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1.
Darren M. Parsons Mark A. Morrison Simon F. Thrush Crispin Middleton Matt Smith Keren T. Spong Dane Buckthought 《Marine Ecology》2013,34(4):492-500
Estuarine and sheltered coastal habitats that contain physical structure are potentially important nurseries for juvenile fish. Many of these structured habitats, however, are potentially vulnerable to stressors such as elevated turbidity. Quantifying the benefits that structured habitats provide to juvenile fish may therefore be an important step in the management process. We investigated the value of structured habitat for juvenile fishes in northeastern New Zealand, using artificial seagrass units (ASUs) with varying blade density. ASUs were predominantly settled by juvenile snapper (Pagrus auratus) and spotty (Notolabrus celidotus). The density of both snapper and spotty was greatest on ASUs with the highest blade density. For snapper, a gradient in abundance was present (with higher abundance closer to the harbour mouth), suggesting either a gradient in the supply of recruits or a potential recruitment shadow effect. The size distribution of juvenile snapper (12–70 mm fork length) was very similar on both sampling trips, despite the 2‐month interim period, suggesting an ontogenetic habitat shift dependent on size. The condition of juvenile snapper from ASUs with the highest blade density was also greater than the other ASU treatments. Overall, these results provide new empirical evidence that habitats with physical structure within shallow estuarine systems are important to early stage juvenile fishes such as snapper, and indicate that the location‐specific context of that habitat is also likely important. 相似文献
2.
Many fish species rely on estuarine nursery habitats as they transition to adult life stages. Quantifying nursery value, however, requires identification of the life stages (often small and short-lived) that utilise nursery habitats, and survey methods that provide comparable estimates across habitats. We focused our surveys on post-settlement snapper (Chrysophrys auratus) using video camera deployments across habitats within a northeastern New Zealand harbour. Post-settlement snapper abundance was higher among structured habitat types relative to bare sediments, with the type of structured habitat not influential. The exception appeared to be for reef habitat (although sampling was limited). Reef sites were structurally complex, but largely inhabited by older life stages (snapper and other fish species). Overall, nursery value for snapper appears to be connected to structure, rather than structure type. This result emphasises the importance of a broadened scope to coastal fishery management, one that incorporates not just fish extraction, but also habitat maintenance or restoration. 相似文献
3.
GP Jones 《新西兰海洋与淡水研究杂志》2013,47(3):334-359
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. 相似文献
4.
Fish assemblages that included known predators of benthic crustaceans were compared between kelp and barren habitats in northeastern New Zealand using baited underwater video census methods. The benthic-feeding fish were observed in winter, spring/summer and autumn, as well as during night-time in spring/summer. Overall, the fish assemblages varied between barren and kelp habitat, being most marked in winter. Individual benthic-feeding species, such as grey mao mao (Scorpis lineolatus) and leatherjacket (Meuschenia scaber) were associated with barren habitat, while the spotted wrasse (Notolabrus celidotus) was more strongly associated with kelp habitat. The results suggest that changes in habitats on coastal reefs affect populations of species that are benthic predators, which may in turn influence the distribution and abundance of their prey species, such as juvenile spiny lobsters. 相似文献
5.
Whereas diel fish migration between mangrove and seagrass habitats has been recognized for decades, quantitative studies have focused mainly on diurnal patterns of fish distribution and abundance. In general, previous studies have shown that fish abundances decline with increasing distance from mangroves; however, evidence for such a pattern at night, when many fishes are actively feeding, is scarce. The present study is the first to report nocturnal fish abundances along a continuous distance gradient from mangroves across adjacent seagrass habitat (0–120 m). Here, we used nocturnal seine sampling to test the null hypothesis (based on diurnal studies and limited nocturnal work) that fish abundance would decrease with increasing distance from shoreline. We focused on species and life‐stage‐specific abundance patterns of Lutjanus griseus, Sphyraena barracuda, Archosargus rhomboidalis, and Haemulon sciurus. Results indicated that assemblage composition and structure differed significantly by season, likely influenced by temperature. However, within each season, the fish habitat use pattern at both the assemblage and species‐specific level generally failed to support our working null hypothesis. Species‐specific analyses revealed that, for most species and life‐stages examined, nocturnal abundance either did not change with distance or increased with distance from the mangrove‐seagrass ecotone. Our results suggest that analyses where taxa are grouped to report overall patterns may have the potential to overlook significant species‐ and stage‐specific variation. For fishes known to make nocturnal migrations, we recommend nocturnal sampling to determine habitat utilization patterns, especially when inferring nursery value of multiple habitats or when estimating fish production. 相似文献
6.
