Spatial variation and commercial fishing of New Zealand abalone (Haliotis iris and H. australis)

The New Zealand abalone fishery produces about 1200 t annually, mostly from southern New Zealand. The fishery, based on Haliotis iris, is managed over broad management areas within which fishing intensity is spatially dispersed. The size composition of the commercial catch depends on location within a management area but is similar for divers fishing individual populations of H. iris and reflects the size composition of natural populations. For most populations, length‐frequency distributions of abalone were normally distributed: the mean shell length of H. iris was found to vary within populations over small spatial scales (100s m). The relative abundance of juvenile H. iris was low in relation to adults suggesting, at least for exposed populations, that rates of recruitment to populations of H. iris may be low. The relative abundance and mean shell length of juveniles and adults of H. australis was much less than that of H. iris. The scarcity of H. australis and the lack of separate catch quotas for the two species are factors which explain the low to zero catch of H. australis. The spatial variation in the size composition of H. iris suggests that management would be more appropriate over spatial scales which reflect local populations rather than the large spatial areas which are used to manage the New Zealand abalone fishery.     

Pigment signatures of phytoplankton composition in the northern Benguela ecosystem during spring

Pigment indices were used to investigate the distribution and composition of phytoplankton in the northern Benguela during the austral spring of 2000, with sampling being conducted on five transect lines between 19°S and 25°S and at other inshore stations on the shelf. Total chlorophyll a concentrations (TChla) at the surface ranged from 18.4mg m^?3 at shallow inshore stations to 0.58mg ^m?3 at offshore localities in deeper water. Phytoplankton communities in the inshore environment were characterised by elevated biomass levels and the dominance of diatoms (high Fuc_DP indices). These diatom populations were associated with cool, higher density, nutrient-rich waters near the coast. Phytoplankton biomass declined with increasing distance offshore and the communities changed to a mixed population where small flagellates were generally dominant (high Flag_DP indices). These flagellate communities were associated with warmer, lower density waters. Whereas dinoflagellates (Per_DP Index) and prokaryotes (Zea_DP Index) were observed throughout the region, their contribution to the communities was of secondary importance.     

The distribution of spiny lobsters in New Zealand waters (Crustacea: Decapoda: Palinuridae)

Two species of spiny lobsters (marine crayfish) inhabit New Zealand waters: Jasus edwardsii (Hutton, 1875), and J verreauxi (H. Milne Edwards, 1851). J edwardsii, the more common species, is present along most rocky coastlines in New Zealand, but is more abundant in the south‐west of the South Island and at the Chatham Islands. The species apparently reaches its northern limit of distribution at the Three Kings Islands (34°S) and its southern limit at the Auckland Islands (51°S).

J. verreauxi, the less common species, is almost solely restricted in New Zealand waters to the north‐east coast of the North Island. It is uncommon in the west and the south of the North Island, and is rare in the South Island. J. verreauxi apparently reaches its northern limit of distribution at the Kermadec Islands (31°S), and its southern limit near Bluff (47°S) in the South Island.     

Ecology of New Zealand abalones,Haliotis species (Mollusca: Gastropoda)

Growth rates of three species of abalone in New Zealand were estimated by fitting data to the von Bertalanffy growth equation. Length‐frequency analysis and tagging were used for Haliotis iris Martyn, and shell growth‐checks were used for H. australis Gmelin and H. virginea Gmelin. The relative growth coefficient (K) and the asymptotic length (L8) were found to be 0.3104 and 146.2 mm respectively for H. iris, 0.3205 and 86.75 mm for H. australis, 0.4460 and 61.5 mm, and 0.3231 and 64.4 mm for H. virginea from two separate localities. An absolute growth curve could be calculated only for Haliotis iris.     

First record of Lepidocybium flavobrunneum (Pisces: Gempylidae) from New Zealand

Lepidocybium flavobrunneum (Smith, 1849) is widespread in warmer oceanic waters and has recently been recorded in the catches of tuna longline vessels in the New Zealand region. Twenty‐five specimens were caught at 31°46′‐32°03′S, 170°49′‐171°11′ E on 23–27 June 1979, thus extending the known range of the species to northern New Zealand.     

