AQD Matters 2023 November - December

In this issue: 1) Aquaculture commodities featured in national science exhibition; 2) SEAFDEC/IFRDMD explores collaborative anguillid eel study with SEAFDEC/AQD; 3) Construction underway for aquaculture feed mill facility; 4) SEAFDEC/AQD's Deputy Chief offers solutions at international symposium; 5) SEAFDEC convenes 46PCM back-to-back with 26FCG/ASSP; 6) LGU-General Luna officials visit SEAFDEC/AQD headquarters; 7) FishWorld Aqua Week; 8) Prized crabs find new home in abandoned ponds; 9) Scientists refine method to trace the complicated diets of Japanese scallops; 10) SEAFDEC/AQD discusses accomplishments, plans with host government; 11) SEAFDEC/AQD, BFAR-6 collaborate for hatcheries, outreach stations; 12) Tourism Secretary Christina Frasco visits heritage destinations in southern Iloil

SEAFDEC/AQD highlights 2023

SEAFDEC/AQD highlights 2023 is SEAFDEC/AQD's annual report updating on its accomplishments and progress for the year 2023

High genetic diversity in anguillid glass eels across three Southeast Asian countries revealed through mitochondrial DNA D-loop sequences, with notes on population structure

Understanding the genetic diversity and population structure of anguillid eels is crucial for effective management. In this study, we used the mitochondrial DNA (mtDNA) D-loop marker to identify anguillid glass eels and assessed their genetic diversity across six sampling sites spanning three Southeast Asian countries. We also examined the population structures of Anguilla marmorata and A. celebesensis. We validated nine distinct species and subspecies of anguillid eels from 465 specimens collected in Indonesia (n = 246), the Philippines (n = 119), and Vietnam (n = 100). High gene diversities were observed across the species, ranging from 0.979 (A. celebesensis) to 1.000 (A. bicolor bicolor, A. marmorata, and A. interioris). Correspondingly, nucleotide diversity values were relatively low, varying from 0.036 (A. marmorata) to 0.057 (A. interioris). A. marmorata (n = 162) displayed a broad distribution, being observed across all six sites, with a significant yet low average fixation index of 0.05755. Pairwise comparisons of FST values between Cimandiri and other locations (except for Cagayan) were relatively high and statistically significant (p < 0.01), indicating significant genetic differentiation of Cimandiri samples compared to most locations in this study. On the other hand, A. celebesensis (n = 110), exhibited a non-significant and low fixation index (0.007), indicating no genetic differentiation in samples from Poso and Poigar Rivers, Indonesia. Our findings highlight the essential need for coordinated management strategies among regions that share common stocks. Additionally, this study underscores the efficacy of the mtDNA D-loop in precisely identifying glass eel species/subspecies and elucidating the genetic diversity and population structure of tropical anguillid eels.This research received financial support from the Japanese Trust Fund under the Project "Sustainable utilization of Anguillid eel in the Southeast Asia region"

The reestablishment of mangrove crabs (Scylla spp.) in an abandoned pond following natural mangrove recolonization

Scylla spp. are among the most economically important fisheries resources derived from the mangroves. However, the widespread mangrove destruction resulted in the loss of habitat, thus the dwindling capture production of many mangrove-associated faunas. Although studies have shown that Scylla populations have reestablished in mangrove-reforested areas, this study was the first in a mangrove-recolonized abandoned pond in the Philippines. Six fishers conducted standardized fishing every spring tide of the month using cylindrical bamboo traps. All crabs caught from July 2010 to December 2011 were recorded for species, sex, sexual maturation of females, carapace width (CW), and body weight (BW). Total landings comprised 14,262 crabs weighing 1,743 kg; 79.67% Scylla olivacea, 20.18% S. tranquebarica, and 0.15% S. serrata. CW ranged 3.1–17.1 cm and BW 10–1,250 g, with the male crabs comprising 39.23–64.65% of the monthly landings and the females distributed as 19.88–45.01% immature, 0.50–16.57% mature, 0.45–16.02% gravid, and less than 0.10% spent crabs. Monthly landings ranged 254–1,231 pcs of crabs or 32.38–160.59 kg. The monthly mean catch per unit effort (CPUE), in terms of number, was 0.101 ± 0.01–0.456 ± 0.02 crab gear−1 day−1 (max = 1.13), while in terms of biomass, 12.86 ± 0.84–54.36 ± 3.16 g gear−1 day−1 (max = 112.50). Length–weight relationships of S. olivacea and S. tranquebarica are expressed as W = 0.224967L2.9864 (r2 = 94.08%, p < 0.001; n = 11,363) and W = 0.173409L3.1074 (r2 = 92.71%, p < 0.001; n = 2,878), respectively. This study revealed that Scylla spp. could reestablish in mangrove-recolonized abandoned ponds.The Project Team greatly appreciates the Government of Japan Trust Fund (GOJ-TF) and the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC/AQD) for jointly funding the project (Study Code FS-03-C2010T

