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| Registros recuperados: 55 | |
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| Morizur, Yvon. |
| The recent developments in collecting techniques for spat of Chlamys operoularis and Chlamys varia make it necessary to find criteria for separating these two species at early life stages. Biométrie criteria for differenciating between species have been found to be usable on individuals of a height superior to 3 mm. A quick différenciation of smaller individuals is possible by observation, under light microscope, of the périostracum external morphology on left valves. |
| Tipo: Text |
Palavras-chave: Chlamys; Aquaculture techniques; Juveniles. |
| Ano: 1977 |
URL: http://archimer.ifremer.fr/doc/1977/acte-2343.pdf |
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| Morizur, Yvon. |
| In crustaceans, size at first maturity is often determined by secondary sexual characters. The present work tries to determine the size at first maturity in Nephrops norvegicus from South-Brittany area with the development of some secondary sexual characters. We study a qualitative character - the presence or absence of ovigerous setae in females and biométrie characteristics - the width of the second abdominal segment in females, the length of the propod at the first pereiopod in males and females - The study of the relative growth of the propod length shows that males may reach sexual maturity at 19mm carapace length. The first maturity in females is reached at 23.5mm later than the coming out of the ovigerous setae. That carapace length is obtained... |
| Tipo: Text |
Palavras-chave: ANE; France Nephrops norvegicus length weight relationships sexual maturity. |
| Ano: 1979 |
URL: http://archimer.ifremer.fr/doc/1979/acte-2344.pdf |
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| Morizur, Yvon. |
| Loss of eggs during the incubation period in ovigerous females of Nephrops norvegicus from the Bay of Biscay is calculated using two different methods. The first calculates the egg loss from incubation stage A to stage D. The second calculates the loss between the end of ovary maturation and incubation stage D. The first method may contain a bias which decreases the loss estimation : loss of eggs during trawling may be higher in stage A than in stage D. In the Bay of Biscay, the loss of eggs in ovigerous females of Nephrops norvegicus would be about 45-50% for the entire incubation period. Our result is quite different from the 75% obtained by other workers in Portuguese waters. Loss of eggs during incubation which may be due mainly to predation may be a... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/1980/publication-5311.pdf |
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| Morizur, Yvon. |
| Ovary development and the presence of spermatophore in females of Nephrops norvegicus (L.) (Nephropidae) from South Brittany were studied from July 1976 to October 1978 through size classes. Percentage of females bearing spermatophores increased slowly up to 1978 during which year a sudden and important decrease was observed. The percentage decreased to the lowest value obtained in 1976. A study of ovarian development showed that the proportion of small females taking part in reproduction was greater in 1978 than in 1977. The beginning of the decrease in the percentage of spermatophores present coincided with the beginning of spawning in each size class. It may be explained by the behaviour of ovigerous females which stay in burrows during the incubation... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/1981/publication-5312.pdf |
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| Charuau, Anatole; Morizur, Yvon; Rivoalen, Jean-jacques. |
| Since 1978, the habits of the french fishermen working with bottom trawl in the Irish Sea and in the Celtic Sea were altered (CHARUAU et M0RIZUR, 198l) under the pressure of the new mesh regulation. Two facts are pointed out: - the shifting, stabilized during 1980 and 198l, of a part of the effort of the vessels fishing for gadoids, from the area VIIa to the areaVIIf - a tendancy inside the area VIIg of a part of the effort of the Nephrops trawlers to be transferred on benthic fishes when the yield of Nephrops is low. |
| Tipo: Text |
Palavras-chave: Celtic sea; Fishing fleets; Irish sea. |
| Ano: 1982 |
URL: http://archimer.ifremer.fr/doc/1982/acte-2342.pdf |
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| Charuau, Anatole; Chesnier, Véronique; Conan, Gérard; Derennes, Marc; Destanque, Catherine; Guenole, Annie; Isifou, Amadou; Jezequel, Michèle; Miossec, Gilbert; Missaoui, Ichmi; Morizur, Yvon; Rivoalen, Jean-jacques. |