Intertidal zone of Delaware Inlet,Nelson, New Zealand

Abstract

A study was made of Delaware Inlet (41° 10'S, 173° 26’ E), Nelson, New Zealand, during February—April 1976. The catchment contains sparse animal and human populations, and supplies unpolluted influent waters.

Over 90% of the inlet was intertidal, with surfaces of predominantly sand interspersed with mud, gravel, cobbles, and shell. Less than 10% of the sediments were colonised by macroscopic vegetation, principally Juncus spp. with Salicornia australis, Zostera muelleri, Viva lactuca and Enteromorpha spp. Two microscopic organisms (Euglena obtusa and Oscillatoria ornata) were studied. Dense aggregations of molluscs, particularly Amphibola crenata (mud snail) and Chione stutchburyi (cockle) were present in specific areas.

Salinity of the water fluctuated widely from <4‰ at the river mouth to 35.0‰ in the main channel at high tide. Nitrogen levels (N0₂‐N, NO₃‐N, NH₄‐N, Kjeldahl‐N) were determined on influent and waters of the inlet. For the main channel, levels of NO₃‐N, NH₄‐N and Kjeldahl‐N tended to be substantially higher around low water than at high tide; respective maxima and minima were 0.016 and 0.001 g.m^?3, 0.050 and 0.001 g.m^?3, and 0.35 and 0.10 g.m^?3. For water from river and streamlets, average levels of nitrogen components were similar to those for the main channel at low tide.     

Small‐scale spatial variation in growth,size at maturity,and yield‐ and egg‐per‐recruit relations in the New Zealand abalone Haliotis iris

Tag‐recapture studies revealed differences in the growth rate of Haliotis iris between headlands and bays separated by as little as 200 m. Individuals off headlands had a significantly higher incremental growth and reached a higher maximum size than those in bays. These results were consistent with observations of the size composition of H. iris which showed that few individuals of harvestable size (> 125 mm shell length) were found in bays. Differences in the growth rate of H. iris may account for the apparent differences in the size at onset of maturity: individuals off headlands, and from a fast‐growing population off Wellington, reached reproductive maturity at a smaller size compared with those in bays. Yield‐per‐recruit modelling showed greater yields from headlands than bays, but egg‐per‐recruit modelling revealed more egg production was conserved in bays than off headlands. Yields could be increased from bays by decreasing the minimum size to 110 mm. Egg‐ and yield‐per‐recruit models were sensitive to the natural mortality rate (M = 0.03, 0.05 and 0.10 compared). The results show that parameters important in the management of commercial fisheries for abalone can vary over small distances: such variation should be incorporated in management strategies for abalone fisheries.     

Limnology of Lake Rotokawa and its outlet stream

Abstract

The water chemistry, flora, and fauna of Lake Rotokawa (38° 37.8’ S, 176° 11.2'E) was studied in 1975–76. The mean pH is 2.1 and thermal inflows may elevate the mean summer temperature of the surface waters 4.2°c above that of nearby cold water Lake Rotongaio (18.9°c). The temperature range of surface water was from 10.1 °c in winter to 23.1°c in summer. The major anions were SO₄ ^2? 679 g.m^?3, and Cl‐ 314 g.m^?3. Mean concentrations of major cations were Na⁺ 224 g.m^?3, K⁺ 28.9 g.m^?3, Ca²⁺ 13.3 g.m^?3, and Mg²⁺ 2.6 g.m^?3.

Two species of flagellate algae were recorded, of which Euglena anabaena was predominant. Only two benthic macroinvertebrates were found, larvae of Chironomus zealandicus, mean density 253 per square metre, and Helobdella sp., 1.3 per square metre.

The Parariki Stream was influenced by thermal springs in its upper and lower reaches, being cooler (24–25°c) about halfway along its length than near its source (27.8–39.0°c) or confluence (26.5°‐28.0°c) with the Waikato River. In the cooler stretch of the stream where unidentified benthic algae were not limited by high temperature, chlorophyll and total pigment increased from 3.9 to 377.9 mg.m^?3 and from 17.5 to 534.4 mg.m^?3 respectively, and nutrient levels fell (NO₃‐N, 22–10.5 mg.m^?3; NH₄‐N, 6440–230 mg.m^?3; and PO₄‐P, 51–19 mg.m^?3).     

