A study of the historical bluefin tuna (Thunnus thynnus) fishery in northern Europe may provide new directions for management and conservation of this increasingly rare species in other regions of the world.

Human use of fish species on a commercial scale is well known to have the potential to change fish populations and even entire ecosystems. High demand for certain seafood products can place enormous pressure on the population and, in some cases, even decimate it. However, modern management efforts seek to sustain harvests of commercially exploited species and prevent detrimental effects to fish species populations. In order to accomplish this task, managers require the ability to detect change in abundance over time, and this requires a baseline state from which to compare potential changes. This baseline is used to represent the state of the population under conditions of no or very low exploitation.

North Atlantic bluefin tuna (Thunnus thynnus) are an important commercially exploited species. This importance as a high value fishery product extends back in history at least 100 years. The fishery itself is now extinct both commercially and recreationally. However, fisheries managers often struggle to answer the question of why and how this happened. The boom to bust period of this fishery was very short and predated modern fisheries management methods. Thus, very little useful information has ever been compiled to describe what happened. By compiling and analyzing historical data and information from all the countries in Northern Europe where bluefin tuna was commercially exploited, researchers from the History of Marine Animal Populations project of the Census of Marine Life have described the total landings and fleet data and gear types associated with this fishery from 1900-1950.

This study determined that bluefin tuna has been present in Northern European waters for hundreds of years and was relatively abundant in the region during the first few decades of the 1900s. In the late 1930s-1940s commercial fishing of this species industrialized and increased dramatically due largely to increased demand and advances in fishing methods and processing capabilities. The bluefin tuna fishery in Northern European waters actually peaked over 30 years ago, and since the 1970s the species has been extremely rare in the region. This study provides information about the stock that is absent from existing officially reported data (maintained by the International Commission for the Conservation of Atlantic Tuna) and extends our knowledge of the species in the region. Hopefully, this can help fisheries managers gain insight into the crash of the population and the failure of it to recover or return. This information could prove critical to future efforts in managing not just bluefin tuna, but many commercially targeted species worldwide.

Research Location: In the North Sea, Norwegian Sea, Skagerrak, Kattegat, and Oresund in hte Northeast Atlantic Ocean.

• What: A study of the historical bluefin tuna (Thunnus thynnus) fishery in northern Europe may provide new directions for management and conservation of this increasingly rare species in other regions of the world.
• Who: HMAP Scientists --> B.R. MacKenzie and R.A. Myers
• When: 2007
• Where: The Norwegian Sea, the North Sea, Skagerrak, Kattegat, and Oresund
• How: Analysis of historical data and documents
• References: MacKenzie, B.R. and R.A. Myers. The development of the northern European fishery for north Atlantic bluefin tuna Thunnus thynnus during 1900-1950. Fisheries Research(2007). Doi: 10.1016/j.fishres.2007.01.013 (In Press)