Fishery Resource Enhancement: An Overview of the Current Situation and Issues in the Southeast Asian Region

The total global production from capture fisheries has plateaued since the mid 90s. This stagnation in production or reduced productivity of the world's coastal and marine wild fisheries is caused by overfishing and degradation of habitats through coastal development and destructive fishing methods. Reports have shown that if the current fishing trends continue, all of the commercial fisheries will have collapsed by 2050. To boost production, scientists, fisheries managers, government agencies, and NGOs have been looking at ways of enhancing fish stocks. Replenishing depleted stocks may be done by regulating fishing effort, restoring degraded nursery and spawning habitats or through resource enhancement. Resource enhancement using individuals reared in aquaculture facilities or seed stocks abundant in the wild is becoming a popular method of supplementing depleted stocks. It is one of the many strategies that could help address the decreasing fisheries production in the wild. A brief history of resource enhancement, the aquatic species released in the different countries in the region, the reasons for releasing stocks, and the issues involved, are discussed briefly in this paper. Among the main reasons for resource enhancement are to increase production or enhance stocks and increase food supply and/or family income. Other reasons include protection of endemic and maintenance of endangered species, rehabilitation of degraded natural habitats and for recreation fisheries, among others. Age or size of seeds, seed quality, genetics, governance, economics, biodiversity conservation, politics, and the introduction of exotics are among the resource enhancement issues identified in the region

Handbook of mangroves in the Philippines - Panay

A 106-page guide is a user-friendly presentation of technical botanical description and illustrations of Philippine mangrove species in Panay Island, Guimaras and Aurora Province. Vegetative and reproductive structures of 34 mangrove species that are readily observed in the field are emphasized and presented in color photographs and as graphic icons. Also discussed: importance of mangroves; mangrove decline and legislation; conservation and rehabilitation; and mangrove-friendly aquaculture

The SEAFDEC/AQD experience in stock enhancement

The Aquaculture Department (AQD) of the Southeast Asian Fisheries Development Center (SEAFDEC) started stock enhancement activities in 2000 as part of the Coastal Fishery Management Project in Malalison Is., Culasi, Antique, Philippines (SEAFDEC/AQD 1998). This was the same year as the Bangkok Declaration and Strategy for Aquaculture Development (NACA/FAO, 2000), which affirmed the potential of stock enhancement to increase fish supply. Since then, research on seed production, and release and monitoring strategies has been initiated on the abalone (Haliotis asinina), seahorses (Hippocampus barbouri, and H. kuda), mud crabs (Scylla serrata, S. olivacea and S. tranquebarica), top shell (Trochus niloticus), and window-pane oyster (Placuna placenta). Closing the life cycle and mass production of juveniles have been attained for most of these species, but actual releases have been conducted only for abalone and mud crabs. In this review article, we describe the present situation of stock enhancement of abalone, mud crab and seahorse at AQD

Estimation of energy budget of sea cucumber, Holothuria scabra, in integrated multi-trophic aquaculture

