Commercial
Sardines compared to a quarter
Sardines compared to a quarter
A pair of sardine otoliths next to a penny
A pair of sardine otoliths next to a penny

Purse Seine Fishery for Pacific Sardine

Sardine Biology

AGING SARDINE

Reading sardine otoliths is the simplest and most reliable method for aging sardine. Scales and vertebrae can also be used but they are not as accurate as otoliths. Otoliths are found in pairs in the top of the head of a sardine just under the skull cap. Determining sardine age is similar to counting the rings in a tree. Age readers magnify the otoliths until they can count the rings, or annuli, and determine the age of the sardine.

Otoliths, which measure about 1.5-3.0 mm in length, are extracted and sent to the WDFW laboratory in Olympia, Washington, for age reading. Catch date, vessel name, sardine length (mm), weight (g), sex, and maturity are also recorded and sent along with the otoliths.

Although sardine can live up to 15 years the majority of commercially harvested sardine are three to five years old.

Washington Department of Fish and Wildlife (WDFW) staff coordinate the collection of biological sampling with Oregon Department of Fish and Wildlife staff to ensure sample coverage is evenly distributed throughout the Northwest fishery.

Sardine otolith location and size

Age distribution of sardine samples, 2009-2013. The current year, 2013, is depicted by the line; previous years are depicted as bars.
Age distribution of sardine samples, 2009-2013.
The current year, 2013, is depicted by the line; previous years are depicted as bars
.
Pie charts of age compostition of sardines sampled in 2012 and 2013.
Age composition of sardine sampled in 2012 and 2013

LENGTH AND WEIGHT

Sardine size varies from year to year depending on the current year class of sardine. Sardine caught in Washington’s seine fishery ranges in size from 100 mm to 300 mm although the average length of sardine in Washington’s fishery is typically 175-225 mm. The weight of sardine in Washington’s fishery can be as small as 80 grams and as large as 300 grams but the average weight of sardine in our fishery is 150-175 grams.

Chart of sardine length by year. Legend for sardine charts.
Chart of sardine weight by year.