Assessment of bias in population abundance estimates for North Atlantic fin whales (Balaenoptera physalus)
An assessment of the accuracy of population abundance estimates for North Atlantic fin whales (Balaenoptera physalus) was performed based upon a review of North Atlantic Sightings Surveys (NASS) conducted since 2001 and peer reviewed scientific literature concerning the appropriate methodological components of line transect surveys for cetaceans. It is shown that fin whale abundance estimates derived through NASS are likely positively biased. This bias is attributable to observer measurement errors that collectively resulted in an underestimate of duplicate sightings, the effective strip width and the track line detection probability. Other factors relevant to the potential sustainability of fin whale quotas based upon these abundance estimates include the effect of regional fin whale population distribution shifts, genetic analysis of pre-whaling era fin whale population levels and the negative effect of the removal of large numbers of pregnant female fin whales.