Analysis on ‘Whole Red’ of patterns Oujiang colour carp (Cyprinus carpio var.color ) by SRAP and SCAR markers

The sequence‐related amplified polymorphism (SRAP) technique was applied to identify the genetic difference between the ‘Whole Red’ (‘WR’) population and the ‘Whole White’ (‘WW’) population. The specific SRAP band, namely SR_2,7^{173 bp} (SR indicates the first two letters of SRAP) from ‘WR’ and ‘WW’, was identified from the amplified bands of 12 primer pairs (PP) screened from 88 SRAP PP. After gel extraction, cloning and sequencing of specific band from the two populations, the sequence was submitted to database of Genome Sequence Survey. blast analysis showed that this SRAP fragment shared high similarity to functional genes of Danio rerio. Four primers (22–26 bases) were designed according to the sequence information. Then, polymerase chain reaction amplification was carried out in the two populations. The experimental results also showed that among four sequence‐characterized amplified region (SCAR) markers, only SC‐3 (154 bp) developing from SR_2,7^{173 bp} (me2‐em7) showed specificity to ‘WR’. Examination with a large sample size showed that SCAR 3 (SC‐3) could be positively amplified with 85% frequency in the ‘WR’ population rather than in the ‘WW’ population. The results indicated that the SC‐3 marker could be used as a specific molecular marker for population identification, providing an effective, easy and rapid method for discriminating different populations and conducting genetic analysis.     

The effects of tank system,water velocity and water movement on survival,somatic and gonad growth of juvenile and adult green sea urchin,Strongylocentrotus droebachiensis

The effects of water velocity and tipping frequency (water movement) on survival, somatic and gonad growth of juvenile and adult green sea urchin, Strongylocentrotus droebachiensis were investigated. Juvenile and adult urchins were held in ‘laminar’ or ‘tipper’ tanks. Both were supplied with three inlet water flows (1.5, 3.0 and 7.5 L min^?1) which converted to water velocities of 0.28, 0.57 and 1.43 cm s^?1 in the ‘laminar’ tanks and tipping frequencies of 30, 10 and 5 s in the ‘tipper’ tanks. Juvenile sea urchins had significantly lower mortality and greater somatic growth when held in ‘laminar’ flow tanks compared with ‘tipper’ tanks. The varying water velocities tested in the ‘laminar’ flow treatment had no effect on the growth of juvenile sea urchins. The juvenile sea urchins in the ‘tipping’ treatment held at high tipping frequency had significantly slower growth than those in the medium and low tipping frequency treatments. There were no differences in mortality or gonad growth in the adult sea urchins regardless of treatment. The ‘laminar’ flow tanks retained significantly more organic material compared with the ‘tipper’ tanks. The authors discuss the effects of water velocity and tipping frequencies in system design for aquaculture of sea urchins.     

Effects of temperature on growth,survival and physiological parameters in juveniles of Lophiosilurus alexandri,a carnivorous neotropical catfish

This study aimed to analyse the effects of different water temperatures on the growth, survival and blood physiological parameters of Lophiosilurus alexandri. Juveniles measuring 12.6 ± 0.5 cm and weighing 30.6 ± 3.6 g were subjected to four water temperature regimes: 23, 26, 29 and 32°C with four replicates. The animals were fed twice daily with formulated diet. The experiment lasted for 35 days. Survival was 100% at all water temperatures, and the best temperature for growth was estimated to be 27.8°C using a quadratic regression model. The estimated temperatures for the best feed conversion and highest feed consumption rates were 26.2 and 28.8°C respectively. The fat visceral‐somatic index was highest at 32°C. The highest haemoglobin and haematocrit values were 29.4 and 32.1°C respectively. For plasma protein and cholesterol, the lowest values estimated were 23.9 and 24.1°C respectively. Glucose and liver nitrogen content increased with rising temperature. Higher values of total ammonia in the water were observed at higher temperatures. No effects of temperature were seen on the amounts of muscle dry matter, nitrogen, energy content and triglycerides or on the hepatosomatic index. Water temperature has an important role in the developmental and blood physiological parameters of juvenile L. alexandri, and the quadratic regression model showed that the appropriate temperature for growth is between 27 and 28°C.     