Continuous intensification of aquaculture production has brought about environmental issues associated with eutrophication worldwide. Environmental deterioration such as hypoxia and sulfide production due to water and sediment eutrophication originating from aquaculture effluents have been problematic, resulting to sporadic disease outbreaks and fish kills in the Philippines. Integrated multi-trophic aquaculture (IMTA) is one of the promising methods for sustainable aquaculture as it also provides a supplementary source of income to the fish farmers. IMTA is a polyculture system that integrates culturing of fed species (e.g. finfish) the main commodity, organic extractive species (e.g. deposit and filter feeding benthos) and inorganic extractive species (e.g. seaweed). In this study, IMTA techniques were established for small-scale coastal fish farmers in the Philippines, with sea cucumber (Holothuria scabra, commonly known as sandfish), as the key species. Sandfish commands the highest price in tropical sea cucumber species. Nitrogen (N) budget of sandfish in polyculture with milkfish (Chanos chanos) and Elkhorn sea moss (Kappaphycus alvarezii), both of which are commonly cultured in the Philippines, was estimated using a simple closed box model. Information on stocking density, stocking size, mortality, growth, feed ration, feed assimilation, NH4-N production and NH4-N absorption of these species was obtained from a series of experiments and existing literature. Culture conditions were as follows: 26 g milkfish were cultured in a 5 x 5 x 4 m cage at an average stocking density of 36.7 ind/m3 (i.e. usual practice in the Philippines) with an initial feeding ration of 10% of body weight which was gradually decreased to 4% over time; 10 g sandfish were cultured in a 5 x 5 x 0.3 m cage hung under the milkfish cage to trap particulate N waste (i.e. feces and leftover feed) from milkfish culture at a stocking density of 35 ind/m2; the stocking weight of Elkhorn sea moss line culture was 10 kg. The culture period was 200 days. It was estimated that milkfish culture under the above-mentioned schemes cumulatively produced 145 kg of particulate N, and milkfish and sandfish together excreted 60 kg of NH4-N in 200 days of culture. Daily assimilation rate of the particulate N by sandfish ranged from 3.4 to 12.4%, and 6.4% of the particulate N was estimated to be removed by sandfish during the entire 200 days of culture. Daily absorption rate of NH4-N by Elkhorn sea moss increased exponentially with time and reached 100% at 125 days of culture. Cumulative NH4-N from milkfish and sandfish excretion was estimated to be depleted by 162 days of culture. For complete utilization of particulate N by sandfish by the end of milkfish culture period (i.e. zero emission), sandfish stocking density should be 805 ind/m2, which is 200 times as high as that in existing sandfish aquaculture operations in countries such as Viet Nam and New Caledonia. The purpose of sandfish culture in IMTA should be emphasized in terms of its economic advantages and not very much on environmental integrity. Cages for sandfish culture should be designed in such a way where only a small fraction of organic matter from milkfish culture (i.e. about 6% in this culture scheme) enters it to avoid sediment quality deterioration and possible death of sandfish. Elkhorn sea moss on the other hand seems very efficient in bioremediation capability

SEAFDEC/AQD stock enhancement initiatives: release strategies

The Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC/AQD) started its Stock Enhancement Program more than a decade ago with the first stock enhancement initiative on the mud crab Scylla spp. funded by the European Commission. This was followed by another stock enhancement program in 2005 supported by the Government of Japan Trust Fund. In preparation for its implementation, a Regional Technical Consultation on Stock Enhancement of Species Under International Concern was convened in Iloilo City, Philippines in July 2005 to identify species for stock enhancement. During the meeting, seahorses Hippocampus spp., giant clam Tridacna gigas, abalone Haliotis asinina, and sea cucumbers Holothuria spp. were among the priority species for stock enhancement work. Stock enhancement, restocking and ranching are management approaches involving the release of wild or hatchery-bred organisms to enhance, conserve or restore fisheries. This paper reports SEAFDEC/AQD release activities and some of the release strategies that have been established for mud crabs, giant clams and abalone

Elemental sulfur in the gills of the mangrove mud clam Anodontia edentula (Family Lucinidae)

Different sizes of the mangrove mud clam Anodontia edentula were collected from the mangroves in Brgy. San Roque in Estancia, Iloilo, central Philippines, and the mantle, gill, and foot tissues were analyzed for elemental sulfur content. Mangrove mud (substrate) was also analyzed for total sulfur content to establish the possibility of clam-bacteria symbiosis in this lucinid clam. Sulfur analysis showed highly significant (p <0.0001) amounts of elemental sulfur in the gills (247.64 ± 63.28 μmoles/g FW) compared with the quantities observed in the mantle (0.84 ± 0.22 μmoles/g FW). Elemental sulfur was absent from the foot tissues. Results also showed a significantly (p <0.05) decreasing elemental sulfur from the newly collected clams (mean = 461.18 μmoles/g FW) compared to those reared in the laboratory (mean = 159.08 μmoles/g FW: with mangrove mud substrate; mean = 45.18 μmoles/g FW without substrate), which were analyzed weekly until week 3, indicating that stored elemental sulfur is being utilized by the bacteria in the absence of sulfide. Total sulfur content of mangrove mud in situ was higher than that used us substrate in the experiment; where there were no significant differences from initial to final readings. This shows that mangrove mud in situ is linked to a steady sulfur source

