Zealand’s only producer of hatchery mussel spat, but there is significant potential to increase the supply of
spat and optimise industry productivity by developing additional hatcheries. Greenshell™ mussel spat has,
however, proven harder to grow than other mussel species and needs a larger scale facility to achieve the
necessary process quality controls and economies of scale. SPATNZ currently produce up to 20 percent of
the industry’s spat supply from one hatchery in Nelson but has potential to increase to 30 percent. Having
hatchery spat produced in only one location could be a risk from a biosecurity and natural disaster (e.g.
flooding, earthquake) perspective. The development of additional hatcheries in other regions would be
one way to mitigate this risk. However, assessments would be required to determine the best locations
for additional hatcheries, and to project industry gains from hatchery spat production.
Breeding programmes
Breeding programmes have been an essential part of terrestrial and aquatic farming systems for centuries,
and the return on investment in well-structured breeding programmes can be very high. New Zealand
currently has one mussel breeding programme based in Nelson. The programme is managed under a
commercial arrangement through a company called BreedCo, which is 80 percent owned by SPATNZ
(owned by Sanford Limited) and 20 percent owned by the Cawthron Institute Trust Board (Cawthron).
Cawthron started breeding from 75 founder families in 2002 and an additional 69 founder families in 2003.
Up until 2008 all cohort traits were evaluated at six sites. The Cawthron breeding programme was
commercialised in 2013 as part of the PGP project that led to the development of SPAT NZ. Under this
arrangement BreedCo has developed a more intensive and rigorous selection index approach that
combines four production-related traits: shell length; meat weight; shell weight; and a semi-quantitative,
visually assessed meat condition score [18]. Increased use of breeding programmes for hatchery spat will
enable the industry to breed for resilience to environmental challenges, overcome any future production
issues, and to realise the opportunities afforded by trait selection for high-value constituents and attributes
that provide a premium product.
Productivity
Currently, the industry uses wild-caught spat from different areas to provide some control of harvest
condition seasonality, and to ensure production is near year-round. Wild spat caught in Golden Bay tend
to be harvestable during spring and summer, while wild spat from Te Oneroa-a-Tōhē tend to be harvestable
from summer through to early winter. However, the degree to which this difference in conditioning time
is related to genetics and, therefore, could be used to extend the condition window, is not clear. To date,
SPATNZ has produced mainly spat with a Golden Bay fattening cycle, as this was in short supply. With
current hatchery production levels, SPATNZ is now also doing production of mussels with Te Hiku fattening
cycle, to balance out the "Golden Bay" stock. The Te Hiku mussels are drawn from the hundreds of families
available in the breeding programme. Another option that will likely provide some control of condition is
the use of triploids, which maintain condition for longer. Triploids are, however, unlikely to completely
replace the use of diploid stock as they do not produce the desirable orange-coloured female mussels.
Although they may prove useful in stocks destined for use in high value nutraceutical markets.
18 | P a g eValue
The mussel industry is also shifting to a value chain focus, and consumer attributes such as shell colour
have started to receive attention. Currently marketed as the Greenshell™ based on shell colour, there is
potential to make use of the differences in shell colour, size, and shape, between families to select for
unique traits that may command a premium in market. Greenshell™ mussels also have high levels of
compounds with potential anti-inflammatory properties, and research is underway to determine if there is
a genetic basis for these attributes.
Resilience
A potentially important opportunity for selective breeding of mussels lies in the potential to expand the
industry by developing strains or breeds that make it economically viable to farm at sites where production
is either not currently possible or marginal. This includes low-productivity sites or sites where
environmental conditions such as water temperature or salinity are such that commercial production of
Greenshell™ mussels is not currently viable. Results from SPATnz show that the relative growth benefits
of hatchery mussels were expressed equally strongly at unproductive sites as productive sites [3].
Photo credit: SPATNZ
19 | P a g ePathway to a resilient spat supply
Understanding of spat Optimised spat
Diverse spat supplies
biology husbandry
Continued access to Minimising spat stress Size at transfer
wild caught spat Understanding spat Transport techniques
Research into new spat behaviour - migration Using the best spat
catching areas triggers retention sites
Increased production Breeding programme Managing biofouling
of hatchery spat and trait selection
Stocking types and
Development of Broodstock techniques
commercially viable conditioning
nursery systems Interseeding
Settlement substrata techniques
Settlement densities Seeding densities
Booster feeds Predation deterrents
Acclimatising spat
Conditioning
(fattening) spat
Photo credit: Paul South – Cawthron Institute
20 | P a g eExisting and future spat research and funding options
Understanding the processes that drive spat supply and retention have been, and continue to be, a focus
for research providers and industry. Research underway by Industry, Cawthron, NIWA, University of
Auckland, AUT Research providers and existing research programmes related to mussel spat are
summarised in the following table:
Shellfish Aquaculture Research Platform (ShARP) SSIF
•Cawthron: (spat retention, spat physiology, spat feeds, probiotics, selective breeding, environmental effects,
stress responses, biofouling impact and mitigation, spat behaviour)
•Ongoing
Aquatic Health MBIE Programme
•Cawthron: (spat health, seasonal mortality, tool development and implementation )
•2018-2023
Enabling Open Ocean Shellfish Aquaculture MBIE Programme
•Cawthron: (novel farming and spat catching structures)
•2019-2024
SFF project - Spat retention
•Coromandel Marine Farmers Association / University of Auckland (spat retention mechanisms, density
dependent effects)
•2018-2020
University of Auckland
•Spat feeding, nursery culture, effects of heavy metals on spat development
•Ongoing
•Tracing origins of Hauraki Gulf and Bay of Plenty spat and ocean connectivity - with MetOcean Solutions -
Moana Project
•2018-2023
Auckland University of Technology (AUT)
•Spat physiology, metabolomics, spat feeding, beachcast spat, spat retention
•Ongoing
NIWA - Core funding
•Environmental monitoring, biogeochemical modelling, spat retention
•Ongoing
21 | P a g ePotential funding sources for future research described in the spat strategy are listed in the table below.
