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1.
M. Flain 《新西兰海洋与淡水研究杂志》2013,47(1):21-24
The distribution of 376 salmon caught at sea between 41 °S and 46 °S up to 48 km off the east coast of the South Island between 1925 and 1978 is discussed. The distribution appears to be related to strong currents in Cook and Foveaux Straits, and to the Southland Current off the east coast of the South Island. Samples from the sea at Moeraki Peninsula had a higher incidence of stream‐reared fish and a lower mean fork length than samples from the Waitaki or Rakaia Rivers at spawning. 相似文献
2.
Postal probability surveys were used to estimate the angler catch of salmon, and the number of anglers fishing for salmon, on the Rakaia River, Canterbury, New Zealand, for the seasons 1973/74 and 1974/75. Response levels of over 97% were obtained. An estimated 3531 fish were caught by an estimated 4405 anglers in 1973/74 and 4875 fish by 5332 anglers in 1974/75. The sample catch frequency distributions returned were highly positively skewed with few anglers catching most of the fish. The effect of this skewness on the estimate of total catch was investigated by bootstrapping and confidence intervals thus set were compared to those derived from the Gaussian assumption. Confidence limits were obtained for the estimate of number of anglers. 相似文献
3.
Landlocked sockeye salmon (Oncorhynchus nerka), ranging in fork length (FL) from 105 to 313 mm, were captured in fine‐mesh gill nets set in the limnetic zone of the Waitaki hydro lakes (44° 30′ S, 170° 10’ E) in the South Island, New Zealand. A total of 443 stomachs was examined and the frequency of occurrence, volume and weight of prey items calculated. In the Ahuriri Arm of Lake Benmore the principal food (54% by weight) was zooplankton (Boeckella dilatata) whereas in the Haldon Arm of Lake Benmore it was larval and juvenile common bullies (Gobiomorphus cotidi‐anus) (73% by volume). In Lake Waitaki in winter, salmon had eaten insects (43% by volume) with smaller amounts of snails (Potamopyrgus antipo‐darum, 23%) and bullies (24%). In Lake Ohau adult insects may be an important food. There were also variations in diet with season and fish size. The stomachs of 147 brown trout (Salmo trutta) and 181 rainbow trout (S. gairdnerii) caught in the same gill nets were also examined. In contrast to sockeye salmon stomachs they contained negligible amounts of zooplankton (< 1% by weight) and large amounts of aquatic insects (50–58% by weight in the Ahuriri Arm of Lake Benmore). Comparisons with juvenile sockeye salmon and kokanee in North American lakes are made. The impact of introductions of sockeye salmon into other New Zealand lakes is discussed. 相似文献
4.
James Crossland 《新西兰海洋与淡水研究杂志》2013,47(4):767-775
Fecundity estimates were made for snapper Chrysophrys auratus, a serial spawning fish, for the 1974–75 and 1975–76 spawning seasons. Weighed sub‐samples of ovaries were used, and eggs were counted manually. All eggs >0.1 mm diameter were considered potentially capable of being spawned; estimates of these eggs were made at the beginning and end of spawning, and their difference was considered to be the actual fecundity. A log‐log transformation of egg numbers against length offish gave a linear relationship. Fecundity estimates ranged from 297 000 at 25 cm to 4 528 000 at 50 cm in 1974–75, and from 83 000 at 25 cm to 6 164 000 at 50 cm in 1975–76. Counts of ripe eggs were also made, and batch sizes ranging from 13 000 at 25 cm to 104 000 at 50 cm were predicted. By combining these data with fecundity estimates the number of batches spawned was estimated to be 23–44 in 1974–75, depending on and increasing with length; and 6–59 in 1975–76. 相似文献
5.