Towards an improved understanding of angler tourism in northern Australia

A human dimensions investigation into tourist anglers in a coastal recreational fishing hotspot in northern Australia is presented. Tourist anglers target one species, javelin grunter, Pomadasys kaakan (Cuvier), raising concerns about the sustainability of the fishery. Data from a survey of 427 tourist angling parties that fished in the coastal water off Karumba (Queensland) were analysed. Exploratory factor analysis was performed on angler target species and motivation for fishing to establish a typology of fishing intentions, with fishing for food found to be the principal factor. Anglers with high fishing for food factor scores were more consumptive, lower spending (per day) and more averse to any potential measures that might reduce legal possession (creel) limits or impose a cost of fishing. It was concluded that a combination of tourism and fisheries management interventions is required to safeguard Karumba's iconic javelin grunter fishery into the future. Diversification of tourist activity options can reduce the tourism industry's current reliance on high‐consumptive tourist anglers and increase the destination's appeal to non‐fishing tourists and low‐consumptive anglers. Modification of angler behaviour can be achieved through reduced possession limits for javelin grunter and possibly other target species, improved monitoring and law enforcement efforts, and targeted education and information.     

Seasonal changes in a deep‐water fish assemblage in response to monsoon‐generated upwelling events

The coastal shelf of the Gulf of Oman experiences periodic upwelling events during the summer months that are driven by the southwest monsoon. It is unclear what role these events play in the spatial and temporal distribution of the region’s fish assemblage. We carried out trials on two different video techniques to characterize the habitat and fish assemblage along the continental shelf margin near Muscat, Oman. Exploratory surveys with a drift stereo‐video revealed three main habitat types: Sand, Reef and Megabenthos. Three areas were chosen for additional sampling using stereo‐BRUVS (‘baited’ remote underwater‐video systems). On two separate occasions (November 2005 and March 2006) replicate stereo‐BRUVS were deployed in each area stratified by the main habitat types. For each teleost and elasmobranch species encountered on the video, an estimate of total body length and the relative abundance (MaxN_i) was made. The stereo‐BRUVS recorded a wide range of demersal and pelagic teleosts including species of conservation interest such as sharks, rays and groupers. The drift stereo‐video recorded significantly fewer species than the stereo‐BRUVS (N = 15 versus N = 43). Species diversity from the stereo‐BRUVS increased by 96% in March 2006 (N = 41) compared to November 2005 (N = 23), a pattern consistent at all three areas. The structure of the overall fish assemblage (using canonical analysis of principal coordinates analysis) was highly variable both in time and space. There was ample evidence of strong habitat associations, particularly with depth and seasonal shifts in abundance and diversity. We argue the upward migration of oxygen‐depleted water into the shallow depths during the late monsoon displaces the demersal fish community along this coast.     

Effects of feeding frequency and dietary protein levels on juvenile allogynogenetic gibel carp (Carassius auratus gibelio) var. CAS III: growth,feed utilization and serum free essential amino acids dynamics

A 8 week growth trial of three feeding frequencies (2, 4 and 6 meals day^?1) and three dietary protein levels (30%, 34% and 38%) was conducted to investigate the influence of feeding frequency and dietary protein level on growth, feed utilization, serum free essential amino acids (EAA) dynamics and nitrogen (N), phosphorus (P), carbon (C) retention in juvenile allogynogenetic gibel carp (Carassius auratus gibelio) ‘CAS III’. The results showed that feeding frequency and dietary protein level increased feed intake (FI), specific growth rate (SGR) and feed efficiency (FE). SGR increased significantly with the increase in feeding frequency and dietary protein level. But, the increase in dietary protein level from 30% to 38% in group 6 meals day^?1 did not result in better growth. Compared with the group of 4 meals day^?1 × 38%, the fish fed the diet containing 30% crude protein at 6 meals day^?1 obtained similar SGR but showed lower FIp (protein intake). Compared with 2 meals day^?1, NREs (nitrogen retention efficiency) of 4 and 6 meals day^?1 were relatively higher. PRE (phosphorus retention efficiency) and CRE (carbon retention efficiency) increased significantly with feeding frequency while TNW (total nitrogen waste output), TPW (total phosphorus waste output) and TCW (total carbon waste output) decreased significantly. Feeding frequency and dietary protein level increased trypsin activity. Serum free EAA concentrations varied more synchronously at 6 meals day^?1 than 2 meals day^?1. It could be concluded that increasing feeding frequency could improve growth by increasing feed intake and feed efficiency for juvenile gibel carp. The increase in feeding frequency showed protein‐sparing effect.     

