Historical distribution of right whales in the North Pacific

Abstract

Fisheries records provide some of the only information on pre‐fishing distribution and abundance for species that were depleted before the advent of modern scientific investigations. This paper interprets records of the early history of whaling for North Pacific right whales (Eubalaena pacifica). The current population occupies only a fraction of its historical range. Historical distributions of several whale species have been inferred from charts prepared by Matthew Fontaine Maury in the early 1850s and Charles Haskins Townsend in the 1930s based on data from American whalers’ logbooks. In the North Pacific, Maury’s chart has been interpreted to show that right whales occurred continuously across the entire basin. However, we find plotting errors when we compare the North Pacific chart to the corresponding data worksheets prepared for Maury (the ‘Maury Abstracts’) and the chart appears to have misled historians and biologists. Although these charts and those in the North Atlantic are wrong, the Maury Abstracts themselves appear largely consistent with the original whaler logbooks. Our analysis shows that right whales were likely not distributed continuously across the North Pacific, but instead had a pronounced longitudinally bimodal distribution and were encountered infrequently in the central‐northern North Pacific. This work shows how valuable information can be obtained by examining original source material. The American whaling logbooks are extensive and have been largely overlooked in studies of whale populations.

Insights into North Pacific right whale Eubalaena japonica habitat from historic whaling records

“…Finally, I investigated how the predictions for the western subpopulation responded to the removal of potentially biasing records (i.e. right whale records from the northern Sea of Okhotsk likely represent bowhead whales [Josephson et al 2008b], while it is unclear whether the Sea of Japan represents a foraging ground, or simply a migratory corridor [Brownell et al 2001]). In total, I built 8 annual and 14 seasonal models by systematically modifying the temporal resolution and spatial extents of the data used.…”

“…Additionally, the Pacific Decadal Oscillation, which has a strong influence on weather patterns in the North Pacific, was actually in a cooler phase from 1950 to 1976 than during the right whale whaling era (Biondi et al 2001). Finally, whaling occurred in the Bering Sea in summer throughout the 1840s (Josephson et al 2008b), and accounts from Arctic logbooks contain no indication of unusually cold conditions (Wood & Overland 2003). Thus, while an overall warming trend in air temperature is evident in the region (Moore et al 2002), there is little to suggest that the ocean climate in the North Pacific during the mid19th century was in any way dramatically different from the 20th century.…”

“…whales were hunted when encountered), any bias will be towards preferred whale habitat, making the resulting model predictions conservative rather than inaccurate. Despite potential transcription errors from original sources (Josephson et al 2008b), such data represent valuable information on the historic distribution of exploited species. The data removal experiments conducted here showed how the removal of potentially unreliable data can improve model performance and thus provide one approach to exploring questions of correct transcription.…”

Estimating North Pacific right whale Eubalaena japonica density using passive acoustic cue counting

“…North Pacific right whales are among the most endangered whale species on earth, and there remain huge gaps in our knowledge of basic biological information about them, including the location of wintering grounds and population structure. Historic and recent observations support the division of North Pacific right whales into an eastern and a western stock , Clapham et al 2004, and a recent reexamination of data from whaling logbooks corroborates a bimodal distribution of right whales, with very few sightings in the central North Pacific (Josephson et al 2008). Omura (1958Omura ( , 1986 suggested that the western stock be further divided into 2 subpopulations, one migrating within the Sea of Japan and summering in the Sea of Okhotsk, and another migrating along the Pacific coasts of Japan and the Kamchatka peninsula, with some animals entering the Bering Sea by early summer.…”

Recent observations of critically endangered North Pacific right whales (Eubalaena japonica) off the west coast of Canada

“…Once common in many areas of the North Pacific and Bering Sea, the species was severely depleted by intensive whaling in the mid 19th century (Brownell et al 2001;Scarff 2001;Josephson et al 2008). Although numbers may have been increasing by the mid 20th century following international protection in 1935 (Brownell et al 2001), large illegal and unreported catches by Soviet whalers in the 1960s likely reversed any nascent recovery and the species remains endangered today (Ivashchenko and Clapham 2012).…”