Research Document - 2001/132

Assessment of Lingcod in the Strait of Georgia

By King, J.R.

Abstract

This working paper examines recreational fishing information, nest density survey results and biological data for lingcod within the Strait of Georgia. Annual catch estimates (pieces) from the Strait of Georgia creel survey program are updated from 1999. Biological data on the length (cm) of lingcod retained by recreational fishers is updated from 1994. Mean lengths and a weight-length relationship is used to convert estimated catch in pieces to estimated catch in tonnes. Recreational catch per unit (CPUE) indices are presented as a relative measure of lingcod abundance trends. In 2001, a nest density SCUBA survey was conducted on Snake Island in Minor Statistical Area 17 and the results are compared to 1990, 1991 and 1994 results. Biological data on nest guarding males and egg mass volume were collected during the 1990 and 2001. The Vancouver Aquarium Marine Science Center conducts an annual egg mass count survey in Howe Sound (Minor Statistical Area 28) and their analyses and results are provided for 1994-2001.

The recreational CPUE index has remained fairly constant from 1982-2000. There have been slight decreases and increases (e.g. decrease 1985-1995) however these are non-significant. Since 1990, there is evidence of two above average year classes (1995 and 1999 or 2000) and following these, increases in the abundance of juvenile lingcod, however there is a lack of evidence for an increase in the abundance of large, adult lingcod. These year classes are above average only compared to very poor year classes in the 1990s. It is important to note, that in some areas the size of landed lingcod in the recreational fishery is below the 65 cm size limit. There is some slight indication that the spawning population has increased, but the evidence is not overwhelming. The size of nest guarding males was not significantly larger in 2001 than in 1990.

Since the closure of the commercial fishery in 1990, lingcod abundance appears to have remained at very low and stable levels. Presently, there is no indication that overall lingcod population abundance has continued to decline nor rebuilt to levels similar to pre-collapse of the commercial fishery. In order to foster an increase in lingcod abundance, commercial fishing should remain closed and recreational closures should be implemented.

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