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.

Hatchery made algae juveniles are planted with culture base according to Okabe.

·         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

The block which has grooves are effective for sea urchin according to Shouha.




Artificial reef for abalone by Sakai consist several concrete layers and it has some openings.

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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