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Déposant : Timothy Parsons
Communauté : Brentwood Bay, BC
Déposé le : Novembre 7, 2010
Résumé :
Le succès anticipé des disciplines comme la médecine et l’agriculture vient du fait qu’elles exercent une surveillance attentive des problèmes et posent des diagnostics réfléchis au lieu d’utiliser des modèles. Malgré le développement de l’océanographie des pêches, qui tente d’étudier tous les types d’interaction de la chaîne alimentaire océanique afin d’évaluer l’abondance des espèces de poissons et leur survie, la complexité des modèles de pêche empêche les spécialistes de ce domaine d’en arriver à des prévisions justes ou utiles. Pour pallier cette lacune, les organismes de financement devraient envisager le financement conjoint de la recherche collaborative sur la vie océanique du saumon, dont on sait très peu de choses. Le financement permettrait de suivre et d’analyser presque en temps réel des phénomènes comme la prolifération soudaine de végétaux planctoniques dans le golfe de l’Alaska ou l’augmentation subite des populations de saumon, ainsi que d’émettre des prévisions avec plus de certitude.
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Représentations :
Some historical notes on fisheries and oceanographic science by T.R.Parsons, Prof.Em.Dept.Earth.Ocean Sci.UBC
In the late 1950s, Dr. Alfred Needler, head of fisheries at the Biological Station, Nanaimo and Dr. John Tully, chief oceanographer at the same location, decided that fisheries forecasts based on population dynamics had not served the needs of the west coast fisheries community. They initiated a new group within the Biological Station, one with the goal of integrating oceanographic information with fisheries forecasts. Dr. John Strickland, an analytical chemist, was hired to lead this group. Our purpose was to study the chemistry and plankton of the sea in as much as they might be applicable to forecasting the survival and growth of commercial fish.
Up to this point in time, fisheries forecasts had been governed by “Population Biology” which has tried to determine forecasts of population size from life history traits. It was a science that based the future probability of events on a hindcast of data on the species. It seemed a sensible approach to a complex environmental problem, but overall it failed repeatedly to make the kind of accurate forecasts needed by the industry.
The evolution of a new science and a new management strategy was needed and this became generally described as “Fisheries Oceanography”. Many developments came under this title, among them one which embodied the “ecosystem approach” to understanding how fish grew and survived on the basis of energy transferred up the ecosystem from sunlight, to nutrients, to phytoplankton and zooplankton and eventually to fish. This approach in turn gave rise to a number of “Ecosystem Models”. These models are an ambitious attempt to include all the steps and interactions in the food chain of the sea culminating in an estimate of the abundance and survival of fish of different species. While these models have had some use in providing analytical understanding to a very complex system, they have failed to present useful forecasts of fisheries. Part of this problem lies in their complexity, with assumed starting conditions for the differential equations, and further assumptions regarding the constants used in those equations, which are often not constant but in reality require to be further sub-modeled.
Analogies to this complex problem of trying to predict life in the ocean environment exist in two much older branches of biology, medicine and agriculture. Both of these fields have obtained much greater funding over the years than ocean science and both are now reasonably well developed to make some accurate forecasts of events. While models are used in both sciences, they are not the primary reason for their predictive success. With the expensive invention of new techniques ( e.g. in medicine, x-rays, MRIs, etc. ) it is the careful monitoring and diagnosis of problems that have lead to successful forecasting and understanding of complex biological issues.
At present the early life stages and the river returns of migrant salmon are monitored, but very little is known of their ocean life. This same monitoring is required during the prolonged period that the salmon are in the ocean. Up until recently, however, the expense of extensive monitoring of the oceans has been prohibitive and mostly confined to research vessel cruises covering relatively small areas in short time periods. This situation is now changing rapidly both in oceanography and fisheries. In the former, the use of satellite oceanography, gliders which can replace some of the cost of ocean research vessels, the Argo float program, and the Hardy recorder program are all relatively new to the Gulf of Alaska. In fisheries the innovative tracking of migratory fish on the high seas (e.g. the POST program), archival tagging and genomic approaches are all comparatively recent additions. If these programs were more fully funded then it can be anticipated that such events as the sudden appearance of a plankton bloom in the Gulf of Alaska, or a surge in salmon populations, could be followed and analyzed in near-time and forecasts issued with more certainty than is available using ecosystem models. In order to do this, it will also be necessary to more closely integrate the sciences of oceanography and fisheries. Funding agencies, including government, international organizations and the private sector, should consider joint funding of collaborative research on ocean monitoring.
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