Chris R. Fowles 《新西兰海洋与淡水研究杂志》2013,47(1):35-43
Electric fishing experiments were made in Woolly Creek, part of the Glenariffe system of tributaries to the Rakaia River, South Island, New Zealand, during December 1972. Two operators electric fished a 25‐m length of stream from the banks, with three runs in both upstream and downstream directions. Large increases in drift were caused by the electric fishing process, which had a marked effect on the Ephemeroptera and the oligochaete families Tubificidae and Lumbriculidae. The invertebrate drift leaving the experimental reach came predominantly from the downstream 10 m section, and larger numbers were caught in drift samples when fishing proceeded in a downstream direction. This was probably because the electrode passed over invertebrates which had previously entered the drift ‘higher’ upstream and re‐settled on the substrate lower in the reach. Electric fishing caused a loss to the drift of 9.6% of the total benthos in the experimental area. This was slightly more than the 8% decrease in benthic numbers calculated from bottom samples. 相似文献
6.
Food and feeding of small fish in the Rakaia River,New Zealand 总被引：1，自引：1，他引：0
Benthic macroinvertebrates and fish species were collected at monthly intervals during a 12‐month period, from 3 areas of the lower Rakaia River. The composition and abundance of the benthos and stomach contents of the fish were analysed for seasonal trends, food niche breadth and overlap between pairs of fish species, and overlap between the benthos and the diet of each fish species. The diets of bluegilled bully (Gobiomorphus hubbsi), upland bully (G. breviceps), juvenile longfinned eel (Anguilla dieffenbachii), Galaxias brevipinnis, G. paucispondylus, and juvenile brown trout (Salmo trutta) were similar to the proportions of prey species in the benthos. Deleatidium and chironomid larvae dominated the benthos in all seasons and formed the majority of food items in the diet of these species. Food niche overlap between these species was high, indicating potential competition, but preferred habitat and feeding habit differences plus low fish population density and abundance of main prey items probably eliminate the occurrence of any serious competition. The diet of the other fish species differed from this pattern. The common bully (Gobiomorphus cotidianus) ate proportionally more chironomid larvae and fish eggs than occurred in the benthos; torrentfish (Cheimarrichthys fosteri) ate proportionally more chironomid larvae than occurred in the benthos; and quinnat salmon (Oncorhynchus tshawytscha) depended largely upon prey species of terrestial origin, such as adult Deleatidium and dipterans. 相似文献
7.
渤海小黄鱼生殖力及其变化 总被引：9，自引：0，他引：9
根据2004年5月在渤海进行的拖网调查资料,分析了小黄鱼(Pseudosciaenapolyatics)在经过近半世纪的捕捞后的生殖群体生殖力及其与体长、纯体质量的关系,并对小黄鱼生殖力的变化作了比较。结果表明,小黄鱼的个体绝对生殖力为14729粒±1360粒;个体绝对生殖力与叉长、纯体质量的关系变化较大;与1964年历史资料相比,相同体长组小黄鱼的个体绝对生殖力F和相对生殖力FL都显著增大(P<0.01)。小黄鱼的生殖力增加可能是小黄鱼在长期捕捞等外部环境影响下的遗传进化以及对其生存环境的适应性响应。 相似文献
8.
Ovarian tissue samples of Atlantic bluefin tuna (ABFT) spawners (n = 49) caught by purse seine in the Balearic Sea (western Mediterranean) were used to assess the stock reproductive characteristics. The frequency of spawning females estimated by the postovulatory follicle method was 84% and the spawning periodicity 1.2 days. Using an unbiased stereological method, the realized batch fecundity was estimated from counts of postovulatory follicles (POFs), whereas the batch fecundity of the subsequent spawn was estimated by quantification of the number of follicles containing oocytes at maturation stage (OMFs). The number of POFs was used as a reliable proxy of the realized batch fecundity, as it represents the actual number of eggs released in the last spawning event. The average relative realized batch fecundity was estimated to be approximately 48 eggs g− 1 of total body mass. While the absolute batch fecundity was isometrically related to the fork length, the relative batch fecundity was not dependent on fish size, which leads to the assumption that all length classes contribute proportionally to their size, towards the total number of eggs spawned by the broodstock. Size-related variations in the sex ratio were observed in the study area and in other Mediterranean locations; females were more abundant in mid-size classes while males predominated in large-size classes. 相似文献
9.
