NOTE Thedmga el al Habitat, age, and diet of Tnchodon tnchodon 



633 



- 57,30 N 



- 57,26 



Figure 2 



Location of sites (see Table 1 for habitat characteristics) sampled for Pacific sandfish {Trichodon 

 tnchodon) near The Brothers Islands, southeastern Alaska, 2001 to 2004. Sampling methods 

 included beach seining and mid-water trawling. 



trawl with 3.0-m- alloy doors: it was 11 m high and 29 

 m wide and was equipped with a 32-mm mesh codend 

 liner. In Frederick Sound, water depth was about 74 m, 

 and the trawl was fished at a depth of 14 m. In Pybus 

 Bay, water depth was about 70 m and the trawl was 

 fished at depths from 50 to 64 m about 400 m offshore. 

 Water temperature and salinity were obtained from 

 deployment of a CTD (conductivity-temperature-depth) 

 profiler in Pybus Bay in 2003. 



Age and size 



A sample of Pacific sandfish was frozen and brought 

 to the laboratory where sagittal otoliths were removed 

 and stored in 95% ethanol. Fish used for otolith collec- 

 tions covered a range of sizes in the catch (Table 2). 

 Fish were measured to the nearest mm FL. and larvae 

 were measured to the nearest mm total length (TL). A 

 sample of fish was individually weighed to the nearest 

 gram. Because a sample of larvae captured with a seine 

 and preserved (lOVf formalin) in 2002 was not measured 

 until 2004, a shrinkage factor of 10.3% was applied to 

 the lengths to adjust for storage in formalin (Marliave, 

 1980). The left otolith of each fish was cut into thin 

 sections by using standard methods described in the 

 otolith manual for microstructural examination (Secor 

 et al., 1991). The otolith was attached to a glass slide, 



medial side down, with thermal resin. The surface of the 

 otolith was then ground to the primordium with 1000- 

 grit silicon carbide paper. Care was taken to leave the 

 edge of the otolith intact and not to grind through the 

 primordium in the center. The otolith was then polished 

 with an 8000- and 12,000-grit cloth on both sides to 

 reveal the internal microstructure. Otoliths collected in 

 2001 were aged separately by two biologists. When age 

 estimates differed, otoliths were re-examined together 

 by both readers, and an age was agreed upon. Otoliths 

 collected in 2002 were aged by one biologist three dif- 

 ferent times. If age readings differed between any of the 

 three readings, the otolith was re-examined and a best 

 estimate of the age was determined. For both years, 

 otoliths were examined without knowledge of fish size 

 or collection date. 



Diet 



A sample of Pacific sandfish (>age-0) was preserved 

 in 10% formalin and analyzed for stomach contents. 

 Preserved fish were measured to the nearest mm FL, 

 weighed to the nearest 0.1 g, and stomachs were excised. 

 Stomachs were weighed before and after removal of 

 contents to obtain an estimate of wet weight by sub- 

 traction. Contents were examined with a dissecting 

 microscope and identified to major taxonomic groups. 



