Use of Otoliths in Identifying Herring Stocks in the Southern Gulf of St. Lawrence and Adjacent Waters

Abstract

Examination of 1423 herring from various fisheries in the southern Gulf of St. Lawrence and adjacent waters indicates that otoliths can be used as "natural tags" for identifying herring stocks. Two types of otoliths are described: an S-type characterizing spring-spawning herring and an A-type characterizing autumn-spawning herring. Over 97% of herring from spring and autumn fisheries had otoliths of the respective types. There appeared to be sub-divisions within each type.The distinguishing of these otolith types provides evidence that spring- and autumn-spawning herring mix on American Bank and off Shippegan in the Gulf of St. Lawrence and in Chedabucto Bay. The validity of otolith types as criteria for separating herring stocks was supported by comparison with relations of otolith length to fish length and with fin ray counts.