A breath of fresh air: avoiding anoxia and mortality of freshwater turtles in fyke nets by the use of floats

相似文献   

Comparing the effects of offset and non‐offset circle hooks on catch rates of fish and sea turtles in a shallow longline fishery

• 1. This study compared the catch rates of targeted dolphinfish or mahimahi (Coryphaena hippurus), and sea turtles and other fish bycatch in a shallow‐set Costa Rican longline fishery using 14/0 circle hooks with and without a 10° offset. The effect of hook offset on hooking location and injury in captured sea turtles, specifically if the hooking was external, in the mouth, or in the esophagus was also evaluated.
• 2. Results were compared from six trips totalling 33 876 hooks with squid (Dosidicus gigas) used as bait. In total, mahimahi catch‐per‐unit‐effort (CPUE, expressed as number caught per 1000 hooks) was similar between hook types (CPUE～52).
• 3. Olive ridley sea turtles (Lepidochelys olivacea) were caught on all 42 sets. In total, 640 olive ridley turtles were caught and released alive. There were no significant differences in the number of sea turtles caught between hooks with and without an offset (CPUE～19) nor between hook type and anatomical hooking location, suggesting similar levels of injury for turtles caught on each hook type.
• 4. These data suggest that a 10° offset on 14/0 circle hooks does not confer any selective advantages over hooks with no offset with respect to capture rates of mahimahi, sea turtles, sharks, or pelagic stingrays in a shallow set pelagic longline fishery. Copyright © 2010 John Wiley & Sons, Ltd.

     

Post‐release mortality estimates of loggerhead sea turtles (Caretta caretta) caught in pelagic longline fisheries based on satellite data and hooking location

相似文献   

Calculating reference points for anthropogenic mortality of marine turtles

相似文献   

Overview of loggerhead turtles coastal nets interactions in the Mediterranean Sea

相似文献   

Sea turtles bycatch in the Adriatic Sea set net fisheries and possible hot‐spot identification

相似文献   

Incidental captures of sea turtles by swordfish and albacore longlines in the Ionian sea

ABSTRACT:   Incidental catches in pelagic longline fishing pose a serious threat to sea turtle populations throughout the world's seas and oceans. In this work, carried out in the framework of the EC-DG-Fisheries 98/008 project, information on sea turtle catch rates from swordfish and albacore longline fishing activities observed in Italian waters off the Ionian Sea during 1999 and 2000, are reported. In addition, biometric data, health status, and tagging return rate of sea turtles captured are provided. A total of 200 sea turtles were caught (198 loggerhead turtles and 2 green turtles), comprising 0.5–15.7% of the total catch in number of individuals. The estimates of the sea turtles caught by the total fishing effort of both longlines in the whole study area were 1084 specimens in 1999 (95% CI = 667–1502) and 4447 specimens in 2000 (95% CI = 3189–5705). Although all sea turtles were released alive, nearly half of them had hooks that could not be removed and remained deeply embedded in the digestive tract.     

养殖龟鳖源气单胞菌耐药性与质粒介导喹诺酮类耐药基因分析

为了解养殖龟鳖源气单胞菌的耐药情况及质粒介导的喹诺酮类耐药(PMQR)、喹诺酮类耐药决定区(QRDR)与耐药表型之间的关系;实验采用K-B纸片法测定了1996—2013年从广东地区患病龟鳖分离的67株气单胞菌对23种常见抗菌药物的耐药性,并检测5种PMQR基因qnrA、qnrB、qnrS、qepA和aac(6')-Ib-cr,同时分析PMQR基因阳性菌株染色体上gyrA、parC基因QRDR的突变情况。结果显示,67株气单胞菌对氨苄西林、头孢噻吩和磺胺复合物的耐药率分别高达100%、92.54%和83.58%,对喹诺酮类药物呈现中等耐药,耐药率介于19.40%~64.18%,而对亚胺培南、呋喃妥因、阿米卡星、头孢噻肟敏感性较高,耐药率低于10%;79.10%(53/67)的菌株对3类或以上抗菌药物具有耐药性。19.40%(13/67)的菌株携带PMQR基因,其中,8.96%(6/67)携带qnrS1基因、5.97%(4/67)携带qnrS2基因、7.46%(5/67)携带aac(6')-Ib-cr基因[其中2株同时携带qnrS2和aac(6')-Ib-cr基因]。13株PMQR基因阳性菌株均分别携带1~4个质粒,大小介于0.8~15 kb;其中6株在gyrA基因及parC基因上均发生变异,3株仅在gyrA基因上发生变异,另外4株未发现QRDR的基因突变。研究表明,广东地区龟鳖源气单胞菌对多种抗菌药物耐药并存在多重耐药现象;而且PMQR机制的存在预示着喹诺酮类耐药性很可能会在水产临床上更加快速而广泛地传播,应引起重视。     

