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21.
Seasonal reproductive cycle of the freshwater mussel, Lamellidens corrianus has been studied. These mussels are functional or simultaneous hermaphrodites. The spawning was at its peak during the months of September to December. The gonads were in growing stages with reduced gonadal activity during January to April, whereas the maturation of gonads was found to be intense during May to August. 相似文献
22.
Detailed life-history observations of Dermatolepis dermatolepis are given, including the location, size and timing of a probable spawning aggregation. These observations emphasize the general rarity of the species and the importance of no-take reserves in the management of offshore islands. 相似文献
23.
《Chronobiology international》2013,30(7):917-924
Reproductive cycle of seasonally breeding fish is synchronized with changes of photoperiod and temperature in environment. We hypothesize that arginine vasotocin (AVT) and isotocin (IT) are involved in timing and synchronization of seasonal reproductive activity in the round goby (Neogobius melanostomus). To verify this hypothesis, we examined the annual profiles of brain AVT and IT in round goby males and females in relation to their reproductive cycle. Wild round gobies were exposed to annual environmental changes in their natural habitats from where they were sampled monthly over a year. AVT and IT were measured using HPLC with fluorescence detection preceded by solid-phase extraction. This study shows seasonal variations in brain AVT and IT levels. Profiles of changes were similar in males and females: the peak of AVT was observed before spawning in March-April, whereas that of IT during spawning in May–June. Furthermore, the lowest AVT level was noted out of breeding season from November to January, while the level of IT decreased immediately at the end of the spawning. The results show that high AVT levels correlate with pre-spawning period whereas the highest IT levels correspond to spawning. A significant decline in AVT and IT in non-spawning season coincided with the quiescent phase of gametogenesis in both sexes. 相似文献
24.
An intersexual adult New Zealand longfinned eel Anguilla dieffenbachii , displaying testicular tissue within its ovaries, is described. Gonad samples were collected at 0, 21, 42 (by biopsy) and 54 days (autopsy) after the start of an experiment that aimed to induce ovarian maturation by repeated treatment with 5 mg kg−1 salmon pituitary homogenate (SPH). Very small patches of testicular tissue (almost always single seminiferous tubules), not visible macroscopically, were observed on all sampling dates. Treatment with SPH resulted in advanced stages of spermatogenesis in these seminiferous tubules, synchronous with the development of oocytes, which reached the migratory nucleus stage after 53 days. This finding is discussed in relation to current knowledge on sexual development in anguillid eels. 相似文献
25.
Jayanta Kumar Nath Minakshi Kalita Anu Saikia Hrishikesh Choudhury D. Khlur B. Mukhim Dandadhar Sarma 《Zeitschrift fur angewandte Ichthyologie》2021,37(2):268-277
The present study provides the first detailed early embryonic development of the Shalyni barb, Pethia shalynius (Yazdani & Talukdar, 1975), a vulnerable cyprinid fish occurring in streams and lentic waters of Meghalaya, northeast India. Induced spawning by synthetic hormone injection in May 2019 was conducted to a pair of mature female and male P. shalynius under controlled conditions in a well-aerated aquarium. Fertilized eggs were spherical, 0.75–0.80 mm (approx.) in diameter, transparent, unpigmented and non-adhesive. A total of 22 developmental stages could be categorized under seven broad periods, viz. the zygote, cleavage, blastula, gastrula, segmentation, pharyngula and hatchling. The first cleavage occurred at 15 min post fertilization (mpf), followed by blastulation at 01:23 hr post-fertilization (hpf), gastrulation at 04:20 hpf, initial somite formation at 07:00 hpf, and pharyngula period at 19:20 hpf, respectively. Embryos hatched between 26–27 hpf and the newly-hatched larvae ranged 2.2–2.5 mm in total length. For naturally-declining populations of this vulnerable fish species, inferences drawn from the present study will help provide a baseline data for its conservation and management, and aid the research fields of developmental biology, biotechnology, molecular biology as well as taxonomy of this species. 相似文献
26.
Patrícia Barros Pinheiro Igor Da Mata-Oliveira Mariana Gomes do Rêgo Bruno Mourato Fábio Hissa Vieira Hazin 《Zeitschrift fur angewandte Ichthyologie》2021,37(4):523-533
The present work describes the reproductive biology of the white marlin (Kajikia albida) caught in the southwestern and equatorial Atlantic Ocean. The gonads of 924 fish were collected by observers on board Brazilian tuna longliners, between November 2004 and December 2006. The spawning season was assessed by the monthly frequency distribution of distinct stages of maturity and monthly mean female gonadosomatic index GSI. Sixty-one percent (n = 656) of the fish examined were female, with a Lower Jaw Fork Length (LJFL) between 83 and 236 cm (mean = 155.5 ± 16.63). The 268 males had a LJFL between 90 and 220 cm (mean = 152.3 ± 34.62). Although the northeastern region of Brazil does not appear to be a significant spawning area for the species, the results suggest a higher reproductive activity in the third quarter of the year. Using a Bayesian logistic model approach, length at 50% maturity was estimated at 145.04 cm (credibility interval of 95%, 143.94–146.09 cm), for females, and at 140.03 cm (credibility interval of 95%, 137.28–142.52 cm), for males. 相似文献
27.
