Human impact on the marine environment extends to many areas and is frequently very detrimental. In particular, the fishing industry affects both target (wanted) and by-catch (non-wanted) species as well as threatening the stability of many habitats. By-catch includes any marine organisms which are inadvertently captured and/or killed through fishermen's activities. It can range from something as small as a snail to dolphins and porpoises. The proportion of by-catch species to target species is frequently as great as 100:1. The target species itself also suffers due to constant overfishing, which disallows the population to sustain its numbers through reproduction. Because populations are fished above their maximum sustainable yields (highest number fishermen can catch of one species without causing population desecration), they can be driven to extinction over time. Finally, habitat destruction occurs during fishing processes such as trawling (form of fishing where a net is dragged on the ocean bottom). Thus human impact extends far beyond the species that are targeted for consumption and threatens the entire marine ecosystem.

Overfishing Activity

• dowel rods
• rulers
• dixie cups
• Swedish fish (candy fish, app. 1-2 lbs.)
• tape

Habitat Destruction Activity

• fish
• aquarium
• plastic aquarium plants (50)
• different colored jacks (20)
• small fish nets
• sanded/rocky bottom

By-catch Activity

• various small-sized plastic fish
• marine animals
• large bucket
• dixie cups

Engage: Prior to beginning the three conservation activities, have students list all the marine species that they consume. In small groups, allow them to brainstorm about the ways in which fishing could be harmful to the marine environment outside of these species.

Preparation: Prior to class, the instructor should collect the required materials and familiarize themselves with the goals and background information supplied for the activities. Also, it is recommended to set up each activity in different corners of the room to avoid congestion. Overfishing activity: collect all materials. Habitat destruction activity: set up tank with rock/sand and plants, set up jacks randomly in rocks, fill with water. By-catch activity: place fish in bucket.

Activity 1: Overfishing
Each student should tape dowels to table and tape two dixie cups to ends of rulers á Label one cup "consumption" and one cup "population" á Ruler acts as balance on dowel rod á Each student starts out with 20 fish á Each student is allowed to choose however many fish they want in the consumption cup á For remaining fish, multiply that number by growth rate number 1 (given by teacher)...this represents the number of offspring produced by remaining population á Place new fish into "population" cup á Compare to see if it is balanced á Repeat with different growth rates

Activity 2: Habitat Destruction
Each jack is considered a target species and is worth 10 points á Each student will get 2 minutes to grab as many jacks as possible with the fish nets á Each plant knocked over is valued at -5 points á Determine final scores

Activity 3: By-catch
Each student receives a cup á A large bucket containing the fish is placed above the students' heads á Bucket should contain 20% target species compared to number of bycatch á Each student scoops out a cupful of plastic fish á One specific fish (target fish) will be valued at 5 points á The remaining species (by-catch) will be valued at -2 points á Determine final scores