Populations of small fish were sampled in 12–20 riffles of the lower reaches of 3 braided rivers in Canterbury, New Zealand, during periods of low, stable flows. In the Ashley, which has been least affected by floods in recent years, the standing stock of fish was severalfold higher than in the Hurunui and Rakaia Rivers, which experienced large floods over much of the time, particularly the Rakaia River. Mean abundance + 1 standard deviation (S.D.) of all species combined, amounted to 5.95 + 2.76 fish m 2 for 10 species in the Ashley, 0.59 + 0.60 fish m 2 for 7 species in the Hurunui, and 0.23 + 0.11 fish m 2for 6 species in the Rakaia. Mean biomass was 24.85 + 9.59, 2.11 + 1.19, and 2.50 ± 3.60 g m 2in the Ashley, Hurunui, and Rakaia Rivers, respectively. The more common species in the Ashley and Rakaia Rivers were torrentfish, longfinned eel, blue‐gilled bully, and upland bully. The same dominant species complex prevailed in the Hurunui River except that the common river galaxias was present instead of the bluegilled bully. The adverse effects of floods on fish, either directly, indirectly, or both, are considered to be a major limiting factor offish populations in braided rivers characterised by highly unstable flows and river beds, and a lack of suitable cover for fish. 相似文献
10.
J. A. Colman 《新西兰海洋与淡水研究杂志》2013,47(1-2):21-43
Spawning grounds and spawning times of the sand flounder, Rhombosolea plebeia (Richardson), and the yellow‐belly flounder, Rhombosolea leporina Gunther, in the Hauraki Gulf are described. The occurrence of female fish at different stages of ovarian development at different stations during the year, the distribution of eggs in the plankton, and changes in ovary weight during the year were used as indicators of spawning grounds and spawning times. The sand flounder was found to spawn in the waters to the east of Waiheke and Ponui Islands, at the northern end of the Firth of Thames, from June to November. Yellow‐belly flounders spawned during September, October, and November, slightly to the south of the sand flounder spawning grounds in a belt extending from Tapu, on the eastern side of the Firth of Thames, north‐westwards towards Ponui Island. Fecundity of both species was approximately proportional to the weight of the fish, or to the length cubed, and less than proportional to the ovary weight. The mean fecundity of sand flounders in the Hauraki Gulf varied from approximately 100,000 eggs in a fish of 18 cm to 500,000 in a 30 cm fish. That of yellow‐belly flounders varied from approximately 250,000 eggs in a fish of 30 cm to 1.25 million in a 45 cm fish. 相似文献
11.
为掌握阿根廷滑柔鱼繁殖特性,根据2021年在西南大西洋公海采集到的阿根廷滑柔鱼样本进行计数和分析雌性成熟个体有效繁殖力,并利用能量密度测定技术测定分析其有效生殖投入。结果显示,阿根廷滑柔鱼雌性成熟个体的平均胴长为(244.90±16.36) mm,平均体质量为(295.16±64.85) g。雌性成熟个体的有效繁殖力为24 363～102 633粒卵母细胞,平均有效繁殖力为(63 158.49±16 782.00)粒卵母细胞;卵子能量密度值为25.01～26.09kJ/g,平均值为(25.71±0.25)k J/g;有效生殖投入为219.80～817.06 kJ,平均有效生殖投入为(465.02±158.71)kJ。在功能性成熟期,雌性个体的有效繁殖力和有效生殖投入均达到最大值。然而,自成熟度Ⅳ期至Ⅵ期,卵子能量密度值、体质量相对有效繁殖力、体质量相对有效生殖投入均没有显著差异。同时,混合模型结果显示,雌性成熟个体的有效繁殖力和有效生殖投入均随着体质量增加显著增大,但与个体体征没有显著相关性。结果表明,阿根廷滑柔鱼雌性成熟个体的有效繁殖力和有效生殖投入均与成熟体型大小密切相关,然而不同... 相似文献
12.
