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DOUGLAS P. SWAIN 《Fisheries Oceanography》1999,8(1):1-17
Density-independent redistribution in response to changing temperature conditions and density-dependent redistribution in response to changing temperature preferences are two contrasting hypotheses to explain changes in the distribution of cod populations. I tested these hypotheses using survey data on the distribution of cod during the feeding season in the southern Gulf of St Lawrence. These tests used indices of cod distribution as the dependent variable and indices of cod abundance and bottom temperature as explanatory variables. Both hypotheses were often supported in univariate tests that ignored confounding between the two explanatory variables. Tests that accounted for this confounding indicated an effect of cod abundance on distribution for ages 4–8+ years, and 3+ , but provided no support for an effect of environmental conditions on distribution except for age 3. Variation in the temperature distribution of cod was consistent with an effect of abundance on interannual variation in distribution and with no effect of environment except for age 3 cod. Age 3 cod were consistently under-represented in areas of very cold bottom water but older cod were not. As predicted by bioenergetic considerations, cod tended to occupy colder water at high levels of abundance, suggesting a mechanism for density-dependent shifts in distribution. Shifts in cod distribution during the feeding season in the southern Gulf appear to be more closely linked to density-dependent changes in environmental preferences than to density-independent responses to changing environmental conditions. 相似文献
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Leszek Satora Jennifer Mytych Anna Bilska-Kos 《Fish physiology and biochemistry》2018,44(5):1291-1297
Bronze corydoras (Corydoras aeneus) is a small diurnal activity fish from South America. Under hypoxia conditions, it uses the posterior part of the intestine as an accessory respiratory organ. The present PCR studies demonstrated higher expression of HIF-1α (hypoxia-inducible factor) gene in the respiratory than that in digestive part of bronze corydoras intestine. Further, immunolocalization studies using antibodies specific to HIF-1α and transmission electron microscopy (TEM) revealed the presence of HIF-1α epitopes in the intestine of Corydoras aeneus. In the respiratory intestine, the numerous clusters of gold particles visualizing HIF-1α antibody were observed within fibroblasts, whereas in the digestive tract of this species, single gold grains in the epithelial cells were noted. On the other hand, the presence of HIF-1α and the cytoplasmic domain of the epidermal growth factor receptor (EGFR) in the respiratory intestine of bronze corydoras assumes their interactions in the system where these factors appeared for the first time. The non-obligatory air-breathing fishes using their digestive tract as an accessory respiratory organ during hypoxia conditions are very interesting for the studies of the processes that control HIF-1α expression and squamous cell proliferation. 相似文献
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1. The aim of this paper is to assess the usefulness of surveying young fish assemblages in tributaries of the Sinnamary River (French Guiana, South America) as a means of assessing fish species diversity and monitoring environmental change in a neotropical river subjected to hydrodam operations. 2. This work confirms that the tributaries of the Sinnamary River are nurseries for more than half the fish species present in the river. 3. It shows that in natural conditions the young fish assemblages at the beginning of the dry season are overwhelmingly dominated by Characiformes, but that species of other orders are favoured in the impacted sections. 4. This study confirms that the evaluation of the reproductive success of the different fish species over large river stretches at the end of the rainy season appears to be an appropriate method for detecting the immediate effects of flow disturbances on fish communities. 5. The results suggest that it is more informative and less time‐consuming to consider the abundance of juveniles only, and to group them at the order level instead of calculating diversity indices. 6. The relative abundance of Characiformes juveniles at the end of the rainy season seems a cost‐efficient way of assessing the hydrological impact of the dam on the Sinnamary River, and this may be the case for other neotropical rivers where these methods may be generally applicable. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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1. Long‐term data sets on macro‐algae, sediment invertebrates, shorebirds and physical parameters are explored for the Ythan estuary, Scotland. 2. Coverage by macro‐algal mats has increased over the last 40 years with significant impacts on the distribution and abundance of benthic invertebrates and their shorebird consumers. Areas of the estuary worst affected by the mats now support fewer Corophium volutator, whilst the abundance of this and other species has increased in areas less affected by mats, possibly through enrichment by non‐local macro‐algal detritus. 3. Shorebird abundance increased between the early 1960s and the 1980s, possibly in response to enhanced invertebrate abundance in unaffected areas, but has declined since, as algal mats continue to spread. 4. The cause of the increased biomass of macro‐algae is contentious, but the present analysis shows that the increase is unlikely to be related to changes in the physical characteristics of the estuary, which appear to have remained fairly constant over at least the last 30 years. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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There has been much recent discussion about the idea that large whales are potential competitors with fisheries for available marine resources. Based on this idea, often referred to as the ‘whales eat fish’ conflict, culling whales has been proposed as a way to increase resources available for human consumption and thereby ensuring global food security. However, the scientific basis for such arguments remains unclear, especially in the Caribbean waters where baleen whales generally do not feed. In this article, we (i) develop an ecosystem model describing the trophic interactions between whales, fish and fisheries in the Caribbean waters, (ii) calculate the level of overlap between cetaceans and fisheries for food resources, and (iii) simulate the removal of cetaceans from the Caribbean waters in order to quantify the potential increase in available biomass of commercially important fish. Ten groups of cetaceans are considered in the model, including baleen whales, toothed whales and small cetaceans. Our results suggest that baleen whales are not a threat to fisheries in Caribbean waters, while toothed cetaceans seem to be more impacted by fisheries than they actually impacting them. Whales target different types of food resources and consume significantly less than what is taken by fisheries. Moreover, simulated reductions in large whale abundance do not produce any appreciable increase in biomass of the commercially important fish species. In some cases, the presence of some whales actually improves fishery yield as a result of indirect predation effects. 相似文献
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《海洋水产研究》2001,(4)
IntroductionAs part of the Bei Dou Fisheries Research and Managements project(1997- 2 0 0 0 ) ,the Institute of MarineResearch participated in a collaborative study with the Yellow Seas Fisheries Institute on approaches to thedevelopment of theoretical models as tools for assessing the carrying capacity of bivalve production.The In-stitute of Marine Research has in recent years engaged in relatively extensive activity on numerical modellingof coastal oceans. To demonstrate some of the po… 相似文献
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What are the drivers of the occurrence of illegal fishing and conservation barriers of sturgeons in the Caspian Sea? 
