NAMMCO Scientific Publications最新文献

{"title":"Review of the ecology of sealworm, Pseudoterranova sp (p) (Nematoda: Ascaridoidea) in Icelandic waters","authors":"D. Ólafsdóttir","doi":"10.7557/3.2961","DOIUrl":"https://doi.org/10.7557/3.2961","url":null,"abstract":"The early life cycle of sealworm in Icelandic waters is not known. Various fish serve as transport hosts but benthic coastal fish, especially bull rout ( Myoxocephalus scorpius ), probably have a major role in transmission of larvae to the final hosts, seals. Grey seals ( Halichoerus grypus ) are more heavily infected with sealworm than common seals ( Phoca vitulina ) and the grey seal population, estimated at 6,000, probably plays a larger role in the dynamics of the worm than the estimated 15,000 common seals. Other seals seem to play a small or insignificant role in sealworm dynamics in the area. Sealworm abundances in fish and final hosts are higher off the west coast than in other areas in Iceland. A combination of shallow, temperate waters, large numbers of small islands inhabited by numerous seals and grey seals’ consumption of heavily infected bull rout during the breeding season in autumn are important factors responsible for maintaining an abundance of sealworm in this area. Future research on sealworm in Iceland should focus on long term monitoring of worm abundance in all potential hosts in order to observe, interpret and predict possible changes, the dynamics of infections in fish frequently consumed by seals and on seasonal and spatial variations in worm fecundity.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"3 1","pages":"95-111"},"PeriodicalIF":0.0,"publicationDate":"2014-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Establishing the relative importance of sympatric definitive hosts in the transmission of the sealworm, Pseudoterranova decipiens : a host-community approach","authors":"F. Aznar, J. Balbuena, Mercedes Fernández, J. Raga","doi":"10.7557/3.2965","DOIUrl":"https://doi.org/10.7557/3.2965","url":null,"abstract":"The importance of a given host to a particular parasite can be determined according to three different criteria: host preference, host physiological suitability and host contribution to transmission. Most studies on the sealworm Pseudoterranova decipiens have focussed on the latter factor, but few attempts have been made to develop a quantitative transmission model evaluating the relative importance of each host. The purpose of this study was to propose a flow-chart model to study sealworm transmission within a seal community. The model was applied to hypothetical data of four seal species acting as definitive hosts of P. decipiens sensu stricto in eastern Canada: harp seal Phoca groenlandica , harbour seal P. vitulina , grey seal Halichoerus grypus and hooded seal Cystophora cristata . The dynamics of the model was studied using population estimates from 1990 to 1996. To illustrate the interrelationship of the seal populations in the flow dynamics, the model’s behaviour was explored by manipulation of the harp seal population size. The results showed that grey seals accounted by far for most transmission from and to the seals. The harbour seal population also sustained a biologically significant proportion of the flow, whereas the role of hooded and harp seals seemed negligible despite their large population sizes. The hypothetical removal of the harp seal population resulted in small increases in the relative flows to the other seals. These results conform to previous qualitative assessments on the relative importance of these seal species in sealworm transmission. The model provided some heuristic rules useful to understand transmission patterns. The data suggested that the harbour seal population should be about twice that of the grey seals to account for a larger share of transmission than grey seals. Although this is unlikely to occur at a large geographic scale, harbour seals outnumber grey seals in some areas and, therefore, the role of each host may change locally. To make this approach more realistic, further work should seek accurate estimates of parasite population parameters, better definition of the host community boundaries (at a local scale) and improved control of confounding variables.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"3 1","pages":"161-171"},"PeriodicalIF":0.0,"publicationDate":"2014-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Review of experimental and natural invertebrate hosts of sealworm ( Pseudoterranova decipiens ) and its distribution and abundance in macroinvertebrates in eastern Canada","authors":"D. Marcogliese","doi":"10.7557/3.2954","DOIUrl":"https://doi.org/10.7557/3.2954","url":null,"abstract":"Experimental and natural invertebrate intermediate hosts of sealworm ( Pseudoterranova decipiens ) as well as transmission experiments of sealworm from invertebrates to fish are reviewed and summarized. Experimental hosts include copepods, mysids, cumaceans, isopods, amphipods, decapods, annelids, and molluscs. Invertebrates collected from eastern Canada between 1989 and 1995 were checked for nematode infections by microscopic examination of dissected animals or enzymatic digestion of bulk samples. Third-stage