Shrimp Stomach Research Articles

Isolation and characterization of two actins of the Pacific white shrimp, Litopenaeus vannamei

Two actin genes named actinT1 and actinT2 were isolated and sequenced from the Pacific white shrimp, Litopenaeus vannamei, by screening from a shrimp eyestalk cDNA library. L. vannamei actinT1 cDNA has a 1,128-bp open reading frame encoding for 376 amino acids while L. vannamei actinT2 cDNA has a 1,131-bp open reading frame coding for 377 amino acids. Alignment of the actinT1 and actinT2 cDNA sequences showed that these two actin genes share a sequence identity of 86% at amino acid residues. When compared with actins of several other invertebrate and vertebrate species, the nucleotide sequence of actinT1 is highly homologous (97–100%) with beta-actins, while actinT2 shares 86–95% identity with alpha-actins on the nucleotide level. Phylogenetic analysis and BLAST searches indicated that the ActinT1 protein is identical to crustacean beta-actins, while the ActinT2 protein is highly homologous to crustacean alpha-actins. Constitutive expression of the actinT1 and actinT2 genes were detected by RT-PCR in all adult shrimp organs, including brain, eye-stalk, gill, heart, hemolymph, hepatopancreas, muscle, swimming legs, and stomach, as well as in the shrimp zygote, nauplius, and mysis life stages. These data will facilitate attempts to clone and identify more shrimp genes and constitutive shrimp promoters.

Predation on winter flounder (Pseudopleuronectes americanus) eggs by the sand shrimp (Crangon septemspinosa)

This study estimated rates of sand shrimp (Crangon septemspinosa) predation on winter flounder (Pseudopleuronectes americanus) eggs and examined the effect of temperature on density-dependent mortality of early-stage flounder. In laboratory experiments, shrimp feeding rates on flounder eggs were positively correlated with temperature and shrimp size. Immunological assays of shrimp stomach contents indicated that 7.2% of shrimp collected from the Niantic River (Connecticut) had flounder eggs in their stomachs. Incidence of egg predation was highest in February (20%) and decreased continuously into early April (1.2%). In a deterministic model simulating predator-induced mortality of flounder eggs during a spawning season, shrimp consumed 0.4%–49.7% of the total flounder spawn. Variations in shrimp population abundance and size structure accounted for the greatest variability in egg mortality. Water temperature during the spawning season presumably alters the population dynamics of early-stage flounder. In a long-term survey, the number of yolk-sac flounder larvae in warm years (≥4.3 °C) was depressed at high egg densities, indicating strong compensatory processes that increased egg mortality and limited the abundance of larvae. Failure of flounder to produce strong year-classes of larvae during warm years, possibly resulting from altered trophic dynamics, may explain the inability of stocks to recover from previous overexploitation.

Feeding rhythms and diet of Farfantepenaeus paulensis under pen culture in Patos Lagoon estuary, Brazil

The feeding habits of Farfantepenaeus paulensis under pen culture in the Patos Lagoon estuary (Brazil) were studied. A total of 1074 shrimp had their stomach contents analyzed. Samples were taken bi-hourly over a 24 h period at about 10 day intervals during 2 months. F. paulensis did not exhibit strict feeding periodicity (except at D 21–22 and D 32–33). Thus, the offering of feed pellets during daylight is recommended but the rates of feeding must be further investigated. F. paulensis showed an omnivorous feeding behavior. Despite daily supply of feed pellets, natural food comprised the major part of the shrimp stomach contents. Among prey organisms, polychaetes and tanaids were the main groups recorded. Consumption of detritus and plant material decreased as shrimp grew. Intake of feed pellets increased significantly in the second month of culture (i.e. 5 g mean shrimp weight), thus it might be possible to reduce the initial input of commercial feed.

Predation on post-settlement winter flounder Pseudopleuronectes americanus by sand shrimp Crangon septemspinosa in NW Atlantic estuaries

Assessing predation risk is necessary to evaluate the functional significance of estuaries as critical nursery habitats for juvenile fishes. The objective of this study was to quantify rates of sand shrimp Crangon septemspinosa predation on post-settlement winter flounder Pseudopleuronectes americanus in 3 NW Atlantic estuaries: Narragansett Bay (Rhode Island), Niantic River (Connecticut), and Navesink River/Sandy Hook Bay (New Jersey). Sand shrimp were collected from designated study sites in late spring and summer (2001 and 2002), and their stomach contents were analyzed with immunological assays to detect the presence of juvenile winter flounder in the diet. The results indicate that sand shrimp are possible sources of intense predator-induced mortality for newly settled winter flounder. There was a direct relationship between the incidence of winter flounder in shrimp stomachs and the body size and density of shrimp. The importance of sand shrimp as a mortality fac- tor for winter flounder in the Navesink River/Sandy Hook Bay was minimal due to the low abundance of large shrimp (≥30 mm total length). Conversely, in Narragansett Bay and the Niantic River preda- tion rates were high because of the presence of large shrimp during peak winter flounder settlement periods (May to early June), when the flatfish are small in size and vulnerable to predation. Thus, sand shrimp predation rates on winter flounder depend on the relative spatial and temporal overlap between the settlement of flounder to the benthos and the movement patterns of large shrimp that migrate into shallow estuaries to reproduce and feed.