Effect of three commercial microbial products on bacterial community in a freshwater fish polyculture system

A 30‐day experiment was conducted to evaluate the effect of three commercial microbial products, Novozymes Pond Plus, Zhongshui BIO‐AQUA and Effective Microorganisms on bacterial community in polyculture tanks stocked with grass carp (Ctenopharyngodon idellus), gibel carp (Carassius auratus) and silver carp (Hypophthalmichthys molitrix). Four treatments were tested. One treatment with no supplementation of the microbial products served as control. In the other three treatments, the microbial products were added at the intervals of 10 days respectively. During the experiment, grass carp and gibel carp were fed with a commercial formulated feed daily. Bacterial count and bacterial composition in water column of the tanks were monitored at the intervals of 3 days, and bacterial composition in sediment was determined at the end of the experiment. Bacterial composition in water column varied with progress of the experiment. Some bacteria from Novozymes Pond Plus and Effective Microorganisms could colonize in the tanks but did not dominate in bacterial community. This study reveals that the competition between the exogenous bacteria and native bacteria might be a factor determining the efficacy of the microbial products in improving water quality.     

New branch line weighting regimes to reduce the risk of seabird mortality in pelagic longline fisheries without affecting fish catch

相似文献   

Spatial and temporal diversity of fish captured by light traps in various habitats in coastal waters in the oldest marine protected area in Vietnam and its implications for conservation

相似文献   

Genetic diversity of immature Kemp's ridley (Lepidochelys kempii) sea turtles from the northern Gulf of Mexico

1. The Kemp’s ridley (Lepidochelys kempii) is the world’s most endangered sea turtle species. Predominately nesting at only one beach in Mexico, this species declined to an estimated 300 females in the mid-1980s. Conservation efforts in the United States and Mexico, including a head start programme in southern Texas in which hatchlings were reared in captivity for several months before being released into the wild, resulted in the recovery of this species.
2. Although genetic data have previously been used to assess the success of the head start programme and dispersal of individual adults, data on immature turtles sampled at foraging areas and adult females sampled at the main nesting beach in Mexico are lacking. Genetic characterization of immature individuals is important for understanding recruitment, survival, and population demography, while genetic data on individuals from Mexico are essential for understanding dispersal and overall genetic diversity in this species.
3. To address these gaps, mitochondrial DNA data were collected from 106 immature individuals sampled at four different foraging sites in the northern Gulf of Mexico and from 18 nesting females at the primary nesting beach in Mexico.
4. Two previously unknown mitochondrial DNA haplotypes were discovered among the immature individuals.
5. Except for these two new haplotypes, the genetic diversity of immature individuals in the northern Gulf of Mexico closely corresponds to that of adults sampled in Mexico, which suggests that much of the diversity within the nesting population can be found among immature animals dispersing to foraging grounds, including locations in the northern Gulf of Mexico.
6. Continued monitoring of the genetic variation of different life stages of this species across its distribution range will help assess the success of conservation programmes by ensuring the maintenance of genetic diversity and representation of this diversity across the species’ distribution range.

     

Integrated management to address the incidental mortality of seabirds in longline fisheries

