Ontogenetic and diel variation in the vertical distribution of larvae of jack mackerel <Emphasis Type="Italic">Trachurus japonicus</Emphasis> in the East China sea

Larvae of jack mackerel Trachurus japonicus were sampled in seven depth layers (0–10 m, 10–20 m, 20–30 m, 30–40 m, 40–50 m, 50–70 m, and 70–100 m), with a closing-type frame net, on 26th–27th February, 2003, at Sta. V (27°50′N, 126°00′E) continental shelf edge in the southern part of East China Sea, to examine their vertical distribution. Most of the larvae (>90%) occurred in the upper 50 m layer during both day and night. In the daytime, larvae of length from 3.0 mm to 4.5 mm were most abundant in the 10–20 m layer, those from 5.0 to 6.0 mm were most abundant in the 20–30 m layer, those from 6.0 to 8.0 mm occurred at greater depth, in the 30–40 m layer, and those more than 9.0 mm were found in the 0–10 m layer and performed ontogenetic vertical migrations. Larvae from 6 mm to 8 mm length performed diurnal vertical migration, for the percentage (16.7%) of larval number in the 0–20 m layer in the daytime increased to 42.1% at night and the percentage (78.1%) in the 20–50 m layer in the daytime decreased to 49.0% at night.     

Reproductive dynamics and nursery habitat preferences of two commercially important Indo-Pacific red snappers <Emphasis Type="Italic">Lutjanus erythropterus</Emphasis> and <Emphasis Type="Italic">L. malabaricus</Emphasis>

Red snappers were examined for reproductive biology and age-0 habitat preferences. Spawning in red snappers occurred throughout the year in northern Australia and eastern Indonesia; at least 10–30% of females and 40–80% of males were in ripe or spawning condition in most months. Northern Australian populations showed a spawning peak from July to December (L. erythropterus) and September to March (L. malabaricus). Eastern Indonesian L. malabaricus had a less defined pattern with two peaks: January–March and October. Size at first maturity was 240 mm for males and 250–300 mm for females. L ₅₀ estimates were similar between species in northern Australia: 270–280 mm (males) and 350–370 mm (females). Maximum batch fecundity was 676,100 oocytes for L. erythropterus and 997,000 oocytes for L. malabaricus. Higher mean abundances of age-0 L. erythropterus were found in silty and coarse sand/rubble estuarine habitats of northern Australia (456 ± 119 fish/km²) compared with sandy coastal habitats (5 ± 3 fish/km²). Most age-0 snapper caught at Sape (eastern Indonesia) were L. malabaricus (91%) with mean abundances of 312 ± 14 fish/km². The similarities in the reproductive characteristics of red snappers suggest that successful management approaches adopted in northern Australia should be considered in eastern Indonesia.     

Dietary value of gametophytes and juvenile sporophytes of the brown macroalga <Emphasis Type="Italic">Eisenia bicyclis</Emphasis> for juvenile abalone <Emphasis Type="Italic">Haliotis diversicolor</Emphasis>

The dietary value of juvenile stages (gametophyte and juvenile sporophyte) of the brown macroalga Eisenia bicyclis for post-larval and juvenile abalone Haliotis diversicolor of 2.0–6.5 mm in shell length (SL) was examined and compared with that of a benthic diatom, Nitzschia sp., in laboratory experiments. Most abalone actively fed on these diets, but there were large variations in the growth rate among the diets and among the growth stages of abalone. Growth rates of abalone fed on Nitzschia sp. were highly variable within each growth stage, but showed no clear differences among growth stages. In contrast, in abalone fed gametophytes or juvenile sporophytes, growth rates linearly increased as abalone grew. Growth rates of >60 μm SL/day were observed in juveniles of >3 mm SL fed gametophytes, and juveniles of >5 mm SL fed juvenile sporophytes. These results indicate that the dietary value of the juvenile stages of E. bicyclis for the abalone changes as they grow, and with growth juvenile abalone begin to efficiently utilize gametophytes and juvenile sporophytes in that order.     

