Science Behind Sustainable SeafoodSolving the Ecosystem Problem

Alaska Fisheries Science Center

What is the effect of removing a primary food source in Alaskan waters?

2

Organisms are interconnected by what they consume.

Free write• Write down what comes to your mind when I say

the word food web.• Underline three things you wrote which are

important to a food web

http://www.afsc.noaa.gov/REFM/REEM/Manuals/Default.htm

Krill video

• http://video.nationalgeographic.com/video/animals/invertebrates-animals/crabs-lobsters-shrimp/krill/

• What animals ate krill in the video? • Describe a food chain they saw in the video• How does a food web differs from a food chain?

http://jonbowermaster.com/blog/2009/01/krill-baby-krill/

Parts of the Bering Sea ecosystem• The sun’s energy is converted into nutrients for plants through a

process called photosynthesis.

• Phytoplankton are microscopic plants that drift in the ocean. They are at the base of all food chains in the Bering Sea

• Zooplankton are microscopic animals and are found near the bottom of the Bering Sea food chain. • Zooplankton like amphipods and copepods are prey to many

small fish.• Big baleen whales eat zooplankton (Humpback whales)

Parts of the Bering Sea ecosystem• Small fish like herring and juvenile walleye pollock can be

both predator and prey since they sit in the middle of the food chain.• Feed on zooplankton

• Adult walleye pollock can also be both predator and prey. they are not the top predator. • Feed on krill and juvenile pollock

• Humans are at the top of the food chain.

• In the Bering Sea, northern fur seals are also a top-predator• Feed on walleye pollock, Atka mackerel and Pacific cod

Stomach data• To better understand the relationships between predators

and prey in the Bering Sea, scientists at the Alaska Fisheries Science Center annually collect and examine the stomachs of thousands of fish.

• What they see tells them a lot about how important all species in the Bering Sea are to maintaining balance within the entire ecosystem.

http://www.afsc.noaa.gov/REFM/REEM/Manuals/Default.htm

year 1999stomachs 2839hauls 164

Prey name Percent weight zooplankton 56.96pelagic invertebrates 4.34

squids 2.24forage fish 8.45flatfish 0.44rockfish 5.5other fish 5.62pollock 2.19benthic invertebrates 4.06shrimp 14.47crab 0.54glopp 0.69

Sum 105.5

Walleye Pollock

WALLEYE POLLOCK STOMACH DATAhttp://www.afsc.noaa.gov/species/pollock.php

year 1999stomachs 1401hauls 136

Prey name Percent weight zooplankton 3.94pelagic invertebrates 0.41

squids 0.74forage fish 2.73flatfish 6.79other fish 9.4pollock 24.29cod 0.72arrowtooth 0.02benthic invertebrates 14.11shrimp 6.99crab 29.21glopp 0.64Sum 99.99

Pacific cod

PACIFIC COD STOMACH DATA

http://www.afsc.noaa.gov/species/Pacific_cod.php#

year 1999stomachs 148hauls 39

Prey Name Percent Weightzooplankton 8.47forage fish 4.47

flatfish 0.05other fish 16pollock 60.4benthic invertebrates 1.16shrimp 5.91crab 3.51glopp 0.02

Sum 99.99

Arrowtooth flounder

ARROWTOOTH FLOUNDER STOMACH DATAhttp://www.dfw.state.or.us/MRP/finfish/sp/flatfish.asp

year 1999stomachs 232hauls 38

Prey Name Percent Weightzooplankton 6.31pelagic invertebrates 0.03

flatfish 0.27other fish 0.94pollock 15.63benthic invertebrates 52.19shrimp 12.06crab 12.31glopp 0.26

Sum 100

Flathead sole

FLATHEAD SOLE STOMACH DATAhttp://www.dfw.state.or.us/MRP/finfish/sp/flatfish.asp

Stomach Data DiscussionWALLEYE POLLOCK, PACIFIC COD,

ARROWTOOTH FLOUNDER, FLATHEAD SOLE

•Which animals have similar diets?•Which prey species occurs in all of the diets?•Which prey species occurs in most of the diets?•Which predator has the most different or specialized diet?

Why do you think a predator has multiple types of prey?

1. What advantages would more prey types in a diet give an animal?

2. Do Pacific cod eat the same prey in all 3 places?3. Do cod eat the most of the same prey in all 3 places?

Make your own food web

http://access.afsc.noaa.gov/REEM/WebDietData/DietTableIntro.php

http://www.sciencedirect.com/science/article/pii/S096706450700197X

Bering Sea Ecosystem

U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 18