The Rise and Fall of Humboldt Squid Bycatch in the At-Sea Pacific Hake Fishery

The at-sea Pacific hake fishery is made up of motherships, which receive catch from a fleet of smaller catcher vessels, and large catcher-processors, operating off the Washington and Oregon coasts. The Northwest Fisheries Science Center administers the At-Sea Hake Observer Program which deploys two fisheries observers on each vessel for real-time data collection, including species composition sampling for bycatch data.  The surprising appearance in 2004 of Humboldt squid (Dosidicus gigas) bycatch in the at-sea hake fishery left scientists and fishers scratching their heads.  The appearance coincided with the geographic expansion of Humboldt squid in the last decade, both north and south along the North and South American coast lines. Various authors suggest the expansion is a result of changing ocean conditions coupled with Humboldt squid’s ability to quickly exploit niches.  From 1991 to 2003 the total bycatch of all squid species within the at-sea hake fishery was low, averaging just 0.03% of the total catch. From 2004 to 2007, squid bycatch increased from the historic average of 0.03% to 0.6%, with overall squid catch for this period averaging about 900 mt year^-1.  During that same period bycatch of other species decreased to lower than average values.  Beginning in 2006, following the recognition of Humboldt squid as the major component of overall squid bycatch in the at-sea hake fishery, observers were directed to identify Humboldt squid to the species level.  In 2008, Humboldt squid bycatch rose to 2,800 mt or 1.5% of the total catch. Humboldt squid bycatch rose again in 2009 when 4,400 mt of bycatch were recorded, representing 5.7% of the total catch in the at-sea hake fishery.  This fishery has an historic overall bycatch rate of less than 2%, so this level of bycatch was unprecedented.   Then in 2010, squid bycatch declined to just 0.2% of total catch (223 mt). Further investigations into the rise and fall of Humboldt squid bycatch will be presented.