Changes in the scotopic vision of juvenile Pacific bluefin tuna (Thunnus orientalis) with growth

In cultured juvenile Pacific bluefin tuna (Thunnus orientalis), reducing the mass deaths caused by collision or contact with tank or net walls at night is a priority for seedling production. Pacific bluefin tuna is a visually dependant species, although its scotopic vision is poor. We recorded electroretinograms to investigate the visual function with growth in the dark-adapted eyes of juvenile Pacific bluefin tuna. Peak wavelengths of spectral sensitivity [38–62 days posthatch (dph), 77–167 mm standard length (SL)] were observed between 474 and 494 nm. Visual light sensitivity has a tendency to increase slightly with growth at 28–64 dph in individuals that measured 29–175 mm SL. However, visual temporal resolution did not significantly increase with growth at 38–62 days dph in individuals that measured 77–167 mm SL. These results suggest that the mass death continues between 28 and 64 dph because of low visual function and increasing swimming speed with growth.     

Diet of young southern bluefin tuna <Emphasis Type="Italic">Thunnus maccoyii</Emphasis> in the southwestern coastal waters of Australia in summer

The diet of juvenile (predominantly age 1) southern bluefin tuna Thunnus maccoyii (SBT, N = 720), caught over 11 years of the recruitment monitoring survey off southern Western Australia during summer, consisted overwhelmingly of teleosts (97.4% by volume). Pilchard Sardinops sagax (27.4%V), blue mackerel Scomber australasicus (16.7%V), and jack mackerel Trachurus declivis (14.2%V) were the major taxa, with pilchard more abundant in coastal waters and jack mackerel more frequently encountered in fish caught closer to the shelf-edge. Prey size varied from 5 to 240 mm, with 67% of ingested items measuring between 30 and 50 mm. Pilchard dominated the prey size category 130–190 mm (84% by number), but the overall contribution of this species to the diet of juvenile SBT was much lower than previously reported. Future research in relation to the feeding ecology of juvenile SBT should focus on the biology and ecology of the young lifestages of the main prey species in this area and on prey distribution and dynamics as a key factor linking environmental change and SBT distribution.     

Domestication of the mud crab <Emphasis Type="Italic">Scylla serrata</Emphasis>

The significant decrease in wild mud crab population highlights the need to manage the resources and domesticate crabs. This paper presents the initial results of the domestication of mud crab Scylla serrata aimed at producing good-quality captive broodstock. The analysis of the genetic structure of the base population was done as a prerequisite for domestication. Adult S. serrata from the northern to southern parts of the Philippines (Cagayan, Camarines, Samar, and Surigao) were obtained for genetic diversity analysis and domestication. Analysis of molecular variance showed that differences in the genetic variability between the four populations were not significant. Moreover, no significant deviation from Hardy–Weinberg Equilibrium was observed in each sample population and even in pooled populations. Body weight was positively correlated with the carapace width. Second spawning occurred 41–46 days after the first spawning and 34 days from second to third spawning. However, there was a decrease in the number of zoea in repeat spawnings. Twenty-four first-generation (F₁) families were produced from the four sites. The duration from spawning of the base population (P₀) to attainment of broodstock size F₁ was 10–14 months. Four second-generation (F₂) families were produced after 11–12 months. Up to the F₂, crabs tested negative for six viruses: white spot syndrome virus, infectious hypodermal and hematopoietic necrosis virus, gill-associated virus, yellow head virus, Taura syndrome virus, and infectious myonecrosis virus. The reproductive performance of P₀ was comparable to the succeeding generations. Several families were obtained from one population in a year. However, due to the cannibalistic behavior of crabs, more space is required for the nursery and grow-out phase. The domestication of S. serrata is the first study done on any mud crab species in the Indo-west Pacific region. The initial results would serve as guide to understand and eliminate the barriers to mud crab domestication. The breeding technology developed from this study will support the production of good-quality seedstock for farming.     

Distribution patterns of loliginid squid paralarvae in relation to the oceanographic features off the South Brazil Bight (22°–25°S)

