Herring stock estimates from diving surveys of spawn for Georgia Strait in 1986 / by J.F. Schweigert and C.W. Haegele.: Fs97-4/1971E-PDF

"Using the results of diving surveys of spawn, we estimated that 60,212 tonnes of herring spawned in Georgia Strait in 1986. In Area 14, 51,092 tonnes were estimated to have spawned on Denman and Hornby islands and along the Vancouver Island shoreline from below Deep Bay to below Little Qualicum River. In Area 15, 1141 tonnes were estimated to have spawned on Harwood and Savary islands. An estimated 7934 tonnes spawned in Area 17: 152 tonnes in Nanoose Bay, 332 tonnes at Icarus Point, 105 tonnes at Sharpe Point and 7344 tonnes along the Vancouver Island shoreline from above Boat Harbour to Coffin Point. Only 46 tonnes were estimated to have spawned in Area 18. All major spawns were surveyed by divers and surface survey results were used to estimate the spawning biomass for the minor spawns. Estimates of egg density from a predictive model based on sample weight and egg layers were uniformly low in 1986 relative to earlier years. Model predictions have generally been fairly accurate for Georgia Strait spawns and the low estimates for this year appear to result from low estimates of egg layers on the various vegetation substrates. The spawns were wider and on more gently sloping beaches in Area 14 than in Area 17. Most of the spawn was deposited between 1 m above to 3 m below chart datum. Egg density declined with depth in Area 14 but not Area 17. Sea grasses and the brown algae, Sargassum muticum, were the most common vegetation type for egg deposition in Area 17, while rockweed and filamentous red algae were more commonly used in Area 14"--Abstract, page iv.

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