Transcript 5.1-MB-HUMANIMPACT-Overfishing

Human Impact on Marine Life
Over Fishing
Marine Biology
Warm Up
1. How does fish get from the ocean to your
plate?
2. What do you believe is the safest way to
fish in the ocean without harming the
ecosystem?
3. Name some types of fishing that you think
could be illegal.
4. Do your best to explain/guess what a
hammerhead shark looks like.
Sea of Cortez
Hammerhead Sharks
Humbolt Squid
Hammerhead Shark Video
(6.03 Minutes)
Use this video to answer the following questions on
Hammerhead Sharks:
1. What body of water are we researching?
2. Where do hammerheads typically swim in the ocean?
3. What organisms are prey to hammerhead sharks?
4. How do they help to keep the ecosystem in balance?
5. What are the hammerhead sharks being hunted for?
6. What is the trophic level of hammerhead sharks?
7. Use the process of cellular respiration in order to explain
why carbon dioxide gas can be poisonous?
Humbolt Squid Video
(6.45 Minutes)
• What is the major problem with declining numbers of
hammerhead sharks? What effect does it have on the
ecosystem here?
• How many squid live in this area now?
• Why has the squid population grown so much?
• What makes them such great hunters?
• How long to they live?
• How big are they?
• How fast can they swim?
• Explain how the squids are able to light up under water.
What is specialized about their cells?
• Why do you think they are called “invertebrates”? (Think
about vertebra)
Overfishing Essay
Use the triangle to
explain how an
ecosystem would be
effected if Sea Bass
were overfished.
Make sure to include:
•identify the trophic level each species
occupies
•explain how these species will be effected if
the Sea Bass population decreases.
HSA Public Release Question:
The energy pyramid below shows the flow of energy through the
organisms in a kelp forest ecosystem in the Pacific Ocean. Use the
energy pyramid to answer the following.
How would the populations of other organisms in the energy
pyramid be affected if the population of sea urchins suddenly
decreased?
A. Both the kelp and the sheephead populations would increase.
B. Both the kelp and the sheephead populations would decrease.
C. The kelp population would decrease, and the sheephead population
would increase.
D. The kelp population would increase, and the sheephead population
would decrease.
Overfishing Practices
LOOKING CLOSER AT
HOW FISH ARE HUNTED
IN THE OCEAN.
BY-CATCH – ALL THE
ANIMALS CAUGHT IN NETS
OR ON LINES WHICH ARE
UNINTENTIONAL AND ARE
USUALLY DEAD AND
THROWN OVERBOARD.
Look at the picture.
List as many types of species
that you can think of.
Do you think this is a healthy
way to fish? Why or why not?
Hammerhead and Stingray =
__________ to __________
Relationship
What are Sting Rays prey to?
Use this information to help
explain how/why this sting ray
was caught.
A True Save!
• http://www.youtube.com/watch?v=4lrKXC
qnBSI
OVERFISHING PRACTICES
Take Cornell Notes on the following practices
for commercial fishing:
GILL NETS
DRIFT NETS
LONGLINES
PURSE SEINE NETS
TRAWLERS
Which of the following is a gill net and which is a drift net? Make a
guess!
Gill Nets
Drift Nets
Drift Net Fishing
Drift net fishing on the high seas beyond the exclusive economic
zone of any nation was banned in 1991 by the UN General
Assembly because of its potential to harm all fish stocks and
marine animals. Fines for drift net fishing are significant. This
type of fishing involves the use of a net, up to twenty miles in
extent, that is generally anchored to a boat and left to float with
the tide. The net is set out at night and pulled in at sunrise,
making it difficult for aircraft surveillance to catch them in the
act. On average, a drift net vessel can scoop up half a ton of fish
per day. This often results in an over harvesting and waste of
large populations of non-commercial marine species (by-catch)
by its effect of “sweeping the ocean clean”. The by-catch also
includes marine mammals and seabirds.
Summarize this paragraph. What is being explained about laws
regarding fishing in the open sea?
Drift Nets
Drift Nets
Nicknamed "walls of death" these nets are made of a
very strong monofilament (single strand) nylon mesh,
and each net is between 8 - 12 meters deep and may be
as long as 65 km, although usually between 32 - 40 km.
The nets are often put into the sea at night, where they
drift with the current, catching and killing anything that
gets in their way, like huge underwater spiders' webs.
This method of fishing is extremely wasteful. Not only is
an estimated 40% to 50% of each catch lost when the
net is hauled in, but uncounted numbers of fish are
injured in the net and may escape only to die later.
These nets also catch many dolphins, whales, seals,
turtles and seabirds which cannot easily see the almost
invisible netting.
Use the following pictures in order to explain how using nets to
fish can be very harmful to the ecosystem and individual species.
Think of a basic ecosystem.
Sharks are consider to be ________________ and top
__________________.
Use this information to explain how the loss of sharks could
harm the ocean ecosystem.
Long Line Fishing
Longline fishing is a technique used to catch fish in open waters,
including those who live near the sea floor. A longline includes a main
fishing line up to 100 kilometers in length, with secondary lines
branching off it, each set with hundreds or thousands of barbed, baited
hooks. This technique is used in international waters, as well as waters
controlled by the United States, South America, Australia, New Zealand,
and southern African countries, and targets fish species such as tuna,
swordfish, and Patagonian toothfish.
Trawl Fishing
What is wrong with this type of fishing?
Trawl Fishing
Trawl Fishing
There are devices to make fishing safer for all species in the ocean!
Look at the picture below… what is happening?
The Turtle Excluder Device or TED is a grid of bars with an opening
either at the top or the bottom. The grid is fitted into the neck of a shrimp
trawl. Small animals like shrimp slip through the bars and are caught in
the bag end of the trawl. Large animals such as turtles and sharks, when
caught at the mouth of the trawl, strike the grid bars and are ejected
through the opening.
Purse Seine Fishing
Orange Roughy Research
• Page 575
• Conduct Research on the Orange Roughy
• Prepare a summary of this article. Make
sure that your article includes answers to the
3 questions at the close of the article.
Personal Essay: Commercial Fishing
• What are your thoughts about commercial
fishing?
– Explain how their “stance” on commercial fishing.
– If you were in change it, what would you do differently?
• Provide at least one reference to what we’ve
covered in class to back up your reasoning
(example-watching the video about
Humpback Whales made me realize).
Fish Research NOAA’s guide to fish nutrition etc.
http://www.fishwatch.gov/index.htm