枸杞岛海藻场大型底栖无脊椎动物摄食类群研究

随着海洋生态学研究的深入和海洋环境监测的需要,一些传统的研究方法如多样性指数等在评价大型底栖生物群落结构变化时显得说服力不足,而摄食功能群的研究越来越受到重视。本实验根据2012年8月对浙江枸杞岛海藻场大型底栖无脊椎动物的调查实验,分析该海域夏季大型底栖无脊椎动物摄食类群的组成、空间及数量分布,并进行相关生态评价。结果表明,枸杞岛海藻场夏季大型底栖无脊椎动物组成以肉食者和滤食者占较大优势,食碎屑者、植食者和食底泥者次之,杂食者最少;肉食者的优势种为布尔小笔螺、寄居蟹、扁平管帽螺、甲虫螺和四齿矶蟹等,滤食者的优势种为条纹隔贻贝、带偏顶蛤、短石蛏和布氏蚶等,植食者的优势种为钩虾、单一丽口螺和锈凹螺等;各摄食类群水平分布较均匀,垂直分布受水深和摄食饵料的限制;基于大型底栖无脊椎动物功能类群的生态参数评价结果表明,枸杞岛海藻场大型底栖无脊椎动物群落健康状态呈虚弱水平,大部分站位大型底栖无脊椎动物群落受到轻度扰动,底栖生态质量状况较好。     

Economic value of conserving deep-sea corals in Irish waters: A choice experiment study on marine protected areas

Deep-water corals are slow growing, fragile and vulnerable to the impacts of deep-water fisheries and the development activities of the offshore industries. In Ireland there is now evidence of major damage to deep-water corals linked to a recent expansion of the Irish deep-water fishery. This fishery uses trawls fitted with robust rock hopping gear and employs a high risk fishing technique, which is potentially very destructive to coral habitats. Consequently resource managers have been exploring the potential of marine protected areas (MPA) as a tool for the conservation of these coral ecosystems in the North East Atlantic. MPAs aim to minimise the socio-economic costs associated with closures or other management restrictions while still achieving the desired conservation objectives. However, the decision to use MPAs (and thereby restrict fishing) is often taken in the light of uncertainty over the value of the reserved habitats to the fishing industry. This paper reports on a choice experiment study carried out in Ireland in early 2007 aimed at partly addressing this uncertainty. The study primarily focused on determining the economic value held by the Irish public for the conservation of deep-sea corals using several variants of the concept of MPAs. They have endorsed MPA strategies that banned trawling in an MPA that included all areas where corals are thought to exist with no personal tax imposed, banned trawling in an MPA covering all known corals with a personal tax imposed of €1 p.a. and banned all fishing in an MPA covering all areas where corals are thought to exist with a personal tax imposed of €1 p.a. In terms of the probabilities attached to the individual attributes, the most preferred policy options were to ban trawling, protect all areas where corals are thought to exist, and pay a ring-fenced personal tax of €1 p.a.     

Temporal and spatial trends in size,biomass and abundance of groupers (Epinephelinae) in Mafia Island Marine Park: fishers’ perceptions and underwater visual census surveys

Fishers’ perceptions of changes in grouper size and abundance were compared with scientific data collected via underwater visual censuses (UVCs) before (1995) and after (2006 and 2011) the establishment of the Mafia Island Marine Park. Perceptions on changes in the size structure of groupers differed among communities due to differences in fishing capacities. Fishers in one village had mixed perceptions, while in another village the majority (66%) perceived a decline in size, with small groupers dominating the catch. Similarly, UVCs indicated that size structure was dominated by small groupers at all times surveyed. Consistent with fishers’ perceptions, UVC indicated that biomass and abundance of groupers declined in both no‐take zones (NTZs) and specified‐use zones (SUZs) between 1995 and 2006, with no substantial changes between 2006 and 2011. The NTZs had higher density and diversity of grouper species than SUZs, as would be expected from the differences in bottom topography in these two types of areas. The idea that NTZs could increase the biomass and abundance of groupers to benefit fished zones was not found, thus indicating that NTZs are not necessarily the best option for managing reef fisheries.     

A survey on Tetracapsuloides bryosalmonae infections in Slovene fresh waters

Slovenia has no history of health problems related to proliferative kidney disease (PKD) either in farmed or in wild fish. However, due to the past molecular evidence for the presence of Tetracapsuloides bryosalmonae DNA in tissues of some fish from open waters, a survey was conducted on wild salmonids that were primarily sampled for other purposes. In winter 2010–2011, specimens from a total of 244 rainbow trout, Oncorhynchus mykiss (Walbaum), and brown trout, Salmo trutta L., from 30 bodies of fresh water were examined for T. bryosalmonae using a PCR method. The sampled fish showed no clinical signs or gross pathological lesions characteristic of PKD. Nineteen (7.8%) fish from seven (23.3%) fresh waters were positive for T. bryosalmonae. The identity of PCR amplicons was confirmed by sequencing. With one exception, all the positive fish were found in waters from the regions where the average yearly temperatures and the environmental pollution are higher. This preliminary countrywide survey provided the first insight into the situation regarding T. bryosalmonae infection of wild salmonids in Slovenia.     

