The recovery of Atlantic halibut: a large, long-lived, and exploited marine predator

Published source details Trzcinski M.K. & Bowen W.D. (2016) The recovery of Atlantic halibut: a large, long-lived, and exploited marine predator. ICES Journal of Marine Science, 73, 1104-1114.
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This study is summarised as evidence for the following.

	Action	Category
	Introduce an overall catch limit (quota cap or total allowable catch) by fishery or fleet Action Link

Introduce an overall catch limit (quota cap or total allowable catch) by fishery or fleet

A before-and-after study in 1970–2010 of an extensive area of seabed in the Northwest Atlantic Ocean, Canada (Trzcinski & Bowen 2016) reported that management actions that included reductions in catch limits (total allowable catch), resulted in a decrease in fishing mortality and an increase in biomass of Atlantic halibut Hippoglossus hippoglossus over a period of 10 years, compared to the previous period. Data were not tested statistically. During the period of management activity from 1988–2009, both a steep increase in fishing mortality and a sharp decline in halibut spawning stock biomass since 1984 were halted: fishing mortality decreased to below targeted levels for sustainable harvest, while biomass gradually increased to well above target limits for sustainable harvest (data reported as trends in the ratios of fishing mortality and biomass to the target sustainable fishing mortality and biomass). In 1988, the first halibut total allowable catch limit was set (3,200 t) for fishing on the Scotian Shelf and southern Grand Banks and reduced in small steps to 850 t in 1994. A minimum size limit (81 cm) was introduced in 1988, fully implemented by 1994. Following signs of population recovery, the total allowable catch was increased again in small steps beginning 1999. Halibut size and age data were obtained from commercial catches and catch-rate data from groundfish and halibut surveys. The data were used in a stock assessment model that estimated population dynamics and exploitation rates over the period 1970–2010.

(Summarised by: Natasha Taylor)