Distribution, abundance, and habitat preferences of native fish were investigated down the length of a relatively pristine, medium‐sized, fourth‐order stream on Stewart Island, New Zealand. A limited fish fauna was recorded (six species), including three threatened large galaxiid species (Galaxias argenteus, Galaxias fasciatus, and Galaxias brevipinnis), which have restricted distributions on mainland New Zealand. Results indicated that these large galaxiids occupy diverse habitats including pools and backwaters within the mainstems of this stream. Their extensive distributions and wide habitat usage were attributed to factors such as the intact catchment vegetation, unmodified stream channel, and the absence of introduced fishes, particularly salmonids. Results suggest that some native species have been excluded from mainstem habitats elsewhere in New Zealand. It was also evident that interactions among the native species influenced habitat use; G. brevipinnis avoided backwaters, runs, and pools in reaches occupied by G. fasciatus and Anguilla dieffenbachii; whereas G. fasciatus appeared to avoid habitats occupied by G. argenteus and A dieffenbachii. Maximum densities and biomass of galaxiids and eels occurred in deepwater habitats (>0.75 m). Furthermore the fish inhabiting these deeper waters were larger and more likely to be female. These findings have significant implications for the design and application of sampling protocols for native New Zealand fishes and for the protection of their habitats. If deeper waters are not sampled then species, sex, and size biased data may result. 相似文献
7.
Snapper (Chrysophrys auratus) is an important coastal fish species in New Zealand for a variety of reasons, but the large amount of research conducted on snapper has not been reviewed. Here, we review life history information and potential threats for snapper in New Zealand. We present information on snapper life history, defining stages (eggs and larvae, juvenile and adult), and assess potential threats and knowledge gaps. Overall we identify six key points: 1. post-settlement snapper are highly associated with certain estuarine habitats that are under threat from land-based stressors. This may serve as a bottleneck for snapper populations; 2. the largest knowledge gaps relate to the eggs and larvae. Additional knowledge may help to anticipate the effects of climate change, which will likely have the greatest influence on these early life stages; 3. ocean acidification, from land-based sources and from climate change, may be an important threat to larval snapper; 4. a greater understanding of population connectivity would improve certainty around the sustainability of fishery exploitation; 5. the collateral effects of fishing are likely to be relevant to fishery productivity, ecosystem integrity and enduser value; 6. our understanding of the interrelationships between snapper and other ecosystem components is still deficient. 相似文献
8.
Peter L. Horn 《新西兰海洋与淡水研究杂志》2013,47(3):419-430
A bottom trawl survey was used to determine the position of a nursery ground for snapper, Chrysophrys auratus, in the North Taranaki Bight, New Zealand, and so indicate what area should be protected from potentially harmful fishing techniques. A nursery ground for trevally, Caranx georgianus, was also identified. The growth rate of snapper from the North Taranaki Bight is shown to be much faster than Hauraki Gulf and East Cape stocks, but quite similar to Tasman Bay fish. The onset of sexual maturity appears to be related to fish size rather than age, with about 80% of snapper being mature at a fork length of 25 cm. Recruitment success varies greatly between years, and successful recruitment may be related to warm spring temperatures. 相似文献
9.
Determining the nursery habitat of fishes that have moved from estuarine nursery habitats is difficult. The elemental fingerprints of otoliths of three species of sparids were determined to investigate their utility as a natural tag of the nursery habitat. Juvenile Pagrus auratus (snapper), Rhabdosargus sarba (tarwhine) and Acanthopagrus australis (bream) were collected from two sites in each of 15, six and three estuaries, respectively, and their otoliths analysed by solution-based inductively coupled plasma-mass spectrometry. Significant differences in otolith chemistry were found for all three species of juveniles collected from different estuaries. The same patterns among estuaries were not seen for all species, although it was not possible to sample the same sites within an estuary for all species. For bream, significant differences in otolith chemistry were found among all three estuaries, whereas for tarwhine the six estuaries were separated into three groups. For snapper, a number of estuaries could be separated, but there was some overlap for other estuaries. All three species were collected from the same site within one estuary and their otoliths analysed. Significant differences were found among species, but the implication of this finding remains unclear as the three species show differences in microhabitat use and may also differ in age. Because the elemental fingerprints of juveniles vary among estuaries or groups of estuaries, the nursery or recruitment estuary of adult fish could now be determined by analysing the juvenile region of adult otoliths. Thus, connectivity between estuaries and open coastal populations could be determined. Such information will have major implications for fisheries management because it will provide information on the distance that fish have moved from their recruitment estuary and the number of estuaries that contribute to each adult population. 相似文献
10.
