Hatchery programs,stock enhancement,and cost effectiveness: A case study of the Albemarle Sound/Roanoke River stocking program 1981–1996     

Wesley S. Patrick  Okmyung Bin  Kurt A. Schwabe  Peter W. Schuhmann 《Marine Policy》2006

Fish hatchery programs commonly are used to enhance depleted fish populations. While these programs are highly valued by the public, most likely due to their nonrestrictive approach to restoring a fishery, the effectiveness of these programs has been often questioned. This study investigates economic and ecological effectiveness of the Albemarle Sound/Roanoke River (AR) striped bass stocking program from 1981 to1996 as a case study.  相似文献   

The Diel Behaviour of Small Demersal Fish on Soft Sediments on the West Coast of Scotland using a Variety of Techniques: with Special Reference to Lesueurigobius friesii (Pisces; Gobiidae)     

R. D. M. Nash 《Marine Ecology》1982,3(2):161-178

Abstract. The diel behaviour of communities of small demersal fishes was studied in situ on the west coast of Scotland using trawling, diving, underwater television and underwater time-lapse photography techniques. Lumpenus lampretaeformis and Pomatoschistus norvegicus were shown to have crepuscular behaviour patterns. Lesueurigobius friesii was a day active fish, spending the night close to or within its burrow and feeding through the day. Disruptions to this behaviour pattern occurred at high abundances of gadoids and during the spawning season. The fish community as a whole showed a crepuscular periodicity. The various observational methods are discussed. There did not appear to be any close association between Lesueurigobius friesii and the decapod Nephrops norvegicus.  相似文献   

Fish Biodiversity in the Vermetid Reef Of Shiqmona (Israel)   总被引：1，自引：0，他引：1  

Menachem Goren  & Bella S. Galil 《Marine Ecology》2001,22(4):369-378

Abstract. A study of the structure of the fish community associated with a vermetid reef at Shiqmona, Israel, revealed the highest fish biodiversity (36 species) of any habitat along the Mediterranean coast of Israel. Despite the prevalence of fish of Erythrean origin in the Levantine littoral, the benthic fish community at the site is entirely autochthonous. The families richest in members were the Blenniidae and the Gobiidae. Eighteen species are benthic, sixteen supra-benthic and two pelagic.  相似文献   

Development of structural modeling techniques for evaluating HDPE plastic net pens used in marine aquaculture   总被引：3，自引：0，他引：3  

David W. Fredriksson  Judson C. DeCew  Igor Tsukrov   《Ocean Engineering》2007,34(16):2124-2137

Finite-element modeling (FEM) techniques are developed to determine the structural capabilities of net pen flotation structures made of high-density polyethylene (HDPE). The modeling approach uses shell elements and localized failure criteria to predict critical loading conditions. Finite element modeling simulations were performed using values for the modulus of elasticity for weathered HDPE determined from a series of tensile tests. Poisson's ratio and yield stress used with the approach were obtained from standard manufacturers values. To investigate the method, a series of experiments were performed in the laboratory by testing circular sections of HDPE pipe to localized failure (“kinking”). The same test was replicated with the FEM using localized failure techniques. Laboratory and model results were within 16%. A FEM was then built to represent the complex geometry of a net pen flotation structure deployed at an operational fish farm located in Eastport, ME, USA. Simulations were performed using attachment line tension values measured at the site. The goal was to assess flotation pipe stress levels for typical operational conditions. Simulations were also performed to investigate the maximum capabilities of the net pen structure with different attachment line configurations. Quantifying the operational limits will become more important as these systems are considered for more exposed, energetic environments.  相似文献   

松花江鱼类总汞与甲基汞污染趋势预测   总被引：4，自引：0，他引：4  

于常荣  张跃明 《海洋湖沼通报》1994,(1):68-73

根据松花江吉林市至三岔河口江段鱼体内总汞与甲基汞含量的多年监测结果，选用多种数字模型进行预测，结果表明，大约大１９９７年以后，该江段鱼体内总汞与甲基汞含量基本能达到环境背景值水平，在彻底解决工业汞污染源后，该江段总汞与甲基汞污染对人体健康的危害，大约也还将持续１５年以上。  相似文献   

An aromatase inhibitor and tamoxifen decrease plasma levels of o,p-DDT and its metabolites in Nile tilapia (Oreochromis niloticus)     

Olga Leaos-Castaeda  Gerardo Gold-Bouchot  Glen Van Der Kraak  Andrea Lister  Victor Ceja-Moreno  Raul Sim-Alvarez 《Marine environmental research》2004,58(2-5):337

The objective of this study was to determine if tamoxifen or an aromatase inhibitor (4-hydroxyandrostenedione; 4-OHA) affected plasma concentrations of o,p^′-DDT and its metabolites, o,p^′-DDD and o,p^′-DDE, in mature tilapia. Male and female tilapia were injected 6 times intraperitoneally with o,p^′-DDT (40 mg/kg) alone or in combination with 4-OHA (2 mg/kg) over a 12 day period. An additional group of male fish was injected with tamoxifen (5 mg/kg) plus o,p^′-DDT. At the end of the treatment period, plasma samples were extracted and analyzed by GC/ECD. Females injected only with o,p^′-DDT had significantly higher levels of o,p^′-DDT compared with males. Interestingly, females and males treated concomitantly with o,p^′-DDT and 4-OHA or tamoxifen had significantly lower concentrations of plasma o,p^′-DDT (about 50%) compared with fish treated with only o,p^′-DDT. These initial results suggest that an interaction between endocrine-active compounds occurs in vivo in tilapia and may involve alterations in metabolism of o,p^′-DDT.  相似文献   