Loliginid squids constitute marine resources of increasing importance in shelf ecosystems off the coast of South Brazil. However, the existing information and knowledge about the occurrence of early‐life stages and causes of distributional patterns are insufficient. Here, we have revisited Brazilian historical plankton samples obtained from 11 oceanographic surveys to identify paralarvae and their abundances over time. The study area and time period cover the region between Cabo de São Tomé (22°S) and Cananéia (25°S) at depths down to 200 m from 1991 to 2005. Of the 246 paralarvae quantified, ~50% were identified to the genus or species level, including Doryteuthis spp. (D. sanpaulensis and D. plei), Lolliguncula brevis and a single specimen of Pickfordiateuthis pulchella. Paralarval occurrence and abundance peaked in different areas and were associated with distinct oceanographic conditions: D. sanpaulensis occurred in the northern region associated with cold waters and upwelling events, D. plei occurred primarily in the southern region of the study area and in warmer waters, and L. brevis was found in shallow and low salinity waters in the estuarine region off the coast of Santos. Overall, the highest abundance of paralarvae occurred in the nearshore, northernmost areas during summer, and this can be associated with the observed retention mechanisms caused by local circulation, seasonal upwelling, the intrusion of nutrient‐rich waters, and spawning peaks. The present study provides new information and evidence for loliginid patterns in the area that may potentially be useful for better understanding the recruitment patterns and fishery assessments of squid populations.     

First description and collection records of juvenile slime flounder <Emphasis Type="Italic">Microstomus achne</Emphasis> from the eastern and western coastal waters off Honshu Island,Japan

Morphological characteristics and body pigmentations of juvenile slime flounder Microstomus achne were described from one specimen [27.8 mm total length (TL)] collected off Niigata Prefecture from the Sea of Japan (35 m depth) in May 1993 and from three specimens (30.1, 36.2, and 40.9 mm TL) collected off Fukushima Prefecture on the Pacific coast of northern Japan (15 and 50 m depths) during April–May 2008 and 2009. These age-0 juveniles had a characteristically slenderly oval-shaped body and slightly protruded front nostrils. Sparsely distributed melanophores and xanthophores were clearly visible throughout the ocular side of one specimen, which was judged as a newly settled juvenile, whereas several spots aggregated by small melanophores were found in the others with elongated pectoral fins and small cycloid scales. Melanophores were only slightly detectable on the blind side. Comparisons of the depth distributions of slime flounder juveniles and sympatrically collected age-0 pleuronectids (Pseudopleuronectes herzensteini, Pseudopleuronectes yokohamae, Platichthys bicoloratus, and Dexistes rikuzenius) suggested that slime flounder can settle on broad nursery areas of coastal and offshore pleuronectid flatfishes, probably depending on local oceanic conditions during the protracted pelagic phase.     

Distribution patterns of five pleuronectid species on the continental slope off the Pacific coast of northern Honshu,Japan

Information on the distributions of demersal and benthic fishes is fundamental for stock assessment and management. Spatiotemporal changes in the distribution patterns of five pleuronectid species (flathead flounder Hippoglossoides dubius, Kamchatka flounder Atheresthes evermanni, roughscale sole Clidoderma asperrimum, slime flounder Microstomus achne, and Korean flounder Glyptocephalus stelleri) off the Pacific coast of northern Honshu, Japan, at depths of 150–900 m, were examined using a generalized linear mixed model (GLMM). Densities of flathead and Korean flounder were highest in the southernmost area, where the fish were small. The body lengths of both of these species increased from 2003 to 2008, suggesting that an abundant year class was recruited in 2003. The density of Kamchatka flounder was highest in the northern area. In roughscale sole and slime flounder, there were no distinctive annual and latitudinal trends in the density distributions. The density distribution of Korean flounder was bimodal; the peaks were at depths of 210 and 410 m. The body length increased as the depth increased from 150 to 410 m, and then decreased from 410 to 550 m. Moreover, “bigger–deeper” trends were observed in flathead, Kamchatka and slime flounder.     

Small-scale variation in feeding environments for the Manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> in a tidal flat in Tokyo Bay

The relative contribution of particulate organic matters (POMs) in water column and sediment as a food source for the Manila clam, Ruditapes philippinarum, was studied using carbon and nitrogen stable isotopic method (δ¹³C and δ¹⁵N) in a tidal flat at Seaside Park, Yokohama, Japan. Comparisons of δ¹³C and δ¹⁵N among R. philippinarum and POMs in surface water, bottom water, and sediment surface indicated that R. philippinarum larger than 5 mm shell length (SL) mainly assimilated benthic POM, and individuals smaller than 5 mm SL assimilated benthic and pelagic POM. Continuous measurements of chlorophyll concentrations in the bottom water revealed tide-driven resuspension of the benthic phytopigments. R. philippinarum showed differences in δ¹³C and δ¹⁵N along an inshore–offshore transect, indicating small-scale spatial differences in POM provision in the tidal flat. These findings suggest that POM in the bottom water, supposedly inhaled by R. philippinarum, is a mixture of a larger proportion of resuspended benthic POM and a smaller proportion of pelagic POM, and that the mixing ratio of the POMs may be affected by the hydrodynamics of flooding water associated with tidal flat topography.     