于2007年和2008年6月、8月,用大型浮游生物网对莱州湾鱼卵、仔稚鱼种类组成与数量分布进行了4个航次调查。结果表明,采集到11271粒鱼卵,隶属于4目、15科、22种(不包括2个未定名物种);仔稚鱼2942尾,隶属于4目、9科、12种(不包括2个未定名物种)。6月份是莱州湾大部分鱼类主要产卵期,鱼卵、仔稚鱼种类达25种,鱼卵优势种以斑(Clupanodon punctatus)和凤鲚(Coilia mystus)为主;仔稚鱼优势种以凤鲚、梭鱼(Mugil soiuy)和斑为主。8月份产卵的鱼类较少,仅采集到15种鱼卵、仔稚鱼,优势种均以凤鲚和鲈鱼(Lateolabrax japonicus)为主。鱼卵、仔稚鱼平面分布极不均匀,黄河、广利河和老弥河口附近海域数量较多,莱州湾中部海域数量较少。通过SPSS软件分析发现,鱼卵数量与仔稚鱼、表层铵盐含量呈显著正相关(r=0.438,0.604,P0.01),与盐度、透明度呈负相关(r=-0.343,-0.329,P0.05);仔稚鱼数量仅与鱼卵数量和表层铵盐含量呈显著正相关(r=0.438,0.536,P0.01),与其它环境因子没有明显相关关系(P0.05)。 相似文献
13.
Reproductive and growth strategies of Idotea balthica basteri (Pallas, 1772) population in the Bizerte lagoon (Tunisia,Southern Mediterranean) 
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下载免费PDF全文 We analysed several life history traits of the marine isopod Idotea balthica basteri (Pallas, 1772) from the Bizerte lagoon, Southern Mediterranean Sea. Growth was continuous throughout the life of the animal with a high growth rate in the first life phase, and the growth curve was described according to von Bertalanffy's model. The lowest growth rate (0.23 mm) was recorded in winter (December, January and February) and the maximum rate (2.31 mm) between April and June. The total number of hatched eggs or embryos was positively correlated with the body length of ovigerous females. This population of I. balthica basteri was iteroparous, showing distinct strategies of reproduction. Large ovigerous females with high fecundity were collected during the whole sampling period, while breeding in smaller females with low fecundity was restricted to the period from late spring to early autumn, Manca size increased significantly with increasing female body size and there was also a significant trade‐off between manca size and the number of eggs per brood. Reproductive allocation, ranging between 17.1 ± 1.2% in winter and 23.2 ± 1.8% in summer, was positively correlated with female weight. Accordingly, parental investment in producing a juvenile varied between 1.02% per manca in winter to 3.38% in spring. Evaluated traits show that late summer and autumn cohorts have a K‐strategy, whereas cohorts born in winter and spring, and which exhibit a shorter life time, exhibit faster development, earlier reproduction and a smaller parental investment tending towards an r‐selected strategy. 相似文献
14.
This study compared the longitudinal size distribution of bluegill bullies (Gobiomorphus hubbsi) from Hutt River with existing data on the size distributions of bluegill bullies and torrentfish (Cheimarrichthys fosteri) from Rakaia River, New Zealand. All populations had longitudinal trajectories that showed some increase in size with distance upstream. This increase in size appeared to primarily reflect the influence of amphidromous life styles, where juveniles diffuse upstream from the sea. However, a quantile regression analysis revealed differences in growth and migration rate between the two bluegill bully populations; bluegill bullies from Rakaia River grew at a slower rate and showed variation in migration rate within their population that was not evident in the Hutt River population. Null models were also generated for each population to test for the presence of all size classes of fish in the lower reaches of each river. Both bluegill bully populations showed a significant absence of the largest size classes in the lower reaches and the size trajectories differed significantly from the null models. This difference suggests that all individual bluegill bullies continuously move upstream throughout their lives. In comparison, the size distribution of torrentfish closely resembled the null model, indicating that some individuals did not migrate upstream to the same extent as others. 相似文献
15.