Conflict over flying fish: The dispute between Trinidad & Tobago and Barbados     

Andon Blake  Gary A. Campbell 《Marine Policy》2007

This paper explains the ongoing conflict between Trinidad & Tobago and Barbados over the right to catch flying fish off the coast of Tobago. The aim of the paper is to present the different scenarios arising from the conflict and to determine the best outcome for managing the flying fish. The history and current situation of the conflict is presented. The possible outcomes are evaluated with a framework developed in the paper. It is concluded that a negotiated agreement between the two countries gives the best result. Future negotiations should focus on developing a limited access program like Individual Transferable Quotas.  相似文献   

The Sample Size Necessary to Assess Changes in Fish Biomass – A Reply     

David Mouillot  Jean‐Michel Culioli 《Marine Ecology》2002,23(1):11-18

Abstract. In this article, we compare biomass results for three fish species (Symphodus ocellatus, Serranus scriba and Diplodus annularis) between May 1993 and May 2000 in the Bonifacio Strait Marine Reserve. The data were obtained from seagrass meadows using the visual census method. A randomised procedure was used to test the null hypothesis of biomass equality. To this end, decreasing sample sizes were used for the May 2000 data to determine the sample size necessary to reject the null hypothesis (5 % level). For Symphodus ocellatus, 10 samples (fixed points) were necessary to reject the null hypothesis, whereas 15 samples were required for Diplodus annularis. The null hypothesis was never rejected for Serranus scriba regardless of the sample size considered.
These results are discussed, as is the power statistical analysis proposed by Ortiz (2002; this issue, pp. 1 – 9) , to determine the optimal sample size necessary to detect perturbation effects in the marine environment. Although the power analysis is certainly a useful method to determine the sampling design in assessment the effect of marine reserves on fish biomass, the magnitude of the marine reserve effect remains problematic in ecology.  相似文献   

Monitoring a Marine Coastal Area: Use of Mytilus galloprovincialis and Mullus barbatus as Bioindicators     

Ilaria Corsi  Michela Mariottini  Valentina Menchi  Christiana Sensini  Cristiana Balocchi  Silvano Focardi 《Marine Ecology》2002,23(S1):138-153

Abstract. Samples of Mytilus galloprovincialis and Mullus barbatus were collected in eight coastal sites along the South Adriatic and Ionic coasts of Italy in spring 2000 for a survey of coastal pollution in the Mediterranean basin. Specimens were analysed using an integrated approach based on residue analysis of common aquatic pollutants like organochlorines such as hexachlorobenzene (HCB), DDTs and polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), heavy metals and nonylphenols (NPnE) and biomarker responses such as acetylcholinesterase (AChE) activity, and the two specific P450 activities benzo(a)pyrene monooxygenase (BPMO) and 7-ethoxyre-sorufin-(9-deethylase (EROD). Biological and morphological parameters like somatic liver index (SLI), gonadosomatic index (GSI) and gonadal and gamete histology (eggs and sperms) were also evaluated in red mullet samples. A contamination gradient in which several hot spots occur were revealed in this study. The hot spots account for high levels of organochlorines in both species near incinerators and of PAHs in harbour areas. Levels of both NPnE and AChE activity were highest in two protected marine areas and were within detectable limits in others. This finding was confirmed by P450 activities, in which maximum levels were detected in harbours and protected marine areas. No morphological alterations of male and female gonads were observed on the histological level.  相似文献   

Differential gene expression in mummichogs (Fundulus heteroclitus) following treatment with pyrene: comparison to a creosote contaminated site     

Roling JA  Bain LJ  Baldwin WS 《Marine environmental research》2004,57(5):377-395

Mummichogs, Fundulus heteroclitus, an estuarine fish with a relatively small home range found along the eastern coast of the United States are well-suited to monitoring contaminant effects, including those of polycyclic aromatic hydrocarbons (PAHs). One of the common PAHs in estuaries is pyrene. We report here on efforts to develop multiple biomarkers of pyrene exposure in this species. Adult male mummichogs were exposed in the laboratory to the weak aryl hydrocarbon receptor (AhR) agonist pyrene at 0, 30, or 50 microg/L in 7-day static renewal exposures. The RNA was extracted from livers and alterations in mRNA expression were assessed by subtractive hybridization and differential display in order to produce multiple biomarkers of pyrene exposure. Genes demonstrating differential expression were confirmed by quantitative-PCR (Q-PCR) and include cytochrome P-450 1A (CYP1A), a putative hepatocyte growth factor activator, a X-ray inducible retrotransposon, and several expressed sequenced tags (ESTs). Some of these genes represent new biomarkers of pyrene exposure and potential biomarkers of PAH exposure. Therefore, similar changes were investigated at a Superfund site in Charleston, SC. Mummichogs from a creosote contaminated site and from a reference site (North Inlet National Estuarine Research Reserve near Georgetown, SC) were trapped, RNA extracted from the livers, and Q-PCR performed. Many of the genes differentially expressed following pyrene exposure were not altered at the creosote contaminated site in comparison to the reference site. However, CYP1A and an EST were induced. CYP1A induction at Diesel Creek indicates that this population of fish does not demonstrate refractory CYP1A phenotypes observed at several sites with high levels of AhR agonists. Ultimately, we anticipate that the use of multiple biomarkers of PAH exposure will provide useful information on the potential effects of toxicants.  相似文献