Distribution of shipworms (Bivalvia: Teredinidae) in the New Zealand region

Bankia neztalia was found in temperate waters around New Zealand, mainly south of New Plymouth and Tauranga. Bankia australis was found in warm‐temperate waters north of Nelson; it requires water temperatures above 19–20°c for successful breeding and is euryhaline. Lyrodus pedicellatus also occurred in warm‐temperate waters north of Nelson and had a lower water temperature limit for survival of about 10 °c. Lyrodus medilobatus occurred in warm‐temperate waters on the north‐east coast of the North Island north of Tauranga. Nototeredo edax is uncommon and occurred over the same range as B. australis.

The presence of shipworms in wood collected from depths of greater than 50 m around New Zealand is reported. Teredora princesae is recorded from driftwood around New Zealand.     

The comparative limnology of some New Zealand lakes

The morphometry, environmental conditions, and some physical and chemical data are given for twenty‐four New Zealand lakes: seven are in the southern part of the South Island, the others, excluding Lakes Waikaremoana and Waikareiti, are in the “thermal region” of the central North Island. These lakes form two separate groups and include the largest and deepest lakes in both islands.

The lakes in which stratification was established were found to belong to the class known as warm monomictic Two lakes, Rotorua and Rotoehu, were found to be homothermous throughout the year. Open water surface temperatures did not exceed 23°c in the North Island lakes or 19°c in the South Island, and minimum temperatures recorded were 7°c in the northern lakes and 5°c in the southern. In deep lakes the range of temperature was much less: Wakutipu had a range of 16–8.85°c.

The disappearance level of a Secchi disc varied from 18 m (Lake Taupo) to 0.8 m (Lake Rotongaio). The transparency of the water in the glacial and volcanic lakes was comparable to that of similar lakes in other parts of the world.

It was found that total ions, measured by the ion‐exchange resins reached high concentrations in lakes fed by thermal waters: Rotomahana 14.32m.e./l. By contrast Tikitapu, a seepage lake, had the low concentration of. 0.28m.e./l, and Wakatipu, a glacial fed lake, a concentration of O.58m.e./1. The pH range was 8.1–5.8, the lowest value being in Tikitapu, a volcanic lake. Slightly lower pH values were recorded in the bottom waters of lakes when stratified. Lakes were usually supersaturated with oxygen at the surface, and only a few small lakes showed a hypolimnial deficiency. Silica and phosphate were found in high concentrations in some thermal lakes but nitrogen in the forms measured, was found to be low.     

Hydrolytic enzymes of the paua Haliotis iris,a marine gastropod (note).

Extracts of the viscera of Haliotis iris (Martyn, 1784) were shown to hydrolyse 2‐hydroxy‐5‐nitrophenyl sulphate at pH 5.5, and the p‐nitrophenyl derivatives of α‐ and β‐D‐galactose, α‐ and β‐D‐mannose, α‐L‐lucose, β‐D‐glucuronic acid, β‐N‐acetyl glucosamine and phosphate at pH 4.0 and 5.5: p‐nitrophenyl‐β‐L‐fucose was not hydrolysed.     

Biomarker records from core GH02-1030 off Tokachi in the northwestern Pacific over the last 23,000 years: Environmental changes during the last deglaciation

We investigated marine and terrestrial environmental changes at the northern Japan margin in the northwestern Pacific during the last 23,000 years by analyzing biomarkers (alkenones, long-chain n-alkanes, long-chain n-fatty acids, and lignin-derived materials) in Core GH02-1030. The U ₃₇^K′-derived temperature in the last glacial maximum (LGM) centered at 21 ka was ∼10°C, which was 2°C lower than the core-top temperature (∼12°C). This small temperature drop does not agree with pollen evidence of a large air temperature drop (more than 4°C) in the Tokachi area. This disagreement might be attributed to a bias of U ₃₇^K′-derived temperature within 2.5°C by a seasonal shift in alkenone production. The U ₃₇^K′-derived temperature was significantly low during the last deglaciation. Because this cooling was significant in the Kuroshio-Oyashio transition zone, the temperature drops are attributable to the southward displacement of the Kuroshio-Oyashio boundary. Abundant lignin-derived materials, long-chain n-alkanes and long-chain n-fatty acids indicate a higher contribution of terrigenous organic matter from 17 to 12 ka. This phenomenon might have resulted from an enhanced coastal erosion of terrestrial soils due to marine transgression and/or an efficient inflow of higher plant debris to river waters from 17 to 12 ka.     

