Kiefer, Dale: USC (Project Lead)
Project Funding:
2017 - 2020
NRA: 2016 NASA: Interdisciplinary Research in Earth Science
Funded by NASA, Other US Funding: NASA
Abstract:
The goal of the TunaScape project is to develop a three-dimensional ecosystem model of the tuna fishery of the eastern tropical Pacific Ocean (ETPO) that will describe how ocean circulation from submesoscale to global scales drives the spatial-temporal distribution of commercial tuna species (skipjack, yellowfin, and bigeye). To meet this goal TunaScape will address a broad range of questions: why does the shallow hypoxic layer that covers thousands of square kilometers of the ETPO appear to shape the distribution of both primary production and the catch of the commercial species? Is the shallow hypoxic layer simply the result of equatorial and coastal upwelling or is it also strongly influenced by vertical compression of the planktonic and pelagic communities? What scale of spatial and temporal resolution is required to resolve vorticity structures that lead to the aggregation of the tuna and presumably their prey? Will this scale be achieved with the new ocean color, thermal, and altimetry sensors soon to be launched?
The TunaScape model will be driven by NASA’s satellite imagery of sea surface temperature, color, height, and wind speed as well as output from its ECCO 18 km and 2.3 km global circulation models. The model will consist of three components: the ECCO global circulation model; a plankton model that will be a modified version of the 18 km Darwin Model and of the 2.3 km BLING Model; and an agent-based, population dynamics model of the three tuna species. The tuna model, which was recently completed as part NSF’s Fishscape project, is based upon the Inter-American Tropical Tuna Commission (IATTC)’s 50-year record on catch and effort. The IATTC purse seine data provided to us was monthly species catch at a spatial resolution of 1 degree. For the TunaScape project we have been offered access to data at submesoscale resolution (<10 km). The coupling of high resolution models of oceanographic conditions with high resolution fishery data will offer new insights into the linkage between circulation and the habitat of species that occupy the highest trophic level of the ecosystem.
Darwin and Bling both run within the 18 km ECCO circulation model and both models track the transformations of oxygen, carbon dioxide, nutrients, and plankton components. The models will be modified to include a formulation for vertically migrating zooplankton and nekton (prey targeted by tuna) since this component plays an important role in the formation of the hypoxic layer. The tuna model describes the movement, growth, metabolism, fishing and natural mortalities, and recruitment of age-classes of metapopulations of the three tuna species. Movement includes horizontal movement by drift and taxis and random swimming, school formation, and vertical positioning by the fish. The tuna model, which runs in the EASy geographic information system, will import output from the 18 km and 2.3 km versions of the plankton model and output monthly maps of tuna species distribution. The model will require improved tuning to match fishery data at both spatial scales, and a more advanced algorithm on the catchability of the fish based upon published data from archival tags on vertical movements.
The project team is interdisciplinary consisting of software engineers, a fishery oceanographer, a physical oceanographer, two plankton ecologists, and a fisheries modeler. TunaScape addresses the NRA’s question of How can the coupling of physical ocean current and ocean ecosystem data improve either the ecosystem-based management of the ocean or our understanding of the organization of the dynamic biogeography of the marine realm? by creating a model that explores the coupling of circulation over a broad range of spatial scales to the tuna fishery as well as generates maps of ecosystem response to changes in ocean state.
Publications:
Carozza, D. A., Bianchi, D., Galbraith, E. D. 2018. Metabolic impacts of climate change on marine ecosystems: Implications for fish communities and fisheries. Global Ecology and Biogeography. 28(2), 158-169. DOI: 10.1111/geb.12832
Harrison, D. P., Hinton, M. G., Kohin, S., Armstrong, E. M., Snyder, S., O'Brien, F., Kiefer, D. K. 2017. The pelagic habitat analysis module for ecosystem-based fisheries science and management. Fisheries Oceanography. 26(3), 316-335. DOI: 10.1111/fog.12194
More details may be found in the following project profile(s):
