This week, scientists from NOAA Fisheries’ Northwest Fisheries Science Center are heading to sea aboard the NOAA Ship Bell M. Shimada to collect data to estimate the biomass of the commercially-valuable fish species, Pacific hake (Merluccius productus). These data will be used by stock assessors to recommend catch limits for the commercial fishery for hake that occurs in U.S. and Canadian waters.
NWFSC has conducted this acoustic-trawl survey since 2003. The methods have remained relatively consistent since then: the acoustic echosounders are used to identify potential hake aggregations and a large trawl net is used to identify fish species and collect biological information (e.g. age, sex, diet). The two data types are combined to generate estimates of distribution and abundance by age.
This summer, the path of the Bell M. Shimada will be duplicated by four unmanned surface vehicles that will be launched by Saildrone, Inc. This effort will allow scientists to compare and evaluate the data collected by the Saildrones with the stock assessment needs of the survey.
Researchers will also use another new tool, environmental DNA (eDNA), during the survey. Water samples will be analyzed to identify the presence and abundance of hake. By comparing the standard hake survey results with the eDNA samples, scientists can determine if eDNA is a reliable tool to provide accurate estimates of Pacific hake distribution and biomass.
A second survey of smaller coastal forage fish will be conducted by Southwest Fisheries Science Center scientists onboard the NOAA Ship Reuben Lasker. Two Saildrone surface autonomous vehicles will be paired with the Lasker, one will sample inshore in water depths to shallow for the Lasker to operate safely and the other will sample offshore, extending the data collection up to 200 nautical miles offshore from the coast.
The use of these two vehicles will help improve the precision of the biomass estimates of these fish that are an important food source for the seabirds, marine mammals and fish that inhabit the California Current ecosystem. The use of the data collected by the Saildrones and eDNA can add to, and help scientists make better use of, the traditional data collected by the ship, potentially increasing the accuracy of stock estimates by NOAA Fisheries and leading to better management of Pacific hake and coastal pelagic species.