Stock enhancement of the mud crabs Scylla spp. in the mangroves of Naisud and Bugtong Bato, Ibajay, Aklan, Philippines

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Molluscan aquaculture in the Philippines: A review

Molluscs are among the most valuable resources of the Philippines, an archipelagic country of 7,107 islands bounded by 36,000 km of coastline and 26.6 million ha of coastal waters. In 2020, production from mussels and oysters alone valued at PhP1.552 billion. As primary sources of food and livelihood for marginalized fisherfolk, they are considered important in food security, nutrition, and poverty alleviation. Nevertheless, for almost a century, mollusc culture remained small-scale, with most fish farmers investing in non-fed species, like mussels and oysters. Moreover, mollusc culture in the country is still dependent on wild sources of seed stocks, making production unsustainable and unreliable. This dependence on the wild seed stocks will continue until the issue of the lack of commercial-scale hatcheries or the limited capacity of existing hatcheries to produce seeds, both for top and emerging mollusc aquaculture species, is resolved. Although technologies from broodstock management to post-harvest are available in some species, the lack of capital and the limited government support limit these artisanal fishers from doing large commercial-scale culture. This paper summarizes what has been done and published on the leading mollusc species cultured in the Philippines. Future research activities may be designed based on the research gaps to refine available technologies and develop new ones to improve culture production. The lack of or limited relevant information on the viable economics of the different culture techniques at different culture phases, the limited availability of post-harvest technologies, and the sparse or lack of genetic information for these leading mollusc species are among the gaps that need to be addressed.Funds for these mollusc studies came from the Southeast Asian Fisheries Development Center Aquaculture Department (SEAFDEC/AQD); the Department of Science and Technology-Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST-PCAARRD); the Government of Japan Trust Fund; the Japan International Research Center for Agricultural Sciences (JIRCAS); and the Ayala Corporation

Field guide to mangrove identification and community structure analysis

The mangrove field guide is a 32-page field guide with a one page introduction on mangroves, followed by a key to mangrove genera and species (with colored pictures of the whole plant and plant parts), then a definition of important terms used in the key, species code for use during mangrove community structure, instructions on how to conduct mangrove community structure analysis plus the formulas for the different indices (relative density, dominance, frequency; importance value and species diversity) and a sample data sheet. The guide, measuring 9 cm x 14 cm, is printed on PVC material hence it can get wet, soaked or be left in the water for days

Oxygen, sulphide and nutrient uptake of the mangrove mud clam Anodontia edentula (Family: Lucinidae)

Oxygen, sulphide and nutrient (ammonia, nitrite and phosphate) uptake of Anodontia edentula was measured. Oxygen and sulphide were measured from sealed containers provided with 1 l fresh mangrove mud (sulphide source) and seawater (oxygen source) with two treatments (with and without clam) at 16 replicates each. Oxygen, sulphide and other parameters were measured at days 1 (initial), 3 and 5 (final). Nutrients were measured from containers filled with 1.5 l wastewater from a milkfish broodstock tank with two treatments (with and without clam) at eight replicates each. Ammonia, NO2 and PO4 were measured at days 0 (initial) 3, 6, 9 and 12 (final). Results showed significantly decreasing oxygen and sulphide concentrations in treatment with clams (ANOVA, p < 0.001). A significantly higher ammonia concentration (ANOVA, p < 0.05) was observed in treatment with clams while no significant difference was observed in nitrite and phosphate between the two treatments. A decreasing ammonia and an increasing nitrite trend was also observed in both treatments starting at day 3