How does eating fish impact others? (Secondary) - Lesson Five

• Social Studies
• History
• +3
• 9th,10th Grade

Introduction

Lesson Five – How does overfishing impact the global ecosystem? This lesson covers how overfishing of specific species impacts an ecosystem. Learning activities:  Discussion and research on the impacts of whaling on the global ecosystem.

Instructions

Time: 45 minutes

Contact: [e-mail]
© Sea Shepherd 2022

Lesson 5 - How does overfishing impact the global ecosystem?

This lesson is provided by Sea Shepherd.  Sea Shepherd was founded in 1977 and is a marine conservation organisation working to protect the oceans and marine wildlife.  Sea Shepherd works globally on a range of issues impacting the oceans, running numerous direct action campaigns each year. 

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How do you impact the
global ocean ecosystem?

Ask students: How they think they impact the global ocean ecosystem?
Answers might include – pollution, climate change or contributing to the demand for fish (resulting in overfishing).

Illegal Fishing

Illegal fishing means that the fishermen enter the territorial waters of a country or regulated marine zone without permission or without a license for the fish they intend to catch.

They are stealing from these waters.

OVERFISHING:

the depletion of fish populations by excessive fishing.

There are many issues but let’s focus on overfishing and how eating fish impacts the ecosystem.
Overfishing means the depletion of fish populations by excessive fishing.
Ask students: “Who sets the requirements for fishing and issues licenses?”
“What basis is used to decide on the quota/quantity of fish that can be taken?”

In setting quotas what
factors could cause authorities
to overestimate fish populations?

We already know from looking at the herring fishery in Canada, that authorities can overestimate the populations of fish.
Ask students: “Which factors could cause authorities to overestimate fish populations?”
    Don’t listen to scientists.
    Failure to take into account changing environmental issues – pollution, climate change, ecosystem changes.
    Base catches on market needs (demand) and ability of fishermen to make a living, rather than fish populations.

Introduction to IUU fishing and the impact of overfishing.

Migratory species

Many species move between countries and international waters.
How do you think that this might impact fish numbers and fishing regulations?
    Think about how fishing in nursery areas might impact the species and ecosystem.
    Think about how illegal fishing in international waters would impact numbers.

Introduction to IUU fishing and the impact of overfishing.

How do whales impact the global ecosystem?

As an example, we can have a look at whales.  Whales are highly migratory, with the majority heading to the Southern Ocean each southern summer to feed, before heading north to their breeding and nursery areas.
In the 1900’s over 2 million whales were killed in the Southern Ocean as part of commercial whaling operations.  This pushed many whale species to be classified as endangered.

Introduction to IUU fishing and the impact of overfishing.

Impacts of whaling

Ask students what role do whales play in the global ecosystem?
    Think about how whales contribute to our oxygen supply /carbon reduction. Their role in upwelling and providing nutrients for phytoplankton.
The massive reduction in whale numbers in the Southern Ocean potentially contributed to two issues:
    Dramatic reduction in phytoplankton numbers with the reduction in nutrient exchange.
    This led to increased levels of carbon in the southern hemisphere that have contributed to the reducing ozone layer in this region.

This video summarises the issues.
https://www.youtube.com/watch?v=b_SK9-Zr71g

www.seashepherdglobal.org

LEARNING ACTIVITIES

Refer Teachers Guide for Learning Activities.