Migration history of Sakhalin taimen <Emphasis Type="Italic">Hucho perryi</Emphasis> captured in the Sea of Okhotsk,northern Japan,using otolith Sr:Ca ratios

Sakhalin taimen Hucho perryi populations have decreased drastically to near extinction. It is urgent to establish an effective conservation strategy based on an understanding of the characteristics of migration and habitat use of this species. We examined the migration history of anadromous Sakhalin taimen captured off the Sarufutsu coast, northern Hokkaido, Japan, using otolith Sr:Ca ratios and also examined the relationship between their otolith Sr:Ca ratios during freshwater and seawater residence in a rearing experiment. Otolith Sr:Ca ratios of some fish from the Sarufutsu coast showed freshwater levels (0.5–4.0 × 10⁻³) near the core, which thereafter increased to brackish water levels (4.0–6.0 × 10⁻³), and then to seawater levels (6.0–10.0 × 10⁻³) in the outermost regions. Those findings indicate that specimens from the Sarufutsu coast migrated to the brackish water region or the sea and spent most of their lives there. The anadromous migration pattern including the timing of downstream migration seems to be flexible among individuals in the species. They migrate between freshwater and seawater or brackish water several times during their lives, showing extensive habitat use. It is essential to secure the continuity among the freshwater, brackish water, and seawater areas for their effective conservation.     

Bathymetric distribution of beni-zuwai crab <Emphasis Type="Italic">Chionoecetes japonicus</Emphasis> in the northern part of the Sea of Japan

Surveys of beni-zuwai crab were conducted to clarify the bathymetric distribution and fecundity of beni-zuwai crab populations without the effects of bias due to fisheries. The results were compared with previous ones obtained at the heavily exploited Yamato Bank. Two sites in the northern part of the Sea of Japan, off southwest Hokkaido (200–2500 m deep) and West-Tsugaru Basin (300–1900 m deep), both of which are experiencing low exploitation levels, were surveyed in August to September, 2007. There was an abundance of morphologically immature crabs of both sexes in the depth range 1800–2100 m, and a few occurred at depths >2200 m. Immature crabs of <40 mm carapace width were found to migrate downslope to depths of 1800–2100 m and then to migrate upslope during molting for males and after maturity molting for females. Although data were lacking for depths >2000 m at the West-Tsugaru Basin, these relationships were significant for the pooled data of both localities, and they were similar to the results at the Yamato Bank. Clutch fullness of ovigerous females was negatively correlated with depth, which indicates that the low clutch fullness was not induced by fisheries, although the similar phenomenon observed at the Yamato Bank had previously been considered to be due to fishery effects.     

Freshwater migration and feeding habits of juvenile temperate seabass <Emphasis Type="Italic">Lateolabrax japonicus</Emphasis> in the stratified Yura River estuary,the Sea of Japan

Juvenile temperate seabass Lateolabrax japonicus were sampled along the Yura River estuary from April to July 2008 to determine their distribution and feeding habits during migration within a microtidal estuary. Throughout the sampling period, juvenile seabass were distributed not only in the surf zone, but also in the freshwater zone, and they were particularly abundant in areas with aquatic vegetation in the freshwater zone. This distribution pattern suggests that the early life history of the temperate seabass depends more intensively on the river (freshwater) than previously considered. Small juveniles in the freshwater zone fed on copepods and chironomid larvae and upon reaching a standard length (SL) of approximately 20 mm did they fed on mysids. In contrast, juveniles (approx. 17–80 mm SL) in the surf zone fed mainly on mysids.     

Swimming depths of the giant jellyfish <Emphasis Type="Italic">Nemopilema nomurai</Emphasis> investigated using pop-up archival transmitting tags and ultrasonic pingers

The swimming depths of 12 individual Nemopilema nomurai with bell diameters of 0.8–1.6 m were investigated using pop-up archival transmitting tags and ultrasonic pingers, and the validity of the research method was evaluated. The N. nomurai studied frequently showed vertical movement, with the swimming depth ranging from 0 to 176 m, The mean swimming depths of most individuals were less than 40 m. The swimming depths of N. nomurai in the northern Japan Sea in the winter were mostly deeper than those of this species in the southern Japan Sea in the autumn. This result suggests that the range of the depths almost depends on the vertical structure of the ocean. Swimming depths during the nighttime were significantly deeper than those during the daytime. More specifically, during the daytime, the swimming depths in the afternoon tended to be shallower than those in the morning, while during the nighttime, the swimming depths after midnight were deeper than those before midnight.     

