Does restocking with Japanese quail or hybrids affect native populations of common quail Coturnix coturnix?

Natural populations of the common quail Coturnix coturnix may hybridize in the wild with non-native individuals (Japanese quail Coturnix japonica or hybrids) as a result of restocking for hunting purposes. Several laboratory studies suggest that this could lead to a decline in the impulse to migrate in the common quail, and a drop in the frequency of phenotypes showing this tendency. This could lead to an increase in common quail populations in North Africa and a decrease in Europe. This paper provides new data on the proportion of hybrids in Catalonia (Northeast Spain) over 24 years (1983-2006) showing how restocking with Japanese quail or hybrids affects native populations of common quail. The first hybrids were detected in 1990 with an estimate of 4.65% of non-native individuals during the breeding season of wild common quail populations. No increase in non-native or hybrid numbers was detected during the study period, indicating that restocking poses no serious conservation problems at present. However, this may change in the near future, either with or without changes in the current scenario. A prudent policy with regard to restocking with non-native individuals is suggested. Moreover, further studies are needed to clarify the extent of this conservation problem.     

Variation in short-term survival of cultured sandfish (Holothuria scabra) released in mangrove–seagrass and coral reef flat habitats in Solomon Islands

Juvenile cultured sandfish (Holothuria scabra) with a mean size of 35.6 mm±11.4 S.D. were released on soft substrata near mangrove–seagrass and lagoonal coral reef flat habitats in the Western Province of Solomon Islands. Mean survival of H. scabra at the mangrove–seagrass sites was 95–100% 1 h after release and approximated 70% 3 days later. At the coral reef flat sites, however, mean survival was as low as 37.5% 1 h after release and total mortality occurred in two of the three releases within 48 h. Mortality of the juvenile H. scabra was due mainly to predation by fish in the families Balistidae, Labridae, Lethrinidae and Nemipteridae. Survival of juvenile H. scabra was improved significantly by releasing them within a cage of 8-mm mesh. This procedure resulted in 100% survival of juveniles in the coral reef flat habitat during the course of the experiment. Our data indicate that mangrove–seagrass areas should be suitable habitats for release of cultured juvenile sandfish in restocking and stock enhancement programs. Release of sandfish at night, to coincide with the time they emerge during their inherent diel burrowing cycle, and the short-term use of protective cages, should be investigated to improve survival of individuals released in mangrove–seagrass habitats.     

Effective fluorochrome marking of juvenile sea cucumbers for sea ranching and restocking

Dermal spicules (or ‘ossicles’) of cultured sea cucumbers can be fluorescently marked with tetracycline and calcein for sea ranching and restocking but optimal immersion conditions are unknown. Lethal and non-lethal effects, and the efficacy of marking spicules in juvenile sandfish (Holothuria scabra), were examined under different immersion conditions. Fluorescence brightness and the proportion of marked spicules generally increased with concentration and duration of immersion. Frequency of burial (an indicator of stress) in sandfish increased with both fluorochromes at concentrations above 50 mg L^− 1. Growth in the two weeks post-marking was unaffected at immersion concentrations of 50 and 100 mg L^− 1 compared to controls, but appeared inhibited by immersion in solutions of 200 and 400 mg L^− 1 of tetracycline or calcein. Sequential marking by tetracycline (yellow) and calcein (green), in either order, showed that calcein was deposited in a higher proportion of spicules. Three other fluorochromes with disparate colors, alizarin complexone, calcein blue and xylenol orange, also marked sandfish spicules and expanded the variety of dichromic combinations. Both tetracycline and calcein fluoresced more brightly when juveniles were marked at 26 or 30 °C than at 21 °C, and this low temperature appears also to reduce the proportion of spicules marked by tetracycline. Our findings show that seawater temperature should be regulated for ex situ immersion marking. The behavioral and biological sensitivities of sandfish demand care in administering the fluorochromes. Fluorochrome immersion at 100 mg L^− 1 for 24 h at ≥26 °C provides a practical compromise between minimizing the fitness of released juveniles and ensuring the efficacy of the markers for studies on the growth and survival of sea cucumbers stocked in the wild.     

“内外联动,三点一线”,助力复养工作

中国是世界养猪大国,同时也是全世界第一猪肉消费大国。非洲猪瘟的暴发给中国的生猪养殖行业带来了巨大冲击。生猪存栏数量下降,散户大部分退出,使得市场上的猪肉供给受到一定程度的影响。依靠从国外进口猪肉来解决国内的消费需求能够起到一定的缓冲作用。但从长远考虑,如何防治非洲猪瘟,抓住“复养”环节所需,才是治本之道。文章借鉴已有研究成果,从政策背景出发,对复养环节的问题和注意事项进行论述,结合四川省和江苏省的成功案例,旨在为生猪养殖业的复养工作提供参考和建议。     

Analysis of the genetic structure of red-legged partridge (Alectoris rufa, Galliformes) populations by means of mitochondrial DNA and RAPD markers: a study from central Italy

The strong hunting pressure on the red-legged partridge, Alectoris rufa, warranted its inclusion into the list of species of European conservation concern. During the last decades, restocking plans with farmed specimens have counterbalanced the hunting drawings from wild populations. Our concern was the study of A. rufa in the easternmost part of its range, the central Italy, to gain insights into the effects of this compensation practice on the genetic structure of its populations. Partridges from both a geographically isolated, long-time protected, wild population (Pianosa island, Tuscan Archipelago National Park) and two Tuscan farms (Bieri and Scarlino) were investigated. All the specimens were very similar in outward appearance, looking much like to A. rufa. Ninety-six sequences of both Cytochrome b and D-loop Control Region of mitochondrial DNA (mtDNA) were analysed to get evidence of ancestry at the population level, whereas, the Random Amplified Polymorphic DNA (RAPD) technique was employed to get fingerprinting at the individual level. Pianosa and Bieri populations showed both the A. rufa and Alectoris chukar mtDNA lineages, whereas the Scarlino one only the A. rufa-mtDNA line. However, a spread overall pattern of A. rufa × A. chukar hybridisation among specimens, whatever their mtDNA lineage could result to be, was disclosed by means of RAPD species-specific markers. This is the first genetically documented record of the A. rufa × A. chukar hybrids. The occurrence of the pure, native A. rufa genome in the easternmost part of the species’ geographical range may be guessed to be virtual.