Where are the fish? Utilizing shearwaters as predictors off California

Shannon Lyday (Hawaii Pacific University, Oceanic Institute, Waimanalo, Hawaii, USA.) and colleagues write in a special issue of the Journal of Marine Systems entitled “California Current System – Predators and the Preyscape” on shearwaters (including the ACAP-candidate Pink-footed Puffinus creatopus) as indicators of fish abundance.

The paper’s abstract follows:

“Shearwaters are ideal for monitoring ocean conditions in the California Current because these predators are abundant, conspicuous, and responsive to oceanographic variability.  Herein we evaluated black-vented (Puffinus opisthomelas), Buller's (P. bulleri), flesh-footed (P. carneipes), pink-footed (P. creatopus), short-tailed (P. tenuirostris), and sooty (P. griseus) shearwaters as fishery-independent indicators of predatory or prey fish availability.  We analyzed four years (1996, 2001, 2005, 2008) of monthly (August–November) National Oceanic and Atmospheric Administration seabird surveys, and United States Geological Survey Pacific Coast Fisheries Database catch, from the California coast to 200 nm offshore.  An ordination of shearwater abundance and fish catch revealed that the shearwaters and 11 fish/squid species were significantly correlated with one or more of three principal components, which explained 86% of the variation and revealed distinct species assemblages.  We evaluated multiple linear regression models for 19 fisheries using five shearwater metrics: density, aggregation, and behavior (traveling, stationary, feeding), three oceanographic indices, and latitude.  Eight of these models had a shearwater metric as the primary predictor.  In particular, feeding black-vented shearwater abundance explained 75% of dolphinfish (Coryphaena hippurus) longline catch.  This research illustrates the utility of shearwaters as ecosystem indicators, with direct application for predicting fishery catch of commercial importance.”

Sooty Shearwater, photograph by John Graham 

Reference:

Lyday, S.E., Ballance, L.T., Field, D.B. & Hyrenbach, K.D. 2015.  Shearwaters as ecosystem indicators: towards fishery-independent metrics of fish abundance in the California Current.  Journal of Marine Systems 146: 109-120.

John Cooper, ACAP Information Officer, 20 April 2015