Spawning patterns provide further evidence for multiple stocks of sardine (Sardinops sagax) off eastern Australia

Previous studies have suggested that sardine, Sardinops sagax, off eastern Australia spawns across its entire range when habitat conditions are suitable. However, recent studies have suggested that separate sub‐populations and spawning groups may occur in the region. Spawning patterns off eastern Australia were investigated using data collected during nine ichthyoplankton surveys conducted between 1997–2015, and adult reproductive data obtained from ad hoc commercial sampling off New South Wales (NSW). The egg surveys covered the known distribution of sardine off eastern Australia and included year‐round sampling in the northern and southern parts of this range. Egg distributions and analysis of gonadosomatic indices identified two spatio‐temporally separate spawning groups; one occurring off southern Queensland to northern NSW during late winter and early spring, and a smaller group off eastern Tasmania to southern NSW during summer. Most eggs were collected from waters 50–90 m deep, with sea surface temperatures of 18–23°C. Additive modelling indicated depth was the most significant factor driving selection of spawning habitat, followed by the interaction of month and latitude. Low egg densities were recorded in waters between 34–37°S, despite conditions within the ranges suitable for spawning. The presence of two spawning groups of sardine off eastern Australia supports recent findings that two sub‐populations occur in the region. Findings of this study will help to optimise the spatio‐temporal extent of future egg surveys and further confirm the need to coordinate future management of each sub‐population among relevant jurisdictions.     

Maturation and spawning of <Emphasis Type="Italic">Spratelloides gracilis</Emphasis> Clupeidae in temperate waters off Cape Shionomisaki,central Japan

ABSTRACT:   The reproductive ecology of Spratelloides gracilis was investigated in the temperate waters off Cape Shionomisaki, central Japan. Cape Shionomisaki is located at the northern margin of the distribution range of this species. Females of S. gracilis with gonadosomatic index (GSI) ≥ 4.0 were defined as mature based on the relationship between GSI and the histological maturity phases of their ovaries. More than 50% of females greater than 60 mm standard length (SL) were mature. Hatch dates of larvae and juveniles collected in the study area were determined by otolith daily ring counts and found to extend from April to November. The size at maturity of females (60 mm SL) and the spawning season of S. gracilis in the temperate waters off Cape Shionomisaki (April–November) was larger and shorter, respectively, than those in tropical waters in the western Pacific. The reproductive traits observed for S. gracilis off Cape Shionomisaki appear to be adaptive to northern temperate waters with seasonal changes in environmental conditions.     

Effects of water depth on survival and growth of <Emphasis Type="Italic">Argopecten purpuratus</Emphasis> (Lamarck, 1819) spat in northern Chile

Collection and suspended culture of Argopecten purpuratus spat in Japanese-type collectors was undertaken in the Rinconada Marine Reserve (Antofagasta, Chile) to determine growth variations between surface and bottom waters. Scallop spat was collected at 16-m depth and grown at 1- and 16-m depths. An initial settlement of ca. 13,000 post-larvae per bottom collector (2 cohorts) was observed on 3 February 2001. Two new cohorts settled in bottom collectors on 3 March, while no spat settlement occurred in surface collectors. The four cohorts exhibited substantial and different mortality rates over the study period, depending on the cohort and on-growing depth. The first and second cohorts exhibited mortality rates of 80.3 and 53.1% in bottom collectors, respectively, versus 29 and 43.6% in surface structures. The third and fourth cohorts exhibited mortality rates of 21.4 and 59.7% in bottom collectors, respectively. Mean shell height of scallop spat after 88 days of culture was 6.46 mm for the first cohort and 4.37 mm for the second cohort in bottom collectors, versus 10.33 and 7.31 mm in surface collectors, respectively. Mean post-larval growth rate in bottom collectors (86 μm day⁻¹) was significantly lower than growth rate in surface collectors (146 μm day⁻¹). Factors explaining the depth-related mortality and growth rates are discussed to improve scallop culture in the Reserve. It was concluded from the results that culture improvement in Antofagasta Bay would require collecting spat in bottom waters and raising it near the surface during initial cultivation stages.     