larval sealworm were found in mysids ( Neomysis americana ,  Mysis stenolepis ) from Passamaquoddy Bay, the Bras d’Or Lakes, inshore Cape Breton, Sable Island and Sable Island Bank. Infected amphipods ( Amphiporeia virginiana , Americorchestia megalophthalma ,  Gammarus spp.) were found only on Sable Island. Typical infection rates in macroinvertebrates were 1-4/1000. No sealworm infections were found in approximately 18,000 amphipods examined from Sable Island Bank, the site of the most heavily infected fishes in eastern Canada. In Wallace Lake, a brackish pond on Sable Island, infection rates were much higher in mysids than in amphipods. Estimates of rates of transmission of sealworm from invertebrates to fish were derived from infection levels in Wallace Lake and feeding experiments involving sticklebacks and invertebrate prey. It is concluded that mysids may be much more important than amphipods in transmitting sealworm to fish hosts.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"690 1","pages":"27-38"},"PeriodicalIF":0.0,"publicationDate":"2014-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sealworm ( Pseudoterranova decipiens ) dynamics in Sable Island grey seals ( Halichoerus grypus ): seasonal fluctuations and other changes in worm infections during the 1980s","authors":"W. T. Stobo, G. M. Fowler","doi":"10.7557/3.2963","DOIUrl":"https://doi.org/10.7557/3.2963","url":null,"abstract":"The abundance of P. decipiens sampled from the stomachs of 553 grey seals (aged 0-48 years) collected during 14 field trips to Sable Island in 1983 and 1989 did not change significantly between years, even though the seal population has been increasing at over 12% annually and there has been a substantial decline in the fish biomass upon which they depend. The proportion of mature worms in the seals’ stomachs has decreased, however. Seal growth, expressed in terms of either age or length, showed the strongest correlation with total worm abundance. These infections were not completely eliminated at any time during the year, but a seasonal pattern in worm abundance was apparent. Among the youngest seals an inverse relationship was demonstrated between the abundance of P. decipiens and another parasitic nematode, Contracaecum osculatum . Sexually mature P. decipiens were found in pups within 3 to 4 months of the commencement of independent feeding, and the abundance of P. decipiens progressively increased throughout the first year of life. Male pups contracted more worms than female pups of the same age. P. decipiens abundances in juvenile seals were primarily associated with seasonal pattern and age, with C. osculatum abundance still influencing the abundance of P. decipiens , but to a much lesser extent than seen with pups. Length of seals was the main predictor of total worm abundance in adult seals, with a seasonal pattern being next in order of importance. Age was also significant, possibly representing a component of growth not accounted for by length alone. No relationship between the abundances of P. decipiens and C. osculatum was apparent for adult seals. The seasonal pattern in total worm abundance of juvenile and adult seals was characterized by declines during the winter and mid-summer. We suggest these declines are due, respectively, to the breeding season fast and one or both of 1) a change in seal diet from primarily highly infected fish species to less infected ones, and 2) a partial fast during the annual moult. The proportion of mature worms increased during reductions in worm abundance throughout most of the year, but during the breeding fast both total abundance and the proportion mature declined.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"3 1","pages":"129-147"},"PeriodicalIF":0.0,"publicationDate":"2014-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of etorphine reversed by diprenorphine for the immobilisation of free-ranging Atlantic walrus ( Odobenus rosmarus rosmarus L.)","authors":"M. Acquarone, E. Born, David Griffiths, L. O. Knutsen, Ø. Wiig, I. Gjertz","doi":"10.7557/3.2944","DOIUrl":"https://doi.org/10.7557/3.2944","url":null,"abstract":"To date no problem-free method exists for the immobilisation of free‑ranging walruses ( Odobenus rosmarus ). In the period 1989-2001, 69 immobilisations with etorphine HCl were performed by remote darting of 41 individual free-ranging adult Atlantic walruses ( O. r. rosmarus ), with body masses 633 ‑ 1883 kg, as a rerequisite for the attachment of radio tracking and dive recording instruments, and for studies of metabolism. Ten individuals were immobilised several times. We present data on these 69 immobilisations and evaluate the method. Full immobilisation was achieved in 58 cases (84 %). The animals were insufficiently restrained in 6 cases (9 %) and 5 animals died (7 %) following the immobilisation. The animals were fully immobilised and approachable after 5 min (n = 38, range = 1.9 ‑ 12.4 min, SD = 2.2) with a dose of etorphine of 6.1 μg/kg (range 2.4 ‑ 12.6 μg /kg, SD = 2.4). Induction time was negatively correlated with the dosage of etorphine. Etorphine-induced apnoea lasted 13.7 min (n = 36, range 17.0 ‑ 26.7 min, SD = 5.1) and was reversed by multiple doses of the antagonist