Monitoring the diurnal and seasonal foraging of Hawaiian monk seals in mesophotic rubble habitat using seafloor event loggers called "electric rocks."

Video from seal-mounted cameras fitted to Hawaiian monk seals showed that seals visited patches of loose mesophotic seafloor rock to flip them and obtain the prey hiding underneath. Diver surveys of rock patches documented 38 species of fish and invertebrates and found 38% of the larger diameter rocks (10-100 cm) flipped with the encrusted live coral and algae side left face down. We developed a set of "electric rocks" (artificial rocks fitted with event loggers) to record the date and time of any movement. We deployed the rocks in multiple clusters on the terraced slope of the seal colony atoll (French Frigate Shoals) close to the beach haulout and at two sites further away on the summits of neighboring banks. The goal was to expand temporal monitoring (diurnally and seasonally) of the seal's use of mesophotic rubble patches without requiring further instrumentation of monk seals. The data from the electric rocks showed patterns consistent with the behavior seen from the seal-mounted video, including rapid rock-to-rock searching and more movements closer to seal haulouts. The electric rocks detected more rock tips on the atoll terrace than on the banks, with higher counts seen during the day at the bank summits. Seasonally, both the terrace and bank detected more movements in summer and fall months consistent with the monk seal's reproductive pupping and molting season than during the rest of the year, suggesting some seasonal change in the foraging habitat of monk seals.

Abstract above is from the Journal Endangered Species Research publication on the topic. This metadata includes sub files that hold the different types of data used in the publication (observations from Seal-mounted video data, diver surveys of the mesophotic habitat and fish community and the raw data from the event loggers in the form of electric rocks.

One of the files included in the associated data is a word document with the online supplemental materials that the article directed readers to refer to.

Parrish F.A., Boland R.C., Sawyer M., Greene B., Buhleier B., Marshall G., (2023).

Monitoring the diurnal and seasonal foraging of Hawaiian monk seals in mesophotic rubble habitat using seafloor event loggers called “electric rocks.” Endangered Species Research 51:293-303 https://doi.org/10.3354/esr01259

Data collected for the three years study as a pilot project and then discontinued

The data are contained in 5 excel files and are accompanied with a READ ME word document that defines the data fields in each of the files and provides Lat Long position for the location of the diver surveys and deployment of the electric rock data loggers . The 5 files are

-1999 survey of fish at individual rocks

-Crittercam data for JUST SEGMENTS with TALUS

-Mesophotic transect fish data

-Mesophotic 1999 rock survey

-Electric rock data

READ ME data code sheet for Parrish et al.docx

While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

The area of the work include the mesophotic depths of the French Frigate Shoals outside the north Barrier near Trig Island out to summits of South east Brooks and Middle Brooks. The depth range is between 30-80 meters

NA

NA

Open

Download

NA

NA

NA

NA

Excel CSV files

Once the CDIP wave buoy data was used to identify the days the wave period (>11 sec) had the potential to move the rocks and those days were dropped from the analysis the movements recorded were consistent with the rock movement seen on the seal-mounted crittercam video

Other than patterns consistent with observations from the seal-mounted video the

movement of the electric rock are inferred to be from monk seals as that is the only known animal that searches large rocks in the region.

NA

Project shelved in 2003 due to redirection of emphasis. Pandemic in 2019-2022 prompted the downloading of the data loggers and subsequent analysis.

Data on seal rock flipping behavior from the Crittercam relational database from annotated video from cameras deployed by PIFSC on French Frigate Shoals Monk Seals.

Data on mean hourly wave energy (ht and period) from the CDIP Waimea buoy on the North Shore of Oahu