Fishing and the Food Chain (Web)

Transcription

Fishing and the Food Chain (Web)
Fishing and the Food Chain (Web) •  To assess this scien4fically, we can assign a trophic value to each organism •  Sustainable fisheries generally start with low values Is everything driven by top-­‐
down impacts, primarily due to humans? -­‐ Collapse of Cod -­‐ Decline of herring -­‐ Northern prawns -­‐ Argen4nian hake -­‐ squid Changes in MTL rela4ve to unfished ecosystem MTL. Authors argue that catch-­‐
based sta4s4cs tell you almost nothing about how the ecosystem actually responds-­‐-­‐argue that we need to directly measure or model ecosystems TA Branch et al. Nature 468, 431-435 (2010) doi:10.1038/nature09528
Halpern et al. Science 319:948-­‐952, 2008 Global Coastal How do you make a map like this? •  Fishing Ac4vity determined by Sea Around Us Program (SAUP) at 1/2 degree scale •  Fish Landings from FAO •  “Pressure” determined as catch density divided by (satellite) primary produc4vity •  Assumes more pressure if equivalent fish are removed from low-­‐produc4vity environments Fig. 1. Quarterly distributions (½° latitude by 1° longitude) of catches from the northeast Atlantic
mackerel stock for 2006 [data from (14)].
M R Heath Science 2008;321:1446-1446
The Rise of “Slime” h\p://news.na4onalgeographic.com/
news/2009/10/photogalleries/
ocean-­‐mucus-­‐sea-­‐pictures/