Sea cucumber hatchery and nursery production

Contains information on the hatchery and nursery culture of the sea cucumber, Holothuria scabra.Revised versionRevised versio

AQD Matters 2024 July - August

In this issue: 1) SEAFDEC expands aquaculture research complex; 2) AQD participates in USAID Southeast Asia Fisheries Partnership Workshop; 3) SEAFDEC/AQD connects with stakeholders at international exhibition; 4) SEAFDEC/AQD harvests vannamei shrimp; 5) Malaysian researchers train on marine fish hatchery, fish health management; 6) SEAFDEC/AQD conducts on-site training in Brunei Darussalam; 7) 51st Anniversary Celebration Highlights; 8) Nine graduate from the training course on marine fish hatchery; 9) Rehabilitated green sea turtle released in Antique waters; 10) Researcher presents study on the predator-induced behavior of hatchery-bred sandfish juveniles; 11) Seminars held for employee development; 12) SEAFDEC/AQD united through sports and teamwor

Establishment of a responsible shrimp farming system using an ecosystem approach

Green algae (Caulerpa), red algae (Gracilaria), and sandfish were nominated as purifying organisms suitable for shrimp farms in this study. Circulating microcosm experiments were conducted to examine the effects of those purifying organism candidates on rearing water quality and disease-causative bacteria and their impact on shrimp production. However, the three nominated purifying organisms could not enhance shrimp survival. Due to mass weight reduction during the experimental period, these purifying organisms were unlikely to be used as aquaculture by-products. On the other hand, the experiment showed that Caulerpa, Gracilaria, and sandfish, while not having the potential to reduce or remove disease-causing bacteria, can still effectively remove NH₄ and total assimilated nutrients (TAN). The removal level did not differ among the three septic organisms, indicating that they can improve water quality equally. The septic organisms are expected to contribute in maintaining a healthy aquaculture environment by mitigating harmful substances for shrimp, such as NH₄ and TAN, in aquaculture effluents. It is essential to note that if these purifying organisms are utilized in an aquaculture system, proper adjustments to their culture environment, such as salinity, should be made to ensure higher rates of survival and efficiency. This valuable information may help small-scale shrimp farmers establish aquaculture management plans to improve productivity through the proper maintenance of the aquaculture environment by using septic organisms

Female mate choice for male size in a freshwater goby under experimental conditions eliminating inter-male interference

The preference of females for male body size was examined in an experimental environment where direct interference between males was eliminated. In this environment, females preferred to spawn with larger males. To understand the preference of females for larger males, paternal care and egg defence abilities and paternal cannibalism intensity were further tested with respect to the body size of males. The dead egg rate for an egg mass during the paternal care period was not related to the body size of the paternal males. However, larger males could defend their egg masses more successfully against nest intruders than smaller ones. During the paternal egg care period, paternal males often consumed eggs in their nests. In particular, smaller males compared to females caused paternal brood cannibalism. High egg defence ability and low paternal cannibalism intensity are the most plausible reasons for females to choose larger males.This study was supported by the management expense grants of National Research Institute of Fisheries Science

Temporal variation in the incidence of seaweed health problems affecting farmed Kappaphycus striatus in relation to environmental conditions in shallow waters

A fixed off-bottom Kappaphycus striatus var. sacol farm was monitored for 12 months (June 2019 to May 2020) and the monthly incidence of disease and pests was recorded. Meteorological information in situ, from the nearest synoptic station and online data were collected to determine the relationships between temporal environmental changes and the incidence of seaweed health problems. The results showed that “ice-ice” disease (IID) was observed in dry months (i.e., from February to April 2020) and was significantly influenced by increased irradiance, salinity, sea surface temperature, and wind speed (p=0.004‒0.030). Also, the IID incidence was positively affected by reduced precipitation, storm surface run-off, water current speed, and inorganic nutrient (nitrite and ammonia) levels (p=0.002‒0.019). In comparison, epiphytic filamentous algae (EFA) were observed in wet months (i.e., from September to December 2019), with incidence varying from low to very high (≤25–100%) as the culture progressed. EFA incidence was significantly influenced by reduced salinity and increased storm surface run-off and inorganic nutrient (nitrate and ammonia) levels (p=0.006‒0.040). An intense tropical cyclone struck the farming area in December 2019, resulting in partial die-offs of farmed seaweed. Such seaweed health problems are expected to become more prevalent in the coming years as weather disturbances brought about by changing weather patterns become more frequent and intense. Hence, mitigation and preventative approaches must be fully considered to sustain the industry’s growth while protecting the livelihoods of many coastal communities dependent on seaweed farming.This study was supported by the United Kingdom Research and Innovation–Global Challenges Research Fund (UKRI-GCRF) “GlobalSeaweedSTAR” Programme (Grant No. BB/P027806/1) and implemented at SEAFDEC/AQD with a Study Code: FH-01-S2017T