摘要:

The migration of adult freshwater eelsAnguilla australisandA. dieffenbachiiwas studied in 3 areas: Lake Ellesmere (Canterbury) (43°48′S, 172°31′E); Lake Onoke (Wairarapa) (41°23′S, 175°08′E); and the Makara Stream (Wellington) (41°13′S, 174°43′E). In Lake Ellesmere, migrating eels began congregating at the outlet area nearest the sea in January and continued until June. Eels arrived in a definite sequence: A.australismales, females;A. dieffenbachiimales, females. Commercial catches exhibited a lunar periodicity with largest catches occurring just after the last quarter and smallest catches during the full moon. No obvious environmental factors were associated with the migration except that the largest commercial catches were made at times of high lake level. If the lake is opened to the sea during migration, fishing for migrating eels ceases and they escape out to sea. In Lake Onoke, aggregation of migrating eels in shallow areas nearest the sea began in February and lasted until May or June. The order of arrival of eels was similar to that of Lake Ellesmere. Catches showed a lunar periodicity with smallest catches being made during the full moon. In the Makara Stream, the downstream migration extended from January to May, but the majority of eels each year were caught in 3 nights. No sequence existed in the movement of eels of each species or sex, but females ofA. dieffenbachiimigrated last. Dominant factors influencing the migration were increases in water level and flow associated with rainfall in the catchment. Catches exhibited a lunar periodicity with major movement during the last half of the lunar cycle and maximum activity just before the last quarter.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515915

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Male adultAnguilla australisand A.dieffenbachiicaught migrating to sea were held in sea water and induced to mature with injections of human chorionic gonadotrophin. Eye size increased during maturation by a factor of 1.5 inA. australisand 1.2 inA. dieffenbachiifrom the pre‐injection migrant stage. Spawning was observed in 4 of the 42 eels that matured.A.australismatured at between 12 and 28°C andA. dieffenbachiibetween 12 and 26°C. Minimum maturation times occurred at 26°C forA. australisand 24°C for A.dieffenbachii. Maturation rate and temperature were linearly related in both species.A. dieffenbachiimatured more quickly thanA.australisat all temperatures; this is probably related to the different state of sexual development of the experimental eels. At the time of seaward migrationA. dieffenbachiiare more sexually advanced thanA.australis.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515916

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Electrophoresis, comparative morphology, and prevalence of parasites were examined in arrow squidNototodarus sloanifrom New Zealand waters. Electrophoresis revealed 2 alleles at the a‐glycerophosphate dehydrogenase locus. Specimens from eastern and southern areas of New Zealand were fixed for a slow allele and specimens from western areas were fixed for a fast allele. Two types of hectocotylised ventral arms were observed in mature males; one type was found in eastern and southern areas and die other in western areas.Nybeliniasp. post‐larvae showed high infestation levels in western squid, but none were found in eastern and southern specimens. It is concluded that there are 2 species of arrow squid in New Zealand and that these are associated with the major water masses. Some overlap between the species was found in fishery areas Cook Strait, Tasman Bay, and Egmont.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515917

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Orange roughy (Hoplostethus atlanticus) occurs in commercially fishable concentrations along the northern Chatham Rise, east of New Zealand. In preliminary analyses for mercury, the mean level in the flesh coincided exactly with the maximum permissible level of 0.5 mg/kg set by the New Zealand Department of Health for fish sold on the local market. Because of its export potential, more detailed studies followed. Flesh samples of orange roughy were collected at sea and from a number of fish factories around New Zealand. Samples were taken at 2 depths below the skin to determine whether mercury was associated with the waxy subcutaneous layer. No significant difference was detected, but the variability in mercury levels between 2 of the sampled groups was found to be significant and was attributed to fish from different size ranges being analysed. The lower figure (0.35 mg/kg) was obtained from fish with lengths representative of the commercial catch. It is recommended that this value be officially accepted as the mean mercury level for orange roughy flesh.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515918

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Eggs ranged from 1.10 to 1.17 mm in diameter and contained a single oil droplet 0.30–0.35 mm in diameter. Hatching occurred after 146 h at 10–13°C and larvae survived for 4 days. Comparison with otherSeriolellaspecies shows features allowing distinction ofS. punctataeggs and larvae.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515919

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Commercial fishing statistics for 4 east coast ports, Gisborne, Napier, Wellington, and Kaikoura, were analysed for seasonal changes in moki abundance. Moki from commercial catches at Gisborne and Kaikoura were sampled for sex, body and gonad weight, and reproductive status. A small‐scale tagging programme was carried out at Kaikoura. Commercial catches of moki were strongly seasonal, with abundance peaks occurring in August‐September at Gisborne, June‐July and September‐October at Napier, September‐October at Wellington, and May‐June and October at Kaikoura. Moki were resting or developing reproductively in May‐June at Kaikoura, ripe and spawning in August‐September at Gisborne, and spent in October at Kaikoura. At Kaikoura the sex ratio in catches was 1: 1 during both abundance peaks, but at Gisborne males outnumbered females 4: 1 in early August, with the sex ratio declining to 1: 1 by mid September. Moki eggs are smooth and spherical with a non‐segmented yolk and a single oil drop. They can be distinguished from copper moki (L.forsteri) eggs on the basis of oil drop diameter.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515920

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The male ofAbergasilus amplexusHewitt, 1978 is described for the first time. Previous records ofA. amplexusare discussed and a new locality, Te Whanga Lagoon, Chatham Islands, is reported.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515921

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Opal Lake, a cold, acid lake on the central volcanic plateau of the North Island, New Zealand, had an average pH of 4.3 and was highly eutrophic. The biota was less diverse than in neighbouring near‐neutral waters. Macrophytes were rare; phytoplankton were mainly represented by the Chlorophyceae, and there were only 4 zooplankton species. The mean standing crop of macroinvertebrates was 6240 per square metre; this was higher than in other eutrophic lakes in the region and comprised more than 98% chironomid larvae represented by 4 species. Molluscs were absent. The fauna was more diverse than in more acid lakes of the .central volcanic plateau.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515922

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Recent cruises to the Chatham Rise and to the Challenger Plateau have provided new material of 3 species of xenophyophores:Reticulam‐mina labyrinthicaTendal, 1972;Syringammina fragillissimaBrady, 1883; andS. tasmanensisLewis, 1966. These records confirm the occurrence ofS. fragillissimain New Zealand waters, indicate a wide distribution of S.tasmanensis, and amend our knowledge of species variation and depth range of the New Zealand xenophyophores.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515923

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Results of a detailed expendable bathythermograph survey in the northern Tasman Sea are presented. The Tasman Front, with its origin in the edge of an East Australian Current eddy, extended throughout the survey region. The front marked a coherent, meandering, zonal jet which crosses the Tasman Sea and hence links at least part of the East Australian Current to the other western boundary currents in the subtropical gyre. The frontal meandering derives from both the variability of the East Australian Current system and the topographic effects of the major ridge systems in the north Tasman Sea. The front is less distinct over the crests of these ridges. The flow field in the survey area contained a number of anticyclonic eddies, and current records show that the oceanic eddies are long‐lived features similar to the eddies in the East Australian Current.

ISSN:0028-8330    

DOI:10.1080/00288330.1981.9515924

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor