Cordell Bank Expedition 2024
Northern West Ridge, Photo © 2024 Robert Lee
Project Overview
This document provides consolidated reports and summary of 2024 Field Activities for the Bay Area Underwater Explorers (BAUE) Cordell Exploration and Monitoring project (jointly conducted in partnership with Lee Oceans Foundation), summarizes key findings and observations, and provides a summary of activities. This work was conducted under NOAA ONMS permit# CBNMS-2023-001, and the full report is available here.
The overall goals for the 2024 season were to support Cordell Bank National Marine Sanctuary(CBNMS) education and outreach with refreshed photo and video documentation of various sites at Cordell Bank, and to capture more macro footage of reef scenes and life for use in CBNMS educational and storytelling programming. In particular, this year we were focused in several specific of areas:
Re-locating Giant Pacific Octopus at NW Ridge to see if this is a consistent location of GPO / GPO den activity
Further documentation of melanistic coloration patterns on the Boccacio
Attempt to document both Blue and Deacon rockfish, as Cordell Bank is right at the range boundary between the species
Further documentation of the nylon fishing gear we have located in the past
Looking for signs of invasive grey tunicates
Looking for signs of other deepwater coral species
While weather conditions in 2024 were not particularly cooperative and resulted in only one day of diving operations, we were nonetheless able to gather further documentation for the education and outreach team, as well as make some very interesting and surprising observations about the reef health which we will work with the sanctuary research team to better understand.
Location and Activity Summary
During the 2024 project season, BAUE/Foundation divers were only able to manage one day of diving operations at Cordell Bank, at NW Ridge. While we attempted to go out again on 10/12, topside weather conditions prevented the boat from reaching the bank, and we were forced to abort the attempt. There were no other divable days throughout the remainder of the weather window (9/15-10/15), and we were forced to transit our vessel ( Escapade ) back to Monterey shortly thereafter.
| Date | Site | Dive Team | Notes |
|---|---|---|---|
| 10/11/24 | NW Ridge | R.Lee, A.Lee | Photo |
| 10/11/22 | NW Ridge | G.Chilcott, Z.Gwirtz | Photo |
Key Observations
Fish Life
NW Ridge continues to be heavily covered in fish life. Consistent with our observations in 2023, most of the schooling fish were juvenile and young-of-year (YOY) rockfish. In particular, we noted juvenile widows and shortbelly rockfish. While there were several larger adult blues/deacons by far the heaviest concentration on the was juveniles and YOY of several species, and a large school of adult widows.
The concentration of fish was apparent before even getting in the water – the sonar was picking up the schools from above, and were thick enough to confuse the vessel’s chartplotter.
The thick school of juveniles was pretty consistently covering the entirety of the top of the site (down to about 130’ or so), and at times extended even deeper (down to about 150’ or so).
Aside from schooling rockfish, we noted the typical concentration of long-lived species such as Yelloweye and Boccacio at NW Ridge. We did not see many Quillback this year - only several individuals at NW Ridge. Perhaps this is reflective of the recent fisheries actions taken in response to sampled quillback population declines.
Absence of Giant Pacific Octopus
We have in the past (2022 and 2023) encountered multiple Giant Pacific Octopus (GPO) individuals at NW Ridge. In 2023, we observed 2 different adult individuals on the same dive. Unfortunately, after conducting a thorough search of the prior years’ dens and surrounding areas, we did not find any signs of GPO this year.Leucistic / aberrantly colored rockfish
Consistent with the 2022 and 2023 project season observations, on multiple dives at NW Ridge, we noted several rockfish with various degrees of a distinct and high-contrast mottled black and white coloration pattern. It is interesting to note that no Blue or Black rockfish exhibiting leucistic color morphs have been observed by BAUE divers during the course of thousands of dives conducted over more than 20 years in the region from Monterey Bay to Pt. Sur. If this phenotype is numerically significant only at Cordell Bank, it could represent a difference in survivorship of this morph at the respective observation areas. Or, perhaps more interestingly, if the Cordell Bank population contains more leucistic individuals than other California locations it may indicate that there is minimal genetic exchange between populations of this species at Cordell Bank and other areas along the northern and central California coastline.