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下载免费PDF全文 Seyed Mostafa Aghilinejhad Saeid Gorgin Daan van Uhm Ramtin Joolaie Rasoul Ghorbani Seyed Yousef Paighambari Jahangir Mohammadi Ali Jalali 《水产资源保护:海洋与淡水生态系统》2018,28(3):690-701
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- 1. The Hawkesbury‐Nepean River provides potable water for 5 million people living in the Sydney basin, and water for agricultural and horticultural production that meets most of Sydney's daily needs for fresh food. Anecdotal evidence indicated that numbers of freshwater mussels have seriously declined in much of the river over recent decades.
- 2. A field survey revealed the presence of populations of three species of mussels, Hyridella depressa, Hyridella australis and Velesunio ambiguus in the river. Higher density mussel populations were most common in catchment areas with little human modification to the channel bed or adjacent vegetation communities.
- 3. Levels of disturbance of riparian vegetation and, to a lesser degree, land use, were identified as being strongly associated with the absence of mussels from some reaches.
- 4. Catchment geomorphology was also shown to be relevant to the abundance, population structure and suite of mussel species present in different geomorphic reaches of the river. Absence of mussels was noted from areas where they had been recorded in previous studies. These results demonstrate that mussel species are under threat in the catchment.
- 5. As filter feeders with the ability to remove excess nutrients and bioaccumulate toxic substances, freshwater mussels play an important role in natural remediation processes in freshwater systems.
- 6. The decline in mussel populations in the Hawkesbury‐Nepean River highlights concerns for the overall health of the river system, and supports the need to identify the subsidiary impacts of physical habitat modification in developing both riverine and riparian management strategies.
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Fisheries or aquaculture? Unravelling key determinants of livelihoods in the Brazilian semi‐arid region 下载免费PDF全文
下载免费PDF全文 Priscila F M Lopes Adriana R Carvalho Sebastián Villasante Gustavo Gonzaga Henry‐Silva 《Aquaculture Research》2018,49(1):232-242
In impoverished semi‐arid regions in the world, reservoirs serve multiple purposes, including food provision through fisheries and aquaculture. Yet, the socio‐economic benefits of promoting both activities remain unclear. We independently assessed the socio‐economic benefits generated from fisheries and aquaculture, in two reservoirs in the Brazilian semi‐arid region (June 2013 to June 2014). These reservoirs produced 27.75 ton of farmed tilapia over a year (USD Purchasing Power Parities [PPP] 88,778.73) and provided at least 16.5 ton of fish through fisheries (USD PPP 37,557.81), based on data from four farmer associations. Our input–output model revealed that the local economy depends on both activities, which, therefore, contribute similarly to providing goods and services to different branches. Aquaculture generated much higher revenues (seven times) than fisheries, but also much higher losses (the most successful farm yielded an average income of USD PPP 592.41 monthly). Still, there were no statistical differences in income among the compared associations. Fisheries provided very but guaranteed income (USD PPP 311.02 ± 82.94) and employed over three times as many people and contributed much more (>3 times) to food security than aquaculture. Encouraging aquaculture through specific policies while overlooking fisheries is not advisable because poor fishers would not be able to deal with unpredictable outcomes and it would put their food security at risk. However, if initial external support is provided to fishers in order to buffer large losses, aquaculture could represent a way out of poverty by generating an opportunity for larger gains, as long as potential negative ecological impacts of aquaculture are accounted for. 相似文献
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Xiao Hui Li Jun Jie Bai Xing Ye Yin Chang Hu Sheng Jie Li Ling Yun Yu 《Fisheries Science》2009,75(2):351-358
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Pollyanna de Moraes França Ferreira Suellen Silva Condessa Juliana Silva Rocha Débora Werneck Caldas Juliana Rodrigues Gomes Maria Tatiana Soares Alex Junio Silva Cardoso Jener Alexandre Sampaio Zuanon 《Aquaculture Research》2017,48(9):4623-4631
