摘要:

Larvae ofHalicarcinus variuswere reared through three zoea stages to the first crab instar in the laboratory. The larval stages and the first crab instar are described. Zoea III develops directly to the juvenile crab stage and a megalopa stage is missing.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516272

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

To determine variation in abundance (m‐2) and biomass (g m‐2) of fish populations in the lower Ashley River, New Zealand, a representative reach was sampled by electric fishing during periods of low, stable flows in two consecutive summers (1981 and 1982). For nine species of fish combined, abundance and biomass in riffles differed by 50% and 41% respectively between the two summers. Size frequency distributions for three of the most common migratory species differed significantly between summers and may partly explain the variation in fish standing stock. Abundance of fish, mostly under 150 mm body length, was highest in riffles (3.0 m‐2), whereas biomass was highest in pools (46.5 g m‐2) owing to the presence of a few large eels and trout. Within riffles, there was no significant difference in the longitudinal and cross‐sectional distributions of the more common fish species present. Both abundance and biomass of fish were lowest in runs, the habitat with the least apparent cover for fish. Limiting sampling of fish populations in braided rivers to riffles, which are easily sampled by electric fishing, provides adequate representation of species composition and temporal variation of their abundance and biomass.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516273

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Lake Okaro is a eutrophic lake on the central volcanic plateau of North Island, New Zealand. Its hypolimnion has become progressively depleted of dissolved oxygen between 1955 and 1964. Since then hypolimnetic anoxia has occurred annually. Secchi disc transparency changed little since 1955. Higher values in 1977/78 and 1983/84 appeared to be caused by greater proportions of the cladoceranCeriodaphnia dubiain the zooplankton. Despite large interannual changes in biological and chemical properties of Lake Okaro, trophic state has changed since 1955. The phyto‐plankton species composition changed from no cyanobacteria in 1955/56 to persistent cyanobac‐terial blooms in 1963 and abundant and extensive blooms ofAnabaena spiroidesandA. flos‐aquaein 1979/80.Elodea canadensisdominated the macro‐phyte assemblage and its abundance has changed little since 1963. Zooplankton numbers decreased between 1979/80 and 1985/86 because of a decline in the calanoid copepod population. The zooplankton assemblage, dominated by rotifers in 1979/80, was crustacean‐dominated in 1982/83. Eutrophi‐cation coincided with a higher proportion of chi‐ronomids, particularly the littoralPolypedilum pavidus,which became abundant in the presence of cyanobacterial blooms.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516274

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Moulting periods, growth per moult, annual and long‐term growth, moult frequency, and growth rates were estimated for recapturedJasus edwardsiitagged between Thompson and Caswell Sounds in Fiordland, New Zealand. Males grew faster than females, and both showed a progressively decreasing growth rate. For females immature at tagging and recapture, there was no relationship between growth per moult or annual growth and size. For females immature at tagging and mature at recapture, and for mature females, there was a significant decrease in growth per moult and annual growth with an increase in size. Some immature females moulted twice each year and others once, while all mature females moulted once. Empirical growth curves were better descriptors of the growth of females than the von Bertalanfiy curve, especially for smaller and younger individuals. For males there was no relationship between growth per moult and size; however, there was a significant decrease in moult frequency and annual growth with an increase in size. The empirical and von Bertalanfiy curves provided a reasonable approximation of size at age for males.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516275

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A maximum likelihood approach is described for the analysis of growth increment data derived from tagging experiments. As well as describing mean growth this approach allows the separate estimation of measurement error and growth variability, and uses mixture theory to provide an objective way of dealing with outliers. The method is illustrated using data for Pacific bonito(Sarda chiliensis)and the growth variability model is compared to other published models. The difference between growth curves derived from tagging and age‐length data is emphasised and new parameters are given for the von Bertalanffy curve that have better statistical properties, and represent better the growth information in tagging data, than do the conventional parameters.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516276

