Environmental impact of capture-based bluefin tuna aquaculture on benthic communities in the western Mediterranean     

Rubén Vita  & Arnaldo Marin 《Aquaculture Research》2007,38(4):331-339

Tuna farming is based on fishing bluefin tuna in their natural habit of the western Mediterranean and fattening them in floating cages. Although this type of aquaculture is expanding rapidly in the Mediterranean Sea, very little information is available for an environmental impact assessment and environmental monitoring of tuna ranching. Spatial and temporal scales of impact need to be established before the norms and regulations affecting this new branch of aquaculture can be properly implemented. The biotic indices measured pointed to detectable impact only under the cages, although multivariate techniques defined an environmental gradient of stressed macrofaunal assemblages. The benthic surveys carried out indicated that high impact was restricted to a radius of roughly 5 m from the cages with a transitional radius at 35 m. This zone was characterized by high densities of opportunistic species. There was a further zone of moderately stressed benthic environment extending to about 180–220 m from the cages. This moderately stressed zone exhibited slight changes in community structure, because the densities of some species were stimulated. At distances greater than 220 m from the tuna farm, the system apparently returned to normal conditions. The fallow period produced partial remediation of the area affected, except in the sediment underneath the cages where even a 6‐month fallow period was not sufficient for the community to totally recover.  相似文献   

Induced ovulation using LHRHa in anadromous obscure puffer Takifugu obscurus cultured entirely in freshwater     

Zhou?YangEmail author  Ya-Fen?Chen 《Fish physiology and biochemistry》2003,29(4):323-326

Puffer fishes of the order Tetradontidae exist in both anadromous and non-anadromous seawater resident forms. The obscure puffer akifugu obscurus is an anadromous species whose intensive culture in freshwater has developed rapidly in China. To mass produce larvae for intensive culture, induction of ovulation of 3-year-old obscure puffer cultured entirely in freshwater was attempted by giving the fish multiple injections of LHRHa. Twenty 3-yearold cultured obscure puffers were treated with multiple injections of LHRHa at a constant dosage of 30 g of LHRHa kg-1 of body weight with 36 h interval between injections. Beginning two days after hormonal treatment, abdominal palpation was performed every day to check expansion and hardening of the abdomen of the fish due to hydration of oocytes that indicates the completion of final oocyte maturation. The first four fish ovulated after the second LHRHa injection on day 3, but most females ovulated after the fourth hormone injection. A total of 18 fish (90%) ovulated over a period of 7 days, while no fish ovulated in the control group. The mean fertilization rate and the mean hatch rate was 67.1% and 87.6%, respectively. The viability of newly hatched larvae was very good, with a high survival rate of 98.6% 24 h post-hatch. These results indicate that cultured obscure puffer, which are not allowed to undergo diadromous migration and are entirely cultured in freshwater, could be induced to complete maturation and ovulate by simple multiple injections of LHRHa and that the eggs could be successfully hatched into viable larvae.  相似文献   

Potential changes in skipjack tuna (Katsuwonus pelamis) habitat from a global warming scenario: modelling approach and preliminary results   总被引：1，自引：0，他引：1  

Harilaos Loukos  Patrick Monfray  Laurent Bopp  Patrick Lehodey 《Fisheries Oceanography》2003,12(4-5):474-482

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Ontogeny of immune system organs in northern bluefin tuna (Thunnus orientalis, Temminck and Schlegel 1844)   总被引：4，自引：0，他引：4  

M Watts  K Kato  B L Munday  & C M Burke 《Aquaculture Research》2003,34(1):13-21

Serial sections, prepared from 0.5 to 30 days posthatch (dph) larval and juvenile Thunnus orientalis (Temminck & Schlegel 1844), were stained with haematoxylin and eosin and examined by light microscopy for immune organ development. The early kidney was present at 0.5 dph, undifferentiated stem cells began to appear at 2 dph, and by 7 dph occasional small lymphocytes were present. The thymus was first obvious at 5 dph, located above the fourth branchial arch, small lymphocytes appeared at 7 dph, and by 15 dph an outer thymocytic zone and an inner epithelioid zone were visible. The progenitor spleen was present at 2 dph, located close to the gut, and by 12 dph it consisted of a mass of sinusoids filled with red blood cells, and remained mainly erythroid throughout the period studied. These results suggest that development of immune organs in this species is precocious relative to other marine teleosts.  相似文献   

Separation of the Taiwanese regular and deep tuna longliners in the Indian Ocean using bigeye tuna catch ratios   总被引：1，自引：0，他引：1  

Ying-Chou?LeeEmail author  Tom?Nishida  Masahiko?Mohri 《Fisheries Science》2005,71(6):1256-1263

ABSTRACT:   Taiwanese longline (LL) fisheries operating in the Indian Ocean usually target albacore tuna (ALB), swordfish (SWO) and yellowfin tuna (YFT) using regular LL. Bigeye tuna (BET), however, is targeted using deep LL. Thus, these two types of LL are considered to be different gears as they target different tuna species. Regular or deep LL fishing is defined by number of hooks per basket (NHB): regular LL if 6 ≤ NHB ≤ 10 and deep LL if 11 ≤ NHB ≤ 20. However, NHB information was available in only some of the recent LL data (1995–1999). This situation had caused problems of biased results in stock analysis in the past. Thus, the objective of our study was to explore an effective method to separate the two types of LL fishing by considering species composition. Some intervals of BET catch ratios were found to be effective in separating the regular and deep LL catches, i.e. 0.0 ≤ BET/(BET + ALB + SWO) ≤ 0.4 and 0.8 ≤ BET/(BET + ALB) ≤ 1.0, respectively. Using these two separators, the LL known data set (1995–1999) (learning data set) was classified. Correct classification occurred in 67.7% of the data, while 23.1% of the data were unclassified (11.9% due to zero catches and 11.2% due to classification into both LL types), and 9.2% were misclassifications. Then, using the methods developed, the LL unknown data set in the historical data (1979–1999) was classified and nominal CPUE values were calculated for four species. The CPUE trends based on this study were likely to be more reliable than those of previous studies.  相似文献   

