Estimating minke whale relative abundance in the North Atlantic using passive acoustic sensors

Abstract

Estimates of abundance and their changes through time are key elements of marine mammal conservation and management. Absolute marine mammal abundance in a region of the open ocean is often difficult to attain. However, methods of estimating their abundance based on passive acoustic recordings are becoming increasingly employed. This study shows that passive acoustic monitoring of North Atlantic minke whales with a single hydrophone provides sufficient information to estimate relative population abundance. An automated detector was developed for minke whale pulse trains and an approach for converting its output into a relative abundance index is proposed by accounting for detectability as well as false positives and negatives. To demonstrate this technique, a 2 y dataset from the seven sites of the Atlantic Deepwater Ecosystem Observatory Network project on the U.S. east coast was analyzed. Resulting relative abundance indices confirm pulse train-calling minke whale presence in the deep waters of the outer continental shelf. The minkes are present December through April annually with the highest abundance near the site offshore of Savannah, Georgia.

Cetacean acoustic occurrence on theUSAtlantic Outer Continental Shelf from 2017 to 2020

“…Future survey programs must engage in long-term, sustainable, year-round monitoring with consistent data ensured for years to come (e.g., Van Parijs et al, 2009. This study and its predecessors have proven the capability of PAM to be informative, and emerging work on density estimation from PAM (e.g., Kiehbadroudinezhad et al, 2021) will prove extremely useful in assessing population trends.…”

“…Ongoing monitoring of this region in conjunction with changes to the Gulf Stream (e.g., due to climactic shifts) is critical to understanding distribution trends for this species over time. A more detailed look at minke whale occurrence and relative abundance based on the ADEON data is described in Kiehbadroudinezhad et al (2021).…”

Estimating Florida manatee (Trichechus manatus latirostris) abundance using passive acoustic methods

“…Of particular importance is the ability to translate acoustic detections into distribution, abundance, and density information. Such methods of using PAM to estimate population information have been demonstrated in many other marine species including numerous species of cetaceans and pinnipeds (Baumgartner et al, 2019;Kiehbadroudinezhad et al, 2021;MacIntyre et al, 2013;Marques et al, 2011;Marques et al, 2013;Mellinger et al, 2007). Widespread application of PAM methods for manatee species would be particularly beneficial for data deficient species like the African (Trichechus senegalensis) and Amazonian (Trichechus inunguis) manatees, for which there are large geographic areas with little to no information available (Keith Diagne, 2015;Marmontel et al, 2016).…”