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531.
Jiménez‐Segura LF, Palacio J, Leite R. River flooding and reproduction of migratory fish species in the Magdalena River basin, Colombia.Ecology of Freshwater Fish 2010: 19: 178–186. © 2010 John Wiley & Sons A/S Abstract – In most tropical rivers subject to a single‐yearly flooding, migratory fish usually spawn in the onset of the flooding and larvae drift to their nursery habitats. To define when the migratory fish species reproduce, its relationship with the water level and when nursery areas in floodplain lakes are supplied with ichthyoplankton in the Magdalena River, a two‐yearly peak flooding river, we sampled the ichthyoplankton weekly throughout 2 years. The fish species Pseudoplatystoma magdaleniatum, Prochilodus magdalenae, Leporinus muyscorum, Sorubim cuspicaudus and Curimata mivartii spawn twice a year in the main channel and its larvae input into the floodplain lakes are not always associated with flooding. Spawning in the main channel and larvae inputs into the floodplain lakes suggest that the habitat used by the migratory fishes may be consistent with some hypotheses on habitats used by these fishes. 相似文献
532.
Ming‐Yih Leu Pei‐Jie Meng Chao‐Sheng Huang Kwee Siong Tew Jimmy Kuo Chyng‐Hwa Liou 《Aquaculture Research》2010,41(9):e39-e52
Successful natural spawning of Chaetodontoplus septentrionalis in captivity from 19 March to 11 May, 2008 is described for the first time. A single male dominates a harem of two females, spawning with each at dusk, from 10 min before to 20 min after sunset. Each female laid an average 119 × 103 eggs during the spawning period. Fertilized eggs were spherical, buoyant and had a diameter of 0.83 ± 0.02 mm (mean ± SD). Embryonic development lasted 15–18 h at 28.1 °C. Newly hatched larvae were 1.60 ± 0.07 mm in total length (TL) with 27 myomeres. Larvae completed yolk absorption within 3 days post hatching (ph) at 3.01 ± 0.08 mm TL. Ten days ph, the larvae had attained 3.95 ± 0.12 mm TL. Larvae were fed either 100% s‐type rotifers (Brachionus rotundiformis), 100% copepods (Microsetella sp.), a combination of the two (50%:50%) or without live feed (starved control) to determine the effect of live feed on the survival rate. The survival was significantly (P<0.001) higher in larvae fed a combination of diet than the others. These results indicate that C. septentrionalis is a potential species for captive breeding programs and the use of a combination of diet (s‐type rotifers and copepods) may be a suitable first food for the larvae. 相似文献
533.
We estimated the stock size of Japanese sardine ( Sardinops melanostictus ) in the Sea of Japan and East China Sea since 1953 using cohort analysis based on the changes of growth patterns. Growth of Japanese sardine, estimated by using annual rings on archived scales since 1961, showed that body lengths were extremely stunted in the 1980–1987 year-classes. The body length at age 3 from February to April in the 1980–1987 year-classes, a period when the stock size exceeded 4 million tons, was 180.0 ± 2.6 mm (mean ± SD), and in the other year-classes was 195.1 ± 7.6 mm. The body length at age 3 and wet weight of zooplankton in August in the offshore area of the Sea of Japan had a significantly positive correlation. We assumed three scenarios for maturation ratios, and estimated Ricker's spawner–recruitment relationships. We analyzed the correlations between logarithmic recruitment residuals (LNRR) and environmental factors in winter, represented by the North Pacific index (NPI), Aleutian low pressure index (ALPI), Pacific decadal oscillation (PDO), monsoon index (MOI), Arctic oscillation (AO) and Southern oscillation index (SOI). Significant correlations were observed between MOI and LNRR and between AO and LNRR. A combination of strong MOI and weak AO would increase the biomass of phytoplankton and zooplankton and subsequently increase the recruitment of Japanese sardine. 相似文献
534.
535.
Abstract – We compared gonadosomatic index (GSI) and histological analysis of ovaries for identifying reproductive periods of fishes to determine the validity of using GSI in future studies. Four small-bodied riverine species were examined in our comparison of the two methods. Mean GSI was significantly different between all histological stages for suckermouth minnow and red shiner. Mean GSI was significantly different between most stages for slenderhead darter; whereas stages 3 and 6 were not significantly different, the time period when these stages are present would allow fisheries biologists to distinguish between the two stages. Mean GSI was not significantly different for many histological stages in stonecat. Difficulties in distinguishing between histological stages and GSI associated with stonecat illustrate potential problems obtaining appropriate sample sizes from species that move to alternative habitats to spawn. We suggest that GSI would be a useful tool in identifying mature ovaries in many small-bodied, multiple-spawning fishes. This information could be combined with data from histology during mature periods to pinpoint specific spawning events. 相似文献
536.
Yaisel J Borrell Gloria Blanco Emilia Vázquez Jorge A Piñera Gemma Gimenez Alicia Estévez & Jose A Sánchez 《Aquaculture Research》2008,39(12):1258-1267
A set of five variable microsatellite markers was used for the genetic characterization of two common dentex ( Dentex dentex ) broodstocks from an experimental hatchery and for the screening of the egg batches spawned during the complete spawn season in 2006. After parentage assignment, simulations were performed for the hatchery 1 broodstocks; the microsatellite set correctly assigned over 93% of descendants to parents when one parent was known and 80% when neither parent was known. Of the 261 eggs that the DNA was correctly amplified from, 254 were successfully assigned to a parental couple. More than one female or male took part (at the same point in time) in the spawning season. However, we observed 'dominant' individuals that produced high proportions of the descendants (unequal reproductive success) in all the sampling periods, although the contributions of these dominant individuals could change over time. This phenomenon reduces the effective breeding numbers, and could lead to inbreeding if this factor is not taken into account when the next parental generation is obtained. This factor should also be considered in aquaculture selection programmes because the dominant breeders may not be the most interesting individuals for commercial or productive schemes. 相似文献
537.