1. Of the myriad of anthropogenic and natural threats to seabirds, one of the most critical global problems is incidental mortality in longline fisheries. Hesitance or failure by fishery managers and longline industries to adequately address this acute problem could result in the extinction of several albatross and petrel species within our lifetimes. 2. An integrated management approach is needed to comprehensively manage longline fisheries to address seabird bycatch. A review of relevant multilateral accords, declarations and actions by regional and international organizations reveals the need to augment international collaboration, especially to address pirate longline fishing. Management authorities and stakeholders need to collaborate to: promote adoption and compliance with effective legally binding accords that cover the ranges of all affected seabirds; ensure that all Range States and relevant distant water fishing nations become contracting parties to these accords; coordinate national implementation of the Food and Agriculture Organization's International Plan of Action on seabirds; set management goals; establish and implement policies to employ seabird deterrent measures; disseminate information on new deterrent measures; locally tailor seabird deterrent measures; standardize data reporting and establish a centralized data repository; coordinate research and monitoring; develop regional surveillance and enforcement systems; and augment less developed countries' capacity and resources to mitigate seabird and longline fishery interactions. 3. Establishing protected areas containing seabird colonies and adjacent waters within a nation's Exclusive Economic Zone (EEZ) is potentially an expedient method to reduce interactions between seabirds and longline fisheries. However, establishing high seas marine protected areas to restrict longline fishing in seabird foraging areas, which would require extensive and dynamic boundaries and large buffer zones, may not be a viable short‐term solution due to the long time it is anticipated it could take to resolve legal complications with international treaties, to achieve international consensus and political will, and to acquire requisite extensive resources for surveillance and enforcement. High seas marine protected areas may eventually become a feasible mechanism to address seabird bycatch if nations develop the will to close ocean areas to commercial fisheries to attempt to rehabilitate depleted pelagic fish stocks. 4. Direct involvement of longline industries, through partnerships with national governments and regional organizations, to develop seabird mitigation measures and policies prescribing the use of these measures, is critical. Direct involvement of stakeholders to find solutions to resource management problems leads to stakeholder groups taking ownership of and supporting rules. Bottom‐up approaches are successful in changing interest groups' attitudes and behaviour, to maximize voluntary compliance and minimize conflict and resources required for enforcement. 5. Data gaps must be filled and scientific uncertainty addressed through multilateral collaboration. Research to develop and improve practicable mitigation measures is most urgently needed. Information on the status and trends of albatross populations, where albatrosses forage, the causes of population declines, seabird mortality rates and levels in each longline fishery, and the type of impacts from longlining on seabird populations is also needed. It is well documented that several seabird species are at risk of extinction, incidental bycatch in longline fisheries significantly contributes to many species' decline, and proven mitigation measures are available. Thus, while additional research is critically needed, we should not delay taking precautionary action to wait for additional information, but should immediately act to protect seabirds from the known acute threat of mortality in longline fisheries. Copyright © 2001 John Wiley & Sons, Ltd.     

The use of fyke nets as a quantitative capture technique for freshwater eels (Anguilla spp.) in rivers

Abstract  Fyke netting is a convenient and effective technique for capturing freshwater eels, and catch-per-unit-effort is usually assumed to be an index of eel abundance. The present study investigated the potential of depletion fishing using baited fyke nets to obtain population estimates of longfin eels Anguilla dieffenbachii Gray, in a river in the South Island of New Zealand. The probability of capture (capture efficiency) of a single night's fishing increased with increasing size of eel, and ranged from 0.2 to 0.9 for eels <400 mm, to 0.7–0.9 for eels ≥500 mm. The capture efficiency of baited vs unbaited nets was assessed in a small stream that was electric fished after netting trials were completed. Baited nets proved to be an effective method of assessing abundance of longfin eels (>400 mm) but not shortfins ( A. australis Richardson); capture efficiency of the population of longfins (the sum of fyke caught and electric fished eels) was 0.4 for a single night's fyke netting, increasing to 0.8 over four nights. Comparable efficiencies for shortfins were <0.1 and 0.3 respectively. Unbaited nets were markedly less efficient for both species.     

Phytase-producing bacteria in the digestive tracts of some freshwater fish

Isolation and enumeration of phytase‐producing bacterial flora in the foregut and hindgut regions of the gastrointestinal tracts of 10 culturable freshwater teleosts of different feeding habits, namely rohu (Labeo rohita), catla (Catla catla), mrigal (Cirrhinus mrigala), bata (Labeo bata), kalbasu (Labeo calbasu), Nile tilapia (Oreochromis niloticus), climbing perch (Anabas testudineus), common carp (Cyprinus carpio), silver carp (Hypophthalmichthys molitrix) and grass carp (Ctenopharyngodon idella), have been carried out. Microbial culture of the gut mucosa on selected nutrient media following the enrichment culture technique was performed for bacterial isolation. The bacterial isolates were screened on the basis of their enzyme‐producing ability. The bacterial population on the tryptone soya agar (TSA) plate was maximum in the hindgut region of bata, followed by mrigal and minimum in the foregut region of Nile tilapia. In modified phytase screening medium (MPSM), phytase‐producing strains were recorded at higher densities in the foregut region of mrigal and grass carp and minimum in the foregut region of bata. In case of the hindgut, maximum phytase‐producing strains were present in grass carp and mrigal and minimum in rohu. In general, in MPSM, the bacterial population was lower in the hindgut region of all the 10 species of fish examined. The phytase‐producing ability of the selected 31 strains (16 from the foregut and 15 from the hindgut region) was determined by clearing zones on phytate‐containing plates. Among these isolates, 22 strains (12 from the foregut and 10 from the hindgut region) were selected as potent phytase producers according to a quantitative enzyme assay. The highest phytase activity was observed in the bacterial strains LF1 and LH1 isolated from the fore and the hindgut regions of rohu respectively. Both the strains were identified as Bacillus licheniformis on the basis of phenotypic characteristics as well as 16S rDNA sequence analysis.     