Genetic differentiation of the soft shore barnacle Fistulobalanus albicostatus (Cirripedia: Thoracica: Balanomorpha) in the West Pacific

This study examined the phylogeography of the barnacle Fistulobalanus albicostatus, which inhabits mangroves and estuarine shores in the West Pacific. Differentiation in the mitochondrial cytochrome c oxidase subunit I (COI) and 12S ribosomal RNA (12S) genes of 401 specimens of F. albicostatus was examined in samples from 16 locations in the West Pacific, ranging from Honshu to Southern China. Our results revealed that F. albicostatus comprises two major clades exhibiting a COI divergence ranging from 1.25% to 2.8%. Clade A demonstrated the widest distribution, ranging from Japan to China, and was divided into three subclades occurring in the South China Sea (A1), Okinawa (A2), and Honshu, Korea and Qingdao (A3). Clade B was determined to be endemic to Okinawa; i.e. two endemic lineages occur in this island. Thus, F. albicostatus resembles several inter‐tidal species in having clades that are endemic to Okinawan waters. Nevertheless, in contrast to the rocky inter‐tidal barnacles Tetraclita spp. and Chthamalus malayensis, F. albicostatus was not found to be separated into continental and oceanic populations, but instead is divided into northern and southern clades, probably because of the Yangtze River discharge, which limits gene flow between the northern and southern populations.     

Physico-chemical study of Dead Sea waters: II. Density measurements and equation of state of Dead Sea waters at 1 atm

The densities (p) of artificial solutions of Dead Sea waters have been measured at 20°, 25°, 30°, 35° and 40°C using a vibrating tube densimeter. The resulting relative densities (p — p_o, where p_o is the density of water) have been used to determine an equation of state for Dead Sea waters. The average deviation between experimental values and those calculated from the obtained equation was 0.000020 g ml^?1. A thermal expansion coefficient and the coefficients characterizing the influence of the changes in salt or ionic concentrations on the density of Dead Sea waters were calculated, and they were shown to be temperature and concentration dependent. The densities of Dead Sea waters were found to be very sensitive to any changes in ionic composition. The partial molal volumes of salt components were calculated and discussed.     

Ecology of New Zealand abalones,Hahotis species (Mollusca: Gastropoda)

Tagging of Haliotis iris Martyn at colonies near low water, and subsequent regular observations over 18 months, showed that significant movement tended to occur only in autumn and winter when rough seas disturbed the habitat. These movements may vary from year to year depending on sea conditions. Tn contrast, subtidal colonies dispersed more gradually, seemingly disturbed by the tagging operation and subsequent rehandling. Other colonies which were not tagged remained apparently unchanged for up to 2 years. Individuals in subtidal H. australis Gmelin colonies also did not move to any great extent over this period: this species inhabits narrow crevices and appears to be a much more active animal than H. iris, both in the field and in the laboratory. Drift and attached algae were virtually absent from the crevices inhabited by H. australis and it seems likely that the species must forage to feed. A homing mechanism may be present because many older H. australis are found in deep scars on the rocks or have characteristically worn shell edges fitting the rock of their particular site.

A 24‐hour watch on a tagged, subtidal colony of Haliotis iris at Kaikoura showed that there was very little movement diurnally, and it seems likely that feeding is passive; drift algae are available at most times. No evidence of homing behaviour was detected.     

