Student Handout: Overfishing of Southern Bluefin Tuna
Southern bluefin tuna (Thunnus maccoyyii) is a very large species of tuna that inhabits the cold temperate waters of the southern Atlantic, Pacific and Indian Oceans. It is estimated that females mature and are able to spawn at approximately 1.5 meters in length, which corresponds with an age of 8 years. Japan, Australia, and New Zealand catch the majority of southern bluefin tuna. The fishing methods used include longline fishing and purse seining. Both methods have impacts on wildlife, including seabirds, sharks, other fish, turtles and marine mammals. Historically, it has been considered a delicacy and has been fished primarily for use in the raw-fish market of Japan as sashimi. The southern bluefin tuna is currently listed as critically endangered, meaning that it is at extremely high risk of become extinct in the immediate future.
The purpose of this project is to explore the characteristics and life history of the southern bluefin tuna and examine the effects of fishing practices on the bluefin tuna population and other ecologically related species.
1. Visit the following websites to learn about the ecology and fishing practices of the southern bluefin tuna:
· Commission for the Conservation of Southern Bluefin Tuna (CCBST)
· ARKive Images - Southern Bluefin Tuna
· Australian Antarctic Division - What are longline fisheries?
· Australian Antarctic Division - Seabirds affected?
· FIGIS - Fishing Technique Fact Sheet - Tuna Purse Seining
2. After reading the information provided by the websites, answer the questions on part A of the student worksheet.
3. Download the Annual catch data by flag or gear from 1952 to 2004 inclusive (excel format) from the CCBST website.
4. Using the Global Catch by Country data, construct a line graph of the total catch per year from 1952 - 2004.
5. Answer the questions on part B of the student worksheet.