Citizen science helps assessing spatio‐temporal distribution of sea turtles in foraging areas

1. Spatio‐temporal distribution is fundamental information for species of conservation concern, like sea turtles, that are threatened by anthropogenic activities at sea such as fishing. While coarse‐scale distribution information is available for several sea turtle populations, fine‐scale distribution informing on hot‐spot areas for spatial management is more difficult to obtain.
2. Here a citizen science approach involving tourism boats was undertaken to investigate the spatio‐temporal distribution of the loggerhead sea turtle (Caretta caretta) in the Pelagie Archipelago, located in a major foraging area for this species in the Mediterranean and where high fishing‐induced mortality occurs. The study was designed to provide data of absence and total sampling effort, commonly under‐reported in citizen science studies, allowing comparison among zones and periods. This was complemented by reports from fishing vessels.
3. Tourism boats reported 584 loggerhead turtle sightings during 1718 daily trips and fishing vessels reported 280 loggerhead turtles captured during 1040 fishing days. The results indicate a strong heterogeneous distribution in the Archipelago, with a low turtle occurrence around the main island, Lampedusa, where the highest human presence and activity occur. This may represent rare evidence of displacement behaviour of turtles that is worth further investigation. This also suggests that the current small marine protected area around Lampedusa has a low conservation impact. Zones with higher loggerhead turtle occurrence appear to be in the south and the west parts of the Archipelago, suggesting that spatial management would be possible when relatively small hot‐spots have been identified through specific surveys.
4. This study shows the potential of citizen science for providing preliminary information to guide more demanding and specific investigations. Such an approach may tremendously and rapidly improve the current knowledge on fine‐scale sea turtle distribution in regions with a great extension of coastlines and intensive tourist activities, such as the Mediterranean.

     

Conservation of freshwater fish in the British Isles: the status of fish in national nature reserves

1. To consider fully the conservation management of freshwater fish, it was important to know which fish were already in the protected environment of National Nature Reserves (NNRs) — the principal sites for nature conservation in Great Britain. For this reason, 235 NNRs declared by the Nature Conservancy Council (NCC) were surveyed for freshwater fish between 1987 and 1990 by questionnaires to the wardens, by compiling data from other sources, and, where necessary, by field sampling. The presence of fresh waters (as lakes, ponds, rivers and streams) was also recorded. The survey was organized to follow the country and regional structure by which nature conservation was administered by the NCC so that the results could be considered accordingly. 2. Seventy five percent of NNRs contain fresh waters and, of these, just over 20% have no fish. Of the 51 fish species available 37 (73%) were recorded in NNRs. NCC regions with most fish species are: SW Scotland, West Midlands and East Anglia, but NW Scotland has the highest total of species occurrences in NNRs. In terms of both the numbers of species and their frequency of occurrence, NW and NE England are notably the lowest. The most common fish in NNRs are Eels, Brown Trout and Three-spined Sticklebacks. 3. The results for species and for sites (NNRs) are discussed from the viewpoint of fish conservation. The majority of fish in NNRs are those most common in Great Britain. Two of the species recorded (Powan and Smelt) are currently important for conservation, but several of those most threatened do not occur in NNRs. A number of NNRs have diverse fish communities, but only six have significant fish conservation value, of which Loch Lomond NNR is outstanding. 4. There is considerable scope through NNR management to improve fish conservation and it is suggested that the acquisition of new reserves for threatened species should be considered.     

Improved line weighting reduces seabird bycatch without affecting fish catch in the Brazilian pelagic longline fishery

相似文献