A review of toothfish conversion factor data submitted by vessels and scientific observers, and implications for estimation of total catch

Conversion factors are an essential parameter used in estimating landed greenweight from the processed product weight of fish on a vessel. Comparisons of observer- and vessel- reported conversion factors for toothfish using the most common processing type by fishery area from 2016 through 2021 showed that observer reported values were more variable and typically higher than vessel reported values. Because product weights associated with each product code in a haul are not reported, the ability to compare greenweight estimated using either the vessel- or the observer- reported CFs is limited. An analogy method was used (and its caveats highlighted) to indicating that that in most cases estimated greenweight would be less than 4% higher when using the observer-reported CFs. Recommendations for consideration focus on standardizing CF calculation and application procedures.