Collaboration with Eric Beamer and Kurt Fresh (tows), and many students/volunteers
1950-2006, about 50 sites around the San Juans have been sampled and have found juvenile salmon. Of 656km of SJI shoreline, 430km is rocky beach. Tow nets (164 tows at 37 sites, monthly from Apr-Sep) caught juveniles of 5 species and 785k fish overall; 657 beach seins at 27 sites caught juveniles of 5 species and~100k fish overall.
% of catch (seine, tow): sculpins (29%,0%); smelt, sand lance, herring (17%, 98%); salmon (16%, 0%?); surf perch (16%, 0%); gadids (7%, <1%); hexagrammids (lingcod, kelp greenling 2%, <1%).
Chinook mostly present apr-sept (mostly august), about 2 months later than in Skagit estuary. Juvenile salmon are common Mar-Sept and were present year-round in all environments at all sites.
Along west side, catch was ~10x higher near Eagle Point than near Henry Island, but Rosario side was generally dominant (especially herring).
What are the interacting relationships between rockfish, the lingcod that eat them, and the fishers who take lingcod (and rockfish)? In reserves we can look at predatory role of lingcod without fishing pressure. We can also look at differences in lingcod population structure and feeding between non/reserves.
Most samples from central San Juan Channel in rocky habitat.
- non-reserve: 35-80cm, mean ~45cm
- reserve: quite a few large females, 80-120cm.
Catch rate: in reserves we had many more days when we caught >3 lingcod/hour.
Acoustic telemetry synopsis
- Limited movement: 8/9 tagged lingcod never left reserve
- Diet composition: rock fish are 20% of diet in reserves, only 5% in non-reserves (maybe because there are more rockfish in reserves, or maybe larger rockfish in reserves eat more rockfish, or maybe there are habitat differences)
- Estimated rockfish consumption (modeled): consumption of rockfish in reserves may have been 5x non-reserve, with implications for how to recover rockfish!
- Pop structure differs between non/reserves
- diet variations suggest local diffs in fish communities
- there are unexpected ecological consequences of creating reserves…
- match scales of research and management (got to get down to pretty small scales!)