Estimates of size for the large octopus Macroctopus maorum from measures of beaks in prey remains

Macroctopus maorum, also known as Octopus maorum and Pinnoctopus cordiformis, grows to 12 kg and is the largest octopod in Australasia. In New Zealand, this species features in the diets of seals and albatrosses. Beaks of depredated octopus resist digestion and accumulate in the stomach until regurgitated or defecated. Beaks of M. maorum were differentiated reliably from those of other octopods in prey remains for octopus > c.100 g. Previous studies estimated the size of depredated M. maorum from measures of lower beaks using equations derived either from a small sample of M. maorum or from related species. Here, allometric equations to estimate ventral mantle length (4.6–27.5 cm), dorsal mantle length (5.1–29.0 cm), total length (20–198 cm), and body mass (36–12 000 g) were derived from measures of both upper and lower beaks of 90 specimens of M. maorum. These regressions were imprecise and reflected innate variability in octopus morphometrics, a characteristic reflected in the results of analyses of published data for M. maorum from northern New Zealand and for two other large octopods, Octopus vulgaris and Enteroctopus magnificus.     

Short-term survival of severe propeller strike injuries and observations on wound progression in a bottlenose dolphin

Until recently, vessel collisions with small cetaceans were presumed rare, mainly as a consequence of limited reporting. Observations on dolphin wound healing from propeller strike injuries also remain scarce. We present an extreme case of a bottlenose dolphin (Tursiops truncatus) with multiple propeller wounds, including a penetration to the bone, where survival was possible for at least 23 days post injury. We used photographic records in conjunction with field observations to describe wound progression in the absence of treatment. Considering the severity of the wounds, it was surprising that the injuries were not immediately fatal. A practical solution remains to be found for the problem of odontocete vessel collisions, in particular for small highly mobile species using neritic waters. In view of the ongoing problem in the Hauraki Gulf and, indeed, worldwide, we recommend continued evaluation of cases and reporting of incidents, in addition to investigations into mechanisms that may reduce the risk of occurrence of vessel collisions with cetaceans.     

An examination of the trout population of five lakes near Rotorua,New Zealand

Five lakes, varying from 10 to 100 hectares in area and each containing an existing population of Salmo gairdneri, were gill‐netted and stocked with tagged fish each year from 1960 to 1965 to determine the effect of regular stocking on the size and numbers of fish present. There was little natural spawning of trout in most of the lakes. Growth in length and weight of tagged fish was computed and an annual estimate of population calculated from the netting returns. Appendices give details of the statistical analyses of the data.

Fish production has been correlated with the trophic status of the lakes as indicated by their temperature and oxygen content. There was no clear relationship between lake size and trout production but trout production decreased as the environment became more eutrophic. Results also showed a close inverse relationship between numbers supported and average weight achieved by the trout. It is concluded that the angling potential of local lakes can be maintained despite the eutrophication resulting from intensive agricultural development of the catchments. These lakes will produce large‐sized fish if the trout population is kept relatively small.

Loss in weight in brown and rainbow trout as a result of spawning activities in local lakes and streams was found to be similar. Both male and female fish lost between 22 and 40 percent of their weight over a spawning period. This probably accounted for the observed low‐condition factor among older fish in the lake populations.     

The Flight Response In Struthiolaria Papulosa Gigas Sowerby

The flight response shown by Struthiolaria papulosa gigas Sowerby on contact with forcipulate asteroids is described. The response consists of repeated somersaults and is similar to that described for Nassarius spp. Tests were carried out to determine the strength and duration of the response after contact with six different species of asteroid. Positive responses occurred only with species of the order Forcipulata and, of the forcipulates tested, Astrostole scabra (Hutton) proved to be the most effective stimulator. It is suggested that this fact may be correlated with the size of the test species. Ecological observations do not support the view that specific predator recognition is necessarily involved in the response.     

Additions to the echinoderm fauna of the chatham rise

Forty species of echinoderms are added to the 54 already known from the Chatham Rise and Chatham Islands. Additional information is given for some of the previously recorded species.     

Observations on the faunas of two warm streams in the taupo thermal region

Observations were made on the biota of two warm streams in the Taupo thermal region during December 1965 and June 1966. Distribution of the fauna was related to the observed water temperatures, and the possible effects and importance of high temperature are discussed. The principal “thermal” species were Protozoa, larval and adult Hydrophilidae (Coleoptera), larval and pupal Ephydridae (Diptera), Nematoda, and Rotifera.     

Two new species of hatschekia (copepoda,dichelesthiidae) from New Zealand waters

Two new species of Hatschekia Poche, 1901 are described from New Zealand specimens of Allomycterus jaculiferus (Cuvier, 1818) and Lepidopus caudatus (Euthrasen, 1878) respectively. Comment is made on the need for revision within the genus Hatschekia.     

Size composition of Jack mackerel catches from the west coast of New Zealand

Catches of iack mackerel Trachurus declivis taken everv 2 months from the west coast of New Zealand show that this species attains lengths of approximately 11 cm and 24 cm at the completion of the first and second years of life respectively. Above these lengths, year classes overlap considerably. Juveniles were found from Westland to North Cape and were most abundant in surface waters.     

Reconnaissance survey of the mineralogy and geochemistry of some New Zealand lake and nearshore sediments

131 sediment samples representing 4 different environments (lakes, sounds, harbours, and fiords) in New Zealand have been studied and characteristic differences in chemical composition and mineralogy noted. These differences are related principally to the lithology of the sediments and the productivity of the lake waters. This study should provide a baseline for future surveys of lake sediment geochemistry in New Zealand.