Herring stock estimate from a diving survey of spawn in Barkley Sound in 1982, with comparisons to other estimates / by C.W. Haegele and J.F. Schweigert. : Fs97-4/1798E-PDF

"Divers surveyed and sampled herring spawns in Barkley Sound on the west coast of Vancouver Island, B.C. in 1982 to determine the distribution of spawn and to estimate the biomass of herring and compare the results to other estimates. Although spawn was deposited to 14 m below Chart Datum, only 10% of spawn was lower than 4 m below Chart Datum. The diving survey estimated 23,500 tonnes of herring in Barkley Sound, of which 14,300 tonnes spawned in a first wave, 5500 tonnes spawned in a second wave, and 3600 tonnes were caught in fisheries between the two waves. Estimates from population models ranged from 7352 to 25,838 tonnes, depending on which assumptions were used. Generally they underestimated stocks, probably because Fishery Officer spawn survey data, used in all the models, considerably underestimated the area of spawn. Hydroacoustic estimates of biomass were slightly lower and echosounder estimates missed completely the build-up of stocks prior to spawning"--Abstract, page iii.

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