Isaac Okyere Juliet Afrah Obeng Samuel Ayitey Jouke Rients Van der Zee Herman Meeus 《Journal of fish biology》2021,99(2):411-417
Aside from ornamental uses, there is growing interest in using killifishes for a multiplicity of purposes including baitfish and mosquito biocontrol. This experiment explored the spawning habits and embryonic development of the banded lampeye, Aplocheilichthys spilauchen in ex situ freshwater (0.04‰) and brackish water (5.01‰) to ascertain the captive breeding prospects for mosquito control in areas where they occur. Significantly higher number of eggs were laid in the brackish water than the freshwater (X2 = 1613.0, P < 0.05), and black mop was the most preferred spawning substrate, followed by green, blue and white mops. Microscopic monitoring of embryos revealed that cleavage occurred within the first 30 min after fertilization, organogenesis commenced on average in the 25th hour and hatching in approximately 230 h. Although freshwater eggs were relatively bigger than brackish water eggs and certain embryonic developmental stages occurred faster in the freshwater than brackish water, these differences were overall not significant and had no effects on the development and hatching. The observed outcome that A. spilauchen can be optimally propagated with black mops in brackish water offers a significant step in its use for the mosquito biocontrol programme, as well as other potential uses not yet explored. 相似文献
28.
《African Journal of Aquatic Science》2013,38(3):263-271
Aspects of the reproductive biology of Bagrus docmak in the Victoria Nile were investigated between November 2005 and October 2006. Macroscopic and histological analysis of the gonads confirmed it as an asynchronous batch spawner which spawns throughout the year with bimodal spawning peaks coinciding with rainfall seasons. The first spawning peak occurred from March to May, the second from September to November. The sex ratio did not significantly deviate from 1:1. Length at sexual maturity was 33.6 cm and 31.6 cm fork length (FL) for females and males, respectively. Batch fecundity ranged from 1 000 eggs in 34 cm FL fish to 43 000 eggs in 79 cm FL fish, and correlated linearly with FL (r = 0.72) and body weight (r = 0.79). Mean relative batch fecundity was 6 eggs g?1 (SE 2). These results could guide research into the possibility of artificially inducing the fish to spawn, and its subsequent culture. 相似文献
29.
Alexey A. Sergeev Anna E. Barmintseva Stanislav A. Vlasenko Sergey S. Fomin Maria E. Tolochkova Natalia I. Chavychalova Nikolai S. Mugue 《Zeitschrift fur angewandte Ichthyologie》2020,36(6):768-771
The state of natural spawning of sturgeons in the Lower Volga River was investigated through genetic monitoring of juveniles (larvae, fingerlings, subadults) captured at seven traditionally used monitoring locations. Sampling was performed during the period 2017–2019. In total, 460 individuals were caught and genotyped using a set of six microsatellite loci (Afug41, Afug51, Afug135, An20, AoxD161, AoxD165) and mtDNA control region sequencing. The observed species-specific microsatellite alleles revealed the presence of juvenile sturgeons originating from natural spawning also included some hybrids between Acipenser stellatus and A. ruthenus. Thus, the majority of sterlet breeding takes place in natural spawning grounds but also sterlet hybridizes with a small number of stellate sturgeons. Juveniles of other sturgeon species were not identified, and it is concluded that natural spawning activities of Russian sturgeon, beluga and ship sturgeon were insignificant or even absent in the Lower Volga during the observation period. 相似文献
30.
Caroline M. Elliott Aaron J. DeLonay Kimberly A. Chojnacki Robert B. Jacobson 《Zeitschrift fur angewandte Ichthyologie》2020,36(1):25-38
Acipenseriformes (sturgeons and paddlefish) globally have declined throughout their range due to river fragmentation, habitat loss, overfishing, and degradation of water quality. In North America, pallid sturgeon (Scaphirhynchus albus) populations have experienced poor to no recruitment, or substantial levels of hybridization with the closely related shovelnose sturgeon (S. platorynchus). The Lower Missouri River is the only portion of the species’ range where successful reproduction and recruitment of genetically pure pallid sturgeon have been documented. This paper documents spawning habitat and behavior on the Lower Missouri River, which comprises over 1,300 km of unfragmented river habitat. The objective of this study was to determine spawning locations and describe habitat characteristics and environmental conditions (depth, water velocity, substrate, discharge, temperature, and turbidity) on the Lower Missouri River. We measured habitat characteristics for spawning events of ten telemetry-tagged female pallid sturgeon from 2008–2013 that occurred in discrete reaches distributed over hundreds of kilometers. These results show pallid sturgeon select deep and fast areas in or near the navigation channel along outside revetted banks for spawning. These habitats are deeper and faster than nearby river habitats within the surrounding river reach. Spawning patches have a mean depth of 6.6 m and a mean depth-averaged water-column velocity of 1.4 m per second. Substrates in spawning patches consist of coarse bank revetment, gravel, sand, and bedrock. Results indicate habitat used by pallid sturgeon for spawning is more common and widespread in the present-day channelized Lower Missouri River relative to the sparse and disperse coarse substrates available prior to channelization. Understanding the spawning habitats currently utilized on the Lower Missouri River and if they are functioning properly is important for improving habitat remediation measures aimed at increasing reproductive success. Recovery efforts for pallid sturgeon on the Missouri River, if successful, can provide guidance to sturgeon recovery on other river systems; particularly large, regulated, and channelized rivers. 相似文献