Document Type

Data Set

Publication Date

2018

Keywords

Predator, white sharks, sharks, seals, sevengill sharks, behavioral ecology, trophic cascades, predation risk, competition, predator-prey interactions

DOI

10.17604/QCYH-P363

Abstract

This dataset is associated to the article “Disappearance of white sharks leads to the novel emergence of an allopatric apex predator, the sevengill shark” by Hammerschlag et al. (2018), published in Nature Scientific Reports, DOI: 10.1038/s41598-018-37576-6. Specifically, these are the data used to create figures 3,4, and 5 as well as supplementary figures S1, S2, and S3. These data are the results of monitoring between 2000 and 2018 of white shark (Carcharodon carcharias) abundance patterns (N=6,333 shark sightings) and predatory activity (N=8,076 attacks on seals) at Seal Island, a Cape fur seal (Arctocephalus pusillus pusillus) colony in False Bay, South Africa. All data are based on standardized boat-based observations. Over the 18-year study, declines in white shark abundance and attack rates were documented between 2015-2018, with anomalous lows occurring in 2017 and 2018. This included prolonged periods of white shark absence from Seal Island. The disappearance of white sharks from Seal Island coincided with the appearance of sevengill sharks (Notorynchus cepedianus; N=120 sightings), an otherwise allopatric kelp-associated apex predator in False Bay. These data provide empirical evidence for behavioral shifts in sevengill sharks following the decline and disappearance of white sharks from a foraging site.

Comments

This dataset contains 9 .csv files which are the data used to create figures 3, 4, and 5, as well as supplementary figures S1, S2, and S3 in Hammerschlag et al. (2019, DOI: 10.1038/s41598-018-37576-6). The .csv file names correspond with the respective paper figures. Data in Figure_5.csv are the number of different white sharks and sevengill sharks sighted per hour for 211 consecutive field days occurring between 1 August 2016 and 4 August 2018. Data in all other .csv files are annual means and standard errors of either white shark predation rates, white shark relative abundance, sevengill shark relative abundance, or temperature between 2000 and 2018.

Description

The zip file contains:

• Figure_3.csv (mean ± standard error of annual white shark predations per hour on cape fur seals between February and September)

• Figure_4_White_Sharks.csv (mean ± standard error of annual white sharks sighted per hour between February and September)

• Figure_4_Sevengill_Sharks.csv (mean ± standard error of annual sevengill sharks sighted per hour between February and September)

• Figure_5.csv (number of white and sevengill sharks sighted per hour between 1 August 2016 and 4 August 2018)

• SupplimentaryFigure_S1.csv (mean ± standard error of annual white shark predations per hour on cape fur seals between May and September)

• SupplimentaryFigure_S2_White_Sharks.csv (mean ± standard error of annual white sharks sighted per hour between May and September)

• SupplimentaryFigure_S2_Sevengill_Sharks.csv (mean ± standard error of annual sevengill sharks sighted per hour between May and September)

• SupplimentaryFigure_S3_Temperature_February-September.csv (mean ± standard error of annual temperatures measured at Seal Island between February and September)

• SupplimentaryFigure_S3_Temperature_May-September.csv (mean ± standard error of annual temperatures measured at Seal Island between May and September)

License

This data is made available under the Open Data Commons Attribution License: http://opendatacommons.org/licenses/by/.

Share

COinS