Alaska Map. Alaska Geography Facts I. 663,268 sq miles, including territorial waters 21% of the area of the entire lower 48. Bounded by: Gulf of Alaska Bering Sea Chukchi Sea Beaufort Sea (Arctic Ocean). Alaska Geography Facts II. Width: West - East 808 miles
663,268 sq miles, including territorial waters
21% of the area of the entire lower 48.
Gulf of Alaska
Beaufort Sea (Arctic Ocean)
Width: West - East 808 miles
Length: North - South 1,479 miles
Controlled by Federal Gov’t: 65% total area
Shoreline: 34,000 miles
Two Time Zones: Alaskan Aleutian
Population (2006) 670,053
Coastline Alaska: 33,904 miles
Coastline Lower 48: 54,729 miles
Alaska has 62% total Tidal Coastline of US
Area of Continental Shelf in Alaska is huge
Most fish are caught near shore and on the continental shelf
Two Major Tectonic Plates
North American Plate & Pacific Plate
Understanding Plate Interactions Important
Transform Boundary - sliding along
Divergent Boundary - mid ocean ridge
Convergent Boundary - subduction zone
North American Plate: NA Craton is the Core
NA Craton Rock: North/East corner of Alaska
Remainder of Alaska is accreted terrain, rocks from further south that have been sequentially transported to Alaska by Plate Tectonics. Many different terrains.
Continental Shelf is part of the Continental Plate
Kula Plate - Oceanic plate subducted under NA but a last fragment accreted to shallow Bering Sea shelf.
Oceanic versus Continental Plates
Ocean Spreading Centers
Volcanic Activity - Black Smokers
Continental Plates Override Oceanic Plates
Oceanic Plates dive into Subduction Zones
Gulf of Alaska
Southeast Alaska Inland Waters
Gulf of Alaska Coast
Western Gulf of Alaska
Yukon Kuskokwim Delta
Seward Peninsula Norton Sound
More than 3 million lakes in Alaska
Marshland & Wetland Permafrost Account for
188,320 sq mi of territory
Alaska has 12,000 rivers, many with salmon runs
51 Tidewater Glaciers
Many Glaciers feed Rivers, Marshes and Lakes
What does this have to do with fishing?
1. Nutrients eroded from rock feed food web
2. Ocean spreading centers & nutrients
3. Volcanism from subducted plates & nutrients
4. Freshwater Habitat for anadromous fish
5. Seamounts bring huge diversity
6. Fish Predators live on land
Latitude: 51° 20’ North to 71° 50’ North
Longitude: 130° West to 172° East
Record High Temp: 100°F Fort Yukon
Record Low Temp: -80°F Prospect Creek
Sea Ice: Cook Inlet, Bering, Chukchi and Beaufort Seas.
What will be the effects of Global Warming?
1.Warmer water species will migrate north
2.Colder water species will migrate north
3. Ocean currents will change
4. Potentially profound effects on species distribution and abundance
El Niño &La Niña:
Short term climatic fluctuations
1997 El Niño
1. Weird milky algal bloom in Bering Sea visible from space.
2. Implicated in protist infestations of many
PDO is a pattern of Pacific climate variability that shifts phases on at least inter-decadal time scale, usually about 20 to 30 years
PDO provokes a faunal regime shift, where the animals found most abundantly change in cold to warm and warm to cold shifts.
Cold - crab, shrimp, herring, capelin
Warm - cod, pollock, salmon
Cold Phase Warm Phase
The PDO Index is calculated by spatially averaging monthly sea surface temperature of the Pacific Ocean north of 20°N. The global average anomaly is then subtracted to account for global warming. Only October to March values are used because year-to-year fluctuations are most apparent during the winter months.
Nutrient Input (Limiting Minerals)
1. Deep-Water Upwelling
2. Loess - Wind Borne Dust
3. Volcanic Ash
4. Tidewater Glaciers
5. Suspended Riverine Sediments
6. Nutrients Released at Ice Edge
Algae Require Mineral Micro-Nutrients
1. Growth of some algal species limited by nutrient availability (eg. Silica & Iron .
2. With appropriate nutrients, temperature and light regulate bloom growth rates.
3. Long days in late spring can promote huge blooms.
4. Single cell algae are the base of marine food chains.