Regeneration and enhancement of costal resources with marine ranching in Chile
Regeneration and enhancement of coastal resources with marine ranching in Chile
Masatoshi
FUTAGAWA / CORDUNAP
June 19, 2012
Marine coastal resource is reducing
since last few decades due to over fishing of high value shellfish and finfish.
Exhaust of those resources broke ecosystem of coastal organisms like un-useful
species take over the place of exhausted species and irregular ecosystem reduces
productivity and biodiversity then costal resources are shrinking rapidly. We
should work for the program which regenerate ecosystem and enhance productivity
after recovering ecosystem.
Marine ranching program is ideal to
regenerate ecosystem and maintain it sustainably which consist seed releasing,
artificial reef installation and area management. The program applying in Japan
almost half century and some resources were regenerated and enhancing with
useful information. I recommend applying the program in Chile which domesticate
to local condition. The program is operated by fishermen, government, institute
and private sectors with short term (2 years), medium term (5 years) and long
term (10 years). I hope it will be well organize and shows regeneration and
enhancement.
1. Algae ground regeneration and enhancement with marine ranching (AGREMAR)
Algae is the base of coastal
organisms which release oxygen, clean water, take care shells, shrimps, crabs
and those are use as feeds for fish, work for shelter and spawning ground of
shellfish and finfish. However, we observed that algae ground are decreasing
due to irregular ecosystem due to over fishing of particular species. Moreover,
irregular ecosystem reduces biomass, biodiversity and productivity, it go round
to negative spiral. Thus, AGREMAR is the first step, and essential, in order to
recover ecosystem with marine ranching and the program guaranty the production
of commercial aquaculture. Even, marine ranching commercialize if recovery
reach to 40 % based on author estimation.
According to the barren
algae ground regeneration manual by Ministry of agriculture, fishery and forestry
of Japan in 2007
and 2009,
I introduce their activities and propose some ideas to regenerate and enhance
algae ground.
1.1. Program goal and term
Operation term and goal are decided to considering about
ground condition, expectation during sea condition, water condition, budget and
availability of techniques.
· Short term (1 – 3 years); Concentrate regeneration
of small algae ground (500 m2). Also consider perennial alga needs
few years to grow. If this happens, the area becomes barren again after recovery
within few years due to bad water condition.
·
Medium term (3 – 5 years), shells yield
increase as twice for example.
·
Long term (5 – 10 years), fish yield
recover as level of 20 years ago for example.
1.2. Site selection
Project site
requirements are shown below as the project operates efficiently.
·
The area is preservation area “Area de
manejo”.
·
Historically, algae had grown before.
·
Water is nutritious to grow algae.
·
No house discharge and chemicals from
factories.
·
Not much suspend matter which reduce
clarity and decrease algae growth.
·
High accessibility from coast.
·
Infrastructure (water, electric, phone,
internet ideally) are available.
·
Close to city.
1.3. Field survey
At first, we should
know the project site before start applying the program as following items
under Belt
transect
method
with quadrat.
·
Water condition (WT, salinity, pH,
transparency, wave, current, tide) and seasonal change
·
Intensity and hours by day and seasonal change
·
Biomass and seasonal change of algae
·
Spawning season of algae
·
Productivity of algae
·
Biomass and seasonal change of predators
Based on field survey, hypothesize
the causes of barren ground and planning operation programs. Simply, there are
three reasons to algae ground barren that predation, wither and buds do not
grow. The points are why those phenomenon occurring and how to know the
reasons. Once we know the reasons, we apply some countermeasure and able to
correct the problems. Then if can’t solve problems, put up new hypothesis after
diagnosing the operation and try it again.
1.4. Regeneration and enhancement of algae ground
In Chile, predation of
algae occurred by sea urchin which should be below 5 to 10 ind./m2, herbivorous
fish like “Baunco” and human fishing. Wither
and bud do not grow are cause of water quality change such as WT, Sa, clarity,
suspend matters, current.
· Seeding with “Open spore bag”
This method applied
several area, in Kochi (2005), Izu (2007) and Nagasaki
(2009), and result shows the method is effective if we choose the right place. The
bag consist of three ellipse buoys (0.62 Kg) which suck in thin hair bag and
connected rope (1 m), the rope connected to cement base.
Premature algae are
tied to the rope and put on target ground or artificial reef. The bag installed
at density of every 30 m2 (radian 3m) during spawning season.
Spawned spores attach to thin hair bag and on the base.
·Seeding by rope
The system shows several broodstock
algae are tied to rope which hung at middle of water. The algae give spore from
top to bottom and excess algae feed to sea urchin when the system touched the
bottom after growth much. This system cannot recover alone and the system
requires high cost.
· Implant juvenile
Several ropes are fixed at rich algae ground or
strings dip in seed source in hatchery and several young algae grow on
materials. Those ropes or strings drive a nail into wood plate or ditch of
artificial reef which stalled at barren ground during growing season of algae. Ideally,
cleaning nailing plate or ditch, remove competitors, before transfer to assist
growing algae quickly. Those young algae need protection from predators if they
are abundant.
· Implant broodstock
We transfer wild matured algae to barren
ground which glued to stone or concrete base. Observation is needed to prevent
predation ant covered by cage or net to protect algae from predators.
· Transplant (algae bank) broodstock
We transplant small ecosystem, algae
including small animal, by the plate which fixed at wild algae ground and grown
naturally and transfer occasionally. The method recovers faster than implant
algae alone but it takes time to prepare the plate. More effectively, remove
sediment and competitive juveniles of shells, sponges and algae around the
transplant area before installation. If target ground has some sediment, we
transplant algae after growth big to avoid wither algae.
