Decadal acoustic monitoring of toothed whales in the Gulf of Mexico post-oil spill

Shortly after the Deepwater Horizon oil spill began in April 2010, a widely spaced passive acoustic monitoring array was deployed in the northeastern Gulf of Mexico to document the impacts of this unprecedentedly large and deep offshore oil spill on oceanic marine mammals. The array was subsequently maintained for over a decade. Here we document decadal density declines for seven of eight monitored species groups, including sperm whales (up to 31%), beaked whales (up to 83%), and small delphinids (up to 43%). Declines were observed both within and outside of the surface oil footprint. Though not conclusively linked to the oil spill, the broad spatial and temporal scale of these declines observed for disparate marine mammal species is consistent with Deepwater Horizon impacts. These declines have exceeded and outlasted post-spill damage assessment predictions, suggesting that the offshore ecosystem impacts of Deepwater Horizon may have been larger than previously thought.,
Passive acoustic recordings were collected using High-frequency Acoustic Recording Packages (HARPs) at five monitoring stations between May 2010 and March 2020 (Table S1). The total recording duration across the five sites amounted to 37 instrument-years of continuous data sampled at 200 kHz. Sites include three deep sites and two shallow shelf sites that monitor primarily shallow water species.
Echolocation clicks and other impulsive signals from odontocete species were detected using an impulse detector and then classified into species groups based on spectral characteristics and inter-click intervals. Automated detection and semi-supervised clustering techniques identified signals from target species, allowing for group-based density estimation of each species across time. Processing steps included high-pass filtering, calibration of hydrophones, and applying a neural network classifier to attribute signal identities. Acoustic presence data were converted into local density estimate..., , # **Decadal acoustic monitoring of toothed whales in the Gulf of Mexico post-oil spill**

[https://doi.org/10.5061/dryad.9zw3r22n4](https://doi.org/10.5061/dryad.9zw3r22n4)

## Dataset Overview

This dataset supports the study of long-term changes in toothed whale densities in the Gulf of Mexico following the Deepwater Horizon oil spill, spanning 2010–2020. It contains passive acoustic detection records from five monitoring sites across various depths and regions, categorized by species and location.

* **Objective**: To provide high-resolution, time-series data on the presence and density of multiple odontocete species in the northeastern Gulf of Mexico.
* **Monitoring Sites**: Five locations with varied distances from the Deepwater Horizon spill site, including both deep and shallow water environments.
* **Species Monitored**: The dataset includes detection events for a range of species, such as sperm whales (*Physeter macrocephalus*), beaked whales (*Ziphius cavirostris*), and delphi..., , **Changes after Nov 19, 2024:** 

An error in the label variable has been fixed to reflect the full range of species codes in the ID files. This error was introduced while simplifying the data files for the original Dryad submission.