The New Zealand snapper Chrysophrys auratus is the object of a major fishery and contributes approximately 30% of the annual landed weight of fin‐fish. Samples of 65 fish from 7 localities on the New Zealand coast were analysed for mercury. Though there is an increase in mercury concentration with size of fish, the larger, older individuals with relatively high mercury levels contribute only a small proportion to the landed catch. Therefore, in establishing the average concentration of mercury in fish, due weight should be accorded to the differences in size composition of the catch. On this basis the average levels of mercury in snapper offered for human consumption are of the order of 0.25 ppm. As this is only half the “permissible safe level” of most other countries where fish consumption is much higher, the risk to the New Zealand consumer is negligible. 相似文献
11.
《Marine Policy》2016
An important component of science-based fisheries policy is the provision of habitat adequate for population renewal. In Canada, the Fisheries Act pays little attention to managing fish habitat, and was further weakened by changes enacted in 2012. Specifically, determining the role of fish habitat in contributing to fisheries and fish stock recovery is challenging when many stocks have severely declined and no longer occupy former habitats. This study compared the abundance of juvenile fish in coastal vegetated habitats before and after collapse or decline of groundfish stocks in Atlantic Canada. This comparison was done by compiling past studies that surveyed juvenile Atlantic cod (Gadus morhua) and pollock (Pollachius virens) in vegetated habitats across three provinces. Two studies were repeated, and one that already had post-collapse data was analyzed to quantify long-term changes in juvenile abundance. In all three cases substantial reduction in juvenile abundance coincided with declines in adult stocks. However, juvenile fish still occur in coastal habitats and could aid in adult stock recovery. The current version of the Canadian Fisheries Act requires presence of an ongoing fishery to trigger habitat protection. This is problematic as low fish abundance may lead to lowered habitat protection and potentially habitat degradation, with less or lesser-quality habitat for fish in the future. Thus, recommendations are made to repeal the 2012 Fisheries Act changes and enhance current fish habitat legislation. Using a precautionary approach for coastal fish habitat management, particularly in valuing its potential for fish stock recovery, would strengthen Canadian fisheries management. 相似文献
12.
Information on the environmental characteristics of the juvenile habitat of many deposit-feeding sea cucumber species is limited, despite most fished species exhibiting rapid localised depletion. The current study combined large and small scale surveying techniques within a New Zealand harbour to identify areas with high densities of juvenile Australostichopus mollis, a commercially valuable aspidochirote holothurian. Data from detailed surveys were used to relate densities of juveniles and adults with measures of physical habitat characteristics including depth, sediment facies type, grain size range, as well as measures of chlorophyll-a, phaeopigment, carbon and nitrogen content of surface sediment. Results revealed a highly localised distribution of juvenile A. mollis focused on one site associated with an area of high adult density. Sites of high juvenile A. mollis density were characterised by sediment qualities favouring epibenthic detritivorous deposit feeding, including high nitrogen content, high phaeopigment:chlorophyll-a ratio and small grain size. The high-density juvenile site had facies that were further characterised by the presence of large shell fragments (>10 cm length) of the horse mussel (Atrina zelandica), which may provide a unique settlement microhabitat for early juveniles. Unlike some other sea cucumber species, juvenile A. mollis shows no distinct spatial separation from adult sea cucumbers, no association with dense macroalgae and no clear preference for shallower depths than adults. Overall, the results illustrate the highly localised pattern of recruitment of this species to a widely distributed adult population, which may help to explain the lack of previous observations of juveniles in this species. These results indicate the importance of identifying and protecting what appear to be very specific juvenile habitats in deposit-feeding sea cucumbers to ensure continuing recruitment to exploited populations. 相似文献
13.