Growth, food intake and feed conversion rates in captive Atlantic bluefin tuna (Thunnus thynnus Linnaeus, 1758) under fattening conditions     

Felipe Aguado-Giménez  & Benjamín García-García 《Aquaculture Research》2005,36(6):610-614

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1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging by protein hydrolyzates from tuna cooking juice   总被引：4，自引：0，他引：4  

CHIA-LING  JAO  WEN-CHING  KO 《Fisheries Science》2002,68(2):430-435

ABSTRACT: Protease XXIII, from Aspergillus oryzae , was used to hydrolyze tuna cooking juice at 37°C for up to 6 h. The hydrolyzate obtained at the degree of hydrolysis of 25.68% (after hydrolysis for 2.5 h) displayed the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging effect, reaching 82.19%. Six major fractions (A, B, C, D, E, and F) of this hydrolyzate were obtained by Sephadex G-25 column chromatography using a 0.05 M phosphate buffer (pH 6.5) as the mobile phase. All six fractions displayed a scavenging effect for the DPPH radical, but the scavenging effect was only obvious in two fractions (B and C). After the solid content of hydrolyzates was concentrated from one to five times, the scavenging effect of the DPPH radical increased from 17% to 75% for fraction B, and from 13% to 66% for fraction C. Seven anti-oxidative peptides were isolated from the hydrolyzates (mixture of B and C fractions) by reversed-phase HPLC. The peptide sequences comprised four to eight amino acid residues, including Val, Ser, Pro, His, Ala, Asp, Lys, Glu, Gly, or Tyr.  相似文献   

A parasite survey of farmed Southern bluefin tuna, Thunnus maccoyii (Castelnau)     

Deveney MR  Bayly TJ  Johnston CJ  Nowak BF 《Journal of fish diseases》2005,28(5):279-284

Farmed Southern bluefin tuna (SBT) were examined for parasites. Samples of harvest fish, mortalities and some fish showing clinical signs of disease were investigated. Targeted screening was conducted for a scuticociliate, Uronema nigricans, the myxosporean Kudoa sp. and a sanguinicolid digenean, Cardicola forsteri. General parasitological investigation revealed a diverse parasite community of didymozoid digeneans, two species of copepods, a polyopisthocotylean monogenean and larval cestodes. Targeted screening for U. nigricans exposed a low prevalence, most probably due to a lack of sensitivity in the test method. Few of the parasites examined pose a risk to the health of farmed SBT.  相似文献   

Determining an optimal release site for juvenile winter flounder Pseudopleuronectes americanus (Walbaum) in the Great Bay Estuary, NH, USA     

Elizabeth A Fairchild  Jennifer Fleck  & W Huntting Howell 《Aquaculture Research》2005,36(14):1374-1383

One of the main elements in developing an optimal release strategy for an enhancement effort is to evaluate and select release sites that will support growth and survival of newly released, cultured fish. Three potential release sites (New Castle (NC), Broad Cove (BC) and Oyster River (OR)) in the Great Bay Estuary, NH, USA were evaluated for pilot‐scale releases of winter flounder (Pseudopleuronectes americanus Walbaum). Cultured juvenile flounder were placed in cages at each of the three sites. Sites were evaluated based on growth and survival of the fish in relation to water temperature, prey availability and sediment composition. Fish grew faster in the two upper estuarine sites BC (0.54 mm day^?1) and OR (0.56 mm day^?1) than at the site at the mouth of the estuary (NC=0.37 mm day^?1). Fish survival (44–53%) and water temperature (17.8–19.7°C) did not vary between sites. Benthic samples showed that prey was available to, and eaten by, the flounder. Sediment composition was the main difference between the three sites, with one site (NC) characterized by gravel whereas the other two sites were sandy. These results corroborate other studies showing the importance of sediment quality for the distribution of flatfish populations. From these results, we can confidently eliminate NC as a potential release area and recommend that sandy sites are better for stocking cultured juvenile winter flounder than gravely sites.  相似文献   

The relationship between the skipjack tuna (Katsuwonus pelamis) fishery and seasonal temperature variability in the south-western Atlantic   总被引：1，自引：0，他引：1  

H. A. Andrade 《Fisheries Oceanography》2003,12(1):10-18

The spatio‐temporal distribution of tuna fishing effort has been related to oceanographic circulation and features in several seas of the world. Understanding the relationship between environmental variables and fishery resource dynamics is important for management decisions and to improve fishery yields. The relationship between sea temperature variability and the pole‐and‐line skipjack tuna (Katsuwonus pelamis) fishery in the south‐western Atlantic Ocean was investigated in this work. Data from logbooks, satellite images (sea surface temperature), and oceanographic surveys were used in the analyses. Skipjack are caught in warm tropical waters of the Brazil Current (BC). The north–south displacement of fishing effort was strongly associated to seasonal variation of the surface temperature, which was coupled to the tropical BC flow. Oceanographic fronts from autumn to spring and a shallow thermocline in summer probably induces the aggregation of skipjack schools over the shelfbreak, favouring fishing operations. Hypotheses are proposed to explain the relationship between peaks of fishing events and the presence of topographic peculiarities of the shelfbreak.  相似文献