Fund (Funding Source) Leader Government Industry Share
Share (%) (%)
Strategic Science Investment Fund Research providers 100 In kind
- SSIF (MBIE)
Endeavour – Research Research providers 100 Cash and in-kind
Programmes (MBIE) support
Smart Ideas (MBIE) Research providers 100 In kind
/ Industry
Sustainable Food Fibre Futures Industry / Research 40 - 80 60 - 20
Fund – SFFFF – (MPI) providers Depends on
project size
Marsden Fund (The Royal Society Research providers 100 In kind
of NZ)
Catalyst Fund (The Royal Society of Research providers 100 In kind
NZ)
Seafood Innovations Limited (SIL) Research providers/ 46.5 53.5
Industry
R&D Project Grants (Callaghan Industry 40 60
Innovation)
Provincial Growth Fund (PGF) Regional LOAN 100
development
projects / Industry
22 | P a g eReferences
1. Government, N.Z., The New Zealand Government Aquaculture Strategy, M.o. Fisheries, Editor. 2019:
Wellington, NZ. p. 20.
2. NZIER, Current and future spat production: Prospects and constraints. 2018, New Zealand Institute of
Economic Research. p. 42.
3. SPATNZ, Transforming mussel aquaculture through hatchery technology and selective breeding., in
Report of the SPATNZ Primary Growth Partnership Programme. 2020, SPATNZ: Nelson, NZ. p. 35.
4. Carton, A.G., et al., Evaluation of methods for assessing the retention of seed mussels (Perna
canaliculus) prior to seeding for grow-out. Aquaculture, 2007. 262(2): p. 521-527.
5. South, P.M., O. Floerl, and A.G. Jeffs, Magnitude and timing of seed losses in mussel (Perna
canaliculus) aquaculture. Aquaculture, 2020. 515: p. 734528.
6. Buchanan, S. and R. Babcock, Primary and secondary settlement by the greenshell mussel Perna
canaliculus. Oceanographic Literature Review, 1997. 12(44): p. 1500.
7. Lurman, G.J., Z. Hilton, and N.L. Ragg, Energetics of byssus attachment and feeding in the green-lipped
mussel Perna canaliculus. The Biological Bulletin, 2013. 224(2): p. 79-88.
8. Webb, S. and K. Heasman, Evaluation of fast green uptake as a simple fitness test for spat of Perna
canaliculus (Gmelin, 1791). Aquaculture, 2006. 252(2-4): p. 305-316.
9. Sim-Smith, C.J. and A.G. Jeffs, A novel method for determining the nutritional condition of seed green-
lipped mussels, Perna canaliculus. Journal of Shellfish Research, 2011. 30(1): p. 7-11.
10. Delorme, N.J., et al., Stress-on-stress responses of a marine mussel (Perna canaliculus): food limitation
reduces the ability to cope with heat stress in juveniles. Marine Ecology Progress Series, 2020.
11. Supono, S., B. Dunphy, and A. Jeffs, Retention of green-lipped mussel spat: The roles of body size and
nutritional condition. Aquaculture, 2020. 520: p. 735017.
12. Jeffs, A.G., et al., Composition of beachcast material containing green-lipped mussel (Perna
canaliculus) seed harvested for aquaculture in New Zealand. Aquaculture, 2018. 488: p. 30-38.
13. Skelton, B. and A. Jeffs, Solving the problem of poor spat retention on New Zealand’s Greenshell™
mussel (Perna canaliculus) farms, in Progress Report on Sustainable Farming Fund (SFF) project #SFF
405275- Greenshell™ Mussel Seed Security. 2019, University of Auckland. p. 50.
14. Skelton, B.M. and A.G. Jeffs, The importance of physical characteristics of settlement substrate to the
retention and fine-scale movements of Perna canaliculus spat in suspended longline aquaculture.
Aquaculture, 2020. 521: p. 735054.
15. Forrest, B.M. and J. Atalah, Significant impact from blue mussel Mytilus galloprovincialis biofouling on
aquaculture production of green-lipped mussels in New Zealand. Aquaculture Environment
Interactions, 2017. 9: p. 115-126.
16. South, P.M., O. Floerl, and A.G. Jeffs, The role of biofouling development in the loss of seed mussels in
aquaculture. Biofouling, 2019. 35(2): p. 259-272.
17. Atalah, J., H. Rabel, and B.M. Forrest, Modelling long-term recruitment patterns of blue mussels
Mytilus galloprovincialis: a biofouling pest of green-lipped mussel aquaculture in New Zealand.
Aquaculture Environment Interactions, 2017. 9: p. 103-114.
18. Camara, M. and J. Symonds, Genetic improvement of New Zealand aquaculture species: programmes,
progress and prospects. New Zealand Journal of Marine and Freshwater Research, 2014. 48(3): p. 466-
491.
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