Estimates of the Abundance of Cetaceans in the Central North Atlantic based on the NASS Icelandic and Faroese Shipboard Surveys Conducted in 2015

Daniel G Pike,Sverrir D Halldórsson,Bjarni Mikkelsen,Gísli Víkingsson,Thorvaldur Gunnlaugsson

doi:10.7557/3.4941

Daniel G Pike, Sverrir D Halldórsson + Show 3 more

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https://doi.org/10.7557/3.4941

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Abstract

The North Atlantic Sightings Survey (NASS), the sixth in a series of surveys conducted between 1987 and 2015, was conducted in June/July 2015 and covered a large area of the northern North Atlantic. The Icelandic and Faroese ship survey component of the NASS covered the area between the Faroe Islands and East Greenland from latitude 52° to 72° N. The survey used 3 vessels and an independent double-platform configuration with each platform staffed by a minimum of 2 observers. Here we present both uncorrected abundance estimates derived using Multiple Covariates Distance Sampling, and corrected abundance estimates derived using Mark-Recapture Distance Sampling, for the following species: fin (Balaenoptera physalus), common minke (B. acutorstrata), humpback (Megaptera novaeangliae), blue (B. musculus), sei (B. borealis), sperm (Physeter macrocephalus), long-finned pilot (Globicephala melas) and northern bottlenose (Hyperoodon ampullatus) whales as well as white-beaked (Lagenorhynchus albirostris) and white-sided (L. acutus) dolphins. We then compare these estimates to those from previous NASS and put them into context with estimates from adjoining areas of the North Atlantic.

Highlights

The North Atlantic Sightings Survey (NASS) was conducted in June/July 2015 and covered a large area of the northern North Atlantic (Figure 1)
Abundance estimates for the above species other than Lagenorhynchus spp. dolphins have been published for most surveys prior to 2007
Best fit of the conditional detection function was realized with a covariate for perpendicular distance, resulting in an estimated average p(0) of 0.83 (CV=0.17) and a total estimated abundance of 3,767 (CV=0.54, 95% CI 1,156 – 12,270) (Supplementary file 5)

Summary

INTRODUCTION

The North Atlantic Sightings Survey (NASS) was conducted in June/July 2015 and covered a large area of the northern North Atlantic (Figure 1). Estimates of the Abundance of Cetaceans in the Central North Atlantic Based on the NASS Icelandic and Faroese Shipboard Surveys Conducted in 2015. The general pattern of whaling operations has in the past been the initial exploitation of an area with high catches, followed by the rapid depletion of stocks leading to an eventual cessation of commercial operations as they became unprofitable (Ingebrigtsen, 1929) This pattern is well illustrated by the example of the North Atlantic humpback whale. We present design-based abundance estimates for fin, common minke, humpback, blue, sei, sperm, long-finned pilot and northern bottlenose whales as well as white-beaked and white-sided dolphins from the Icelandic and Faroese components of the NASS-2015 ship survey.

MATERIALS AND METHODS

RESULTS

DISCUSSION AND CONCLUSIONS