Scar-based Long-term Assessment of Trends in whale Entanglements

Investigators : Leigh G. Torres, Solène Derville, Craig Hayslip, John Calambokidis (CRC), Lindsay Wickman

Background

Reports of whale and other marine life entanglements have been on the rise over the last decade on the US West Coast, with Dungeness crab fishing gear implicated in many cases. State agencies play a critical role in managing this major environmental issue that has implications both for the endangered whale sub-populations that are subject to entanglements, and for the fishing activities, which play an important social, cultural, and economic role for coastal communities.

Current marine life entanglement monitoring primarily relies on opportunistic reports from ocean users. However, entanglements are rare events on the U.S. West Coast, notoriously under-detected and under-reported (Tackaberry et al., 2022). Moreover, entangled large whales are often able to carry the fishing gear for some time away from the initial gearset location, which makes it hard to locate the origin of the gear causing problems (van der Hoop et al., 2017).

Scar-based methods have been used as a proxy to detect undocumented whale entanglement events by several researchers (e.g., Basran et al., 2019; Bradford et al., 2009; George et al., 2017; Knowlton et al., 2012; Robbins, 2012). Photographs of different parts of the whale’s body, particularly the caudal peduncle, are examined for wrapping scars and notches indicating a previous entanglement.

Summary

Building on prior research using scarring patterns from photographs of whales to estimate entanglement rates, the objective of this project is to develop methods to monitor undocumented whale entanglements and the effectiveness of management measures in reducing entanglements off Oregon. We will monitor spatio-temporal changes in humpback whale entanglement rates through scar analysis, mark-recapture modeling, and enhanced community-based science.

Objectives

The SLATE project includes three main tasks:

  • collecting, compiling, and processing photographic data to assess scaring rates
  • engaging with interested fishermen to collect photographs of whales
  • developing a statistical indicator to monitor rates of undocumented entanglement takes in Oregon
Collaborators

Troy Buell and Kelly Corbett (Oregon Department of Fish and Wildlife)

Dr. Scott Baker (Cetacean Conservation and Genomic Laboratory, Marine Mammal Institute)

Dr. Daniel Palacios

Blog & Media

Disentangling the whys of whale entanglement

Announcing our new project: SLATE – Scar-based Long-term Assessment of Trends in whale Entanglements

Funding

Direct congressional Community Project Funding run through NMFS and ODFW

 

Building on prior research using scarring patterns from photographs of whales to estimate entanglement rates, the objective of this project is to develop methods to monitor undocumented whale entanglements and the effectiveness of management measures in reducing entanglements off Oregon. We will monitor spatio-temporal changes in humpback whale entanglement rates through scar analysis, mark-recapture modeling, and enhanced community-based science.

Basran, C. J., Bertulli, C. G., Cecchetti, A., Rasmussen, M. H., Whittaker, M., & Robbins, J. (2019). First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters. Endangered Species Research, 38(February), 67–77. https://doi.org/10.3354/ESR00936

Bradford, A. L., Weller, D. W., Ivashchenko, Y. v., Burdin, A. M., & Brownell, R. L. (2009). Anthropogenic scarring of western gray whales (Eschrichtius robustus). Marine Mammal Science, 25(1), 161–175. https://doi.org/10.1111/j.1748-7692.2008.00253.x

George, J. C., Sheffield, G., Reed, D. J., Tudor, B., Stimmelmayr, R., Person, B. T., Sformo, T., & Suydam, R. (2017). Frequency of injuries from line entanglements, killer whales, and ship strikes on bering-chukchi-beaufort seas bowhead whales. Arctic, 70(1), 37–46. https://doi.org/10.14430/arctic4631

Knowlton, A. R., Hamilton, P. K., Marx, M. K., Pettis, H. M., & Kraus, S. D. (2012). Monitoring North Atlantic right whale Eubalaena glacialis entanglement rates: A 30 yr retrospective. Marine Ecology Progress Series, 466(Kraus 1990), 293–302. https://doi.org/10.3354/meps09923

Robbins, J. (2012). Scar-Based Inference Into Gulf of Maine Humpback Whale Entanglement : 2010 (Issue January). Report to the Northeast Fisheries Science Center National Marine Fisheries Service, EA133F09CN0253 Item 0003AB, Task 3.

Tackaberry, J., Dobson, E., Flynn, K., Cheeseman, T., Calambokidis, J., & Wade, P. R. (2022). Low Resighting Rate of Entangled Humpback Whales Within the California , Oregon , and Washington Region Based on Photo-Identification and Long-Term Life History Data. Frontiers in Marine Science, 8(January), 1–13. https://doi.org/10.3389/fmars.2021.779448

van der Hoop, J., Corkeron, P., & Moore, M. (2017). Entanglement is a costly life-history stage in large whales. Ecology and Evolution, 7(1), 92–106. https://doi.org/10.1002/ece3.2615