Survival and growth of hatchery-reared individuals of the European lobster, Homarus gammarus (L.), in field-based nursery cages on the Irish west coat

At present, one of two strategies is employed by fisheries managers for enhancing wild stocks of homarid lobsters using hatchery-reared individuals. The first is repeated releases of large numbers (>5000 at a time) of postlarvae (stage IV and V; carapace length [CL]=5–7 mm) to selected bottom locations. This option exists primarily because these programs lack space, time, and/or the finances to rear animals to larger sizes that would most likely have initially higher survival rates. The second is to rear animals in the laboratory for 5–8 months to stage XII+ (CL=12–16 mm) and then release small numbers (<1000) of these relatively large juveniles. To date there has been no attempt to release large numbers of relatively large juveniles because the costs are too prohibitive.

We have developed a low-cost, low-maintenance, field-based nursery caging system for rearing cultured lobsters, Homarus gammarus (L). Individuals (780 and ranging in CL from 5.2 to 7.2 mm) were reared in pre-fouled and unfouled containers (360 cm³) fabricated from an extruded plastic netting (3.2 mm aperture) and in pre-fouled plastic petri dishes (200 cm³) that were deployed in five near-bottom cages for 10 months (September 2000 to June 2001) at two subtidal sites located in a shallow, relatively exposed embayment on the west coast of Ireland. Animals apparently were able to survive and grow by suspension feeding on the plankton and/or foraging on the fouling community that settled on and within individual containers. Mean recovery rate (±95% CI) was independent of a priori fouling treatments, but was site-specific (42.1±7.9% and 27.8±13.7%; n=5). These rates are minimal estimates of survival because we found that at least 20% of the animals were capable of escaping from the mesh containers. Mean recovery in petri dishes that prohibited emigration was 53.3±37.02% at one site and 75.0±23.1% (n=5) at the other. These recovery rates compare favorably with survival rates of fed conspecifics held in the laboratory over the same time (54/81=66.7%). At the end of the experiment, animals in field cages had mean CLs that were significantly smaller than the fed controls. Because of costs incurred with maintaining small lobsters under laboratory conditions, results of this short-term, manipulative field experiment indicate that field-based nurseries represent an economically viable, third option for managers of lobster stock enhancement programs.     

The growth of larval cod and haddock in the Irish Sea: a model with temperature,prey size and turbulence forcing

We applied a physiological individual‐based model for the foraging and growth of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) larvae, using observed temperature and prey fields data from the Irish Sea, collected during the 2006 spawning season. We used the model to estimate larval growth and survival and explore the different productivities of the cod and haddock stocks encountered in the Irish Sea. The larvae of both species showed similar responses to changes in environmental conditions (temperature, wind, prey availability, daylight hours) and better survival was predicted in the western Irish Sea, covering the spawning ground for haddock and about half of that for cod. Larval growth was predicted to be mostly prey‐limited, but exploration of stock recruitment data suggests that other factors are important to ensure successful recruitment. We suggest that the presence of a cyclonic gyre in the western Irish Sea, influencing the retention and/or dispersal of larvae from their spawning grounds, and the increasing abundance of clupeids adding predatory pressure on the eggs and larvae; both may play a key role. These two processes deserve more attention if we want to understand the mechanisms behind the recruitment of cod and haddock in the Irish Sea. For the ecosystem‐based management approach, there is a need to achieve a greater understanding of the interactions between species on the scale a fish stock is managed, and to work toward integrated fisheries management in particular when considering the effects of advection from spawning grounds and prey–predator reversal on the recovery of depleted stocks.     