Melanistic Boccacio coloration
In addition, we continue to observe a notable population of the resident Boccaccio rockfish at NW ridge to have pronounced brown spots believed to be lesions. We again located several individuals with the melanistic coloring, including the same individual which we photographed in 2023.
Rockfish Coloration and Lesions
In the same general area of NW Ridge as the Boccacio are normally found, we came across a number of rockfish with strange coloration patterns that appeared to be open lesions on them. It is unclear if these lesions (which were apparent on several individuals) are the result of physical injury/wounds, or some other physiological or infectious cause. We also found several Widow rockfish with the melanistic spots (previously we’ve only seen these on the Boccacio). It is interesting and perhaps worth further study whether the concentration of rockfish in this one small location is indicative of an environmental cause/condition.
White Barnacle Coverage
A significant observation and change from 2023 conditions at NW Ridge was the very heavy reef coverage of white barnacles. The barnacles (assumed to be Balanus sp.) were present but in much smaller quantities in prior years, but in 2024, nearly every reef surface showed some sign of white barnacles. The heaviest coverage was at 150’ depths and shallower, with several areas of reef completely covered in white barnacles (both live as well as unoccupied shells).In several areas, barnacles were noted to have significantly displaced other invertebrate cover, either crowding out species like Corynactis anemones, or growing on top of other invertebrates like the Stylaster hydrocorals.
The sudden increase in white barnacle cover is both very notable and disturbing, and we look forward to working with Sanctuary research staff to better understand the dynamics of this in 2025 and future seasons. It is unknown and unclear if this is a normal cyclical pattern of population boom and bust, or if some environmental, predatory or other factor has resulted in the sudden population change.
It is perhaps worth noting that the greater Monterey Bay area (Monterey, Carmel, Big Sur) has seen several periods where white barnacle populations similarly exploded and displaced significant invertebrate coverage throughout the area. The last such period occurred around (roughly) 2010-2014, and coincided with a period of elevated water temperatures, which has also been associated with the sudden spread of seastar wasting disease, and resulted in a purple urchin population explosion. Eventually, the barnacle population itself died off, perhaps accelerated by several periods of predatory nudibranch (Onchidoris muricata) blooms, leaving behind empty shells, which were eventually displaced by other invertebrates.
It is unclear whether or not the barnacle explosions we have seen in Monterey are correlated with environmental or water conditions, or if there are other factors that lead to an abnormally large recruitment year that takes several years to re-equilibrate.
Surface Observations
The 2024 season was a challenging one with respect to surface weather conditions. For much of the weather window, surface winds, swell and fog made boating and dive operations unmanageable. On our transit to and from Monterey, we passed several humpback whales. We also passed a number of humpbacks on the way to and from the bank on October 11th. During the dive, we could hear very loud and consistent whalesong throughout the dive. Other surface sightings included Mola mola, California sea lions, and Dall’s porpoises. We encountered the majority of the whales about halfway between Bodega Bay and Cordell Bank, unfortunately concentrated around the north-south Vessel Traffic Separation (VTS) lanes. We encountered fewer seabirds than we had in the past (a few albatross, shearwater and murres). We also noted that, consistent with last year, all of the large container ships that we encountered on our transit up and back from Monterey, as well as our project days out to Cordell Bank, were complying with the voluntary vessel speed reduction guidelines (traveling at <10kt).
Data and Documentation
Overall, we collected several hundred still photos (both macro as well as wide-angle). The collected media has been provided to CBNMS staff electronically, and made available for public use.
Project Team
| Team Member | Role |
|---|---|
| Clinton Bauder | Diver, Photo |
| Jim Capwell | Boat Captain |
| Gavin Chilcott | Diver |
| Zach Gwirtz | Diver, Photo |
| John Heimann | Diver |
| Bobby O'Connell | Crew |
| Allison Lee | Diver, Video |
| Rob Lee | Diver, Photo |
| Kevin Schapansky | Diver, Video |
| Ash Whipple | Crew |