A rapid non-enzymatic method of DNA extraction for PCR detection of white spot syndrome virus in shrimp

The present study describes a simple method of extraction of white spot syndrome viral DNA (WSSV) from infected shrimp for the polymerase chain reaction (PCR) detection of WSSV. The DNA preparation using this method was found to be free from the host DNA, RNA and protein, and is suitable for different PCR protocols such as single-step PCR, nested PCR and single-tube semi-nested PCR. This method of extraction has worked successfully for extracting the WSSV-DNA from different organs (haemolymph, eyestalk, carapace, head muscle, heart, gills, appendages, heptopancreas, stomach, intestine, abdominal muscle and tail muscle) of WSSV-infected adult shrimp, and WSSV-infected larvae and postlarvae.

Settlement patterns of newly settled plaice ( Pleuronectes platessa ) in a non-tidal Swedish fjord in relation to larval supply and benthic predators

In demersal fish species with a pelagic larval stage, settlement patterns may be a consequence of variations in larval supply, habitat selection at settlement, and processes acting between the time of settlement and the time of benthic sampling. This study describes temporal (1994–1998) and spatial variation in plaice (Pleuronectes platessa L.) settlement densities in four semi-isolated nursery areas with similar habitat characteristics, in the non-tidal Gullmarsfjord on the west coast of Sweden. Juvenile abundance varied by a factor of ten, both among years and among nursery grounds. For the 3 years when larval sampling was undertaken (1994–1996) and all nursery areas, there was a significant positive relationship between larval supply and juvenile abundance (linear regression: r 2=0.45, n=24, P<0.001). On the southern side of the fjord, a significant positive relationship between larval and juvenile abundance was found in one area (r 2=0.62, n=6, P<0.05). The absolute mortality rate of plaice after settlement was related to the initial settlement density (r 2=0.95, n=20, P<0.001), and to the abundance of predatory shrimps Crangon crangon (r 2=0.44, n=20, P<0.01). Plaice otoliths were found in 6% of the shrimp stomachs analysed from an area with high density (13.3 m–2) of newly settled plaice. The present study suggests that the density of juvenile plaice was limited by larval supply to the nursery grounds. Consistency in the relative abundance of juveniles among nursery grounds between years also suggested that some nursery areas may be in the settlement shadow of others. The irregular nature of the coastline in combination with larval depletion could thereby cause small-scale (103–104 m) variation in settlement densities of the same order of magnitude as the inter-annual variability in recruitment to individual nursery grounds.

Size-related feeding and gastric evacuation measurements for the Southern brown shrimp Penaeus subtilis

Studies attempting to optimise feeding methods in penaeid aquaculture have often relied on results of growth, survival performance and food conversion ratios. At present, data relating to maximum ration, ingestion rates (IRs), faecal production rates (FPs), foregut evacuation and appetite revival are lacking for Penaeus spp. despite their relevance to the development of models aimed at maximising food use in shrimp culture systems. Size-related feeding and gastric evacuation (GE) measurements were determined for Penaeus subtilis by conducting laboratory-based feeding trials on individual animals. A total of 3482 samples of feed and (or) faeces were collected for quantitative analysis derived from 307 shrimp. Food ingestion was a function of shrimp body weight (BW). Feeding intensity increased progressively with shrimp size, but inversely in percentage terms, resulting in a larger faecal production per BW for smaller shrimp. On average, P. subtilis food ingestion was equivalent to 2.3% of its BW per hour, but consumption in shrimp with empty stomachs reached 4.9% BW/h. Foregut clearance rates (13%) peaked 3 h after food recovery, with the bulk of faeces being produced within 1 h. Food load occurred progressively as more feed was given and evacuated from shrimp stomachs, while feeding continued at reduced levels. Data indicated that control of feeding intensity and resumption of food intake by P. subtilis were not markedly affected by the level of their stomach fullness or by longer food administration intervals. The daily administration of food in shorter feeding intervals, although at continually reduced amounts, may be advantageous in the culture of P. subtilis.

