Fish communities in New Zealand rivers and their relationship to environmental variables

Fish abundance data from selected electric‐fishing records in the New Zealand Freshwater Fish Database (NZFFD) were used to identify riverine fish communities and to examine their relationship to environmental variables included in the NZFFD. Only 21 fish species, 18 native species, and three introduced salmonids, were present at 1% or more of the sites. We defined 12 fish communities characterised by a dominant species: two salmonid communities, two non‐diadromous native communities, and eight communities characterised by diadromous native species. Altitude and distance inland were the two most significant variables, reflecting differences between communities dominated by diadromous and non‐diadromous species. The next most important variables were related to the geographic location of the site. Other environmental variables that were highly correlated with the fish community assignments were stream width and percentage of native forest or farming land use in the catchment upstream of the site. Of the local habitat variables, percentage of cascade habitat and percentage of sand substrate were the most important discriminators between communities. Despite having only a limited set of broad‐scale environmental variables, we achieved 47% success in the prediction of community membership using multiple discriminant analysis, with another 21% of sites being near misses. A greater knowledge of barriers to migration of diadromous species and fine‐scale variables describing in‐stream habitat would probably increase the predictive ability of the model, although collection of such data is time consuming and therefore impractical on a national scale.     

Some pathological abnormalities of New Zealand fishes

A number of pathological abnormalities previously unrecorded in New Zealand fishes are described. A silver trevally (Pseudocaranx dentex) captured from the Bay of Islands exhibited swim bladder ectasia. Black oreo (Allocyttus niger) and smooth oreo (Pseudocyttus maculatus) had cysts of unknown aetiology (CUEs) in the gills at prevalences up to 76% and 81%, respectively, in some fishing areas. The CUEs appear long lived and may have some utility for stock discrimination. A hoki (Macruronus novaezelandiae) with X‐cell pseudotumours in the gill was recorded from the Chatham Rise. Alfonsino (Beryx splendens) had conspicuous Kudoa sp. cysts in the gills at prevalences of up to 28%. Smelt (Retropinna retropinna) from the Waikato River were infected with a xenoma forming, Glugea‐like microsporidian.     

Ecology of rocky reef fish of northeastern New Zealand: 50 years on

Abstract

This review examines the history and current understanding of the ecology of rocky reef fishes in northeastern New Zealand, marking the fiftieth anniversary of the Leigh Marine Laboratory. The cumulative number of publications increased steadily to c. 180 by 2012. Most attention has been on the snapper (Pagrus auratus, f. Sparidae), the largest in size and economically most important species, and on triplefins (Tripterygiidae), the smallest in size and most diverse family. A strong quantitative school emerged in the 1980s, a period when there was little research on temperate reef fishes elsewhere. A ‘bottom-up’ view of the effects of habitat structure on fish emerged, identifying the key roles of depth, topography and macroalgae. By 2000, attention shifted to using marine reserves as laboratories for ecological research. A ‘top-down’ view of fish as predators emerged, documenting cascading effects on prey communities and habitats. The two different viewpoints have not yet been integrated. Research gaps, including population connectivity and climate change, represent major challenges for the next 50 years.     

白令海和楚科奇海鱼类种类组成及其对生态环境变化的响应

根据第4次中国北极科学考察在白令海与楚科奇海进行的鱼类拖网调查资料,分析了白令海与楚科奇海鱼类生物的种类组成、优势种、物种多样性和区系特征,探讨了鱼类生物对北极气候快速变化的响应。结果表明,白令海与楚科奇海两个海域共鉴定鱼类生物14科41种;主要优势种类为粗壮拟庸鲽(Hippoglossoides robustus)、北鳕(Boreogadus saida)、短角床杜父鱼(Myoxocephalus scorpius)、斑鳍北鳚(Lumpenus fabricii)、粗糙钩杜父鱼(Artediellus scaber);从适温性来看,冷水性种类最多,有35种,冷温性种类6种;从栖息地生态类型来看,底层鱼类、近底层鱼类和中上层鱼类分别为35、5和1种;Shannon-Wiener多样性指数平均为1.21,呈现南高北低的特点,整体多样性水平不高;气候变化引起部分北极、亚北极海区鱼类出现不同程度的纬向和纵向移动,由此将引起北极渔业资源分布格局的变化。     

