From Lance et al.:
From 2005 to 2008, fecal samples (scats) were collected seasonally over 3 collection periods: March to early June (‘spring’), late July to September (‘summer/fall’), and January to February (‘winter’). Scats were collected from 23 haul-out locations during daytime low tides. The sites were dispersed throughout the study area, represented various habitat types used by harbor seals, were the largest haul-outs where adequate sample sizes could be collected, and were easily accessible by boat. Two or three collection trips were made each season, with a target sample size of 60 scats per season per region.

Samples were stored frozen. In the lab, samples were enclosed in fine mesh paint-strainer bags and cleaned using a washing machine or nested sieves. Hard parts were cleaned and stored dry. Prey were identified to lowest possible taxon using a dissecting microscope, reference fish bone collections, and published keys.