Replacement of fish oil with alternative lipid sources in plant‐based practical feed formulations for marine shrimp (Litopenaeus vannamei) reared in outdoor ponds and tanks

The objective of this study was to demonstrate the feasibility of partial substitution of menhaden fish oil by alternative lipid sources (soybean oil, poultry grease and flaxseed oil) in non‐marine protein‐based shrimp production diet, its influence on fatty acid profile and its final product flavour. Results for the pond study (17 weeks) showed no differences (P ≥ 0.05) in shrimp production among different test diets. Production ranged from 5070 to 5363 kg ha^?1; mean final weight, 18.0 to 21.6 g; weekly growth, 1.04 to 1.25 g; survival, 65.6 to 75.4%; and FCR, 1.37 to 1.45. Results from the tank trial (12 weeks) confirmed these findings, final weight, 13.8–14.8 g; weekly growth, 1.1–1.2 g; survival, 92.5–98.3%; FCR, 1.05–1.11; and final standing crop, 4738–5024 kg ha^?1. The fatty acids profiles of edible tail muscle reared on the various diets displayed a similar fatty acid profile to that of the diets. The sensory test showed no statistical differences in texture, appearance, aroma and flavour between the shrimp fed diets containing menhaden fish oil and soybean oil. These studies demonstrated that practical shrimp feeds containing non‐marine protein ingredients and a percentage of fish oil replaced by alternative lipid sources had no negative impact on mean final weight, weekly growth, survival, FCR, final standing crop, fatty acids profile and organoleptic properties of Litopenaeus vannamei.     

Low levels of Aflatoxin B1 could cause mortalities in juvenile hybrid sturgeon,Acipenser ruthenus ♂×A. baeri♀

Toxicity of aflatoxin B₁ (AFB₁) was investigated in juvenile hybrid sturgeon Acipenser ruthenus ♂ × A. baeri♀, an important coldwater finfish farmed in China and other countries. Seven experimental diets (Diet A–G) containing different levels of AFB₁ (0, 1, 5, 10, 20, 40 and 80 μg kg^?1 diet) were fed to juvenile sturgeon weighing 10.53 ± 0.17 g kg^?1 to determine its effect on survival, growth, feed consumption, hematocrit, liver histology as well as muscular and hepatic toxin accumulation. The experiment lasted for 35 days and was conducted in two periods of 25 and 10 days each. No external changes or unusual behaviour was observed in the fish fed diets with AFB₁. Mortality was observed in fish fed with highest levels of AFB₁ (80 μg kg^?1– Diet G) from day 12 onwards. After 25 days, fish fed the diet of 80 μg AFB₁ kg^?1 showed significant lower survival (50 ± 5.77%) followed by those fed 40 μg AFB₁ kg^?1 diet (80 ± 5.77%) and 20 μg AFB₁ kg^?1 diet (86.66 ± 3.33%). No significant difference was observed in specific growth rate (SGR) or hepatosomatic index (HSI) between groups. Hematocrit was significantly higher in the fish fed the diet of highest AFB₁. The fish were weighed at day 25 in some treatments (Diets F and G) because of high mortality. However, feeding was continued for another 10 days to observe mortality or behavioural changes if any in the other groups. After 35 days, survival in the fish fed Diet F (40 μg AFB₁ kg^?1) was 40% and those fed Diet E (20 μg AFB₁ kg^?1) was 36.2%. Significant histopathological changes including nuclear hypertrophy, hyperchromasia, extensive biliary hyperplasia, focal hepatocyte necrosis and presence of inflammatory cells were observed in the liver of fish fed high levels of aflatoxin (40 and 80 μg kg^?1). AFB₁ accumulation in fish muscle and liver increased with increased dietary AFB₁ levels. It could be confirmed that 10 μg AFB₁ kg^?1 diet was the maximum allowable level in hybrid sturgeon diet.     

Differences in stable isotope ratios of Dall’s porpoises (Phocoenoides dalli) between coastal and oceanic areas of the North Pacific

Carbon and nitrogen stable isotope ratios in the muscle of Dall’s porpoises were measured. Samples were collected from the catches of the hand harpoon fishery, incidental catches of drift net, and scientific research on the use of drift nets. Samples were from the North Pacific, Sea of Japan, Sea of Okhotsk, and Bering Sea. Although no variation in δ¹⁵N was observed, δ¹³C was significantly different between population groups near Japan and the oceanic North Pacific and Bering Sea. The difference may be due not only to local variation in prey species, but also to an overall difference in carbon stable isotope ratios that originate from coastal benthic or oceanic pelagic‐based food webs. We differentiated Dall’s porpoise population groups from both areas using carbon stable isotope ratios with an error rate of <5%. Although further study is needed, our results suggest that carbon stable isotope ratios could possibly be an indicator of whether a Dall’s porpoise belongs to a coastal benthic or oceanic pelagic food web.     

