Fish Biomass: Northwestern Hawaiian Islands versus Main Hawaiian Islands:

a lesson on the Scientific Method and caring for the environment



Lesson’s Activities At a Glance:

The overall purpose of this unit is to have students complete a bar graph to represent actual biological data from the main Hawaiian Islands and the Northwestern Hawaiian Islands. The students will reach a conclusion as to how the data from the two locations compares. Finally, the students will discuss and form an opinion about what kind of protection the NWHI should have.


Appropriate Grade Levels: middle and high school


Subjects: Science--Biology (ecology)


Minimum Time Required for the Unit:

The unit should take about three 45-minute periods, with additional homework.


Hawaii Content and Performance Standards:


Grade 8:

Š      Science Standard 1; Benchmark 8.1.1 “Determine the link(s) between evidence and the conclusion(s) of an investigation”


Š      Science Standard 1; Benchmark 8.2.1 “Describe significant relationships among society, science, and technology and how one impacts the other”


High school:

Š      Science Standard 1; Benchmark BS.1.4 “Determine the connection(s) among hypotheses, scientific evidence, and conclusions”


Š      Science Standard 1; Benchmark BS.2.2 “Compare the risks and benefits of potential solutions to technological issues”










1.     Although this lesson is not a full lab activity, it is presented in the format of an investigation.


2.     BACKGROUND: Take as much time as you’d like to set the background for this lesson. You may want to begin by asking the students if there are any islands northwest of Kaua’i and Ni’ihau. Perhaps you would like to do a full geographical lesson on the NWHI. From that, lead a discussion, as much as you’d like, about the general ecology & wildlife of the NWHI. Perhaps you’d like to show a video, and/or have students visit NWHI website. Or, perhaps you’d like to have the students go into this lesson rather “blind” as to the beauty and wildlife presence of the NWHI!


3.     HYPOTHESIS: Help the students to understand that, although they don’t have any real personal experience with the NWHI and the marine life there, they should think about what sort of a place it is, in terms of human impact. From thinking about that, have each student form his/her own hypothesis as to what they expect the biomass of fish to be in the NWHI, compared to the main Hawaiian Islands (MHI). Stress at this point that they will not be graded higher if their hypothesis turns out to be right…or lower, if it turns out to be wrong. Although scientists should make EDUCATED “guesses,” they don’t know what the actual right answer is before they do an experiment! That’s why they’re doing the experiment!


4.     MATERIALS & METHOS: Once each student is committed to a hypothesis, tell the students to imagine that they are “ichthyologists,” or scientists who study fish. They are going on an expedition to all the Hawaiian Islands to collect data on how much biomass, or amount, of fish is found around the various islands. It might be fun to have different groups of students make up skits, with posters & props perhaps, to enact the REA methods; that might help the students to better envision the procedures!


5.     RESULTS: As much as you needed, guide the students in reviewing graphing skills. See the document “Graphing Techniques” for some pointers.

Š      Guide students to do a stacked bar graph for each island, with the herbivores at the bottom of the stack, other secondary consumers in the middle, and the apex predators on top. They can use colored pencils, and a key, to convey which part of the graph bar is which trophic level.

Š      Furthermore, tell the students that their X axis should be “Hawaiian Islands, NW to SE” with Kure closest to the graph’s origin and the Big Island of Hawai’i at the far right along the X axis. This will duplicate most maps, showing the Hawaiian archipelago going from NW (left side of map) to SE (right side of map).

Š      As the students complete their graph, they will “discover” that the NWHI has significantly more biomass, especially in the apex predator level, than the MHI. EXCITING!! The students have produced the same type of graph as professional scientists! As an option, you could even show the students a copy of “Contrasts in density, size, and biomass of reef fishes between the northwestern and the main Hawaiian islands: the effects of fishing down apex predators,” a scientific report by Alan Friedlander and Edward DeMartini, published in Marine Ecology Progress Series, Vol. 230: 253-264, 2002, to show the students. This document is available from NOAA’s Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve in Hawai’I Kai. Call Andy Collins, Education and Outreach Coordinator for the NWHICREF, at 397-2660, ext. 222.


6.     CONCLUSION: Assign the two questions and recommendation as a written homework assignment.


Š      In answer to the original question, in general, there is more fish biomass in the NWHI, as compared to the MHI.


Š      In addressing whether their hypothesis was right or wrong, a student could either be “right,” meaning the data supported his/her hypothesis, or “wrong,” meaning the data didn’t support his/her hypothesis. Stress to the students that most of the time in science hypotheses (plural of hypothesis) turn out to be only partly correct, if not entirely wrong. Therefore, their grade will not be based on the accuracy of their original hypothesis. In lab reports, they should never go back and change their hypothesis, after they’ve done an experiment; that would be dishonest science.


Š      In addressing the recommendation……


o      Put a line of tape on the floor, or stretch a rope, across the classroom from one wall to another. Explain that the tape/line represents the spectrum of public opinion about how to treat the NWHI:


--CLOSED: At one extreme, some people feel that the NWHI should be completely closed, period. Nobody should trespass on the NWHI: no scientists, visitors, or fishermen. There should be no fishing of any kind, no matter what species, size, season, or anything else. Furthermore, there should be no research ships going to the NWHI. No scientists or cultural practitioners should even visit out there. Keep all hands off the NWHI


--OPEN: At the other extreme are people who feel that anybody can go to the NWHI anytime they want. Scientists or tourists can go by airplane or by ship, if they can afford the cost of the ticket or boat fuel. Furthermore, fishermen know best. They have been fishing for generations, in some cases, and they feel they know how to control their fishing to best protect the fish populations. They should be allowed to fish any species of fish or lobster, of any size, at any season of the year, with any kind of fishing hooks and gear. There is no need for government regulation.


o      Have each student stand along the line, representing his/her own opinion. Remind the students that the line represents a “spectrum” of opinion; maybe there are some opinions that are in-between the two extremes stated above.


o      After students position themselves, call upon volunteers or selected students to explain their opinion and why they are standing where they are. Accept all student opinions; encourage understanding of conflicting opinions. Some students may come from families with strong conservation leanings; others may come from fishing or seafood restaurant families.


o      Depending upon the maturity of the students and if time allows, perhaps show videos, newspaper clippings/inserts, or websites that present different opinions. In education, it is important to encourage students to grapple with information to form their own opinions. However, in my opinion it would be the teacher’s responsibility to tell the students that ichthyologists don’t know all the reasons why there is so much fish biomass in the NWHI. Neither do they understand all the reasons for the great number of NWHI apex predators.


o      Author: Barbara Mayer,