Urban Humpback Whales: Seasonal sightings, distribution, and residency in the western New York Bight

Methods

Summary

Fluke and dorsal fin photographs will be evaluated based on photographic quality using criteria defined by Friday, et al. including clarity, contrast, angle, half, and partial, and overall quality. Each photograph will be given a ranking between one and five (Friday, et al 2000). Only photographs of grades one and two will be used for identification. Photo analysis will involve identifying any unique markings including natural and anthropogenic scars, dorsal fin damage or deformities, and the shape of peduncle knobs. The best photo of each of the flukes, and both sides of the dorsal will be selected for comparison to the existing New York Humpback Whale Catalog managed by Gotham Whale. A team of 2-4 people will determine whether a photographed whale matches any previously catalogued individuals. Photos of previously identified whales will be entered into the catalog with the date and location of where the individual was sighted. If it has been determined that a new individual has been photographed, all three photos will be entered into the catalog with a unique identification number. All photographs taken during the field season will be compared to regional and basin-wide catalogs in the North Atlantic and Mid-Atlantic in order to determine long-term movements of individuals

In order to ascertain whether humpback whale sighting rates have increased, sightings during the field season will be compiled and analyzed together with historical humpback whale sighting data recorded by Gotham Whale since 2011. Non-parametric trend analyses will determine sighting and stranding trends over months and years, as well as whether human interaction cases involving humpback whales are increasing. Statistical tests for normality will determine whether humpback whale sightings have a normal temporal distribution. If temporal distribution is determined not to be normal, a rank correlation will be employed to assess the connection with bathymetry and SST data.

All sightings will be digitized into a GIS database using ArcMap (version 10.3). Home ranges will be determined using the Minimum Convex Polygon (MCP) method, utilizing the outermost sighting coordinates. The created polygon layer will be overlaid with SST and bathymetry data in order to identify any potential relationships. To determine site fidelity, the length of time between the first and last sighting of an identified individual within the study period will be considered. This data will be compiled with historic sightings of the same individual in order to ascertain individual residency times.