Pacific Northwest Coastal Ecosystem Complex social, economic, ecological and climate interaction…the future of conservation ecology??? ECOL 6080 F 09
Kelp harvest for algin (you have all eaten it) 40 million dollars 170,000 tons in 1970s off California coast alone
Common purple sea urchin: major grazer on alga; destroys holdfasts of kelp; populations kept low by sea otters. Unchecked, sea urchins virtually eliminate kelp
From central California north Sea otters are the main predators on sea urchins
Sea otter is well-adapted to feeding on shellfish and requires high feeding rate to maintain metabolic demands in cold water
Sea otter skull and teeth Short powerful jaw
Sea otter populations (California) show no Increase after mid-1990s
Positive association with disease and presence of tributylin, a fungicide added to marine paint. PCBs and pesticide degradation products also sometime present in carcasses of diseased animals
Sea otter decline off Alaska • Decline is more severe than off California • Carcasses show less evidence of disease, toxins, or emaciation • Carcasses often show evidence of attack by Orcas (killer whales)
Sea otter positives and negatives • Maintains kelp (+) • Helps to maintain commercial and recreational fisheries (+) • Helps maintain kelp harvest (+) • Ecotourism value (+) • Does it by eating sea urchins and abalone which are commercial species (-)
The bigger picture • Sea temperatures are warmer • Plankton populations down • Plankton-feeding fish (anchovies) down • Larger predatory fish down (e.g., salmon) • Apex predator (Sooty Shearwater) major decline • Sea lions closer to coast • Young of great whales caught in drift nets • Orcas (killer whales) feeding closer to shore
Orca (killer whale) • Three subspecies in northwest Pacific Salmon predators (tourists see these) Off-shore generalized fish predators Oceanic predators of whales, seals, etc • Oceanic predators moving closer to shore and feeding on sea otters
Orca individual tracking tissue missing Tissue notch Tissue tear Saddle scar Saddle patch
Shallow bays provide refuges for sea otters from Orcas
Sea otters in metapopulation • Populations semi-isolated in shallow bays • Orcas pick off migrants between bays • Some bays are source, others sink habitat • Genetic and population dynamics of sea otters transformed by social-economic forces
Five large species of Pacific salmon; all spend most of their life cycle in the ocean and return to same freshwater river or lake for spawning. Most die after spawning.
Salmon have genetically Separate populations defined by season of spawning (runs) and river. For example, there might be a Snake River spring run and a Snake River fall run of Sockeye. Note how the morphology changes when they return to spawn.
Salmon play important cultural, recreational, and ecological, roles. Even to the extent of significant return of ocean-based nutrients back to freshwater and the land.
Populations of wild salmon have seriously declined and some river runs have disappeared. Due to over-fishing, pollution, effects of dams. Now, climate change seems to be emerging as an important source of mortality, primarily from declining summer river flow. But, there are decadal cycles that make interpretation difficult.
Salmon from “farms” are replacing wild-caught salmon. Farms are now generally stocked with Atlantic salmon.
Problems with salmon farms • Fed on marine fish protein, so continue to affect wild fish stocks • PCB concentration is high because food is based on oily fish meal (why?) • Disease and parasites are a problem Can these problems be overcome??
Farm salmon may contain as much as 40X the amount of PCBs found in other food.
Salmon parasite (sea lice) on wild salmon near salmon farms (exposed) and far from salmon farms (less-exposed) Farm salmon carry heavy parasite loads.
Restoring a coastal ecosystem • Reduce nutrient run-off • Improve municipal waste treatment • Ban endocrine disruptors • Farm-raised fish??? • Change undesirable alternative stable ecosystem states