The importance of trophology investigations for multispecies fishery analysis
a Federal Research Institute of Fisheries and Oceanography (VNIRO), 107140 Moscow, V. Krasnoselskaya str., 17
bA.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071 Moscow, Leninskii prospect, 33
#E-mail: tbulgakova@vniro.ru
##E-mail: abobyrev@mail.ru
Previously, we applied simple analytical models to show that disregarding the interspecific food relations may disrupt the structure of the community. The primary aim of multispecies modelling is to insure sustainable existence of a community or ecosystem, and a possible rise in its production level, which entails a higher catch level. Potentials of the two major multispecies models (the cohort MSVPA and the balance production ECOPATH/ ECOSIM) were analyzed. More structured feeding data (by species and age, for predators and preys) are needed for the former model, while the second model requires the trophic level data only. The MSVPA model involves only the fishing species and “external” predators, but the second model considers matter flows among all levels of the food web but disregards the seasonal and inter-annual variability in feeding. The identification of parameters for a multispecies model involves labour-intensive research in trophology. One of the first Russian trophology scientists was V.S. Ivlev who set up a number of experiments to identify feeding rates among fish. Another important venue included experiments to assess the rates of digestion of various prey species in the stomachs of a particular species of predators. Our estimates of mortality from predation for the fish community of the Barents Sea, obtained with the help of MSVPA, are sometimes higher than those for the fishery mortality. Another important factor contributing to the recruitment into the North-East Arctic cod stock (the major one in the Barents Sea), is cannibalism. In order to study the dynamics of the aquaticcommunities and in making fishery management advice it is particularly important to consider the predation mortality in the stocks of prey species, one example being capelin which is the most preferable food item for many predators among fish, mammals and birds.