· Predation control
Predation is very common cause of disappearing
algae by sea urchin and fish, and it can be confirmed by looking at the leaves
that show bit marks. Sea urchin is one of the top predators and makes algae
ground barren. Sometime un-useful sea urchins are abundant due to over fishing
useful species.
There are three methods to protect and
control algae from predators which are elimination, diffusion and protection. We
choose or combine the methods in each ground depending on the situation.
· Elimination
Sea urchin are eliminated at density below 0.03 ind./m2 manually
or a hook from boat, traps and suction pump regularly. The method is applicable
at calm area and costly but it can recycle captured sea urchin for feeds and
fertilizer. Herbivorous fish are eliminated by gillnet or hook and line.
· Diffusion
We feed algae or trash fish at particular
area to gather sea urchin. The method is costly and does not function well.
Applications of chemicals, pulse or electric for both predators are under
development, based on trial of 200 items only large sound diffuse fish. It
needs more study and we should give attention about negative impact for
environment.
· Protection
Algae are protected from herbivorous fish
and sea urchin by cage or net physically. The method protect well long period
but it can utilize only small area due to material and maintenance cost. Thus,
the methods apply particularly in small area which is core of regeneration.
Rolled net obstacle sea urchin to climb
or path it and the net tied to chain then close or divide sea ground to avoid
sea urchin. It should minimize opening between ground and net and remove
sponges once a year.
Another method is that
attaching some materials at the reef foot and stop sea urching creeping up
according to Okabe.
1.5. Sediment control
Suspended matter settles on bottom and become sediment
which obstructs spore clung to the rocks and contaminate water. Also some sponges
or useless algae competes growth of useful algae. Thus, it is necessary to
clean bottom by dredger, chain dragging, backhoe or water blowing.
1.6. Artificial reef for algae
· Porous concrete
Porous concrete is ideal material
which has porosity structure like sponge and alga larvae attach to surface
easily and other small animals as well. Also, using gravel substitute discarded
concrete from construction excess to minimize cost.
Moreover, it is lighter than solid concrete due to porosity
structure and can transport and install easily at sea bottom.
However, it is attached to solid concrete base for use due to not strong
material as solid concrete.
· Kelp knob
Kelp knob is the point below the reef edge where
kelp grows well due to the spore clung at concrete surface easily. Idea is
artificial reef for algae should equip kelp edge.
·
Scallop shells
Scallop shells
assists settlement of alga larvae compare to solid concrete. It is
recommendable to put shell pieces at surface of AR to enhance growth of algae.
Several reefs are invented by Kaiyoh.
·
Artificial macroalga
Artificial macroalga,
made of plastics or nylon, that aggregate arthropods instantly and it is use
for substitute of macroalga until real algae grow. Artificial alga (C-lant) is
available at the tripole.
· Block type artificial reef
There
are several designs of concrete cement blocks which can extend by assembly according
to Shouha.
· Post type artificial reef
Artificial reef for algae is designed for predation
control and algae growth. According to study,
sea urchin climbs post up to 50 cm at 10 ̊C, 80 cm at 15 ̊C and 100 cm at 18 ̊C.
Thus, the reef forms concrete base and posts which is over 2 m height. Post
type reef invented by Okabe
and there are many variations.
· Artificial reef for algae by author
Artificial reef for algae, invented by author,
shaped like diamond (1 x 1 x 1 m) which has shell surface finishing, bury half shell
piece in solid concrete, kelp knob, wood plates (implant algae juvenile) and
two spore collectors (4 m long) are attached at top. Spore collector consist
buoy, rope and sinker (solid concrete with shell surface finishing) and
possibly some part of rope covered by cage which protect alga bud from
predators. The reef set 5 to 10 depth where there is medium current, strong
sunlight, clear and nutrient water.
1.7. Monitoring
Monitor
the items which was decided in operation plan at least once a month and when
sea condition change like high wave,
wind, turbid occasionally. Usually, monitor the following items.
·
Water quality (WT, pH, Sa, transparency,
turbidity, chemical analysis, etc.)
·
Biological analysis (Biomass,
biodiversity, distribution, growth, predation, etc.)
·
Status and progress
·
Problems and solutions
1.8. Workshop
Open workshop regularly (every 6 or 12 month)
to share knowledge based on review, status and problems, and revise plan if
necessary. Moreover, it is important to get consensus among the fishermen,
government, private sectors and scientist, and assign duties to each sectors.
2. Artificial reef for sea urchin
2.1. Concepts
The reef produces algae which care sea urchin from
larva to adult and protect from predators. It is installed shallow bottom, less
than 10 m, where has enough sunlight for algae growth and medium current due to
wave. Thus, the shapes flat and wide pyramid like shape, with several grooves.
Additionally, it has spore collector to maintain algae, some part covered by
cage which rotate regularly and maintain algae juvenile. Moreover,
prefabricated reef is ideal which is easy to make, minimize cost of
transportation and installation.
2.2. Design
Artificial reef for abalone by Kaiyoh
consist concrete base, concrete blocks, shells cylinder and releasing unit.
The
AR concrete consist 50 % of scallop shell bricks (5-8 mm), iron and steel slag
and cement to make rough surface with tiny holes which enhance algae
propagation.
Pyramid type (120615), invented by author,
consist concrete base (1.8 x 1.8 x 0.2 m) four layers of concrete plats (7 cm
thickness and space) which shell surface finishing and cage, for transplanted algae
protection, at top of the reef. Those parts are preassembled by pilling up to
insert in groves at corners of layer. It is advisable to add spore collectors or
artificial algae at top of the reef and enhance growth of algae.
2.3. Operation
Hatchery
made sea urchin juvenile are released to the reef after algae grown.
Monitoring
and workshop are same as 1.5. and 1.6.
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