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. Fish species from fecal samples were placed into 11 non-overlapping prey groups based on taxonomy. Taxonomic resolution (species vs. family or genus) was based on resolution of the prey remains. The category ‘other’ included for all remaining prey species with unweighted occurrence frequencies <5%. Rockfish were included as a prey group despite an overall low occurrence frequency because of conservation interest and the objectives of the present study. To gain insights into seasonal diet variation, the frequencies were weighted by the numbers of seals present in each region in the spring and summer/fall