Sofie Vandendriessche Marlies Messiaen Sarah O'Flynn Magda Vincx Steven Degraer 《Estuarine, Coastal and Shelf Science》2007,71(3-4):691-703
Floating seaweed is considered to be an important habitat for juvenile fishes due to the provision of food, shelter, a visual orientation point and passive transport. The importance of the presence of the highly dynamical seaweed clumps from the North Sea to juvenile neustonic fishes was investigated by analysing both neuston samples (without seaweed) and seaweed samples concerning fish community structure, and length-frequency distributions and feeding habits of five associated fish species. While the neustonic fish community was mainly seasonally structured, the seaweed-associated fish community was more complex: the response of the associated fish species to environmental variables was species specific and probably influenced by species interactions, resulting in a large multivariate distance between the samples dominated by Chelon labrosus and the samples dominated by Cyclopterus lumpus, Trachurus trachurus and Ciliata mustela. The results of the stomach analysis confirmed that C. lumpus is a weedpatch specialist that has a close spatial affinity with the seaweed and feeds intensively on the seaweed-associated invertebrate fauna. Similarly, C. mustela juveniles also fed on the seaweed fauna, but in a more opportunistic way. The shape of the size-frequency distribution suggested enhanced growth when associated with floating seaweed. Chelon labrosus and T. trachurus juveniles were generally large in seaweed samples, but large individuals were also encountered in the neuston. The proportion of associated invertebrate fauna in their diet was of minor importance, compared to the proportions in C. lumpus. Individuals of Syngnathus rostellatus mainly fed on planktonic invertebrates but had a discontinuous size-frequency distribution, suggesting that some of the syngnathids were carried with the seaweed upon detachment and stayed associated. Floating seaweeds can therefore be regarded as ephemeral habitats shared between several fish species (mainly juveniles) that use them for different reasons and with varying intensity. 相似文献
14.
From 1998 to 2003, we observed large fluctuations in the abundance and distribution of four pelagic predatory (piscivorous) fishes off northern Oregon and southern Washington, USA. Fluctuations in predatory fish species composition and abundance were strongly linked to the date of the spring transition and to ocean temperatures. Predatory fishes, forage fishes, and juvenile salmonids had distinct spatial distributions, with predators distributed primarily offshore and forage fish and salmonids onshore, but this varied depending on ocean conditions. We suggest that predatory and forage fish distributions respond to ocean temperatures, predator/prey interactions, and possibly turbidity. A shift in ocean conditions in 1999 decreased overall predator fish abundance in the Columbia River plume, particularly for Pacific hake. Marine survival of juvenile salmon started to increase in 1999, and forage fish densities increased in 2000, lagging by one year. 相似文献
15.
Laboratory experiments have shown that the juvenile migratory stage of banded kokopu (Galaxias fasciatus (Gray 1842)) is more sensitive to turbidity than other native fish species and avoids turbidity levels of >25 nephelometric turbidity units (NTU). Field trials using juvenile fish collected from the Tarawera River and Hays Stream, New Zealand, were used to test the results from these laboratory experiments by measuring the effects of turbidity on the migration direction and rate for banded kokopu in a natural stream setting. In the stream setting, neither the migration rate nor the migration direction were affected at turbidity <25 NTU. At higher turbidity levels, significantly fewer fish migrated up stream within a given time period. Because there was rarely any downstream movement, this suggests the fish either halted or slowed their upstream movement. A slower rate of migration could result in fewer juveniles reaching adult habitat, and would account for the reduced abundance of adult banded kokopu in rivers that are turbid during the migration season. Achieving turbidity levels of <25 NTU in rivers and streams during the migration season would therefore help maintain upstream migrations and populations of banded kokopu, and hence other native fish species. 相似文献
16.
Shallow soft-bottom habitats including mangroves and mudflats provide important nursery functions for juvenile fishes, but little information exists concerning the relative nursery value of these habitats for juvenile fishes. We compared the potential of a mangrove and a mudflat in a semi-enclosed bay in Hong Kong to serve as fish nurseries by measuring species composition, dietary composition, gut fullness and diet breadth of juvenile fishes. Fish abundance was higher in mangrove than mudflat, but species richness was almost similar between the two habitats. After excluding Ambassis gymnocephalus, which was found mainly in the mangrove, difference in fish abundance between the two habitats was small. The gut fullness and diet breath of most species did not differ between mangrove and mudflat, suggesting that the two habitats were very similar in terms of providing feeding opportunity for juvenile fishes. While the importance of mangrove as nursery of fishes has been repeatedly emphasized, our data suggest that other soft-bottom habitats, such as mudflats, are also important and need to be protected. 相似文献
17.