Biology and feeding habit of &lt;i&gt;Palaemon modestus&lt;/i&gt; (Heller) in Taihu Lake

对太湖秀丽白虾怀卵亲体进行培养,两次共获苗1.35万余尾,在实验室内成功地完成了虾苗至亲体一个生命周期的饲养。同期结合对太湖白虾的定期采样测定,分析描述了太湖白虾的生长与繁殖规律,并对其食性进行了定性与定量的研究分析。;Through the investigation of Palacmom modestus (Heller) in Taihu Lake, we explored the resource alternation and food com posit iun of shrimp. The shrimp resources decreased rapidly with the increase of ice-fish resources. Its catching yield reduced from 231 0.90 ton in 1975 to 156.25 ton in 1992. The shrimp was omniovorus and had no distinct selection to zooplankton. The residues of zooplankton in the shrimp stomach are similar to the dominant populations of zooplankton in the lake. We also cultured the shrimp larvae hatched in labolratory and studied their growths reproduction and quantitative assay of feeding, 2.7 percent of the larvae which were cultured 2.5 months and hatched in June or July might reach to their biological minimal form and others reached to their biological minimal form at eleven-month-age in May next year, and bore eggs in the second time at 1 A. 5-month-age, but the egg number was clearly less than the first time. Parent shrimps died continuously after their larvae hatched. It is proved indirectly that the age of the shrimp was about fifteen monthes through culture in two times' egg-laying of the same repruduction population. By means uf labolratory experiment, we also conclude that the feed rate of the shrimp was 30.82, and the food efficient change 3.25 percent.

Shrimp trawl catches and stomach contents of redfish, Greenland halibut and starry ray from West Greenland during a 24-hour cycle

A total of 179 redfish (Sebastes spp.), 495 Greenland halibut (Reinhardtius hippoglossoides) and 133 starry ray (Raja radiata) stomachs were collected from the catch in four bottom trawl hauls carried out at 6-hour intervals on a shrimp fishing ground off West Greenland in September 1991. Between 90 and 96% of the total catch in each of the four trawl hauls consisted of northern shrimp (Pandalus borealis). The fish catches were small and dominated by redfish, Greenland halibut, starry ray and polar cod (Boreogadus saida). The stomach contents of redfish consisted of crustaceans (mysiids, hyperiids and copepods) followed by cephalopods, northern shrimp and redfish. Fish (mainly redfish), cephalopods and northern shrimp were the most important stomach content of Greenland halibut. The stomach content of starry ray consisted mainly of northern shrimp and redfish. Plots of redfish and shrimp sizes found in the stomachs of Greenland halibut and starry ray versus predator size showed only weak associations indicating that availability overruled the importance of size-dependent prey preference. The present study indicates that redfish, Greenland halibut and starry ray feed throughout the 24-hour cycle with no clear diel feeding rhythms.

Shrimp trawl catches and stomach contents of redfish, Greenland halibut and starry ray from West Greenland during a 24-hour cycle

A total of 179 redfish (Sebastes spp.), 495 Greenland halibut (Reinhardtius hippoglossoides) and 133 starry ray (Raja radiata) stomachs were collected from the catch in four bottom trawl hauls carried out at 6-hour intervals on a shrimp fishing ground off West Greenland in September 1991. Between 90 and 96% of the total catch in each of the four trawl hauls consisted of northern shrimp (Pandalus borealis). The fish catches were small and dominated by redfish, Greenland halibut, starry ray and polar cod (Boreogadus saida). The stomach contents of redfish consisted of crustaceans (mysiids, hyperiids and copepods) followed by cephalopods, northern shrimp and redfish. Fish (mainly redfish), cephalopods and northern shrimp were the most important stomach content of Greenland halibut. The stomach content of starry ray consisted mainly of northern shrimp and redfish. Plots of redfish and shrimp sizes found in the stomachs of Greenland halibut and starry ray versus predator size showed only weak associations indicating that availability overruled the importance of size-dependent prey preference. The present study indicates that redfish, Greenland halibut and starry ray feed throughout the 24-hour cycle with no clear diel feeding rhythms.

Effects of fertilization and stocking rate on the performance of Penaeus japonicus (Bate) in pond culture

The effects of fertilization and stocking rate on the grow-out phase (123 days) of Penaeus japonicus were studied in earth ponds in a ‘valle’ of the Grado Lagoon (north Adriatic Sea). Water was fertilized by broadcasting poultry manure (2000 kg/ha), ammonium nitrate (8 kg N/ha) and mineral superphosphate (10 kg P 2O 5/ha) in drained ponds. During the trial, half of the initial dose of inorganic fertilizers was also spread fortnightly. Stocking shrimp at 3/m 2 as opposed to 1.5/m 2 lowered the average final weight of the shrimps and negatively influenced the distribution of live-weight classes. Fertilization significantly increased the live weight of the shrimps ( P<0.01) after the 42nd day of rearing. It also significantly lowered the incidence of shrimp weighing less than 16 g but did not affect survival rate. Stomach content analysis confirmed the benthic omnivore habits of P. japonicus, although, within each class, few species were shrimp prey. Both fertilization and stocking density affected shrimp stomach contents.