厦门海域鱼类群落分类学多样性的研究

根据厦门海域鱼类种类组成历史资料和调查资料,系统整理了厦门海域的鱼类总名录和现有名录,并应用分类学等级多样性指数和分类差异变异指数分析了厦门海域鱼类群落分类学多样性的时空变化。结果表明:厦门海域有记录鱼类共649种;现有鱼类有331种,隶属2纲22目90科181属,其中软骨鱼纲共5目9科9属15种,辐鳍鱼纲共17目81科172属316种。厦门海域鱼类总名录的等级多样性指数Δ+和分类差异变异指数Λ+分别为79.267和220.96;现有鱼类群落分类多样性指数Δ+和分类差异指数Λ+分别为77.504和245.34。分类多样性指数Δ+在冬、春季较高,秋季次之,而夏季最低;而分类差异指数Λ+夏季较高,秋季次之,冬春季较低。秋季和冬季鱼类组成的相似度最高,其次为夏季,最后为春季。与历史总名录相比,厦门海域的现有鱼类群落分类学范围较小,生态幅变窄,群落稳定性较差。     

Conus pennaceus: a phylogenetic analysis of the Mozambican molluscan complex

The genus Conus has over 500 species and is the most species-rich taxon of marine invertebrates. Based on mitochondrial DNA, this study focuses on the phylogenetics of Conus, particularly the pennaceus complex collected along the Mozambican coast. Phylogenetic trees based on both the 16S and the 12S ribosomal genes grossly revealed the same groupings: one that clustered the individuals from the north (Pemba, Nacala and Island of Mozambique), another that grouped the individuals from the central/southern coast (Pomene/Massinga and Inhambane) and a third that assembled the specimens from the central/southern islands (Bazaruto and Inhaca). The 16SrRNA-based trees further distinguished the northern group into a Nacala group and a Pemba+Island of Mozambique group. In all trees, C. p. bazarutensis and C. lohri collected on the central/southern islands grouped separately from the C. p. bazarutensis and C. lohri collected on the central/southern coast, suggesting a genetic similarity between these species. Likewise, C. praelatus revealed greater proximity to C. pennaceus from Pemba. Although different topologies were produced by each gene (low bootstrap support in some nodes), we support the hypothesis of a southward ancestral colonisation pattern, indicated by the 16SrRNA trees. The common ancestor would have shifted from planktonic to non-planktonic larval development and this weak vagility would have promoted the divergence between north and south specimens. Our results suggest that the separation of these groups might have been a relatively recent event, and part of the current morphological variability could be the outcome of phenotypic plasticity and/or ecological adaptation.     

Evidence of deep genetic divergence between populations of an important recreational fishery species,Lichia amia L. 1758, around southern Africa

Lichia amia is an important coastal recreational fishery species with a cosmopolitan distribution in the eastern Atlantic. In southern Africa, it is distributed from southern Angola to northern KwaZulu-Natal in South Africa. A recent biological survey revealed differences between Angolan and South African individuals suggesting that they may represent separate stocks. As fishery management decisions should be based on accurate knowledge of population structure, an initial survey of the genetic substructuring of L. amia was conducted on samples collected in southern Angola and South Africa. Assessment of genetic diversity and population structure was conducted using a fragment of the mitochondrial Control Region. Obtained genetic diversity levels were within the expected range for marine teleosts (h = 0.867, π = 0.007), and two deeply divergent (southern Angolan and South African) populations were identified (average φ _ST = 0.78) across the Benguela Current system. These results suggest that Angolan and South African L. amia should be managed as two independent stocks. This work represents the first assessment of population genetic substructuring across the Benguela Current of a valuable coastal fishery resource, and has application for future fisheries management.     