Comparative dietary analysis of a recently described fish species complex (Galaxiidae) in a New Zealand river 总被引：1，自引：1，他引：0
The diets of several populations of four recently described species of galaxiid with allopatric distributions were examined in the Taieri River, New Zealand. Comparisons of available prey items and prey consumed were carried out to examine whether the distributions of the galaxiid species might be influenced by food availability and preferences. Seventy‐three prey categories were identified. The availability of four of these (Deleatidium, Oligochaeta, Elmidae larvae and adults) differed among the streams occupied by different galaxiid species. Three differences in the frequency of prey consumption (Deleatidium, Oxyethira, and Elmidae larvae) were detected. Despite differences in diet it was concluded that all four fish species were generalist predators of invertebrates with similar diets that were influenced mainly by prey availability. Furthermore prey availability was not considered responsible for the allopatric distribution of the four species, rather, spawning habitat availability, physical nature of the streams, and prior geological history of the Taieri catchment are considered the controlling influences on galaxiid distribution. 相似文献
18.
Effective conservation requires knowledge of the effects of habitat on distribution and abundance of organisms. Although the structure of coral reef fish assemblages is strongly correlated with attributes of reef structure, data relating reef types to fish assemblages are scarce. In this study we describe the influence of gross habitat characteristics and seasonality on coral reef fish assemblages of fringing and patch reefs in Kenya. Results showed that total fish abundance was not significantly different between the reefs; however, the fringing reef had higher species diversity during both the northeast (42 spp.) and southeast (36 spp.) monsoon seasons when compared to the patch reef. The more fished species (e.g. Siganus sutor and Lethrinus mahsena) were more abundant on the patch reef in both seasons. Statistical analysis indicated common species between the reefs were more abundant on the fringing reef. Seasons affected abundance of the more vagile species (S. sutor), whereas the reef‐attached sky emperor, L. mahsena was affected more by reef type than by seasons. No significant interaction effects of habitat and seasons were found, indicating independence of habitat and environmental variability in affecting fish assemblages on the reefs. Smaller sized fish dominated the fringing reef more than the patch reef, whereas the skewness index (Sk) indicated a normal‐sized frequency distribution on the patch reef. Trophic structure of the fishes varied more within than between reefs, whereas fish assemblage structure was affected more by seasons on the fringing reef. These results suggest that conservation measures such as marine protected area (MPA) design and setting should consider effects of reef morphology and environmental variability on coral‐reef fish assemblage structure. 相似文献
19.
ABSTRACT Echinoderms play important ecological roles in the benthic community, but the processes that regulate their distribution are still poorly understood. The aim of this study was to describe the community structure in the shallow rocky reefs of the Wellington region of central New Zealand. Five sites from a harbour and an open coast were surveyed for adult echinoderm density and habitat composition. Additionally, artificial collectors were deployed to assess recruitment patterns. Five taxa were responsible for the assemblage variation within sites and their abundance was highly correlated with habitat composition. Patiriella regularis was highly abundant in all sites, while Coscinasterias muricata and Evechinus chloroticus were dominant in the Harbour. Echinoderm settlement showed interannual variations, as well as differences between locations. There was a significant pulse of C. muricata settlers, while ophiuroids were present in lower numbers but constantly during the studied period. E. chloroticus settlement was sporadic and the absence of a juvenile cohort in the open coast sites suggests that recruitment might not occur for up to 4 years. The present study provides insights on the echinoderm assemblage in the shallow rocky reefs of the Wellington region and contributes to a better understanding of recruitment patterns shaping population structure. 相似文献
20.
本文根据2007年3月至2008年2月期间在泉州地区3个海湾的调查资料，对其浮性鱼卵和仔稚鱼的种类组成与数量分布特点进行初步研究和探讨．结果表明，本调查海域共出现鱼卵和仔稚鱼51种（含未定种），隶属于21科，主要是近岸底层鱼类、近海中上层鱼类和港湾河口型鱼类三个生态类型．各站鱼卵总平均丰度是81．2彬网，仔稚鱼总平均丰度31．0个／网．数量平面分布呈现优势种明显，占总量比例大，不同季节不同海湾差别较大，规律性不强等特点．整体数量上与往年比有下降趋势． 相似文献