JODY L. CALLIHAN LYNN T. TAKATA RYAN J. WOODLAND DAVID H. SECOR 《Fisheries Oceanography》2008,17(3):191-205
Atlantic bluefish exhibit cohort splitting, whereby two modes of juvenile recruits originate from spatially distinct spring‐ and summer‐spawning regions in US Atlantic shelf waters. We evaluate the pattern of cohort splitting in a transition area (US Maryland coastal region and Chesapeake Bay) between the two major spawning regions. Spring and summer cohorts were differentially represented in Maryland estuarine (Chesapeake Bay) and coastal waters. The spring cohort was dominant in Chesapeake Bay, but was not well represented in the ocean environment, and the converse true for the summer cohort. We hypothesized that ocean temperatures control the bimodal spawning behavior and extent of cohort splitting. As evidence, we observed an intervening early summer cohort produced in years when shelf temperatures during early summer were suitably warm for spawning. In most years however, two dominant cohorts were evident. We propose that vernal warming dynamics in the mid‐Atlantic Bight influence spawning behavior and the resultant bimodal pattern of seasonal juvenile cohort production commonly observed along the US east coast. 相似文献
538.
Abstract Reliability of underwater snorkel counts of adult Atlantic salmon, Salmo salar L., was analysed in the tributaries of the River Teno, close to the spawning period. In small (width 5–20 m) rivers, the replicated total counts of salmon were reasonably precise (CV = 5.4–8.5%), while in the medium-sized river (width 20–40 m) the precision of the counting method was considerably lower (CV = 15.3%). Low precision in a medium sized river was also observed in an experiment using marked live fish where the observation efficiency varied between 36.4% and 70.0%. In a small river, the detection efficiency of artificial fish silhouettes (test salmon) was almost perfect in pools (98%), but decreased in rapids (84%). Separate counts of males, females, grilse and large salmon were usually more variable than total counts, indicating that divers were more capable of locating a fish than properly identifying its sex and sea-age. The behaviour of adult salmon was favourable to conduct snorkel counts, as fish normally stayed still, or after hesitating, moved upstream (>95%of the cases) when encountering a diver. The high observation efficiency (>90%) and precision, favourable behaviour of salmon and congruence between snorkel counts and catch statistics in small rivers suggest that reliable data on Atlantic salmon spawning stock can be collected by snorkeling provided that the environmental conditions are suitable and the divers are experienced. 相似文献
539.
- 1. The topmouth gudgeon Pseudorasbora parva is a small Asian cyprinid species that has proved invasive throughout many European countries. Following an initial introduction into the wild in 1996, the species is now proving invasive in the UK, with at least 25 infested waters in England and Wales, of which 10 are known to have direct connection to a major river catchment.
- 2. To demonstrate the threat of P. parva to fisheries in the UK, a case study is presented on a lake located in the Lake District of England where the species was introduced in 2000. The species rapidly established a breeding population that, by 2003, was the dominant species in size classes <70 mm. In 2004, they were the only species in the lake that produced young‐of‐the‐year.
- 3. Individual P. parva adopted the reproductive tactics of early maturity, multiple spawning, male dominance and male nest guarding; sexual dimorphism was manifested in larger body size of males. These traits were in contrast to the resident, native species of the lake, including roach Rutilus rutilus and gudgeon Gobio gobio, which adopted traits of later maturity and single spawning.
- 4. This case study, therefore, revealed relatively rapid establishment of a P. parva population, their subsequent numerical dominance of the fish community, and the impediment of the recruitment of native fish. The implications for UK fisheries are concerning: should P. parva continue to disperse and individuals adopt similar traits as those in this case study, there may be few waters immune from their invasion, numerical dominance and subsequent impacts.
540.
Chrysoula Gubili Robert Schabetsberger Christine Poellabauer Becky Bates Rosa M. Wagstaff Lewis M. Woodward Ursula Sichrowsky Alexander Scheck David T. Boseto Eric Feunteun Anthony Acou Robert Jehle 《Fisheries Management and Ecology》2019,26(1):31-41
Understanding the population structure of tropical anguillids residing in the Pacific is vital for their conservation management. Here, the population genetic structure of five sympatric freshwater eels (Anguilla marmorata Quoy & Gaimard, A. megastoma Kaup, A. obscura Steindachner, A. reinhardtii Günther and A. australis Richardson) across 11 western South Pacific (WSP) islands was investigated based on partial nucleotide sequences of the mtDNA control region and the nuclear GTH2b genes of 288 newly collected samples jointly with existing sequences. WSP anguillids are characterised by overall high levels of genetic diversity. Both mtDNA and nuclear sequences provided no evidence for distinct geographic clines or barriers in any of the species across the WSP. The occurrence of admixed individuals between A. marmorata and A. megastoma was confirmed, and a new possible occurrence of a further species was revealed (A. interioris Whitley on Bougainville Island). All species showed evidence for demographic population growth in the Pleistocene, and a subsequent population reduction for A. megastoma. Common spawning grounds and mixing of larvae by ocean currents could promote the lack of pronounced isolation by distance, a finding that has significant implications for the future management of anguillids in the area. 相似文献