Polydorid polychaetes (Spionidae) on farmed and wild abalone (Haliotis midae) in South Africa: an epidemiological survey

Although there has been an increase in our understanding of the shell-boring polydorids that infest abalone Haliotis midae in South Africa, abalone from a limited number of farms, and wild populations from east of Cape Agulhas only, have been examined. To gain further knowledge and a more complete understanding of the local distribution of polydorids, we examined up to 30 abalone from each of 14 farms in the Northern, Western and Eastern Cape provinces, and five wild sites in the Western Cape, west of Cape Agulhas. Farm and wild communities were significantly different from each other (ANOSIM, r = 0.632, p < 0.002) and Bray–Curtis cluster analysis showed that most farms clustered separately from wild sites. Boccardia proboscidea was present on all but one of the infested farms, whereas some were also infested by Dipolydora capensis. By contrast, D. capensis was present at all wild sites sampled, whereas B. proboscidea was absent from these sites. Polydora hoplura, a common shell-boring pest, was present at only two farms and two wild sites. There appeared to be some exchange of polydorids among farms and between farms and wild abalone. The farm on the East Coast did not cluster with any other sites, indicating a unique composition of polydorids on that coast. No new, potentially problematic, species was encountered, although four species showed an increase in their known distribution.     

Chromosomal population structuring in carangids (Perciformes) between the north-eastern and south-eastern coasts of Brazil

The family Carangidae comprises 151 species, of which only 19 have been so far karyotyped, including a few representatives from the Western Atlantic Ocean. This study compared the cytogenetic features of three Atlantic carangids, Chloroscombrus chrysurus, Trachinotus goodei and T. falcatus, from north-eastern Brazilian coast, with previously obtained cytogenetic data from southern populations. All species presented 2n = 48 chromosomes. Chloroscombrus chrysurus showed a conserved karyotypic macrostructure (2n = 48a, FN = 48) whereas T. goodei (2m + 2sm + 44a; FN = 52) and T. falcatus (2n = 10m/sm + 38a; FN = 58) presented more diversified karyotypes. Data showed that the samples of C. chrysurus from the north-eastern and south-eastern regions did not differ cytogenetically. However, the frequency or position of ribosomal sites (Ag-NOR/18S rDNA) were effective in discriminating the populations of Trachinotus between these coastal regions. The distinct chromosomal patterns suggest a historical genetic fractionating of the Trachinotus populations along the Brazilian coast.     

Can long-term content analysis of print media be used to examine species composition,population demography and changes in distributional range of recreational fishery species?

Although marine recreational fisheries are socially and economically important, there is often limited funding for their monitoring and assessment. With South African anglers reporting catch declines for almost all targeted species and little long-term monitoring data available, novel methods need to be explored to provide managers with additional information. This study aimed to evaluate the efficacy of content analysis of print-media records for detecting long-term trends in species composition, size composition and distribution of selected recreational fishery species. Information for eight fishes captured in the marine shore-based fishery was collected from South Africa’s most popular recreational fishery magazine, between 1960 and 2009. During the five decades, there were shifts in the catch composition, from being dominated by slow-growing, large predators to faster-growing, large predators and lower-trophic-level species. There were no significant trends in the mean and maximum sizes of the dominant species, except for dusky kob Argyrosomus japonicus, which increased significantly in the maximum size reported during the study period. The distributional range of A. japonicus and leervis Lichia amia significantly increased, and that of galjoen Dichistius capensis significantly decreased. However, it was uncertain whether these trends could be attributed to population changes, changes in angler technology and/or behaviour, or climate signals. Overall, this type of content analysis may provide a cost-effective method to examine changes in species composition and fish distributions over time, but, without detailed knowledge of shifts in angler behavioural patterns, it may not be as useful for understanding changes in the population dynamics of recreational fishery species. It is suggested that fishery-independent monitoring programmes are most suited for this type of complex fishery.