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Growth rate estimates are presented for male and female sand flounder,Rhombosolea plebeia,in Canterbury, New Zealand. These are derived from a maximum likelihood growth model fitted to length increment data on 1830 fish (1276 female, 554 male) tagged between 1964 and 1966. The model allows estimation of parameters describing individual and seasonal growth variability, and comparisons of growth rates between areas, years, and tag type. The new growth rates are compared to two previously published estimates and found to be slightly higher than ones derived from a small subset of the same data, and considerably higher than ones that were based on age‐length data. It is suggested that the present growth estimates are more reliable than the latter and that the most likely reason for the difference is inaccuracies in aging. Published yield per recruit estimates based on the age‐length data growth estimates are probably conservative.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516277

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Blood films and imprints of orbital lymphomyeloid tissue, spleen, and thymus of six species of holocephalan(Callorhynchus milii, Chi‐maera phantasma, Hydrolagus novaezelandiae, Hydrolagussp.,Harriotta raleighana, Rhinochi‐maera pacifica)were examined for peroxidase, alkaline and acid phosphatases, β‐glucuronidase, non‐specific and chloroacetate esterases, and periodic acid‐Schiff (PAS)‐positive substance. Peroxidase was only observed in splenic coarse granulocytes ofHydrolagussp. and then it was very weak. Fine granulocytes of all species exceptH. raleighanaandR. pacificastained strongly for alkaline phosphatase, and lymphoid cells inHydrolagussp. were alkaline phosphatase‐positive. Acid phosphatase was variable but often weak in all leucocytes. Granulocytes also stained moderately for esterases although coarse granulocytes of some species stained strongly for α‐naphthyl acetate ester‐ase, but were usually negative or occasionally stained weakly for α‐naphthyl butyrate esterase and chloroacetate esterase. InHydrolagussp. andR. pacifica,cells resembling monocytes stained strongly for α‐naphthyl butyrate esterase. In fine granulocyte alkaline phosphatase and moderate esterase content, holocephalans showed more similarity to agnathans than elasmobranchs.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516278

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Ultrastructural observations on the lymphomyeloid tissue of 4Rhinochimaera paci‐fica, 2 Harriotta raleighana,4Hydrolagussp., and 4Callorhynchus miliiwere correlated with blood granulocytes under the light microscope.Rhinochimaeraonly had fine eosinophilic granulocytes (FG) in blood and orbital tissue, but inHarriottaorbital tissue also contained coarse eosinophilic granulocytes similar to the eosinophils of higher vertebrates. Whereas FG ofHarriottacontained homogeneous electron‐dense granules, those ofRhinochimaeracontained whorl, plate‐like, and multivesiculate inclusions.Hydrolagussp. andCallorhynchusalso had a third granulocyte type that showed some similarities to the coarse granulocytes. They differed, however, in having granules containing a lucent core, apparently bounded by an ovoid vesicle‐like inclusion that may pass from the granule into the cytoplasm. InHydrolagusthese granules also contained tubular structures projecting from, or connecting, granules. Granulocyte interrelationships are discussed.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516279

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The cod‐end mesh selection relationship was investigated for five New Zealand commercial fish species: tarakihi(Cheilodactylus macropterus),sand flounder(Rhombosolea ple‐beia),red gurnard(Chelidonichthys kumu),red cod(Pseudophycis bacchus),and leatherjacket(Parika scaber).Low variance selection factor estimates of 2.54, 1.93, 2.37, 3.58, and 1.98, respectively, were obtained using the covered cod‐end method. Each mean selection factor was then compared to existing estimates available for the same species.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516280

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Genetic variation was surveyed at 10 polymorphic enzyme loci in six samples of green‐lipped mussels,Perna canaliculus,from around New Zealand. There is a significant heterogeneity at five loci and at four of these the heterogeneity is produced by significant differences between northern and southern samples. The differences may be explained by limited genetic exchange owing to current movements coupled with local selection. Four loci were tested in spring and autumn seed mussels from Marlborough Sounds and Ninety Mile Beach. There is a significant difference between spring and autumn seed at one locus. Seed mussels show a significant excess of homozygotes at 6 out of 16 tests whereas for adult mussels at the same loci only 4 out of 24 tests are significant. It is suggested that the differences between spring and autumn seed and the greater homozygosity in seed mussels may be produced by partial assortative mating. For farming operations there may be genetic disadvantages in transferring seed from one water mass to another for ongrowing.

ISSN:0028-8330    

DOI:10.1080/00288330.1988.9516281

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor