Echo integration-trawl survey of Pacific hake, Merluccius productus, off the Pacific coast of the United States and Canada during July-August, 1998.

Abstract

Results are presented for the eighth triennial echo integration-trawl (EIT) survey of Pacific hake, Merluccius productus, along the west coasts of the United States and Canada during the summer 1998. Scientists from the United States and Canada conducted the joint survey aboard two research vessels. The increased Canadian effort during this coastwide survey occurred because of an anticipated northward displacement and possible expansion of the Pacific hake distribution in response to the strong 1997-98 El Niño conditions. Results from an intership calibration of the acoustic systems aboard each country's vessel are also reported.

The total area surveyed, based on the efforts of both countries, was greater than any previous EIT survey. The U.S. survey was conducted from 6 July to 27 August 1998, and extended along the Pacific coast from Monterey, California (37°N), to Queen Charlotte Sound, British Columbia (51°N). The Canadian survey was conducted from 4 to 24 August, 1998, and covered the area beginning at the northern limit of the U.S. survey and progressed northward to Cape Spencer (58°N), then southward through Dixon Entrance, Hecate Strait, and Queen Charlotte Sound.

Aggregations of Pacific hake were detected throughout the study area. The heaviest Pacific hake echo sign observed from the U.S. vessel occurred off south-central Oregon between about 42-44°N, near the U.S. (Washington)-Canada border, and along the continental shelf break in Queen Charlotte Sound. Canadian survey results documented concentrations along the central portions of the west coasts of the Queen Charlotte and Chichagof Islands, near the entrance to Dixon Entrance, in northern sections of Hecate Strait, and throughout Queen Charlotte Sound. Trends in size composition for Pacific hake exhibited a latitudinal cline over the study area, with larger fish generally more abundant in the northern areas. Overall, 68% of the population was composed of the 1993-96 year classes. The coastwide estimate of Pacific hake was 2.6 billion fish weighing 1.19 million metric tons (t), which represents a decrease of about 14% from the 1995 estimate of 1.39 million t.


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