diprenorphine HCl. The first dose of antagonist of 12.2 mg (n = 39, range 6.0 ‑ 21.0 mg, SD = 3.5) was administered 8.4 min (n = 38, range 4.7 ‑ 18.0 min, SD = 2.8) after injection of the agonist. The total dose of diprenorphine per animal ranged between 7.7 and 41.7 μg/kg (n = 31, mean  = 17.2 μg/kg, SD = 7.5). For some animals blood pH values were measured following the apnoea and reached low levels (min pH 6.8). For animals that were immobilised several times there were no indications of changed sensitivity to etorphine as reflected in unchanged induction times. Mortalities could neither be related to the doses of agonist and antagonist, nor to the times of administration of the drugs. From this (n = 69) and other (n = 103) studies involving etorphine immobilisation of walruses (both Atlantic and Pacific) the overall success rate is 83 % (8 % casualty rate). We conclude that the combination etorphine‑ diprenorphine is suitable for both single and multiple immobilisations of walruses provided that (a) a casualty rate of 7-8% is acceptable (b) the antagonist diprenorphine is administered fast and well into a tissue with good blood irrigation, and (c) the animal is promptly intubated endotracheally to facilitate the restoration of breathing after drug-induced apnoea.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"9 1","pages":"345-360"},"PeriodicalIF":0.0,"publicationDate":"2014-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A note on a walrus’ European odyssey","authors":"E. Born, E. Stefansson, B. Mikkelsen, K. Laidre, L. Andersen, F. Rigét, M. V. Jensen, D. Bloch","doi":"10.7557/3.2921","DOIUrl":"https://doi.org/10.7557/3.2921","url":null,"abstract":"This study reports on the first successful identification of the site of origin of an extralimital walrus in Europe. On 24 February 2010 an adult male Atlantic walrus ( Odobenus rosmarus rosmarus ) migrant was instrumented with a SPOT-5 satellite-linked transmitter (SLT) while hauled out on a beach on the Faroe Islands at 62° 15' N/06° 32' W. This SLT transmitted until 5 March during which period the walrus made local movements, likely for feeding. Transmissions were not received during 6-25 March, however, visual observations during this time indicated that the walrus remained at the Faroe Islands. A second transmitter was deployed on the same animal on 25 March 2010 at another site on the islands (62° 16' N/07° 04' W). Activity data collected over 13 days indicated that the walrus hauled out in three different places in the Faroe Islands and used a total of 24% of its time resting on land.  On 29 March 2010 the walrus left the Faroe Islands and headed WNW towards NE Iceland. On 2 April it took a NNE course and swam towards Svalbard where the last location was received from a sea ice covered area on 25 April 2010 at 78° 27' N/09° 20' E (i.e. ca. 40 km west of the island of Prins Karls Forland in the western Svalbard archipelago). During 29 March-22 April the walrus swam a minimum distance of 2216 km between the last location at the Faroe Islands and the first location at Svalbard, with an average swimming speed of 4.5 km/h. A genetic analysis indicated that this walrus belonged to the Svalbard-Franz Josef Land subpopulation, thereby confirming that it returned to its site of origin.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"54 1","pages":"75-91"},"PeriodicalIF":0.0,"publicationDate":"2014-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Status of the belugas of the St Lawrence estuary, Canada","authors":"M. Kingsley","doi":"10.7557/3.2847","DOIUrl":"https://doi.org/10.7557/3.2847","url":null,"abstract":"A population of belugas ( Delphinapterus leucas ) inhabiting the estuary of the St Lawrence river in Quebec, Canada, was depleted by unregulated hunting, not closed until 1979. Surveys in 1977 showed only a few hundred in the population. Surveys since then have produced increasing estimates of population indices. An estimate of the population, fully corrected for diving animals, was 1,238 (SE 119) in September 1997. The population was estimated to have increased from 1988 through 1997 by 31.4 belugas/yr (SE 13.1). Observations of population age structure, as well as data on age at death obtained from beach-cast carcasses, do not indicate serious problems at the population level, although there are indications that mortality of the oldest animals may be elevated. Few animals appear to live much over 30 years. From examination of beach-cast carcasses, it appears that most deaths are due to old age and disease; hunting is illegal, ship strikes and entrapments in fishing gear are rare, ice entrapments and predation are unknown. Among beach-cast carcasses recovered and necropsied, about 23% of the adults have malignant cancers, while most of the juveniles have pneumonia; other pathological conditions are diverse. No factors are known to be limiting numbers of this population. Habitat quality factors, including persistent contaminants, boat traffic and harassment, may affect the population’s rate of increase, but these effects have not been quantitatively evaluated. Comprehensive legislation exists with powers to protect the population and the environment of which it is a component, but application and enforcement of the laws is not without problems.