Dietary supplementation of autolysed yeast enhances growth,liver functionality and intestinal morphology in African catfish

A feeding trial was conducted to evaluate the potential of dietary supplementation of autolysed brewer's yeast (AY) on African catfish. The catfish (22.5 ± 1.15 g/fish, 20 fish 33 L/tank) were fed with either of diets (390 g/kg crude protein, 140 g/kg lipid) supplemented with 0, 3, 6 or 10 g/kg AY (n = 3). After 49 days of feeding, the final body weight and metabolic growth rate of the catfish fed 3 g/kg AY (3‐AY) diet were higher than those fed the control diet (p < .05). The lowest level (p < .05) of alanine transaminase was detected in the blood of the catfish fed 3‐AY diet. The mid‐intestinal histology of the catfish revealed no significant difference (p > .05) in intestinal perimeter ratio. However, an elevated (p < .05) abundance of goblet cells and intraepithelial leucocytes were found in the intestine of catfish fed 3, 6 and 10 g/kg AY diets, with the highest level of abundance recorded in the mid‐intestine of the catfish fed 3‐AY diet. The results suggest that dietary 3 g/kg autolysed brewer's yeast supplementation improves growth performance of African catfish without deleterious effect on liver functionality and gut morphology.     

Tissue and organ distribution of 14C‐activity in dextrin‐adapted Atlantic salmon after oral administration of radiolabelled 14C1‐glucose

Accumulation of ¹⁴C in various tissues and organs was studied in three different groups of 0.8‐kg Atlantic salmon Salmo salar force‐fed with ¹⁴C₁‐glucose in order to evaluate if metabolism of glucose depended on adaptation to dietary carbohydrate level. The salmon had been fed diets supplemented with 0, 100 and 200 g maize dextrin kg^?1 for 10 months before the experiment. The fish were force‐fed 6.65 × 10⁴ Bq of ¹⁴C₁ glucose kg^?1 BW, in gelatin capsules. Fish for analysis were obtained 16 h later. ¹⁴C was measured in blood plasma, gill, kidney, liver and white muscle, and in lipid extract of liver. The liver contained most ¹⁴C, followed by heart, blood plasma, gill and liver lipid extract, while kidney and muscle contained the least ¹⁴C per gram or millilitre tissue. The muscle contained most radioactivity, on an estimated total tissue basis, followed by liver, blood plasma, gill, liver lipid extract, kidney and heart tissue. Thirty‐eight per cent of the orally administered ¹⁴C was recovered in the salmon adapted to the diet without dextrin after 16 h. This was significantly (P < 0.05) higher than the 30% and 32% recovered in the salmon adapted to diets with 10% and 20% dextrin. This effect on adaptation to dietary dextrin level in glucose uptake or metabolism was supported by a trend (P < 0.10) toward higher radioactivity per gram or millilitre of each individual tissue in the fish adapted to the diet without dextrin, when compared with the other two adaptation regimes.     

Pearl formation in the Japanese pearl oyster (Pinctada fucata) by CaCO3 polymorphs: Pearl quality‐specific biomineralization processes and their similarity to shell regeneration

Pearl oyster shell consists of two layers: a calcite prismatic layer (outer layer) and an aragonite nacreous layer (inner layer). Calcite and aragonite are CaCO₃ polymorphs, and their formations are controlled by shell‐forming tissue called mantle. Pearl sacs originating in the mantle form cultured pearls. Therefore, it has been widely accepted that pearl and shell are produced by the same process. However, this idea has been called into question by some recent mineralogical studies indicating microstructural and crystal‐polymorphic diversity in pearls. The pearl biomineralization process is still not fully understood in detail. Thus, in this study, we focused on the diversity of CaCO₃ polymorphism of non‐nacreous structures (NNSs) underlying the nacreous layer in pearl and regenerated shell, to reveal the biomineralization process of the Japanese pearl oyster (Pinctada fucata). Using Meigen's stain and scanning electron microscope‐energy dispersive X‐ray (SEM‐EDX), NNSs polymorphs in valuable and valueless pearls, in addition to regenerated shell, were compared. Aragonite was exclusively observed in the NNSs of valuable pearls, whereas calcite was dominant in those of valueless pearls. The same analysis of NNSs of regenerated shells was carried out. As in valueless pearls, almost all regenerated shell NNSs consisted of calcite, but one NNS was composed of aragonite. Accordingly, it seems that pearls are formed by the same biomineralization process as shell regeneration rather than shell formation.