The University of British Columbia

Trends in Global Jellyfish Populations
Supervisors: Daniel Pauly & Evgeny Pakhomov

Although anecdotal evidence seems to point to a global increase in jellyfish populations, the lack of longterm data in most ecosystems makes it difficult to prove an increase scientifically. My research involves synthesizing reports on jellyfish abundance in order to examine global trends.

Reports of jellyfish interfering with human activities are on the rise in many locations around the world. Ironically, humans may be responsible for this apparent increase in jellyfish blooms. There is evidence to show that fishing, pollution, aquaculture, global warming, and coastal development can all create conditions which favour jellyfish over fish. In addition to affecting tourism by stinging swimmers, jellyfish can interfere with fishing activities and clog industrial cooling intakes, resulting in significant economic losses.
The fact that jellyfish can bloom in huge numbers is due to their fascinating ability to reproduce both sexually and asexually. Many species of jellyfish spend their early life as a polyp that lives on the ocean floor, which can survive harsh conditions. When environmental conditions change (potentially as a result of human activity) it switches the polyps into jellyfish-production mode and they can bud off massive numbers of jellyfish ephyrae, resulting in a bloom.
Some ecosystems may enter a ‘jellyfish spiral', where jellyfish will continue to dominate an altered food web. Once established, jellyfish can prevent the recovery of fish, as they reduce the amount of food available or eat fish eggs and larval fish directly.
As humans populations continue to increase and impact the marine environment, jellyfish may increase with us. Finding uses for jellyfish products, including food and medicines, has been suggested as one strategy to deal with increasing numbers. Although the value of jellyfish fisheries is increasing, this solution is concerning, as it can lead to even further increases of jellyfish. Indeed, we may need to decide now whether or not we want our children to be eating jellyfish burgers. If our behaviour doesn't change, they might not have a choice.

Publications

Brotz, L., M. Lebrato, K.L. Robinson, M. Sexton, A. Sweetman, K. Pitt, & R. Condon (2011) Implications of increased carbon supply for the global expansion of jellyfish blooms. Limnology & Oceanography Bulletin (20): 38-39.

Brotz, L. (2011) Are jellyfish the food of the future? INFOFISH International (4): 60-63.

Brotz, L. (2010) Gelatinous Seas. Discovery, Nature Vancouver (39): 14-20.

Brotz, L. (2010) Mi Querida Argentina (My Beloved Argentina). Sea Around Us Project Newsletter (60): 1-3.

Brotz, L. (2010) What's for dinner? Sea Around Us Project Newsletter (57): 4-5.

Media Coverage

Jellyfish Swarms: Menacing or Misunderstood? LiveScience, October 20, 2010.

Interview - Fisheries Broadcast, CBC Radio Newfoundland, August 20, 2010.

Tofu of the Sea. Edible Vancouver (12): 18-19, Summer 2010.

Invasion of the Holiday Snatchers. The Economist.com, March 28, 2008.