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"4 1","pages":"239-258"},"PeriodicalIF":0.0,"publicationDate":"2014-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Size and trends of the bowhead whale, beluga and narwhal stocks wintering off West Greenland","authors":"M. Heide‐Jørgensen, M. Acquarone","doi":"10.7557/3.2844","DOIUrl":"https://doi.org/10.7557/3.2844","url":null,"abstract":"To assess the size and trends of the abundance of the bowhead whale ( Balaena mysticetus ), the beluga, or white whale ( Delphinapterus leucas ), and the narwhal ( Monodon monoceros ) visual aerial surveys were conducted in West Greenland in March 1998 and 1999. An estimated 49 bowhead whales (95% CI: 13 to 188) were present at the surface in 1998. Data from land-based observations enabled correction for bowhead whales that were not available at the surface to be seen during the survey. By applying a rounded average of 80% (SE=3) for submergence an estimate of 246 bowhead whales (95% CI: 62 to 978) in 1998 was obtained. The 76 and 47 sightings of beluga pods in 1998 and 1999, respectively, had distributions similar to those of previous surveys with the highest concentration at the northern edge of the northern part of Store Hellefiskebanke. No belugas were seen in the southernmost area between Maniitsoq and Paamiut. The index estimate of the abundance of belugas comparable with previous surveys was 929 (95% CI: 563 to 1,533) in 1998 and 735 (95% CI: 436 to 1,239) in 1999. When analysing the sightings as a line-transect survey and correcting for whales that were either submerged or at the surface but missed by the observers an estimated 7,941 (95% CI: 3,650 to 17,278) belugas wintered in West Greenland in 1998-1999. The uncorrected estimate of narwhal abundance was 524 (95% CI: 214 to 1,284) and correcting for the same biases as for the belugas gives a total abundance of 2,861 (95% CI: 954 to 8,578) narwhals in 1998-1999.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"4 1","pages":"191-210"},"PeriodicalIF":0.0,"publicationDate":"2014-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resource assessment and projections for the belugas off West Greenland using the population model of HITTER-FITTER","authors":"D. Butterworth, É. Plagányi, H. F. Geromont","doi":"10.7557/3.2845","DOIUrl":"https://doi.org/10.7557/3.2845","url":null,"abstract":"The population model of the HITTER-FITTER package is applied to compute trajectories for single and two stock scenarios for the beluga population wintering off West Greenland. Values of MSYR1+ from 1% to 4% are considered, with results computed to hit best estimates and lower 5%-iles for total abundance in 1999. Twenty year projections show that even for the most optimistic of these options in the single stock case, the resource is rendered extinct within 20 years if recent estimated annual catch levels of some 700 are continued. A time series of relative abundance information from surveys indicates that MSYR1+ may be no more than 0.5%. All scenarios considered are suggestive of a heavily depleted resource for which catch levels need to be substantially reduced to secure against possible further reduction of the population.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"4 1","pages":"211-224"},"PeriodicalIF":0.0,"publicationDate":"2014-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Population size and yield of Baffin Bay beluga ( Delphinapterus leucas ) stocks","authors":"S. Innes, R. Stewart","doi":"10.7557/3.2846","DOIUrl":"https://doi.org/10.7557/3.2846","url":null,"abstract":"A surplus production model within a Sampling, Importance Resampling (SIR) Bayesian analysis was used to estimate stock sizes and yields of Baffin Bay belugas. The catch of belugas in West Greenland increased in 1968 and has remained well above sustainable rates. SIR analysis indicated a decline of about 50% between 1981 and 1994, with a credibility interval that included a previous estimate of 62%. The estimated stock sizes of belugas wintering off West Greenland in 1998 and 1999 were approximately 5,100 and 4,100 respectively and were not significantly different than an estimate based on aerial surveys combined for both years. Projected to 1999 this stock can sustain median landings of 109 whales with a total kill of about 155, based on posterior estimates of struck and lost plus under-reporting. The declining stock size index series did not provide sufficient information to estimate the potential maximum rate of population growth, the number of whales struck and lost, or the shape of the production curve with precision. Estimating these parameters requires an index time series with a marked step change in catch or a series with increasing stock sizes. The stock size estimate for the belugas wintering in the North Water in 1999 was approximately 14,800 but there is no information about the population biology of these whales. The estimated maximum sustainable yield (landed) for the North Water stock was 317 belugas.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"4 1","pages":"225-238"},"PeriodicalIF":0.0,"publicationDate":"2014-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}