Date of Award

1993

Degree Type

Major Paper

Degree Name

Master of Arts in Marine Affairs

Abstract

The interaction of the herring (Clupea harengus) with the oil and gas industry in the North Sea is reviewed. The population crash of the herring in the early 1970's and the subsequent closing of that important fishery between 1977 and 1983 has drawn considerable attention to the influences, both biotic and abiotic, affecting the recruitment to the North Sea stock. Current accepted theory points to a change in oceanic current and the subsequent decrease in salinity in the North Sea region, resulting in a change in plankton availability for larval herring as the cause of the recruitment failure during the 1970's. The vulnerability of the herring population to large fluctuations in recruitment makes the maintenance of this fishery a difficult prospect. Clupeiod species, in general, which exhibit schooling behavior as well as wide fluctuations in year class strength are far more susceptible to overfishing than are commercially important demersal species (e.e. gadoids - cod, haddock) since a significant portion of a school may be removed in a single net haul leaving behind a population that may be removed in a single net haul leaving behind a population that may not be able to rebound. This is especially true if intense fishing pressure occurs during a period of a natural trough in population fluctuations. The oil industry in the North Sea has shown steady increases in production over the last 5 years and analysts are predicting a continuation of the present trend. Hydrocarbons have been shown to have negative effects on various species, including herring, in particular, the larval stages. A combination of naturally occurring reductions in larval numbers due to hydrographic changes and reductions due to hydrocarbon effects may result in dramatic stock changes before fishing quotas and hence fishing pressures can be altered. Further research along with insightful management is needed to better understand the dynamics of North Sea herring by itself as well as with the added parameters resulting from the oil and gas industry.