With this study, we aimed to assess the safety of using Curcuma longa in fish feed. Juvenile Astyanax aff. bimaculatus (0.83 ± 0.04 g) were kept in 24 80‐L aquaria, at a density of 0.5 fish L?1 for 60 days. Six diets supplemented with 0.0, 20.0, 40.0, 60.0, 80.0 and 100.0 g kg?1 were evaluated. Histopathological analysis of the gills showed that there was an increasing linear effect of turmeric on the frequency of lamellar aneurysm, hypertrophy of mucous cells, oedema and necrosis. There was a quadratic effect of turmeric supplementation on the frequency of fusion and disruption of secondary lamellae, vacuolation and hypertrophy of the epithelial cells, and the estimated values to minimize these variables were 4.63, 25.93 and 24.46 g kg?1 respectively. There was a quadratic effect of turmeric on the gills index (IBRA), and the estimated value to minimize this index was 30.23 g kg?1. No effect of turmeric on the frequency of histopathological changes and organ index in fish liver was observed. Thus, we conclude that turmeric is not hepatotoxic for A. aff. bimaculatus; however, its use is safe at concentrations up to 30.23 g kg?1 diet as a function of its gill toxic effect at higher doses. 相似文献
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ABSTRACTThis study was aimed to investigate the effects of dietary β-carotene supplement for 42 days on lipid and protein oxidation biomarkers in carp meat at different times of storage. Seventy-five fish were divided into three groups: group 1 as control group was fed with basic diet; groups 2 and 3 received 50 and 100 mg kg?1 diet β-carotene, respectively. Based on the present study results, muscle malondialdehyde concentrations were significantly lower following β-carotene consumption at 0, 24, 72, and 96 h after harvest in group 3 compared to the control group (p < 0/05). Muscle protein carbonyl contents showed a significant decrease following β-carotene supplementation at 0, 48, and 96 h after harvest in group 3 compared to the control group. Ferric reducing antioxidant power values were significantly increased following β-carotene supplementation at 72 and 96 h after harvest in group 3 compared to the control group. The results indicated that β-carotene supplementation with a dose of 100 mg kg?1 diet is largely effective to improve the oxidative status of carp meat by reducing lipid and protein oxidation. 相似文献
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The duration of efficacy of emamectin benzoate in the control of Caligus curtus infestations in Atlantic cod, Gadus morhua L., was studied following an administration of 50 μg kg?1 for seven consecutive days. No lice were found on medicated fish when challenged 1 week (challenge 1) or 5 weeks (challenge 2) following termination of medication, whereas the mean abundance of lice among the unmedicated fish was 17.9 and 19.3 lice per fish in challenge 1 and 2, respectively. Muscle concentrations of 19.5 ± 8.2 ng g?1 and 3.4 ± 0.9 ng g?1, respectively, and skin concentrations of 23.1 ± 10.8 and 4.2 ± 1.0 ng g?1, respectively, were found 27 and 55 days following the termination of medication. Tissue concentrations and the duration of efficacy indicate a dosing regime for emamectin in cod, similar to the regime used for Atlantic salmon, Salmo salar L. 相似文献
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Amano Masafumi Kubota Hisanori Kaneda Hideko Aoki Daisuke Yamamori Kunio 《Fisheries Science》2022,88(1):75-81
To clarify the mechanism of tetrodotoxin (TTX) accumulation in pufferfish, we compared the toxicity of two sets of wild juvenile “komonfugu” Takifugu flavipterus. The first set was sampled from Onisawa Fishing Port (FP) located in Okirai Bay, the Pacific Coast of Sanriku, Tohoku Area, Northern Japan. The second set was collected from the Onisawa FP and reared in an outdoor laboratory tank supplied with different seawater (Yoshihama Bay). The fish were sampled regularly and on the same days. The amount of TTX (mouse unit (MU)/fish) in the fish at Onisawa FP increased until 20 days and thereafter it did not change, while the amount of TTX in the fish in the laboratory tank remained low, and the TTX concentration (MU/g fish) decreased. Next, we compared the toxicity of wild juvenile T. flavipterus collected from Okirai Bay (Onisawa FP and Okirai FP) and Yoshihama Bay (Yoshihama FP). Large differences in TTX levels were observed among the fish from the three FPs. The amounts and concentrations of TTX in the fish at Onisawa FP were higher than those in the fish from the other two FPs. These results indicate that a large variation in toxic activity exists in the juvenile T. flavipterus in the bay of the Sanriku Coast.
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