R. A. Watson, T. Morato, (2013). Fisheries Research 140, 63-65.

New estimates of the global mean depth of fishing, which consider both the between and within species changes over time, showed a stronger shift to deeper water than estimated previously based only on between-species changes. The new estimates show a linear increase in the mean depth of fishing of 62.5m decade-1, corresponding to an increase of about 350m for the period since 1950. These values are about 5 times higher than those obtained by using between species change in catch composition over time, suggesting that deep water species and habitats are under a more serious threat from fishing than hitherto assumed.

10.1016/j.fishres.2012.12.004, http://www.ecomarres.com/downloads/deeper2.pdf