Expert elicitation of seasonal abundance of North Atlantic right whales Eubalaena glacialis in the mid-Atlantic

Abstract

North Atlantic right whales Eubalaena glacialis are among the most endangered of the large whales. Although protected since 1935, their abundance has remained low. Right whales occupy the Atlantic Ocean from southern Greenland and the Gulf of St. Lawrence south to Florida. The highly industrialized mid-Atlantic region is part of the right whales' migratory corridor, and gaps in knowledge of their movements through this region have limited the ability to make informed decisions about management of the species. To help fill these gaps, we elicited estimates of the relative abundance of adult right whales in the mid-Atlantic during 4 months (each month representing each season) from 10 experts on right whale ecology and management. We elicited the minimum, maximum, and mode as the number of individuals in a hypothetical population of 100 right whales, and confidence estimates as percentages. For each month−sex combination, we merged the 10 experts' answers into 1 distribution. The estimated modes of relative abundances of both sexes were highest in January and April (females: 29 and 59; males: 22 and 23) and lowest in July and October (females: 5 and 9; males: 3 and 5). In some cases, our elicitation results were consistent with the results of studies based on sightings data. However, these studies generally did not adjust for sampling effort, which was low and likely variable. Our results supplement the results of these studies and will increase the accuracy of priors in complementary Bayesian models of right whale abundances and movements through the mid-Atlantic.

North Atlantic right whale Eubalaena glacialis occurrence in offshore wind energy areas near Massachusetts and Rhode Island, USA

“…In this study, concurrent acoustic monitoring by the Cornell University Lab of Ornithology revealed a longer period of occurrence than the shorter seasonal period that was detected by aerial surveys . Re cent studies of E. glacialis distribution in coastal areas that used a combination of acoustic and visual assessment techniques found that aerial surveys were useful for estimating abundance and identifying individuals, but that acoustic monitoring detected occurrence over longer periods of time (Whitt et al 2013, Hodge et al 2015, Oedekoven et al 2015.…”

Understanding the population consequences of disturbance

“…This has been referred to as an interim PCoD approach (King et al, 2015) because this function should be replaced with one based on empirically derived values as soon as they become available. In some of these cases, structured elicitation of information from multiple experts (known as expert elicitation) can provide both estimates of the appropriate parameters and a measure of the associated uncertainty (King et al, 2015;Martin et al, 2012;Oedekoven, Fleishman, Hamilton, Clark, & Schick, 2015). In alternative, the measured effect of changes in prey availability can be used as a proxy for the relation between energy intake and vital rates (Williams, Thomas, Ashe, Clark, & Hammond, 2016).…”

Evaluating elicited judgments of turtle captures for data‐limited fisheries management

“…Related to the small sample size, sample selection bias could also impact the results. Overestimation has been observed when gathering data from both small‐scale fishers (O'Donnell, Pajaro, & Vincent, ) and scientific experts (Burgman et al, ; Oedekoven, Fleishman, Hamilton, Clark, & Schick, ). While the four‐step elicitation method we employed is more likely to reduce overconfidence than three‐point procedures (Speirs‐Bridge et al, ), it is possible that an overconfident attitude towards risk influenced several of our fishers’ judgments (Figure ).…”