| Introduction : Since 1978, new measures to better manage lobster fisheries were implemented in the Celtic Sea within the context of Community regulations. Meshing, in particular, was set at 60mm, but many owners, in order to maintain sufficient leeway vis-à-vis the regulations and to avoid administrative hassles adopted at the outset fish meshing at 70mm, even 80mm. Certain habits aiming to compensate for the losses due to these increases were established: Adoption of better-performing trawls, increase in the secondary catch and enlargement of the fisheries. At the same time, especially because of strong demand from international bodies, OEM and especially EEC, knowledge about the lobster spread and more reliable assessments were achieved, the main problem... |
| Tipo: Text |
Palavras-chave: Stock assessment; Norway lobster; Celtic sea; Nephrops Norvegicus; Crustacea; Lobster fishery; Mer Celtique; Nephrops Norvegicus; Crustacea; Effort Peche; Sex Ratio; Capture; Relation Taille Poids; Maillage; Chalut; Gestion stock; Peche. |
| Ano: 1982 |
URL: http://archimer.ifremer.fr/doc/1982/rapport-2337.pdf |
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| Morizur, Yvon. |
| The average length at which female Nephrops norvegicus attain their first maturity was determined during 1977 and 1978 by following the presence of spermatophores and development of the ovaries. During 1978, females were sexually mature at the age of 2 but in 1977 they did not mature before the age of 3. The cumulative maturity curves are sigmoid, due to an overlapping of Gaussian curves. A logistic equation was developed to calculate the percentage of mature females at each length. There is no evidence that the present fishing levels reduce the chances of a female with developing ovaries to be fertilized, since 90 to 100% of such females bear spermatophores. |
| Tipo: Text |
Palavras-chave: Brittany; France; ANE; Crustacea; Nephrops norvegicus; Females; Growth; Sexual maturity. |
| Ano: 1983 |
URL: http://archimer.ifremer.fr/doc/1983/publication-2349.pdf |
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| Le Guen, J.c; Morizur, Yvon. |
| Length measurements on Pseudotolithus elongatus ' samples from the Congo were recorded in the 60s. Subsamples were collected in order to be "aged" by otoliths' reading. The size frequency distributions were splitted into successive unimodal distributions by different methods. Their results were compared. The results obtained from the "successive maximums' method" were similar to those from the "otoliths' reading." The programs NORMSEP and MIX gave results far more difficult to interpret biologically speaking in spite of their mathematical quality. Because many length frequency distributions of a cohort are symmetrical in nature, we suggest applying the "successive maximums' method"if there is no evidence of normality |
| Tipo: Text |
Palavras-chave: Frequency analysis; Size distribution; Pseudotolithus elongatus; Sciaenidae; Pisces. |
| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/1989/rapport-2336.pdf |
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| Bennet, D; Casey, J; Dare, P; Dawson, W; Flatman, S; Hulme, T; Macer, C; Millner, R; Pickett, G; Vince, M; Lorance, Pascal; Souplet, A; Giret, M; Morin, Jocelyne; Berthou, A; Latrouite, Daniel; Morizur, Yvon; Bossy, S; Ozanne, S. |
| At present, the majority of fisheries are monitored and regulated in areas which are delineated by arbitrary ICES boundaries which do not necessarily have logical or consistent relationships with biological processes or fish movements. The biogeographical identification of Channel stocks is, therefore, an important step towards developing a rational strategy for the management of their fisheries. This synthesis is based on the wide available knowledge which has not been yet entirely exploited with the purpose of stock identification, for 25 commercially important species in the Channel. In addition, principal technics for stock identification are reviewed likewise environmental characteristics of the Channel, which represent fundamental components in... |
| Tipo: Text |
Palavras-chave: Environnement physico chimique; Méthodes d'identification; Migrations; Zones de ponte; Distribution géographique; Espèces exploitées; Identité de stock; Manche; Physical environment; Identification methods; Migrations; Spawning areas; Geographical distribution; Exploited species; Stock identification; Channel. |
| Ano: 1993 |
URL: https://archimer.ifremer.fr/doc/1993/rapport-719.pdf |
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| Registros recuperados: 55 | |
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