Demographic and Reproductive Characteristics of New Brunswick River Otter Populations Based on 13 Years of Harvest Data

Posted on May 8, 2017


Roderick Eugene CUMBERLAND and Jean-Michel DeVINK

CWBM 6 (1): 31–41.

Correspondence: R. E. Cumberland, Maritime College of Forest Technology, 1350 Regent Street, Fredericton, New Brunswick, E3C 2G6, Canada.



Long-term biometric datasets for North American river otters (Lontra canadensis) are sparse and few have been analyzed to assess factors influencing harvest rates. We analyzed demographic data from over 6,000 trapper-harvested otter carcasses between 1997 and 2010 from a mandatory carcass submission program. Variations in annual harvest was most influenced (R² = 0.74, P<0.001) by otter pelt value from the previous year. Average age of harvested otter was 2.36 for males and 2.31 for females over the 13-year period; the sex ratio was 1.13 males:1 female, and based on blastocyst counts, pregnancy rates were estimated to be 41% for females aged yearling and older. Pregnancy rate for ≥2.5-year-old otters was 55%, and litter size was 1.75 based on blastocyst counts. Over 15% of yearling females carried an average of 1.67 blastocysts and contributed 12% to the overall productivity. This is a greater contribution to productivity by yearling females than previously reported in scientific literature, and it should be considered in otter population models and harvest management strategies. We note existing disparities in approaches to otter data collection and suggest that managers and researchers use standardized methods for carcass analysis. In addition, otter harvest managers should consider previous year’s otter pelt value when predicting potential harvest of otter populations.

Key Words: Harvest Management, Lontra canadensis, New Brunswick, Reproduction, River Otters.



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