排序方式: 共有4条查询结果,搜索用时 0 毫秒
1
1.
The spotfin burrfish Chilomycterus reticulatus (405 mm standard length) is recorded for the first time on the shoreline of the Mediterranean Sea. The adult specimen was found dried on a beach near the south Sardinian Sea (S. Antioco's Island). Photographs and morphometrics of the specimen are given. 相似文献
2.
The karyotypes of four gerreids of the western Atlantic Ocean are documented. A diploid chromosome complement of 48 telocentric chromosomes was found in the four species (2N=48t, fundamental number FN=48). No differences were detected either in the number of chromosomes of the standard karyotype, in their karyotype size, or between the karyotypes derived from male or female specimens of any of the species. Chromosome length decreased progressively and slightly from pair 1 to pair 24. The Ag–NOR karyotypes of E. argenteus and E. harengulus were characterized by the position of the nucleolar organizer regions next to the centromere in chromosome pair 1, whereas in E. gula and E. plumieri Ag–NORs were detected in pair 4. The other 46 chromosomes showed a light staining of the centromere with no terminal or intermediate heterochromatic blocks. All Eucinostomus species showed Ag–NORs of similar size, while Eugerres plumieri showed Ag–NORs 10–20% larger than Eucinostomus species. A combination of size and position of the Ag–NORs identified E. gula, while size alone identified E. plumieri. However, the ancestral state for size and position of Ag–NORs could not be established. There was no differential staining of the chromosomes by G-banding. The karyotype of the gerreids appears similar to the hypothetical ancestral karyotype of fish. The phylogenetic relationships among these species could not be established because of the lack of chromosome G-bands. Most likely this indicates a homogeneous distribution of GC nucleotides in the chromosomes. 相似文献
3.
Reproductive Behavior, Captive Breeding, and Restoration Ecology of Endangered Fishes 总被引:1,自引:0,他引:1
Species recovery efforts generally focus on in situ actions such as habitat protection. However, captive breeding can also provide critical life history information, as well as helping supplement existing or restoring extirpated populations. We have successfully propagated nine species in captivity, including blackside dace, spotfin chubs, bloodfin darters, and boulder darters. Threatened blackside dace, Phoxinus cumberlandensis, were induced to spawn in laboratory aquaria by exposing them to milt from a reproductively mature male stoneroller, Campostoma anomalum or river chub, Nocomis micropogon. The latter are nest-building minnows, with which Phoxinus may spawn in nature. Eggs are broadcast among gravel and pebbles. Blackside dace individuals reared in captivity were used for translocation. Threatened spotfin chubs, Cyprinella monacha, fractional crevice spawners, deposited eggs in laboratory aquaria in the spaces created between stacks of ceramic tiles. Captively produced spotfin chubs were used as part of a larger stream restoration and fish reintroduction project in the Great Smoky Mountains National Park. The bloodfin darter, Etheostoma sanguifluum, was first used as a surrogate to develop techniques for spawning a closely related species, the endangered boulder darter, E. wapiti. Both darter species mated in a wedge created between two ceramic tiles. Our efforts have had variable but generally high success, with survival rates of 50–90% of eggs deposited. Captive production of nongame fishes can aid recovery of rare species or populations, aid in watershed restoration, and can help to refine water quality standards. In addition, captive breeding allows discovery of important behavioral or life history characteristics that may constrain reproduction of rare species in altered natural habitats. 相似文献
4.
Omar Hernando Avila-Poveda Sandra Liliana Lamouroux-López 《Reviews in Fish Biology and Fisheries》2007,17(1):11-19
The main objective of the current study was to determine an optimal dosage of commercial carp pituitary extract (CPE) of the
conventional heteroplastic hypophysation technique to induce spawning in the wild caught striped mojarra broodstock Eugerres plumieri under laboratory conditions. We also describe trials testing saline acclimation regimes (changes from 10‰ to 30‰) prior to
hormonal induction. For saline acclimation, three treatments were performed: first and second treatments began 1-day after
conditioning of broodstock fish with a total duration of the saline changes lasting 1-day and 2-days, respectively. The third
treatment began 30-days after conditioning with a 7-day saline regime. After reaching 30‰, all fish from the first and second
treatments died after the fourth and ninth days, respectively; while the fishes in the third treatment survived more than
two years. These fish remain on public exhibit in the “Mundo Marino” Aquarium, Santa Marta, Colombia. Four treatments of hormonal
induction were tested on females using a total concentration of 5-mg of CPE per kg of body weight: first, second and third
treatments were applied in two hormonal doses that corresponded to 10%–90%, 30%–70% and 40%–60%, respectively, with time intervals
between doses of 14-h for the first and second treatment and of 12-h for the third treatment. The fourth treatment was applied
in four hormonal doses that it corresponded to 20%–20%–30%–30% with 12-h time intervals between doses. Only the fishes of
the fourth treatment resisted the induction, continued to live and reached spawning artificially. Water temperature remained
at 28 ± 1°C and at 30‰ salinity during the study. The “dry” method of fertilization was used. The fertilized eggs were incubated
at 30‰ and 35‰ salinities. These eggs reached the Morula early stage, but were later attacked by protozoan. These results
suggest that fast changes of saline and limited hormonal dosages do not offer effective results in Eugerres plumieri. This work provided fundamental procedures for the culture and maintenance of live broodstock for striped mojarra in saltwater
and/or coastal lagoon habitats and provides an effective and viable dosage of CPE for artificial spawning and commercial production
in this species. 相似文献
1