Nereus Fellow Mathieu Colléter will be giving a seminar entitled “Impacts of fishing on the world’s ocean biomass from 1950 to 2010” at UBC’s Institute for the Oceans and Fisheries, AERL 107 on April 12, 2016 at 11:30am.
Abstract: Ecosystem models are increasingly used to assess fishing impacts on marine ecosystems, as well as the additional impacts of climate change. Here, we used EcoTroph (ET), a simple ecosystem model representing the biomass flow through trophic levels (TLs), to compute biomass estimates between 1950 and 2010 on a half-degree spatial grid covering all oceans. Based on primary production, sea surface temperature, transfer efficiency, Sea Around Us catch data and associated TLs of species, we applied ET in each cell of the grid and estimated the biomass by TLs in an unexploited state and for each year between 1950 and 2010. We also assessed the effects of parameter uncertainty on predicted ocean biomass. Trends in the decline of marine biomass from the unexploited state were analyzed with a special emphasis on predator species (TLs=3.5). Results highlighted several robust trends in the global past effects of fishing, notably that predator biomass declines expanded across all latitudes in the last 60 years and were mostly driven by fishing impacts. Furthermore, sensitivity analyses showed that a particular focus should be put on the validation of transfer efficiencies that greatly affect absolute values of the ocean biomass.
Speaker’s bio: Dr Colléter is a fisheries scientist whose research focuses on ecosystem modelling and trophic networks. He received his PhD from UBC/Agrocampus Ouest in 2014, and works as a postdoctoral fellow for Sea Around Us/Nereus program. He is currently working on the production of biomass estimates for the 180,000 ½ degree Sea Around Us cells covering all oceans, from 1950 to 2010, using ecosystem modelling (EcoTroph) and the Sea Around Us’ new spatialized catches. This will be used to model future changes in global biomass and fisheries catch under climate change scenarios. He also developed EcoBase used to perform meta-analyses of EwE models.