The passage of jet boats through spawning areas can kill salmon eggs buried in the river bed. By using a jet boat on the Ashley River the pressure gradients created in a redd were determined. At the maximum boat speed investigated (11 m.s‐1) gradients up to 9.32 kPa.m‐1 were recorded. The induced water velocities through the gravel were then estimated from the equation of motion and reproduced in a gravel‐filled tube in the laboratory. For the test conditions discharge velocities ranged from 0.18–0.3 m.s‐1. Studies of the effect of these flows on salmon eggs revealed fatality rates of up to 40% at their most critical stage on the ninth day of development. 相似文献
16.
M. Flain 《新西兰海洋与淡水研究杂志》2013,47(3-4):516-518
Early Marine Department records (1930–42) show that of about 100,000 parr, of quinnat salmon Oncorhynchus tshawytscha (Walbaum), fin clipped at the Marine Department's Hakataramea Salmon Hatchery in south Canterbury, only 3 were positively recovered; later independent readings of scales from these fish agreed with the known age. A further 11 scale samples (for 1937 and 1939) of fin clipped fish have been read, but details of their recovery and of their fin‐clip combinations cannot be found. Thus, from approximately 100,000 fin clipped parr, only 14 recoveries can be substantiated. 相似文献
17.
M. Flain 《新西兰海洋与淡水研究杂志》2013,47(2):217-222
Samples of yearling parr of quinnat salmon Oncorhynchus tshawytscha (Walbaum) from Lake Heron and the Glenariffe Stream were examined, and precocious ripe males were found. The proportion in the population (29.2%) was higher than is recorded in North America (2.6%). 相似文献
18.
日本沼虾(Macrobrachium nipponensis)池养越冬抱卵亲虾表型性状对个体繁殖力的影响效应 总被引：2，自引：0，他引：2
采用多元分析方法定量研究了日本沼虾池养越冬抱卵亲虾体重(BW)、净重(NW)、体长(BL)、头胸甲长(CL)、胸宽(CW)、胸高(CH)、腹节长(AL)、额剑长(RL)、尾节长(TL)等11项表型性状对其个体繁殖力的影响效应。结果表明:(1)实验对象所测各表型性状间均呈极显著相关(P<0.01),它们在对个体繁殖力各评价指标的影响上具较好的区分度;(2)影响个体绝对繁殖力(FJ)、体重相对繁殖力(FW)和体长相对繁殖力(FL)的关键表型性状及其直接作用强弱排序分别为BW>BL>CH>RL>AL>NW,BW>CL>RL>CH>TL>NW和BW>CL>CH>RL>NW,相关指数依次为0.810、0.621和0.798,其中BW-NW组合和CH-RL组合分别为决定个体繁殖力的核心变量和公共从属变量;(3)适用于估算个体繁殖力的回归方程分别为:FJ=5087.802BW-6599.877NW+200.927CH+114.774RL+211.878BL-154.965AL-6266.840,FW=1140.538BW-2018.663NW+85.217CH+70.852RL+78.694CL+74.623TL-1152.576,FL=105.453BW-134.613NW+4.307CH+2.709RL+3.623CL-61.737;(4)W(♀)=0.029BL+0.065CL+0.121CW+0.105CH-2.448可精确估算其净重值。 相似文献
19.
Reproductive aspects of the golden ling, Genypterus blacodes, from the southern Chilean fishery are presented. Gonad samples were obtained from commercially caught fish between September 1999 and October 2000. Stage of sexual maturity, gonadosomatic index (GSI), and size of females at 50% maturation determined by logistic methods and by plotting the mean GSI by total length, are presented for both years. Batch fecundity was calculated from subsampling mature ovaries containing oocytes in advanced stages of maturity. Changes in GSI and monthly diameters of oocytes showed that ling had a spawning season which extended between August and November. The sizes at first maturity in 1999 and 2000 were 86.6 and 84.8 cm total length (TL), respectively, using the logistic model, and 84 cm for both years using the mean GSI‐size plotting method. The mean batch fecundity was 333 330 oocytes per individual for fish sized 85–120 cm TL. Fecundity increased with increasing weight and total length. 相似文献