Live blog of a talk entitled “Managing Puget Sound’s Groundfish Resources from the Bottom Up“ by Wayne Palsson at NWFSC
28 species of rockfish, but poor habitat maps (compared with spotted owls, say)
Decline of groundfish like Pacific Cod in south Puget Sound has been prominent in last 10-15 years. Walleye pollock is endangered; 18 species were covered in ESA petitions in 1999. Many PS species are vulnerable. Copper and quillback petition was judged not warranted in 2006. 2007 petitions are pending for ~5 species.
Lingcod is an exception. North and south populations have been increasing since about 1995. Fisheries were restricted ~1990 after overfishing in late 70’s and early 80’s (big drop in catch/trip in 84-85).
11;17 History of habitat studies:
- Miller mid-1970s — nearshore habitat surveys
- Moulton 1977
- Cross 1991, Rocky intertidal
- Becker 1984, English sole
- Richards 86-87, depth substrate, relief (sub-based?)
- Matthews, 1990abc, rockfish, telemetry
- Murie, 1994, depth, complexity, wall
Rockfish, lingcod, greenling are associated with boulders and walls
- Fish are randomly distributed
- Distributions are independent of: depth, substrate, slope, complexity, water quality, time, light, food, life stage
11:23 Showed map of continuous bathymetry map in a GIS for all PS, N to Pt. Roberts, and offshore to about outer boundary of Sanctuary
11:24 Bottom trawl surveys (since 1987, ~only in springtime) yield maps with consistent coverage that gets sparse only in SJdF and Georgia Strai [~200 trawls in San Juan Islands since 2001; about 130 are within uniform substrate areas)
- Starry flounder associated with shallower water
- Some English sole in S Haro Strait
- Three geographic groups of similar species: Western Strait of Juan de Fuca, N Puget Sound, and S Puget Sound
- Depth patterns: Dover, Hake, Skate are deep species > 120 fathoms; Dogfish and English sole are at all depths
- Substrate patterns (based on Gary Greene’s multibeam data):
- flathead sole characteristic of deep mud stations
- ROV surveys in San Juan Channel (58 in 2004; 70+ in 2005) reveal:
- rockfish like rocks (especially copper and quillback), so do lingcod and greenling
11:43 Drop camera results (consistent with ROV results)
Philip Block got substrate maps out of NOAA, but still have need for better seafloor maps in the Salish Sea…
11:47 Conclusions: managing from the bottom up
200-300 ROV transects in the San Juans happening now!
- seasonality? is a factor, but we’ve not looked for it yet
- what are threats to sub-tidal habitats? Not clear what really matters, but likely factors are trawling and climate change
- Recreational fishing is a threat to rockfish populations (see recent stock assessment)
- What’s controlling population structure? Fishing, climate change, marine mammal predation… We can probably recover from all these… Ling cod are now dominant biomass at Edmonds.