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| Registros recuperados: 15 | |
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| Eigaard, Ole Ritzau; Marchal, Paul; Gislason, Henrik; Rijnsdorp, Adriaan D.. |
| Many marine fish stocks are overexploited and considerable overcapacity exists in fishing fleets worldwide. One of the reasons for the imbalance between resource availability and fishing capacity is technological development, which continuously increases the efficiency of the vessels—a mechanism referred to as “technological creep.” We review how the introduction of new and more efficient electronic equipment, gear design, engines, deck equipment, and catch-handling procedures influences the capture efficiency (catchability) of commercial fishing vessels. On average, we estimate that catchability increases by 3.2% per year due to technological developments, an increase often ignored in fisheries management. The documentation and quantification of... |
| Tipo: Text |
Palavras-chave: Catchability; Fishing mortality; Fishing power; Fisheries management; Fleet capacity; Technological development. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00222/33368/35784.pdf |
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| Marchal, Paul; Andersen, B; Bromley, D; Iriondo, A; Mahevas, Stephanie; Quirijns, F; Rackham, B; Santurtun, M; Tien, N; Ulrich, Clara. |
| The scope of this paper is to quantify, for a wide selection of European fisheries, fishing tactics and strategies and to evaluate the benefits of adjusting the definition of. fishing effort using these elements. Fishing tactics and strategies were identified by metiers choices and a series of indices. These indices have been derived to reflect shifts in tactics (within a fishing trip) and in strategies (within a year). The Shannon-Wiener spatial diversity indices of fishing tactics (FT_SW) and strategies (YE_SW) had the greatest impact on catch rates. In particular, FT_SW was always negatively correlated to catch rates. One may anticipate that during a fishing trip, vessels with high FT_SW have been searching fish aggregations for a long time, while... |
| Tipo: Text |
Palavras-chave: Fishing effort; Fishing mortality; Catch rates; GLM modeling; Skipper effect. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/2006/publication-1339.pdf |
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| Marchal, Paul; Andersen, Bo; Caillart, B.; Eigaard, Ole; Guyader, Olivier; Hovgaard, Holger; Iriondo, Ane; Le Fur, Fanny; Sacchi, Jacques; Santurtun, Marina. |
| Face-to-face interviews were conducted to identify the main changes in gear and vessel technology that may have improved the fishing efficiency of a number of French, Danish, and Basque fleets over the past few decades. Important changes include the gradual appearance of twin trawls (Danish and French trawlers) and trammel-nets (French gillnetters), and the increased polyvalence of Basque bottom trawlers. The results suggest that fishing effort descriptors that are not traditionally measured (gear type, groundrope type, length of net used per day, headline length, crew size, number of winch or net drums) may have a substantial impact on catch rates. Adjusting fishing effort using such descriptors may generally improve the relationship between fishing... |
| Tipo: Text |
Palavras-chave: Twin trawls; Technological creep; Groundrope; Generalized linear models; Fishing mortality; Fishing effort; Catch rate. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2611.pdf |
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| Hernández, D.R.; Perrotta, R.G.. |
| Pope's Cohorts Analysis was modified to extend its application to a wider range of natural mortality, M and fishing mortality, F rate values. The modified method maintains the simplicity of the one established by Pope and does not require to resolve any non lineal equation in each cohort reconstruction process. The relative errors obtained when estimating the number of individuals per age (maximum and mean in absolute value) showed acceptable levels within the five domains (M and F pairs of values) analyzed in this work. The new method can be adapted to a particular situation (M and F values range) simply solving an optimization problem (minimization of the maximum relative error absolute value) easily achieved using a calculation sheet or considering the... |
| Tipo: Journal Contribution |
Palavras-chave: Fishing mortality; Natural mortality; Stock assessment; Stock assessment; Http://aims.fao.org/aos/agrovoc/c_24251. |
| Ano: 2008 |
URL: http://hdl.handle.net/1834/3143 |
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| Wöhler, O.C.; Giussi, A.R.; Hansen, J.E.. |
| Sequential population analysis on Long Tail Hake (Macruronus magellanicus)from the Southwest Atlantic. Years 1985-1995. VPA on the Long Tail Hake (Macruronus magellanicus), based on data covering the years 1985 up to 1995, was performed to assess the current state of the stock. Simulation trials, inducing uncertainty about both the natural mortality rate and recruitment were also accomplished, to evaluate the risk of overfishing which is associated to different fishing alternatives, always under the assumption of a single and closed Long Tail Hake population. CPUE data were not appropriate for tunning, so the traditional VPA has been applied. During the period of study, stock biomass and spawning stock biomass showed an increased trend. Long and short-term... |
| Tipo: Journal Contribution |
Palavras-chave: Stock assessment; Fishery management; Catch/effort; Fishing mortality; Overfishing; Biomass; Sexual maturity; Stock assessment; Fishery management; Biomass; Overfishing; Sexual maturity; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_24026; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_34068; Http://aims.fao.org/aos/agrovoc/c_7016. |
| Ano: 1999 |
URL: http://hdl.handle.net/1834/1875 |
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| Koné, Vamara. |
| L'influence de la température sur la mortalité des oeufs d'anchois dans l'écosystème du Benguela sud apparaît très variée. Les simulations ont montré une sensibilité à la valeur seuil de température létale, une variabilité de l'indice de mortalité en fonction de la zone, de la période et de la profondeur de ponte. L'approche IBM utilisée dans le cadre de cette étude est un bon outil d'investigation des processus essentiels, aussi bien physiques que biologiques, qui contrôlent le transport des oeufs et des larves de la zone de ponte à la zone de nourricerie sur la côte ouest. Cette étude est applicable aux ressources des petits pélagiques associés à l'upwelling Ivoiro-Ghannéen au nord du golf de Guinnée. |
| Tipo: Journal Contribution |
Palavras-chave: Temporal variation; Fishing mortality. |
| Ano: 2011 |
URL: http://hdl.handle.net/1834/5807 |
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| Registros recuperados: 15 | |
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