Growth and survival of hatchery-bred giant clams (<Emphasis Type="Italic">Tridacna gigas</Emphasis>) in an ocean nursery in Sagay Marine Reserve,Philippines

To restore the diminishing population of the giant clam Tridacna gigas in Sagay Marine Reserve (SMR), Negros Occidental, central Philippines, two size classes [8- and 10-cm shell length (SL)] of hatchery-bred T. gigas were reared in an adjacent ocean nursery for restocking to Carbin Reef later upon reaching grow-out size of ≥20 cm SL. Growth rates did not significantly differ for both sizes and were on average 0.67 cm month⁻¹. However, survival after 382 days of rearing T. gigas was significantly higher in the 10-cm SL clams than the 8-cm SL clams (96 and 83%, respectively). For future restocking projects, the use of 8-cm SL clams is recommended because the lower survival of this size class is compensated by its cheaper price. While rearing the clams to attain grow-out size, the population of wild clams (Family Tridacnidae) in Carbin Reef was assessed using ten 50 × 2-m belt transects. Four species of tridacnid clams have been recorded: Hippopus hippopus, Tridacna crocea, T. maxima, and T. squamosa. T. crocea comprised 12.5–93.9% of all the clams observed in all ten transects. There was a significant difference in clam density between species (ANOVA, F = 6.94, P < 0.001), with T. crocea having the highest density. Living T. gigas were absent, but presence of dead shells was indicative of its presence in the reef in the past. It can be expected that the release of hatchery-bred T. gigas juveniles in Carbin Reef could provide future breeders that will repopulate this reef and the adjacent reef communities.     

Occurrence of toxic <Emphasis Type="Italic">Dinophysis acuminata</Emphasis> (Dinophyceae) in Uranouchi Inlet,Japan

In the Uranouchi Inlet, which has a commercial fishery of littleneck clam Ruditapes philippinarum, potentially toxigenic species of Dinophysis acuminata showed an annual occurrence except for the summer of 2000–2002. Relatively high abundances of D. acuminata were observed in April 2000 and November 2002. Some samples of D. acuminata cells, which were collected from the inlet in autumn 2002, contained pectenotoxin-2 (0.9–2.8 pg/cell) and okadaic acid (1.9–2.8 pg/cell). Cell length and hypotheca width of D. acuminata found in the Uranouchi Inlet were 33.7–45.0 and 21.0–31.6 μm, respectively. The length-width ratios ranged 1.21–1.71. Sequences of the 5.8S ribosomal RNA gene and flanking internal transcribed spacers, 1 and 2 of cells of D. acuminata from the inlet fell into a D. acuminata complex clade that included, D. acuminata-D. sacculus-D. acuta reported by others. In the inlet, occurrences of D. acuminata were detected within a broad water temperature range between 13.0 and 26.9°C, and those showing more than 25 cells/L were within 16.4–17.3°C for temperature and 27.6 and 34.1 for salinity. This is the first report that cells of Dinophysis acuminata from southern Japanese coastal waters contained okadaic acid and pectenotoxin-2.     

Weaning of the wedge sole <Emphasis Type="Italic">Dicologoglossa cuneata</Emphasis> (Moreau): influence of initial size on survival and growth

The weaning phase can be decisive in fish-culture viability. In this work, the relationship between the initial size and weaning success has been studied in wedge sole (Dicologoglossa cuneata). For each age (30, 50, and 70 days after hatching, DAH), two to three sizes were selected, and all were put on the same feeding schedule for 20 days. Each batch (three replicates) was sampled at 1, 10, and 20 days. Specific growth rate (SGR) and survival were compared at the end of the co-feeding period, after 10 days on dry feed only. The best results for survival and growth were found with the smallest larvae, and vice versa. The SGRs and survival rates recorded during the co-feeding period were higher (0.8–15.6 day⁻¹ and 68.3–97.8%) than those from the dry-food phase (0.9–4.7 day⁻¹ and 56.3–66.7%). Successful weaning (survival = 65% and SGR = 9.3 day⁻¹) is possible with 30 DAH larvae (7.6–8.1 mm and 3.9–4.6 mg). In conclusion, the most effective weaning would be possible at 30 DAH, implying significant Artemia savings (25–50%).