Thermal constraints on the respiration and excretion rates of krill,Euphausia hanseni and Nematoscelis megalops,in the northern Benguela upwelling system off Namibia

Rates of respiration and ammonia excretion of Euphausia hanseni and Nematoscelis megalops were determined experimentally at four temperatures representative of conditions encountered by these euphausiid species in the northern Benguela upwelling environment. The respiration rate increased from 7.7 µmol O₂ h^?1 g_ww ^?1 at 5 °C to 18.1 µmol O₂ h^?1 g_ww ^?1 at 20 °C in E. hanseni and from 7.0 µmol O₂ h^?1 g_ww ^?1 (5 °C) to 23.4 µmol O₂ h^?1 g_ww ^?1 (20 °C) in N. megalops. The impact of temperature on oxygen uptake of the two species differed significantly. Nematoscelis megalops showed thermal adaptations to temperatures between 5 °C and 10 °C (Q₁₀ = 1.9) and metabolic constraint was evident at higher temperatures (Q₁₀ = 2.6). In contrast, E. hanseni showed adaptations to temperatures of 10–20 °C (Q₁₀ = 1.5) and experienced metabolic depression below 10 °C (Q₁₀ = 2.6). Proteins were predominantly metabolised by E. hanseni in contrast to lipids by N. megalops. Carbon demand of N. megalops between 5 and 15 °C was lower than in E. hanseni versus equal food requirements at 20 °C. It is concluded that the two species display different physiological adaptations, based on their respective temperature adaptations, which are mirrored in their differential vertical positioning in the water column.     

Summer distribution of the pelagic copepod Centropages aucklandkus in New Zealand waters

The quantitative distribution of Centropages aucklandicus in summer is described. This coastal species, endemic to New Zealand, is found round the whole country except in the north. It has a northern limit coincident with the 19°c isotherm. Possible factors operating to conserve C. aucklandicus in coastal waters, temperature, salinity, food and behaviour, are discussed.     

Distribution of zooplankton biomass in the southeastern East China Sea

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Multi-sensor satellite time series of optical properties and chlorophyll-a concentration in the Adriatic Sea

Advanced remote sensing techniques and regional algorithms are combined to produce and analyze a 12-year multi-sensor time series of bio-optical properties for the Adriatic Sea. First, a multi-sensor series of normalized water-leaving radiance L_WN is created with an optically-based merging technique applied to SeaWiFS and MODIS data, then distributions of inherent optical properties (IOPs) are obtained with a semi-analytical bio-optical model. Additionally, Chla is computed by two regional empirical algorithms associated with two classes of optical properties representative of open ocean waters and Adriatic coastal regions (Classes 1 and 2, respectively). The domain of applicability of each algorithm is dynamically determined on the basis of the L_WN input spectrum by a novelty detection approach. The various satellite products are validated using a comprehensive bio-optical time series collected in the northern Adriatic. At the basin level, the frequency of occurrence of Classes 1 and 2 are 61% and 10%, respectively, with Class 2 waters particularly located in the northern part and characterized by higher levels of Chla and IOPs. The annual cycle of Chla over the 12-year period exhibits significant variations in amplitude and phase; moreover, the annual cycle shows a reduced amplitude during a period centered on 2004 for a time interval that varies with the region. In the northern Adriatic, the overall level of Chla appears lower between 2003 and 2008 compared to the beginning of the series.     

Ecology of New Zealand abalones,Haliotis species (Mollusca: Gastropoda)

The spawning season of Haliotis iris Martyn, as indicated by a gonad index and examination of ovaries, was late summer to autumn at Kaikoura, New Zealand, in 1967–68. In contrast, H. australis Gmelin spawned twice, once in the spring and again in the late summer to autumn. Both patterns are typical of haliotids. But in the 1968–69 year neither species spawned; full gonads with apparently ripe eggs were maintained through the winter of 1969. No reason for this inconsistency can be offered. Haliotis iris at Taylors Mistake, 154 km south, followed essentially the same pattern as Kaikoura H. iris through 1968, but spawned slightly in autumn 1969.

Haliotis iris first produces mature eggs when it is about 60 mm long and probably spawns substantially for the first time when it is 4 years old. Although fecundities of larger animals reached about 11 million eggs, not all of these were necessarily spawned. Haliotis australis also first produces mature eggs when it is about 60 mm long, but the age at which first spawning takes place could not be determined; maximum fecundity is about 3 million eggs. The sex ratios did not differ significantly from 1: 1 for either species.