Fishing down Brazilian marine food webs, with emphasis on the east Brazil large marine ecosystem

Abstract

An analysis of Brazilian marine fisheries catch data covering the years 1978–2000 is conducted with emphasis on testing for the occurrence of the ‘fishing down the marine food web’ phenomenon in the East Brazil Large Marine Ecosystem (LME). The results show that this phenomenon becomes apparent only after national data are disaggregated into smaller entities, as exemplified here for seven states of Northeastern Brazil (corresponding to the East Brazil LME). Once the disaggregation was performed, the decline of trophic level occurring through most of Northeastern Brazil was shown to occur at a rate of 0.16 trophic level per decade, one of the highest rates of trophic level decline documented in the world. Also, fishing ‘through’ the food web, proposed as an alternative to fishing down, did not occur. Overall, this indicates that the Marine Trophic Index (i.e., the mean trophic level of the catch) is indeed a robust indicator of biodiversity loss, as envisaged by the Convention of Biological Diversity, and that the marine biodiversity of the East Brazil LME is being eroded.