Is current management of the Antarctic krill fishery in the Atlantic sector of the Southern Ocean precautionary

Abstract

This paper explains the management of the Antarctic krill (Euphausia superba) fishery in the Atlantic sector of the Southern Ocean, and current knowledge about the state of the regional krill stock. In this region, krill fishing is permitted in an area of approximately 3.5 million km2 which is divided into four subareas (labelled Subareas 48.1 to 48.4) for management and reporting purposes. The effective regional catch limit (or ‘trigger level’), established in 1991, is 0.62 million tonnes year–1, equivalent to ~1% of the regional biomass estimated in 2000. Each subarea has also had its own catch limit, between 0.093 and 0.279 million tonnes year–1, since 2009. There is some evidence for a decline in the abundance of krill in the 1980s, but no evidence of a further decline in recent decades. Local-scale monitoring programs have been established in three of the subareas to monitor krill biomass in survey grids covering between 10 000 and 125 000 km2. Cautious extrapolation from these local monitoring programs provides conservative estimates of the regional biomass in recent years. This suggests that fishing at the trigger level would be equivalent to a long-term exploitation rate (annual catch divided by biomass) of <7%, which is below the 9.3% level considered appropriate to maintain the krill stock and support krill predators.
\nSubarea catch limits exceed 9.3% of conservatively estimated subarea biomass in up
\nto 20% of years due to high variability in krill biomass indices. The actual exploitation
\nrate in each subarea has remained <3% because annual catches have been <50% of the
\ntrigger level since 1991. Comparison with the 9.3% reference exploitation rate suggests
\nthat current management is precautionary at the regional scale. The subarea catch limits
\nhelp prevent excessive concentration of catch at the subarea scale. Finer-scale management
\nmight be necessary to manage the risk of adverse impacts which might occur as a
\nresult of concentrated fishing in sensitive areas or climate change. Frequent assessment
\nof the krill stock will enhance CCAMLR’s ability to manage these risks. Continuing the
\nlocal monitoring programs will provide valuable information on krill variability, but more
\ninformation is required on how the monitored biomass relates to biomass at the subarea
\nand regional scales.