SEMINAR: MBF602 9/2/11 S/A 103, 12 NOON Francesca Forrestal: Global Tuna and Ecological Implications of Teleost Bycatch

["Maxine Williams" <mwilliams@rsmas.miami.edu>]

MBF602 9/2/11 S/A 103, 12 NOON Student Speaker Francesca Forrestal

 

Global Tuna Fisheries and Ecological Implications of Teleost Bycatch

 

The five major species of tuna that comprise the global tuna fisheries are albacore (Thunnus alalunga), bigeye (Thunnus obesus), bluefin (Thunnus thynnus, Thunnus orientalis, Thunnus maccoyii), skipjack (Katsuwonus pelamis) and yellowfin (Thunnus albacores). Despite their highly migratory nature, each of these stocks is managed independently by five regional fishery management organizations (RFMOs). The combined global catch in 2009 amounted to 4.38 million tonnes and has been relatively stable since 2002. Skipjack represent 57% of the catch, followed by yellowfin (26%), bigeye (9%), albacore (6%) and bluefin (1%). Most of this tuna is caught by purse seines set on either free-swimming schools or on those associated with various floating objects, including logs, marine mammals and man-made (fish aggregating devices) FADs.

The use of artificial FADs has greatly expanded in recent decades. While skipjack tuna are usually targeted on FADs, juvenile yellowfin and bigeye tuna are unintentionally caught in the nets. Removals of these immature fish can result in a reduction of the potential yield of the fishery and a decrease in the spawning stock biomass (SSB) of tuna. In addition to non-target tuna species, bycatch from FAD-associated fisheries also includes numerous other teleost species, including billfish, triggerfish, mahi-mahi, rainbow runner and wahoo. The ecological impacts of the removals of these fish are, as of yet, poorly quantified. However, the removal of this non-target biomass has the potential to significantly influence the surrounding ecosystems as well as the food-security of nearby costal states. Field and laboratory studies will be conducted to characterize the quantity, composition, ecological role, and survivability of this bycatch. These data will be used to parameterize a multi-species trophic model to provide insight into ecosystem-level responses to tuna fisheries and, potentially, help evaluate the need for bycatch mitigation.

 

BSc. Marine Biology, UC Santa Cruz May 2006

MSc.  MAF, University of Miami June 2010

Entered Program:  Fall 2010

Advisor:  Dr. David Die