Research Document - 2005/049

An Update on Harp Seal (Pagophilus groenlandicus) By-Catch Estimates in the Newfoundland Lumpfish Fishery

By Sjare, B., D. Walsh, G.B. Stenson, and S. Benjamins

Abstract

By-catch of marine mammals in fishing gear occurs throughout the world’s oceans and is a major conservation concern. While entrapment of cetaceans is increasingly well documented, less effort has gone into quantifying the by-catch of seals. This is certainly the case in Newfoundland waters where catch rates for many of these species are thought to be under-reported. This research provides estimates of the number of harp seals taken annually as by-catch in the Newfoundland lumpfish gill net fishery from 1970 to 2003. Data were obtained from a By-catch Monitoring Program that required lumpfish fishermen around the coast of Newfoundland to record fishing effort (roe landings) and the number of seals caught on a daily basis from 1989 to 2003. Prior to 1989, annual seal by-catches were estimated using historic roe landings and pooled by-catch levels based on the fishermen’s logbook data from 1989 to 1991. From the beginning of the lumpfish roe fishery in 1970 until 1985, the by-catch of harp seals remained below 5,000 animals. In 1987 catches increased to a high of about 13,100 seals and then declined to approximately 3,600 animals in 1990. The peak by-catch for the time series was 46,394 seals in 1994; catch levels remained higher than 18,000 animals until 1997. In more recent years annual catches declined and became increasingly variable. In 2002 and 2003 there was a major down-turn in the fishery and seal by-catch levels dropped to below 10,000 animals. These estimates of annual by-catch vary depending on several key assumptions; however, they do provide a long-term view of by-catch as a source of mortality for harp seals and can be used for population modeling initiatives.

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